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IVF laboratories routinely adopt morphological pronuclear assessment at the zygote stage to identify abnormally fertilized embryos deemed unsuitable for clinical use. In essence, this is a pseudo-genetic test for ploidy motivated by the notion that biparental diploidy is required for normal human life and abnormal ploidy will lead to either failed implantation, miscarriage, or significant pregnancy complications, including molar pregnancy and chorionic carcinoma. Here, we review the literature associated with ploidy assessment of human embryos derived from zygotes displaying a pronuclear configuration other than the canonical two, and the related pregnancy outcome following transfer. We highlight that pronuclear assessment, although associated with aberrant ploidy outcomes, has a low specificity in the prediction of abnormal ploidy status in the developing embryo, while embryos deemed abnormally fertilized can yield healthy pregnancies. Therefore, this universal strategy of pronuclear assessment invariably leads to incorrect classification of over 50% of blastocysts derived from atypically pronucleated zygotes, and the systematic disposal of potentially viable embryos in IVF. To overcome this limitation of current practice, we discuss the new preimplantation genetic testing technologies that enable accurate identification of the ploidy status of preimplantation embryos and suggest a progress from morphology-based checks to molecular fertilization check as the new gold standard. This alternative molecular fertilization checking represents a possible non-incremental and controversy-free improvement to live birth rates in IVF as it adds to the pool of viable embryos available for transfer. This is especially important for the purposes of 'family building' or for poor-prognosis IVF patients where embryo numbers are often limited. [ABSTRACT FROM AUTHOR]

Triploidization influences various biological characteristics of fish, which is associated with reductions in the number of multiple cell types in different tissues/organs. Our behavioral analyses revealed that triploid Pacific bluefin tuna (Thunnus orientalis) larvae exhibit lower sensitivity to light compared to diploids. Furthermore, histological analyses revealed a reduction in the number of ganglion cells and an increase in their size in the retinas of triploid T. orientalis larvae. Our findings provide the first evidence indicating that triploidization reduces sensory perception during the larval stage of fish. [ABSTRACT FROM AUTHOR]

Megalobrama amblycephala, which belongs to the genus Megalobrama of the subfamily Culterinae in the family Cyprinidae, is an important freshwater cultured species in China because of its low culture cost and high growth rate. Culter alburnus, belonging to the subfamily Culter, is another slender carnivorous species, whose meat is more delicate and delicious than that of M. amblycephala; however, the scales of C. alburnus are small and thin and are easily injured and fall off, and these fish are slow-growing and expensive to feed. Although both the fish are quite different in terms of diet, growth, and stress resistance, they are highly complementary to each other. Crossbreeding can combine the desired characteristics of both parents; however, this advantage is usually limited to the F1 generation. Theoretically, because the gonads are almost undeveloped during triploid growth and development, F1 heterosis can be maintained to avoid germplasm decline caused by continuous reproduction, and energy can be saved to accelerate growth and improve muscle quality. This will greatly expand the breeding space of new hybrid varieties and ensure high economic, social, and ecological value. Therefore, the triploids of M. amblycephala ♀ × C. alburnus ♂ have superior growth and economic value. To understand the growth and morphological characteristics of the triploids of M. amblycephala ♀ × C. alburnus ♂, the triploid population of M. amblycephala ♀ × C. alburnu ♂ was induced by hydrostatic pressure, and successfully induced triploid (hybrid-3n) and uninduced diploid (hybrid-2n) populations were obtained. At the same time, two self-breeding populations of Megalobrama (MA) and Culter (CA) were established. The growth performance and morphological characteristics of the four kinds of fish were compared and analyzed in growth contrast experiments. The results showed that during the 210-day growth cycle, the absolute weight gain (0.88±0.11 g/day) of hybrid-3n was 8.64% higher than that of hybrid-2n, 20.55% higher than that of MA, and 120.00% higher than that of CA. In terms of countable traits, the hybrid index of hybrid-3n and hybrid-2n was 41.05 and 36.07, respectively. In terms of measurable traits, the hybrid index of hybrid-3n and hybrid-2n was 36.73 and 57.57, respectively. Cluster analysis showed that hybrid-3n was first grouped with hybrid-2n, then grouped with maternal MA, and finally grouped with paternal CA. The results showed that hybrid-3n and hybrid-2n were closer to their mothers in quantifiable traits and frame structure, showing a maternal effect. Discriminant analysis showed that the discriminant accuracy of hybrid-3n was 90%, and the comprehensive discriminant rate of the four populations was 95%. A scatterplot of the discriminant analysis showed that the distribution centers of hybrid-3n and hybrid-2n were located between the parents and closer to the mothers. Hybrid-3n and hybrid-2n occupied partially overlapping areas, which indicates that the two are similar in proportion and frame structure, making it difficult to distinguish between them. These results are basically consistent with those obtained by cluster analysis. Most of the 11 biological traits used to construct the discriminant function were related to the longitudinal axis of the body, especially the ratio of the height of the body to the trunk, which is similar to the results obtained by principal component analysis. During principal component analysis, four principal components with a cumulative contribution rate of 75.10% were obtained, which mainly reflect morphological variations of body height and trunk length. In this study, the experimental fish were cultured in still water ponds with abundant bait. The morphological differences may be attributed to the adaptation of the fish to this ecological environment. Comprehensive analysis showed that: Hybrid-3n has a fast growth rate and has the basic conditions for promotion and application in production; The body size of hybrid-3n and hybrid-2n is between the parents, and both are slightly biased towards the mother, which mainly reflect the morphological variations of body height and trunk length; In this study, three multivariate analyses were used to effectively reflect the morphological differences among the four populations of hybrid-3n, hybrid-2n, MA, and CA from different perspectives, which has made them irreplaceable. In conclusion, this study confirmed the superior breeding potential of triploids of M. amblycephala ♀ × C. alburnu ♂, and provided basic data for the morphological comparison of hybrid offspring of M. amblycephala and C. alburnu, which is significant for the identification and protection of fish resources, and is expected to provide a theoretical basis for the establishment of new strains of M. amblycephala and C. alburnu. The results are of great significance for population identification and ploidy breeding of hybrid offspring of M. amblycephala and C. alburnu.

Rainbow trout (Oncorhynchus mykiss) is one of the world's most widely farmed cold-water economic fish. It is also the primary cold-water fish species in China. Since the 1960s, the rainbow trout germplasm has been introduced from North Korea, the United States, Denmark, and other countries, and a systematic study has been carried out on germplasm preservation, identification, breeding, and variety breeding. Compared with rainbow trout diploid, the triploid has the advantages of a high feed conversion rate, fast growth rate, and good meat quality. Moreover, the triploid gonadal hypoplasia can mitigate risks associated with high mortality and meat quality decline during spawning and avert the ecological risk of invasive alien species caused by breeding escape. Therefore, breeding triploid rainbow trout has more significant market and ecological benefits. As diploid and triploid rainbow trout are very similar in terms of morphology, it is difficult to distinguish the ploidy of rainbow trout by morphology alone. Currently, DNA content analysis by flow cytometry is the main method used to identify the ploidy of rainbow trout, but this method necessitates the collection of fish blood or tissue samples, and the body length of the fish to collect the blood must be at least 5 cm. Additionally, these sampling operations may harm the fish. This method also involves a delicate operation, complicated technical process, and expensive consumables, thus, the popularization and application of triploid identification of rainbow trout are greatly restricted. Considering the limitations of the technical test for the ploidy of rainbow trout, a minimally invasive and economical method with only a small amount of sampling is needed to identify and analyze the ploidy of rainbow trout in batches. Microsatellite markers (SSR markers) are simple repeated sequences widely distributed in eukaryotic genomes and have been widely used in ploidy and pedigree analyses of fish. The advantages of microsatellite (SSR) analysis include high reproducibility, low sample requirements, and rapid population genetic analysis. In order to achieve the use of a minimally invasive method to collect samples for trout ploidy identification, this study analyzed 153 SSR markers using PCR amplification and electrophoresis separation technology. Among them, 139 SSR markers could be successfully amplified in diploid and triploid, and 132 SSR markers were screened for polymorphism. Finally, seven markers showed high variability in triploid. By verifying 52 reference samples with a known ploidy level and 48 samples with an unknown ploidy level, three SSR markers (SSR1054, SSR1056, and SSR1468) were further screened to distinguish the ploidy level. Moreover, three pairs of primer sequences with good stability were redesigned according to the three marker sequences for ploidy analysis application. When SSR markers were selected for ploidy identification, amplification sites with high variability were preferred because they greatly improve the efficiency of SSR-assisted ploidy identification. Differentiation of the variability of amplification sites mainly considers the number of alleles expressed and the relative frequency of these alleles. Furthermore, having clear map bands that are easy to observe and analyze is an important criterion for screening high-quality specific SSR markers. Statistical clear map bands can correctly judge the allelic configuration at each locus, thus, determining the ploidy level of rainbow trout. However, when the number of microsatellite DNA alleles shown in the electrophoretic map was less than the maximum number of alleles that may occur at the ploidy level of the polyploid species, it was difficult to accurately judge the ploidy by direct observation of the number of alleles. In diploid individuals, highly heterozygous SSR amplifies at most two alleles at a given site. Similarly, three and four alleles can be observed in triploid and tetraploid individuals, respectively. However, in some rare cases, the actual number of alleles cannot be correctly determined by looking directly at the number of alleles. For example, individuals with unknown ploidy show multiple possible genotypes for two alleles, which can occur with both diploids (AB) and triploids (AAB or ABB). Therefore, this study combined the analysis results of multiple specific SSR markers to improve the accuracy of ploidy detection. In addition, this study found three specific labeling bands that can assist in the differentiation of diploid and triploid rainbow trout, namely, SSR1054-305bp, SSR1056-463bp, and SSR1468-363bp. These three specific markers will greatly improve the accuracy of using SSR markers to identify triploid rainbow trout. Microsatellite null alleles are another potential limitation in SSR ploidy identification, which can be eliminated or avoided by changing the binding site of primers and flanking sequences due to the failure of normal gene amplification due to mutations in SSR lateral sequences. Although the results of this study cannot eliminate the presence of null alleles in future samples, the present experimental data suggest that the frequency of null alleles is so low that their impact on polyploid identification is minimal. SSR markers screened in this study solve the existing problems of a complex technical process and expensive consumables in the identification of rainbow trout ploidy, providing a minimally invasive, economical, reliable, and batch-operable molecular method and contributing to the study of the genetic diversity of rainbow trout with different ploidy.

Crassostrea gigas, also known as Pacific oysters, are economic shellfish with the widest range of cultivation, the highest yield in the world, and the most important type of mariculture shellfish in China. However, many C. gigas have died during summer in coastal areas worldwide in recent decades. In 2008, the mortality rate of C. gigas cultured in France reached 40%–100%. In 2009, the mortality rate of C. gigas in some area of Sanggou Bay reached 51%. In 2019, the mortality rate of the Rushan area reached 50%–90%, with the death peak occurring in middle and late August. There were many reasons for the large-scale death of C. gigas, such as temperature, dissolved oxygen, salinity, disease, food availability, and reproduction levels, among which high temperature was the most important abiotic stress factor. The high temperature in summer disturbed the enzyme metabolism of C. gigas, resulting in slow or impeded growth. Furthermore, the reproduction and spawning of C. gigas caused a large amount of protein consumption, and physical weakness combined with high-temperature stress induced many deaths. Therefore, considering the problems faced by C. gigas culture during high summer temperatures, the introduction of new varieties will increase the economic benefits to the industry.Due to its high sterility, triploid C. gigas has attributes such as a fast growth rate, resilience excellent economic characteristics, and high energy conversion efficiency. In recent years, a certain farmed scale has formed in China, especially in northern coastal areas. There have been many studies on the biological and physiological differences between triploid and diploid C. gigas worldwide, mainly focusing on the differences in growth characteristics, soft tissue components, gonadal development, disease resistance, and gill structure. However, comparisons between triploid and diploid C. gigas feeding, metabolic physiology, energy budget, and carbon budget have not been reported. Focusing on the specific period of high temperatures in summer, this study investigated the feeding and metabolic physiological characteristics of triploid and diploid C. gigas using the field flow method, and compared and analyzed their energy allocation strategies in response to a high-temperature environment. The study provide data support for revealing the physiological differences caused by the ploidy effect of C. gigas in order to assist with evaluating the culture capacity.Triploid and diploid C. gigas were selected as research objects in August 2022 to analyze the differences in feeding and metabolic physiology and energy/carbon allocation strategies during high temperatures in summer. Physiological parameters related to intake and metabolism, such as water filtration rate, absorption efficiency, oxygen consumption rate, and ammonia discharge rate, were determined based on the field flow method in Sanggou Bay, Rongcheng, Shandong Province, and energy allocation and carbon allocation were estimated based on the principle of the energy budget. The results revealed that the water filtration rate and assimilation efficiency of triploid C. gigas were higher than those of diploid C. gigas, but there were no significant differences (P > 0.05). There were significant differences in the oxygen consumption rate and ammonia discharge rate between triploid and diploid C. gigas (P < 0.05). The oxygen consumption rate of triploid C. gigas was significantly lower than that of diploid C. gigas (P < 0.05), but ammonia discharge rate was significantly higher than that of diploid C. gigas (P < 0.01). The results of the energy and carbon budget analyses showed that the feeding energy/carbon and assimilation energy/carbon values of triploid C. gigas were higher than those of diploid C. gigas, but there was no significant difference (P > 0.05). There were significant differences in respiratory energy/carbon, excretion energy/carbon, and growth power between triploid and diploid C. gigas (P < 0.05). Respiratory energy/carbon values of triploid C. gigas were significantly lower than those of diploid C. gigas (P < 0.05), but excretion energy/carbon and growth power values were significantly higher than those of diploid C. gigas (P < 0.05). The oxygen/nitrogen ratio of triploid and diploid C. gigas fluctuated in the range of 7.91–14.11 and 59.81–94.19, respectively. Moreover, the main energy supply substances of triploid C. gigas were proteins, while the main energy supply substances of diploid C. gigas were carbohydrates and fats. These results revealed the differences in energy allocation patterns associated with the ploidy effect of C. gigas during high temperatures in summer.From the perspective of individual physiology and ecology, this study found that, compared with diploid C. gigas, triploid C. gigas showed certain advantages in energy allocation strategies by adjusting feeding and metabolic physiological behaviors during the high-temperature summer. However, the internal molecular mechanism of response strategies adopted by triploid C. gigas to cope with an adverse environment is still unclear. Further interpretation at the molecular level needs to be combined with omics and other systems biology techniques.

The Pacific oyster, Crassostrea gigas, is an important cultured species in the northern coastal areas of China. In recent years, the triploid oyster was popular worldwide because of its fast growth and high meat quality and has rapidly occupied a large portion of the oyster market. As a multi-generation selection strain, "Haida No.2" of C. gigas has good growth performance. At the same time, we have successfully obtained the triploid and tetraploid "Haida No.2." This study was conducted to evaluate the performance of the triploid of "Haida No.2" under different rearing environments. The results showed that there was no significant difference in fertilization rate and hatching rate between diploids and triploids, and so did the survival rate at the larval stage, while the cumulative survival rate of triploids was significantly lower than that of diploids. At grow-out stage, the growth and survival rate of triploids were significantly higher than diploids on day 420 at two sites; meanwhile, the triploid rate was slight decline but still kept a high level (96–98%) on 420 days at two sites. However, high gametogenesis and subsequent mass spawning of triploid females were observed at two sites (32% at Rongcheng and 54% at Rushan), and the fecundity of triploid females relative to diploid females was high (23.73% at Rongcheng and 41.15% at Rushan) under different rearing environments. Our results showed that the triploid of "Haida No.2" had better performance at grow-out stage than diploids. However, the phenomenon of high gametogenesis of triploid and spawning is not favorable for the industrialization of triploid oysters, and the mechanism of high gametogenesis of triploids needs further study. [ABSTRACT FROM AUTHOR]

Phenotypic differences between diploid parents and their allotriploid offspring are common in aquaculture breeding. Some allotriploid populations exhibit rapid growth rates and increased body weight, which are significant for supporting fisheries development. Understanding the genetic mechanisms underlying these traits is crucial for implementing diverse breeding strategies to achieve high production in fish farming. Here, we collected the following fish species for our study: red crucian carp (Carassius auratus red var., 2nRR), common carp (Cyprinus carpio L., 2nCC), and two allotriploids (3nR2C and 3 nRC2). These allotriploids were obtained through backcrossing an allotetraploid of C. auratus red var. × C. carpio L. (4nR2C2, ♂) with C. auratus red var. and C. carpio L. (♀), respectively. These allotriploids demonstrated faster growth rates compared to their diploid inbred parents, contributing to the Chinese fisheries industry for several decades. We conducted a systematic comparison of mitochondrial DNA (mtDNA) copy numbers in the liver and muscle tissues of 2nRR, 2nCC, 3nR2C, and 3 nRC2 under different seasons. When entering winter (low water temperature: 13 °C), the triploid fish (3nR2C and 3 nRC2) exhibited lower mtDNA copy numbers in the muscle, indicating a reduction in individual activity and energy expenditure to facilitate weight maintenance when food availability is limited. Furthermore, we analysed the expression levels of three nuclear-regulated mitochondrial genes (tfam, tfb1m, and tfb2m) and observed an imbalance of allelic expression in tfam and tfb1m in the two triploid fish. These findings enhance our understanding of the molecular regulatory mechanisms underlying growth trait differences among fish with different ploidy levels.

Exposure to temperatures outside of a fish's optimal range results in suppression of the immune system, ultimately leaving aquaculture stocks susceptible to disease outbreaks. This effect is exacerbated in triploid fishes, which demonstrate greater susceptibility to stress than their diploid counterparts. This study investigates the impacts of acute heat stress on the abundance of immune transcripts and proteins in diploid and triploid Chinook salmon (Oncorhynchus tshawytscha), an important finfish crop. This study also demonstrates that acute heat stress induces significant increases in the abundance hsp70, hsp90 and il1b transcripts in the head kidneys, gills and heart ventricles of both diploid and triploid Chinook salmon. Widespread dysregulation of antigen‐presentation transcripts was also observed in fish of both ploidies. These results suggest that acute heat stress activates acute‐phase responses in Chinook salmon and dysregulates antigen presentation, potentially leaving fish more susceptible to infection. At the protein level, IL‐1β was differentially expressed in the head kidney and ventricles of diploid and triploid salmon following heat shock. Differential expression of two tapasin‐like proteins in diploid and triploid salmon subjected to heat shock was also observed. Altogether, these data indicate that diploid and triploid Chinook salmon respond differently to acute thermal stressors. [ABSTRACT FROM AUTHOR]

Miscanthus ×giganteus (giant miscanthus), first found as a naturally occurring hybrid, has shown promise as a bioenergy/biomass crop throughout much of the temperate world. This allotriploid (2n = 3x = 57) hybrid resulted from a cross between tetraploid Miscanthus sacchariflorus (2n = 4x = 76) and diploid Miscanthus sinensis (2n = 2x = 38) and is particularly desirable due to its low fertility that minimizes reseeding and potential invasiveness. However, there is limited genetic diversity in commonly grown cultivars of triploid M. ×giganteus and breeding and development efforts to improve and domesticate this crop have been minimal. Here, we report on newly developed M. ×giganteus hybrids compared with the industry standard M. ×giganteus '1993‐1780'. Dry biomass yields of new hybrids ranged from 19.5 to 32.4 Mg/ha/year for the fourth growing season, compared with 21.0 Mg/ha/year for M. ×giganteus '1993‐1780'. Plant reproductive fertility remained low for all accessions with overall fertility [(seed set × seed germination)/100] ranging from 0.3% to 4.5% for new hybrids compared to 0.4% for M. ×giganteus '1993‐1780'. Culm density and height varied among accessions and were positively correlated with increased biomass. Based on compositional analyses, theoretical ethanol yields ranged from 9, 740 to 16,278 L/ha/year for new hybrids compared to 10,406 L/ha/year for M. ×giganteus '1993‐1780'. Relative feed value indices were low overall and ranged between 66.0 and 72.8 for new hybrids compared to M. ×giganteus '1993‐1780' with 71.3. The genetic diversity of new hybrids, compared with existing cultivars, was characterized using whole genome sequences. Based on pair‐wise distances, cluster analysis clearly showed increased diversity of new hybrids compared with earlier selections. These results document new triploid hybrids of M. ×giganteus with enhanced biomass and theoretical ethanol yields in combination with broader genetic diversity and lowreproductive fertility. [ABSTRACT FROM AUTHOR]

Hybridization and polyploid breeding are the main approaches used to obtain new aquaculture varieties. Allotriploid crucian carp (3n) with rapid growth performance was generated by mating red crucian carp (RCC) with allotetraploids (4n). Fish growth is controlled by the growth hormone (GH)/insulin-like growth factor (IGF) axis. In the present study, we examined the expression characteristics of GH/IGF axis genes in hybrids F1, 4n, 3n, RCC and common carp (CC). The results showed that GHRa, GHRb, IGF1, IGF2, and IGF- 1Ra were highly expressed in 3n compared with RCC and CC, whereas IGF3 was undetectable in the liver in RCC, CC and 3n. GHRa and GHRb had low expression in the 4n group. In hybrid F1, GHRa expression was low, whereas GHRb was highly expressed compared to the levels in RCC and CC. Moreover, in hybrid F1, the expression of IGF3 was higher, and the expression of IGF1 and IGF2 was lower than that in the RCC and CC, whereas the expression of IGF-1Ra was similar to that in RCC and CC. For the IGFBP genes, IGFBP1 had higher expression in 3n compared than that in RCC and CC, while other IGFBP genes were not high expressed in 3n. Among the genes detected in this study, 11 genes were nonadditively expressed in 3n, with 5 genes in the transgressive upregulation model. We proposed that the 11 nonadditive expression of GH/IGF axis genes is related to growth heterosis in 3n. This evidence provides new insights into hybridization and polyploid breeding from the perspective of hormone regulation. [ABSTRACT FROM AUTHOR]

Cross-incompatibility is the major challenge in inter-sectional distant hybridization between tree peonies (Paeonia sect. Moutan) and herbaceous peonies (Paeonia sect. Paeonia). Most of the intersectional cross combinations rarely produce hybrid progenies or even seeds. However, a combination with Paeonia × lemoinei Rehd. (P. delavayi × P. suffruticosa, tree type) as the pollen parent and P. lactiflora (herbaceous) as the seed parent resulted in many progenies. This research focuses on cytogenetics of two highly compatible intersectional combinations, P. lactiflora ‘Martha W.’ × P. × lemoinei ‘Golden Era’ (‘MW’ × ‘GE’) and P. lactiflora ‘Fen Yun Fei He’ × P. × lemoinei ‘L’Esperance’ (‘FYFH’ × ‘LE’). Karyotype analysis combined with genomic in situ hybridization (GISH) showed that the seed parents, ‘MW’ and ‘FYFH’, are both diploids (2n = 2x = 10, CC), while the pollen parents, ‘GE’ and ‘LE’, are tetraploid (2n = 4x = 20, AABB) and diploid (2n = 2x = 10, AB) respectively. Four progenies from ‘MW’ × ‘GE’, and another four progenies from ‘FYFH’ × ‘LE’, are all triploids (2n = 3x = 15, ABC). P. × lemoinei contributes two sets of chromosomes (AB) showing distinct signals in all tested triploids. The essential of a successful intersectional hybridization is to obtain 2x gametes from tree peony. P. × lemoinei has better compatibility in intersectional hybridization than other tree peony species, probably because of its higher frequency of 2x gamete (unreduced in diploid, or reduced in tetraploid) generation. Tetraploid tree peonies, such as ‘GE’, might produce abundant 2x gametes through normal meiosis, which is the possible reason for their better fertility and superior intersectional compatibility than diploid tree peonies. The mechanism of compatibility in intersectional hybridization is supposed to be a rebalance between the distant divergent parents, tree peonies and herbaceous peonies, triggered by ploidy increase of gametes from tree peonies. The discovery of tetraploid tree peony also provides valuable materials to study the mechanism of polyploidization in sect. Moutan, and to promote the distant hybridization breeding in Paeonia. [ABSTRACT FROM AUTHOR]

The genus Disporum (Colchicaceae) comprises approximately 20 species distributed throughout Asia, of which four species (Disporum sessile, D. smilacinum, D. uniflorum, and D. viridescens) are currently recognized in Korea. Mixed-ploidy variations, including odd-ploidy levels within the same species, are important in evolution as they enable backcrosses with their parental cytotypes. However, Korean Disporum species have not been examined in detail with regard to ploidy variation and pollen fertility. Therefore, we document the occurrence of diploids and triploids among the Disporum spp. in Korea and report for the first time that D. sessile and D. smilacinum are both diploid (2n = 2x = 16) and triploid (2n = 3x = 24), though they were previously known as diploids from Korean natural populations. The total haploid chromosome length is variable, ranging from 67.32 µm in diploid D. smilacinum to 108.11 µm in triploid D. smilacinum; however, the karyotypes of the investigated species are similar regardless of the ploidy levels. The occurrence of fertile pollen grains from triploid individuals is approximately two-thirds that from diploid species, but triploid plants show no pollen tube germination compared to their diploid counterparts. Overall, this study presents the first comprehensive chromosomal and pollen fertility data for Korean Disporum species, and thus lays the foundation for better understanding the evolution and diversification of morphologically and cytologically variable plant groups. [ABSTRACT FROM AUTHOR]

Objective: The sunshine bass (female White Bass Morone chrysops × male Striped Bass M. saxatilis) is an important food fish raised in U.S. aquaculture. Spawning is performed by manually stripping and fertilizing White Bass eggs with Striped Bass sperm. Embryos hatch in approximately 48 h. Mature sunshine bass females can become fertile and produce viable eggs, which is problematic in commercial food‐fish production; therefore, triploid fish are desired. Methods: The present nonreplicated study incorporated three warm and three cold temperature shocks, along with three postfertilization initiation times and three exposure times for each temperature, during initial stages of incubation to induce triploidy. After exposure to temperature shocks, fertilized eggs were incubated in experimental hatching systems. The best performing cold and warm temperatures and times (and an ambient diploid control) were then used to incubate fertilized eggs in a commercial‐scale trial using standard industry practices with a single batch of eggs. Larvae were stocked at about 185,000 larvae/ha (75,000 larvae/acre) in newly filled and fertilized ponds. Fry were sampled weekly and harvested at 30 days. Result: There were 15 survivors from the pond containing fish derived from cold‐shocked fertilized eggs; these individuals were tested via Coulter Counter, and no triploids were detected. Testing of 50 survivors from the pond containing fish derived from warm‐shocked fertilized eggs indicated that 14% were triploid. Conclusion: Therefore, initial trials indicate that warm temperature shock is preferable to cold shock for inducing a greater percentage of triploid sunshine bass. Impact statementSuccessful use of temperature shock during the initial stages of fertilized egg incubation to produce triploid sunshine bass leads to a new method to improve sustainability and profitability for farmers. [ABSTRACT FROM AUTHOR]

Self-compatibility is a highly desirable trait for pear breeding programs. Our breeding program previously developed a novel self-compatible pollen-part Japanese pear mutant (Pyrus pyrifolia Nakai), '415-1', by using g-irradiated pollen. '415-1' carries the S-genotype S4dS5S5, with "d" indicating a duplication of S5 responsible for breakdown of self-incompatibility. Until now, the size and inheritance of the duplicated segment was undetermined, and a reliable detection method was lacking. Here, we examined genome duplications and their inheritance in 140 F1 seedlings resulting from a cross between '515-20' (S1S3) and '415-1'. Amplicon sequencing of S-RNase and SFBB18 clearly detected Shaplotype duplications in the seedlings. Intriguingly, 30 partially triploid seedlings including genotypes S1S4dS5, S3S4dS5, S1S5dS5, S3S5dS5, and S3S4dS4 were detected among the 140 seedlings. Depth-of-coverage analysis using ddRADseq showed that the duplications in those individuals were limited to chromosome 17. Further analysis through resequencing confirmed an 11-Mb chromosome duplication spanning the middle to the end of chromosome 17. The duplicated segment remained consistent in size across generations. The presence of an S3S4dS4 seedling provided evidence for recombination between the duplicated S5 segment and the original S4haplotype, suggesting that the duplicated segment can pair with other parts of chromosome 17. This research provides valuable insights for improving pear breeding programs using partially triploid individuals. [ABSTRACT FROM AUTHOR]

Date palms are a vital part of oasis ecosystems and are an important source of income in arid and semi-arid areas. Crossbreeding is limited due to the long juvenile stage of date palms and their dioecious nature. The aim of this study was to create triploid date palms to obtain larger and seedless fruits and to increase resilience to abiotic stresses. A tetraploid date palm mutant was crossed with a diploid male palm, yielding hundreds of seeds suspected of containing triploid embryos. Six years after planting, four palms with confirmed triploidy reached maturity. They are phenotypically distinct from diploids, with a thicker rachis, thinner spines, wider and longer midleaf spines, and a longer apical spine. They were classified as sterile bisexual, sterile male and fertile female. One of the latter produced very tasty dates with a very small seed, which is promising for the marketability and profitability of date palm fruits. This first report on triploid date palms provides a way in which to make a significant leap forward in date palm breeding. Given the vigor and fruit quality of female triploid date palms, compared to their diploid counterparts, they will be the target of breeding programs and may spearhead new oases. [ABSTRACT FROM AUTHOR]

Seedlessness is the most important characteristic of citrus and one of its breeding purposes. Triploids are the most reliable way to secure seedlessness and can be developed through crosses between tetraploids and diploids or between diploids and diploids. We evaluated the characteristics of seed formation and recovery frequency of triploids in interploid crosses in this study. Normal seed formation was the highest (85.0%) in crosses of 2x × 2x, followed by crosses 4x × 2x and 2x × 4x. Partially developed seeds were obtained at the highest rate (35.3%) from crosses of 4x × 2x with 0.7 seeds per fruit, followed by 2x × 2x and 2x × 4x with 0.2 and 0.1 seeds per fruit, respectively. The number of undeveloped seeds per fruit was 1.1, 1.0, and 0.3 from the 4x × 2x, 2x × 4x, and 2x × 2x crosses, respectively, and the lowest frequency was recorded in the 2x × 2x cross. Diploid plants were mostly obtained in the 2x × 2x cross (98.8%), while 73.0% triploids and 27.0% tetraploids were obtained with 4x × 2x, and 14.3% diploids, 57.1% triploids, and 28.6% tetraploids were achieved with the 2x × 4x cross. Diploid plants were mostly obtained from normal seeds, while ad triploid and tetraploid plants were mostly obtained from partially developed and undeveloped seeds. The results indicated that crosses of 4x × 2x were the most efficient and that in vitro culture should be applied to rescue plants from partially developed and undeveloped seeds in triploid breeding programs. [ABSTRACT FROM AUTHOR]

Nonapomictic citrus tetraploids are desirable in citrus breeding for the production of triploid, seedless varieties, and polyploid rootstocks. However, only a few lines have been reported, and they were all generated using chemical methods. A 2x + 4 × cytochimera of the nonapomictic citrus variety 'Orah' mandarin, which developed from a bud mutant, was found due to its morphology differing from that of diploid plants and characterised via ploidy analysis combining flow cytometry and chromosome observation. The chimaera was stable, and there were 1.86–1.90 times as tetraploid cells as diploid cells. Anatomical structure observation revealed that the 'Orah' chimaera may be a periclinal chimaera with diploid cells in the L1 layer and tetraploid cells in the L2 and L3 layers. The chimaera showed some typical traits of polyploid plants, including thicker shoots, wider and thicker leaves, larger flowers and fruits, and fewer but larger seeds in fruits than in diploid plants. Almost all the seeds of the chimaera were monoembryonic. Most of the self-pollinated progenies of the chimaera were identified as tetraploids, and some triploid, pentaploid, and hexaploid plants were found. As a female, the chimaera produced allotriploids when crossed with Australian finger lime. In addition, 6 plants developed from polyembryonic seeds of the chimaera were identified as sexual tetraploid progenies with low-level recombinant genomes. Therefore, the 'Orah' 2x + 4 × chimaera can be used as a female parent to produce hybrid triploid and tetraploid citrus plants with high efficiency. Identification of the chimaera demonstrated that tetraploid citrus plants, especially nonapomictic varieties, can be generated from shoot bud mutants. [ABSTRACT FROM AUTHOR]

The sterility advantages of triploids make them paramount for oyster aquaculture. Tetraploids are always used as male parents for triploid industrial breeding in current hatcheries, thus they are the core asset for triploid oyster culture. The oyster Crassostrea angulata is the most productive oyster species in China. However, the optimal conditions for tetraploid induction have never been examined. In this study, we investigated the effectiveness of three induction methods (Method I, 2n ♀ × 2n ♂ + inducer abbreviated as DD + ind; Method II, 3n ♀ × 2n ♂ + inducer abbreviated as TrD + ind; Method III, 2n ♀ × 4n ♂ + inducer abbreviated as DT + ind) and three inducers (salinity; cytochalasin B, CB; and 6-dimethylaminopurine, 6-DMAP) for tetraploid induction in C. angulata. The optimal induction conditions for the three induction methods were a CB concentration of 0.5 mg/L treated for 20 min, 0.75 mg/L CB for a constant induction treatment of 20 min and 6-DMAP at a concentration of 100 mg/L for 20 min, respectively. When the optimal induction conditions were applied to a single pair of oysters, the D-larval tetraploid rate for the three methods were 18.93 ± 1.46%, 58.32 ± 1.03% and 51.61 ± 1.37%, respectively. After 30 days, the survival rates of the experimental groups were only 10.36 ± 2.51%, 28.07 ± 2.03% and 21.99 ± 1.27%, respectively, at day 30. The tetraploid rates in DD + ind and DT + ind were both decreased significantly over time, but they still reached 11.81% and 21.99% at 30 days, and 8% and 16% at day 180, respectively. Tetraploid rates in TrD + ind were 58.32 − 71.28% at the larval stage and 80% at day 180. In summary, despite very different induction rates, surviving tetraploids of C. angulata could be obtained in all three methods. Method II (TrD + inducer) was regarded as the optimal method to induce C. angulata tetraploids, and the optimal induction condition was a CB concentration of 0.75 mg/L and treated for 20 min under this method. [ABSTRACT FROM AUTHOR]

The fecundity of triploid female Crassostrea gigas exhibited significant variation and was lower compared to diploid individuals. Previous studies categorized mature stage triploid female C. gigas into two groups: female α, characterized by a high number of oocytes, and female β, displaying few or no oocytes. To investigate the molecular mechanisms underlying irregular oogenesis and fecundity differences in triploid C. gigas, we performed a comparative analysis of gonad transcriptomes at different stages of gonadal development, including female α, female β, and diploids. During early oogenesis, functional enrichment analysis between female diploids and putative female β triploids revealed differently expressed genes (DEGs) in the ribosome and ribosome biogenesis pathways. Expression levels of DEGs in these pathways were significantly decreased in the putative female β triploid, suggesting a potential role of reduced ribosome levels in obstructing triploid oogenesis. Moreover, to identify regulatory pathways in gonad development, female oysters at the early and mature stages were compared. The DNA repair and recombination proteins pathways were enriched in female diploids and female α triploids but absent in female β triploids. Overall, we propose that decreased ribosome biogenesis in female triploids hinders the differentiation of germ stem cells, leading to the formation of a large number of abnormal germ cells and ultimately resulting in reduced fecundity. The variation in fertility among triploids appeared to be related to the degree of DNA damage repair during female gonad development. This study offers valuable insights into the oogenesis process in female triploid C. gigas. [ABSTRACT FROM AUTHOR]

Abstract Experiments were conducted to optimize triploid induction parameters, and assess triploid sterility, in burbot. Duration and timing of shocks were based on degree minutes, temperature multiplied by time, denoted as °C min. Hydrostatic shock experiments investigated the duration of shock using 7500 or 8500 psi at 180°C min post‐fertilization. Thermal shocks investigated duration of shock and post‐fertilization shock timing using a shock of 16°C. Sterility experiments investigated egg survival when diploids were crossed with triploids. Hydrostatic shock of 7500 psi for 10 or 20°C min can induce triploidy ≥90% and exhibits survival that is statistically similar, p ≤ 0.05, to controls. Hydrostatic shock of 8500 psi for 5 or 10°C min yielded triploid induction of 93% and 100%, respectively, with survival that is statistically similar to controls, p ≤ 0.05. Thermal induction experiments indicated shocks at 120°C min post‐fertilization, for durations between 350 and 450°C min, have potential to induce triploidy ≥90% while facilitating survival statistically similar to controls, p ≤ 0.05. Induction of tetraploidy was observed. Sterility experiments determined that triploid burbot are functionally sterile. These results may allow production of burbot where sterility is required.

Bawang putih merupakan tanaman yang dibudidayakan melalui umbinya karena tidak mampu menghasilkan bunga. Hal tersebut mengakibatkan keragaman tanaman bawang putih rendah. Teknik-teknik pemuliaan tanaman dilakukan untuk memperoleh karakter yang diinginkan dan memperbaiki karakter yang telah ada. Salah satu teknik pemuliaan adalah pemuliaan mutasi menggunakan mutagen kolkisin.Tujuan penelitian ini adalah untuk mengetahui pengaruh konsentrasi kolkisin terhadap pertumbuhan, karakter fisiologi, jumlah kromosom, dan memperoleh nilai lethal concentration 50% (LC50) dari varietas Lumbu Kuning dan Lumbu Hijau. Penelitian dilaksanakan bulan Mei-September 2021 di Desa Ngroto Kecamatan Pujon Kabupaten Malang. Metode penelitian yang digunakan adalah metode perlakuan pada tanaman tunggal yang disusun dalam barisan dengan perlakuan dua varietas Lumbu Kuning dan Lumbu hijau yang diberi larutan kolkisin (0, 750, 1000, 1250 dan 1500 ppm). Hasil analisis uji t memperlihatkan bahwa kolkisin konsentrasi 0-1500 ppm memberikan pengaruh nyata pada panjang tanaman, diameter batang, jumlah daun, panjang daun dan lebar daun. Tanaman triploid (2n=3x=24) memiliki jumlah dan kerapatan stomata lebih rendah dibandingkan tanaman diploid, namun ukuran stomata lebih besar. Varietas Lumbu Kuning adalah 698,055 ppm dan varietas Lumbu Hijau adalah 1383,041 ppm.

Citrus polyploidy is associated with a wide range of morphological, genetic, and physiological changes that are often advantageous for breeding. Citrus triploid hybrids are very interesting as new seedless varieties. However, tetraploid rootstocks promote adaptation to different abiotic stresses and promote resilience. Triploid and tetraploid hybrids can be obtained through sexual hybridizations using tetraploid parents (2x × 4x, 4x × 2x, or 4x × 4x), but more knowledge is needed about the inheritance pattern of tetraploid parents to optimize the efficiency of triploid varieties and tetraploid rootstock breeding strategies. In this work, we have analyzed the inheritance pattern of three tetraploid genotypes: ‘Chandler’ pummelo (Citrus maxima) and ‘Cleopatra’ mandarin (Citrus reticulata), which represent two clear examples of autotetraploid plants constituted by the genome of a single species, and the ‘Sevillano’ sour orange, which is an allotetraploid interspecific hybrid between C. maxima and C. reticulata. Polymorphic simple sequence repeat (SSR) and single-nucleotide polymorphism (SNP) markers were used to estimate parental heterozygosity restitution, and allele frequencies for centromeric loci were used to calculate the preferential pairing rate related to the proportion of disomic and tetrasomic segregation. The tetraploid pummelo and mandarin displayed tetrasomic segregation. Sour orange evidenced a clear intermediate inheritance for five of the nine chromosomes (1, 2, 5, 7, and 8), a slight tendency toward tetrasomic inheritance on chromosome 3, and intermediate inheritance with a tendency toward disomy for chromosomes 4, 6, and 9. These results indicate that the interspecific versus intraspecific phylogenomic origin affects preferential pairing and, therefore, the inheritance patterns. Despite its high level of heterozygosity, the important preferential chromosome pairing observed in sour orange results in a limited diversity of the genotypic variability of its diploid gametes, and consequently, a large part of the genetic value of the original diploid sour orange is transferred to the tetraploid progenies. [ABSTRACT FROM AUTHOR]

Polyploidy is a significant evolutionary process in plants that involves the duplication of genomic content and has been recognized as a key mechanism driving plant diversification and adaptation. In natural populations, polyploids frequently arise from unreduced gametes, which subsequently fuse with reduced or unreduced gametes, resulting in triploid or tetraploid offspring, respectively. Cannabis sativa L. is a diploid species, but recent work using artificially induced polyploidy has demonstrated its potential advantages in an agricultural setting. Further, recent work has identified that some elite clonal cultivars, vis. Mac1, are triploid, with no indication that they were artificially produced. The current study was conducted to determine if polyploidy is a naturally occurring phenomenon in cannabis and to estimate the frequency of this phenomenon across populations. To do this, the presence of natural triploid individuals was evaluated in 13 seedling populations of cannabis using a flow cytometry analysis. Among the examined populations, natural triploids were identified in 10 groups with an average frequency of approximately 0.5%. The highest frequency of natural triploids was observed in a self-pollinated population at 2.3%. This research demonstrates that polyploidy is a naturally occurring event in cannabis and triploids are present at an average of approximately 0.5%, or 1 in 200 plants. These data shed light on the natural variation in ploidy within cannabis populations and contribute valuable insights to the understanding of cannabis genetics and breeding practices. [ABSTRACT FROM AUTHOR]

Experiments were conducted to optimize triploid induction parameters, and assess triploid sterility, in burbot. Duration and timing of shocks were based on degree minutes, temperature multiplied by time, denoted as °C min. Hydrostatic shock experiments investigated the duration of shock using 7500 or 8500 psi at 180°C min post‐fertilization. Thermal shocks investigated duration of shock and post‐fertilization shock timing using a shock of 16°C. Sterility experiments investigated egg survival when diploids were crossed with triploids. Hydrostatic shock of 7500 psi for 10 or 20°C min can induce triploidy ≥90% and exhibits survival that is statistically similar, p ≤ 0.05, to controls. Hydrostatic shock of 8500 psi for 5 or 10°C min yielded triploid induction of 93% and 100%, respectively, with survival that is statistically similar to controls, p ≤ 0.05. Thermal induction experiments indicated shocks at 120°C min post‐fertilization, for durations between 350 and 450°C min, have potential to induce triploidy ≥90% while facilitating survival statistically similar to controls, p ≤ 0.05. Induction of tetraploidy was observed. Sterility experiments determined that triploid burbot are functionally sterile. These results may allow production of burbot where sterility is required. [ABSTRACT FROM AUTHOR]

Curcuma kakchingense Bidyaleima, Kishor & Sharma, a new species of Curcuma subg. Curcuma (Zingiberaceae) from Manipur, northeast India is described and illustrated. The species has close resemblance to C. phrayawan and C. longa but is distinguished by having lemon‐yellow coloured rhizomes with a very bitter taste, glabrous dark reddish‐brown bladeless sheaths, reddish‐brown petiole fading towards the edges, densely pubescent coma and upper fertile bracts on both surfaces with mucronate tip, broadly ovate bracteole, elongated and revolute apex of the middle lobe of the labellum and stigma protruding through the anther lobes. The chromosome number is established as 2n = 3x = 63. [ABSTRACT FROM AUTHOR]

Self-compatibility is a highly desirable trait for pear breeding programs. Our breeding program previously developed a novel self-compatible pollen-part Japanese pear mutant (Pyrus pyrifolia Nakai), ‘415-1’, by using γ-irradiated pollen. ‘415-1’ carries the S-genotype S4dS5S5, with “d” indicating a duplication of S5 responsible for breakdown of self-incompatibility. Until now, the size and inheritance of the duplicated segment was undetermined, and a reliable detection method was lacking. Here, we examined genome duplications and their inheritance in 140 F1 seedlings resulting from a cross between ‘515-20’ (S1S3) and ‘415-1’. Amplicon sequencing of S-RNase and SFBB18 clearly detected S-haplotype duplications in the seedlings. Intriguingly, 30 partially triploid seedlings including genotypes S1S4dS5, S3S4dS5, S1S5dS5, S3S5dS5, and S3S4dS4 were detected among the 140 seedlings. Depth-of-coverage analysis using ddRAD-seq showed that the duplications in those individuals were limited to chromosome 17. Further analysis through resequencing confirmed an 11-Mb chromosome duplication spanning the middle to the end of chromosome 17. The duplicated segment remained consistent in size across generations. The presence of an S3S4dS4 seedling provided evidence for recombination between the duplicated S5 segment and the original S4haplotype, suggesting that the duplicated segment can pair with other parts of chromosome 17. This research provides valuable insights for improving pear breeding programs using partially triploid individuals.

Fast somatic growth is important considerations for successful and competitive aquaculture industry. In rainbow trout reared in South Korea, triploid induction was used to suppress negative influence of reproductive maturation to body growth. However, the effects of triploidy are visible in both mature fish and developing juvenile fish. Thus, it is also important to explicate the effect of triploid induction on growth during the early-life stages of rainbow trout-alevins and fry. Rainbow trout fertilized eggs were subjected to triploid induction and polyploidy was checked by flow cytometry. Diploid and triploid alevins and fry were reared separately in tanks with constant flow of freshwater through flow-through water system and growth measurements were done from zero days after hatching (DAH 0) until DAH 134. The egg-yolk morphometrics of alevins-yolk length, yolk height, yolk volume and yolk weight-were statistically similar (p > 0.05) in both genotypes from DAH 0 to DAH 22. The total length, body height, and body weight of alevins and fry were statistically better (p > 0.05) in both genotypes until DAH 92 but thereafter, triploid had a significantly better growth performance (p < 0.05) over diploid fish until the completion of study at DAH 134. With that, triploid induction did not influence alevin yolk regions and body growth and fry somatic growth until around 3 months after hatching, but considerable growth enhancement was subsequently apparent.

Abstract Background Lignin is a major restriction factor for the industrial production of biomass resources, such as pulp and bioenergy. Eucalyptus is one of the most important sources of pulp and bioenergy. After polyploidization, the lignin content of forest trees is generally reduced, which is considered a beneficial genetic improvement. However, the differences in the lignin content between triploid and diploid Eucalyptus and the underlying regulatory mechanism are still unclear. Results We conducted a comprehensive analysis at the phenotypic, transcriptional and metabolite levels between Eucalyptus urophylla triploids and diploids to reveal the effects of polyploidization on the lignin content and lignin metabolic pathway. The results showed that the lignin content of Eucalyptus urophylla triploid stems was significantly lower than that of diploids. Lignin-related metabolites were differentially accumulated between triploids and diploids, among which coniferaldehyde, p-coumaryl alcohol, sinapaldehyde and coniferyl alcohol had significant positive correlations with lignin content, indicating that they might be primarily contributing metabolites. Most lignin biosynthetic genes were significantly downregulated, among which 11 genes were significantly positively correlated with the lignin content and above metabolites. Furthermore, we constructed a co-expression network between lignin biosynthetic genes and transcription factors based on weighted gene co-expression network analysis. The network identified some putative orthologues of secondary cell wall (SCW)-related transcription factors, among which MYB52, MYB42, NAC076, and LBD15 were significantly downregulated in Eucalyptus urophylla triploids. In addition, potential important transcription factors, including HSL1, BEE3, HHO 3, and NAC046, also had high degrees of connectivity and high edge weights with lignin biosynthetic genes, indicating that they might also be involved in the variation of lignin accumulation between triploid and diploid Eucalyptus urophylla. Conclusions The results demonstrated that some lignin-related metabolites, lignin biosynthetic genes and transcription factors in Eucalyptus urophylla triploids may be relatively sensitive in response to the polyploidization effect, significantly changing their expression levels, which ultimately correlated with the varied lignin content. The analysis of the underlying formation mechanism could provide beneficial information for the development and utilization of polyploid biomass resources, which will be also valuable for genetic improvement in other bioenergy plants.

Citrus polyploidy is associated with a wide range of morphological, genetic, and physiological changes that are often advantageous for breeding. Citrus triploid hybrids are very interesting as new seedless varieties. However, tetraploid rootstocks promote adaptation to different abiotic stresses and promote resilience. Triploid and tetraploid hybrids can be obtained through sexual hybridizations using tetraploid parents (2x × 4x, 4x × 2x, or 4x × 4x), but more knowledge is needed about the inheritance pattern of tetraploid parents to optimize the efficiency of triploid varieties and tetraploid rootstock breeding strategies. In this work, we have analyzed the inheritance pattern of three tetraploid genotypes: ‘Chandler’ pummelo (Citrus maxima) and ‘Cleopatra’ mandarin (Citrus reticulata), which represent two clear examples of autotetraploid plants constituted by the genome of a single species, and the ‘Sevillano’ sour orange, which is an allotetraploid interspecific hybrid between C. maxima and C. reticulata. Polymorphic simple sequence repeat (SSR) and single-nucleotide polymorphism (SNP) markers were used to estimate parental heterozygosity restitution, and allele frequencies for centromeric loci were used to calculate the preferential pairing rate related to the proportion of disomic and tetrasomic segregation. The tetraploid pummelo and mandarin displayed tetrasomic segregation. Sour orange evidenced a clear intermediate inheritance for five of the nine chromosomes (1, 2, 5, 7, and 8), a slight tendency toward tetrasomic inheritance on chromosome 3, and intermediate inheritance with a tendency toward disomy for chromosomes 4, 6, and 9. These results indicate that the interspecific versus intraspecific phylogenomic origin affects preferential pairing and, therefore, the inheritance patterns. Despite its high level of heterozygosity, the important preferential chromosome pairing observed in sour orange results in a limited diversity of the genotypic variability of its diploid gametes, and consequently, a large part of the genetic value of the original diploid sour orange is transferred to the tetraploid progenies.

Triploid breeding with large individuals, high yield, and excellent disease resistance is widely used in aquaculture. However, the functional roles of triploid in the Zebra Calm II strain of Manila clam Ruditapes philippinarum has not been highlighted. In this study, the Zebra Clam II strain of the Manila clams were treated with cytochalasin B (CB) at a final concentration of 0.5 mg/L at 26 °C for 17 min to induce triploidity. The results showed that triploid induction rate of first-hatched D-larvae was 64.73 % and the triploid proportion of 180-day-old larvae was 72.5 %. Furthermore, the hatching rate in triploid (60.54 ± 2.19 %) was significantly lower than that in the control group (92.47 ± 0.58 %) (p 0.05). However, the daily relative growth rate of experimental group was significantly higher than that the control group at all daily ages except 360 days (p

Large rainbow trout marketed as steelhead are gaining considerable attention for production in recirculating aquaculture systems (RAS). Diploid and triploid trout with varying genetics are available from several commercial suppliers; however, the performance and processing metrics of these lines have not been compared when raised in freshwater RAS. Current data on these outcomes could support more accurate cost and profitability estimates for potential RAS projects and optimize operation for existing farms. Accordingly, the objective of this study was to quantify performance metrics, processing yield, and fillet composition of six all-female rainbow trout lines (three diploid and three triploid) exposed to an artificial winter (12:12 light: dark at 40 g (Artificial Winter Photoperiod; AWP)) or continuous, 24-h light (No Winter Photoperiod; NWP) grown in a semi-commercial scale freshwater RAS to 3.5 kg. Overall, growth was impacted by line, ploidy, and artificial winter photoperiod. Diploid and AWP trout were smaller than triploids and NWP trout at stocking and 500 g. Mean diploid and triploid weight was similar at larger sizes (>1 kg); however, triploid performance compared to diploids varied by commercial supplier. Mortality was lower in lines from commercial supplier 1 than lines from commercial supplier 2 and the United States Department of Agriculture (14.4 ± 0.8 vs 27.5 ± 2.0 and 29.8 ± 4.3%, respectively). Head-on gutted and skin-on fillet yields were related with larger fish weight. Mature prevalence in diploids may have led to differences observed between diploids and triploids in fillet lipid (10.9 ± 0.8 vs 13.3 ± 0.6%) and moisture (67.0 ± 0.6 vs 65.1 ± 0.4%). The results provide guidance for rainbow trout RAS producers to make informed decisions on optimal harvest size targets and tailor their rainbow trout line or ploidy selection to those harvest sizes.

The mass production of triploid turbot Scophthalmus maximus is expected to enhance the economic benefits of aquaculture due to its sterility, growth, and survival advantages. Among the methods for inducing triploidy in teleost, pressure shock has been considered a more consistent and reliable approach. In this study, the optimal parameters for inducing triploidy in turbot through hydrostatic pressure shock were investigated in a series of trials, including the intensity (55–75 MPa), timing (3.5–8.5 min after fertilization, maf) and duration (4–12 min). The ploidy level was determined by flow cytometry analysis. Under a water temperature of 14.5 ± 0.5 °C, treatment optima for pressure shock were determined to be 4.5–5.5 maf with 60 MPa for 6 min, resulting in 100% triploidy rate. A comparison of induction efficiency between pressure shock using this combination and cold shock initiated at 6.5 maf in −2 °C sea water for 25 min was carried out using eggs from three females. The higher hatching rates and triploidy rates, and lower abnormality rates were investigated with pressure shock treatment compared with cold shock treatment. The optimized parameters were successfully applied to three large batches of eggs (∼ 250, 300 and 330 mL) for mass production of triploid turbot. The total length and body weight of triploids were significantly lower than those of diploid counterparts at 2 months after hatching (mah), however, they exhibited a significant increase at 8 and 11 mah, respectively, and maintained this higher level thereafter. Additionally, the survival rates remained similar from 2 to 12 mah. The results of this preliminary study indicate that pressure shock rather than cold shock is more beneficial for the commercial production of triploid turbot under farming conditions.

Triploid Atractylodes chinensis (DC.) Koidz. is a valuable genetic resource for medicinal plant breeding, and there is a demand to develop an efficient in vitro regeneration protocol to resolve triploid sterility in production. In this study, the effects of sterilization, bud type, 6-benzyladenine (6-BA) combined with 1-naphthaleneacetic acid (NAA) or indole-3-butyric acid (IBA) and transplanting materials on shoot regeneration, rooting and growth were explored. The genetic stability of regenerated plants was verified using flow cytometry (FCM) and simple sequence repetition (SSR) molecular markers. When axillary buds were sterilized with sodium hypochlorite for 30 min and cultured on Murashige and Skoog (MS) + 1.5 mg·L-1 6-BA + 0.4 mg·L-1 NAA medium, the regeneration rate was 61.33%. Strong roots occurred on 1/2 MS medium combined with 3% sucrose and 0.6 mg·L-1 IBA. Rooting plantlets transplanted into a mixture of peat soil: perlite (1:1, v:v), the survival rate up to 90.00%. Histological analysis revealed that shoot meristematic cells derived from cambium cells developed into the apical meristem and formed shoots. FCM analysis determined that the ploidy levels of 20 random regenerated plants were coincident with explants, the number and size of bands obtained by 6 pairs of SSR polymorphic primers were consistent. The results of this study show that our in vitro adventitious regeneration and plantlet transplantation protocol of triploid A. chinensis was efficient and produced strong genetic stability. Key message: In this study, an efficient and genetically stable adventitious regeneration of triploid A. chinensis was established for the first time. [ABSTRACT FROM AUTHOR]

Standing genetic variation is a major driver of fitness and resilience and therefore of fundamental importance for threatened species such as stony corals. We analyzed RNA-seq data generated from 132 Montipora capitata and 119 Pocillopora acuta coral colonies collected from Kāneʻohe Bay, Oʻahu, Hawaiʻi. Our goals were to determine the extent of colony genetic variation and to study reproductive strategies in these two sympatric species. Surprisingly, we found that 63% of the P. acuta colonies were triploid, with putative independent origins of the different triploid clades. These corals have spread primarily via asexual reproduction and are descended from a small number of genotypes, whose diploid ancestor invaded the bay. In contrast, all M. capitata colonies are diploid and outbreeding, with almost all colonies genetically distinct. Only two cases of asexual reproduction, likely via fragmentation, were identified in this species. We report two distinct strategies in sympatric coral species that inhabit the largest sheltered body of water in the main Hawaiian Islands. These data highlight divergence in reproductive behavior and genome biology, both of which contribute to coral resilience and persistence. [ABSTRACT FROM AUTHOR]

Previous studies have provided evidence of a reduced aerobic metabolic capacity, both at the cellular (metabolic enzyme activity) and the whole organism (aerobic scope) level in juvenile triploid white sturgeon, compared to diploid siblings. The downstream costs of this reduced metabolic capacity are still unclear, yet a lower aerobic scope suggests triploid white sturgeon likely have less energy to allocate to biological processes like growth and development. We conducted a 15-week growth trial to assess energy allocation to somatic growth in 2-month-old diploid and triploid white sturgeon. Spontaneous swimming activity, hepatosomatic index, condition factor, and deformities were also measured throughout the growth trial as indices of energy allocation to activity and fish condition. In general, our results indicate that triploid white sturgeon may have less energy available for processes beyond basal maintenance. This could be linked to a reduced overall performance as evidenced by lower weights and more deformities when compared with their diploid counterparts. However, many indices were still mostly unaffected by triploidy (condition factor, hepatosomatic index, and swimming activity). Whether this lower growth performance seen in juvenile triploid white sturgeon continues through sub-adulthood, puberty and final maturation requires further long-term studies.

Date palms are a vital part of oasis ecosystems and are an important source of income in arid and semi-arid areas. Crossbreeding is limited due to the long juvenile stage of date palms and their dioecious nature. The aim of this study was to create triploid date palms to obtain larger and seedless fruits and to increase resilience to abiotic stresses. A tetraploid date palm mutant was crossed with a diploid male palm, yielding hundreds of seeds suspected of containing triploid embryos. Six years after planting, four palms with confirmed triploidy reached maturity. They are phenotypically distinct from diploids, with a thicker rachis, thinner spines, wider and longer midleaf spines, and a longer apical spine. They were classified as sterile bisexual, sterile male and fertile female. One of the latter produced very tasty dates with a very small seed, which is promising for the marketability and profitability of date palm fruits. This first report on triploid date palms provides a way in which to make a significant leap forward in date palm breeding. Given the vigor and fruit quality of female triploid date palms, compared to their diploid counterparts, they will be the target of breeding programs and may spearhead new oases.

The U.S. Gulf of Mexico contains the largest remaining wild oyster fishery in the world, but populations have declined in recent decades. A growing interest in off-bottom aquaculture that relies on triploid eastern oysters (Crassostrea virginica) has emerged in the Gulf region, yet these faster growing oysters suffer high mortality as adults during low salinity (

Background: Lignin is a major restriction factor for the industrial production of biomass resources, such as pulp and bioenergy. Eucalyptus is one of the most important sources of pulp and bioenergy. After polyploidization, the lignin content of forest trees is generally reduced, which is considered a beneficial genetic improvement. However, the differences in the lignin content between triploid and diploid Eucalyptus and the underlying regulatory mechanism are still unclear. Results: We conducted a comprehensive analysis at the phenotypic, transcriptional and metabolite levels between Eucalyptus urophylla triploids and diploids to reveal the effects of polyploidization on the lignin content and lignin metabolic pathway. The results showed that the lignin content of Eucalyptus urophylla triploid stems was significantly lower than that of diploids. Lignin-related metabolites were differentially accumulated between triploids and diploids, among which coniferaldehyde, p-coumaryl alcohol, sinapaldehyde and coniferyl alcohol had significant positive correlations with lignin content, indicating that they might be primarily contributing metabolites. Most lignin biosynthetic genes were significantly downregulated, among which 11 genes were significantly positively correlated with the lignin content and above metabolites. Furthermore, we constructed a co-expression network between lignin biosynthetic genes and transcription factors based on weighted gene co-expression network analysis. The network identified some putative orthologues of secondary cell wall (SCW)-related transcription factors, among which MYB52, MYB42, NAC076, and LBD15 were significantly downregulated in Eucalyptus urophylla triploids. In addition, potential important transcription factors, including HSL1, BEE3, HHO3, and NAC046, also had high degrees of connectivity and high edge weights with lignin biosynthetic genes, indicating that they might also be involved in the variation of lignin accumulation between triploid and diploid Eucalyptus urophylla. Conclusions: The results demonstrated that some lignin-related metabolites, lignin biosynthetic genes and transcription factors in Eucalyptus urophylla triploids may be relatively sensitive in response to the polyploidization effect, significantly changing their expression levels, which ultimately correlated with the varied lignin content. The analysis of the underlying formation mechanism could provide beneficial information for the development and utilization of polyploid biomass resources, which will be also valuable for genetic improvement in other bioenergy plants. [ABSTRACT FROM AUTHOR]

Telomerase activity has been found in the somatic tissues of rainbow trout. The enzyme is essential for maintaining telomere length but also assures homeostasis of the fish organs, playing an important role during tissue regeneration. The unique morphological and physiological characteristics of triploid rainbow trout, when compared to diploid specimens, make them a promising model for studies concerning telomerase activity. Thus, in this study, we examined the expression of the Tert gene in various organs of subadult and adult diploid and triploid rainbow trout females. Upregulated Tert mRNA transcription was observed in all the examined somatic tissues sampled from the triploid fish when compared to diploid individuals. Contrastingly, Tert expression in the ovaries was significantly decreased in the triploid specimens. Within the diploids, the highest expression of Tert was observed in the liver and in the ovaries of the subadult individuals. In the triploids, Tert expression was increased in the somatic tissues, while the ovaries exhibited lower activity of telomerase compared to other organs and decreased compared to the ovaries in the diploids. The ovaries of triploid individuals were underdeveloped, consisting of only a few oocytes. The lack of germ cells, which are usually characterized by high Tert expression, might be responsible for the decrease in telomerase activity in the triploid ovaries. The increase in Tert expression in triploid somatic tissues suggests that they require higher telomerase activity to cope with environmental stress and maintain internal homeostasis. [ABSTRACT FROM AUTHOR]

Many recent studies have provided significant insights into polyploid breeding, but limited research has been carried out on trees. The genomic information needed to understand growth and response to abiotic stress in polyploidy trees is largely unknown, but has become critical due to the threats to forests imposed by climate change. Populus alba 'Berolinensis,' also known "Yinzhong poplar," is a triploid poplar from northeast China. This hybrid triploid poplar is widely used as a landscape ornamental and in urban forestry owing to its adaptation to adverse environments and faster growth than its parental diploid. It is an artificially synthesized male allotriploid hybrid, with three haploid genomes of P. alba 'Berolinensis' originating from different poplar species, so it is attractive for studying polyploidy genomic mechanisms in heterosis. In this study, we focused on the allelic genomic interactions in P. alba 'Berolinensis,' and generated a high‐quality chromosome‐level genome assembly consisting of 19 allelic chromosomes. Its three haploid chromosome sets are polymorphic with an average of 25.73 nucleotide polymorphism sites per kilobase. We found that some stress‐related genes such as RD22 and LEA7 exhibited sequence differences between different haploid genomes. The genome assembly has been deposited in our polyploid genome online analysis website TreeGenomes (https://www.treegenomes.com). These polyploid genome‐related resources will provide a critical foundation for the molecular breeding of P. alba 'Berolinensis' and help us uncover the allopolyploidization effects of heterosis and abiotic stress resistance and traits of polyploidy species in the future. [ABSTRACT FROM AUTHOR]

The basal monocot genus Acorus comprises essential oil-producing plants widely used in traditional medicine in various countries, including India. Acorus calamus sensu lato is a polyploid complex where the essential oil composition, to some extent, depends on the ploidy level. The literature recognizes diploids (in temperate Asia and North America), triploids (Asian in origin, naturalized elsewhere) and tetraploids (temperate to tropical Asia) at the rank of varieties of A. calamus. We show that the current use of the name A. calamus var. angustatus for the tetraploids is not properly justified. The earliest name based on the Asian material is A. calamus var. verus published in 1753 by Linnaeus. We justify the use of the Linnaean variety for tetraploids by selecting an epitype based on the material cultivated in Peninsular India, for which direct chromosome counts are provided. The name A. verus is available if the tetraploid cytotype is recognized at the species rank. We support earlier data on the importance of leaf anatomy for cytotype diagnostics in Acorus, but also show the limitations of the use of this approach. The growth pattern of the tropical Indian tetraploid material is discussed, and the evergreen nature of the accession studied here is documented. The exact chromosome number of the tetraploid Acorus requires further clarification. All metaphase plates examined here showed at least 44 chromosomes, but plates apparently showing more than 44 chromosomes were found as well. They may be explained by technical difficulties in counting chromosomes in Acorus. Alternatively, our data may indicate the occurrence of aneuploid mixoploidy. [ABSTRACT FROM AUTHOR]

Heinrich Wilhelm Schott (1794–1865) was one of the pioneering researchers in the taxonomy of the species-rich monocot family Araceae. He described numerous new plant species in various genera, including Acorus, which is currently segregated as a monogeneric family and order occupying a position sister to the rest of the monocots. While describing his new species of Acorus, Schott mostly used characters that are currently considered of low, if any, taxonomic value. His descriptions lack some key characters including, for obvious reasons, chromosome numbers. Therefore, Schott's species concepts cannot be properly interpreted according to the current understanding of the taxonomic diversity of Acorus, even though his species names must be examined for implementation of the principle of nomenclatural priority. The only way of resolving the taxonomic identity of Schott's species names is through the identification of type specimens among historical herbarium collections, by inferring taxonomically significant characters that are missing in Schott's descriptions. On the basis of herbarium collections of the Komarov Botanical Institute, St. Petersburg (LE), we were able to infer ploidy levels of the materials used by Schott to describe Acorus triqueter (diploid, Siberia), A. tatarinowii (tetraploid, China), A. nilaghirensis (tetraploid, India), A. griffithii (tetraploid, Bhutan), and A. commutatus (tetraploid, Bhutan). Leaf anatomy and pollen stainability were used as cytotype markers. All five species belong to the polymorphic Acorus calamus complex that comprises important medicinal plants. Detailed historical and nomenclatural analyses of Schott's species names and herbarium collections are provided. [ABSTRACT FROM AUTHOR]

Vaccinium meridionale (section Pyxothamnus), a tetraploid species native to higher altitude locations in Jamaica, Colombia, and Venezuela, is of interest to Vaccinium breeders for its profuse, concentrated springtime flowering and monopodial plant structure, both of which may be useful in breeding for mechanical harvest. In this study, tetraploid V. meridionale was hybridized successfully as a male with 4x V. macrocarpon (section Oxycoccos, American cranberry). The first-generation hybrids with 4x cranberry were intermediate in morphology and notably vigorous. The 4x F1 hybrids displayed a vining plant structure, increased flower bud numbers, and white campanulate flowers. The F1 hybrids displayed modest fertility as females upon selfing and backcrossing to 4x V. macrocarpon. Evaluations of male fertility found good pollen production and a range of pollen quality ranging from very good to poor. Hybrids functioned well as males in crosses that used US 1930, a V. meridionale–V. vitis-idaea hybrid as the female. The fertility suggests that these hybrids, despite being derived from intersectional crosses, might be used conventionally in cranberry breeding without significant difficulty.

The Pacific oyster, Crassostrea gigas, is a successive irregular hermaphrodite mollusk which has an annual breeding cycle. Oysters are naturally diploid organisms, but triploid oysters have been developed for use in shellfish aquaculture, with the aim of obtaining sterile animals with commercial value. However, studies have shown that some triploid oysters are partially able to undergo gametogenesis, with numerous proliferating cells closed to diploids (3n alpha) or a partial one with an accumulation of locked germ cells (3n beta). The aim of our study therefore was to understand the regulation of spermatogenesis in both groups of triploid oysters (alpha and beta) from the beginning of spermatogenesis, during mitosis and meiosis events. Our results demonstrate that the reduced spermatogenesis in triploids results from a deregulation of the development of the germinal lineage and the establishment of the gonadal tract led by a lower number of tubules. Morphological cellular investigation also revealed an abnormal condensation of germ cell nuclei and the presence of clear patches in the nucleoplasm of triploid cells, which were more pronounced in beta oysters. Furthermore, studies of molecular and cellular regulation showed a downregulation of mitotic spindle checkpoint in beta oysters, resulting in disturbance of chromosomal segregation, notably on spindle assembly checkpoint involved in the binding of microtubules to chromosomes. Taken together, our results suggest that the lower reproductive ability of triploid oysters may be due to cellular and molecular events such as impairment of spermatogenesis and disruptions of mitosis and meiosis, occurring early and at various stages of the gametogenetic cycle.

Loquat (Eriobotrya japonica Lindl.) is an evergreen fruit tree of Chinese origin, and its autumn–winter flowering and fruiting growth habit means that its fruit development is susceptible to low-temperature stress. In a previous study, the triploid loquat (B431 × GZ23) has been identified with high photosynthetic efficiency and strong resistance under low-temperature stress. Analysis of transcriptomic and lipidomic data revealed that the fatty acid desaturase gene EjFAD8 was closely associated with low temperatures. Phenotypic observations and measurements of physiological indicators in Arabidopsis showed that overexpressing-EjFAD8 transgenic plants were significantly more tolerant to low temperatures compared to the wild-type. Heterologous overexpression of EjFAD8 enhanced some lipid metabolism genes in Arabidopsis, and the unsaturation of lipids was increased, especially for SQDG (16:0/18:1; 16:0/18:3), thereby improving the cold tolerance of transgenic lines. The expression of ICE-CBF-COR genes were further analyzed so that the relationship between fatty acid desaturase and the ICE-CBF-COR pathway can be clarified. These results revealed the important role of EjFAD8 under low-temperature stress in triploid loquat, the increase expression of FAD8 in loquat under low temperatures lead to desaturation of fatty acids. On the one hand, overexpression of EjFAD8 in Arabidopsis increased the expression of ICE-CBF-COR genes in response to low temperatures. On the other hand, upregulation of EjFAD8 at low temperatures increased fatty acid desaturation of SQDG to maintain the stability of photosynthesis under low temperatures. This study not only indicates that the EjFAD8 gene plays an important role in loquat under low temperatures, but also provides a theoretical basis for future molecular breeding of loquat for cold resistance. [ABSTRACT FROM AUTHOR]

Fitness of fish is assumed to be influenced by locomotion performance, but empirical evidence linking swimming capacity to survival in nature remains sparse. Poor triploid (3N) fish aerobic swimming performance in conjunction with production of sibling diploid (2N) and 3N populations of genetically identical origin to minimize variability among compared populations make 3N trout an informative system to test hypotheses about fitness consequences of fish locomotion. Here, we ask if reduced survival of 3N relative to 2N trout in natural ecosystems during periods of high temperature relate to a lower aerobic swimming capacity and aerobic scope of 3N compared with 2N conspecifics. Three-yearly cohorts of conspecific 2N and 3N hatchery-reared, yearling rainbow trout were ranked for swimming endurance, externally marked for their endurance quantile, and then stocked into two lakes as yearlings to quantify their survival in the wild over summer as a function of ploidy, temperature and endurance; all while tracking temperature and depth habitat utilization via telemetry. As expected, 3N swimming endurance was lower than that of 2N, but with considerable individual overlap. Aerobic swimming endurance, especially for 3N, was predictive of summer survival in a warm lake where piscivorous birds potentially exerted high predation pressure, resulting in low fish survival. This empirical evidence of a connection between swimming endurance and fitness provides support for long held assumptions of this relationship and could inform future sport fishing stocking industry practices to match fish strains to ideal habitats. [ABSTRACT FROM AUTHOR]

Occurrence of Festuca apennina De Not. (4 × Fape), F. pratensis Huds. (2 × Fp) and the triploid, sterile hybrid F. apennina × F. pratensis (3 × Fape × Fp) was studied in 12 regions of the Swiss Alps. In total, 1908 plants were sampled in elevational strata scaled by 50 m between 850 and 2000 m a.s.l., and accompanying vegetation was assessed for each sampling point. The hybrid 3 × Fape × Fp was more frequent and more dominant than both parental species around 1400 m, and had a wider elevational distribution than 2 × Fp and 4 × Fape, which were confined to lower and higher elevation, respectively. As evidenced by their preferred accompanying species, 2 × Fp colonizes dryer, nutrient poorer environments than 4 × Fape which clearly prefers wet and nutrient rich environments. On the contrary, 3 × Fape × Fp thrives similarly well in both environments. The ability to reach an important biomass proportion in a sward, and the wide environmental adaptation of 3 × Fape × Fp is favored by its capacity to strongly expand by rhizomes. A single genotype of 3 × Fape × Fp was found to colonize an entire field of 2.3 ha with a maximum distance between clonal plants of 304 m. It is concluded that 3 × Fape × Fp is a potentially valuable pasture plant for use at higher altitudes, but it may reduce biodiversity via suppressing less competitive plant species. [ABSTRACT FROM AUTHOR]

Background: Flooding is a major stress factor impacting watermelon growth and production globally. Metabolites playa crucial role in coping with both biotic and abiotic stresses. Methods: In this study, diploid (2X) and triploid (3X) watermelons were investigated to determine their flooding tolerance mechanisms by examining physiological, biochemical, and metabolic changes at different stages. Metabolite quantification was done using UPLC-ESI-MS/MS and a total of 682 metabolites were detected. Results: The results showed that 2X watermelon leaves had lower chlorophyll content and fresh weights compared to 3X. The activities of antioxidants, such as superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), were higher in 3X than in 2X. 3X watermelon leaves showed lower O2 production rates, MDA, and hydrogen peroxide (H2O2) levels in response to flooding, while higher ethylene production was observed. 3X had higher levels of dehydrogenase activity (DHA) and ascorbic acid + dehydrogenase (AsA + DHA), but both 2X and 3X showed a significant decline in the AsA/DHA ratio at later stages of flooding. Among them, 4-guanidinobutyric acid (mws0567), an organic acid, may be a candidate metabolite responsible for flooding tolerance in watermelon and had higher expression levels in 3X watermelon, suggesting that triploid watermelon is more tolerant to flooding. Conclusion: This study provides insights into the response of 2X and 3X watermelon to flooding and the physiological, biochemical, and metabolic changes involved. It will serve as a foundation for future in-depth molecular and genetic studies on flooding response in watermelon. [ABSTRACT FROM AUTHOR]