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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 inter-sectional crosses, might be used conventionally in cranberry breeding without significant difficulty. [ABSTRACT FROM AUTHOR]

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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.

Frog species of the genus Xenopus are widely used for studies of cell and developmental biology, and recent genome sequencing has revealed interesting phylogenetic relationships. Here we describe methods to generate haploid, triploid, and hybrid species starting from eggs and sperm of Xenopus laevis and Xenopus tropicalis that enable investigation of how genome size and content affect physiology at the organismal, cellular, and subcellular levels.

The plant hormone gibberellin (GA) regulates many physiological processes, such as cell differentiation, cell elongation, seed germination, and the response to abiotic stress. Here, we found that injecting male flower buds with exogenous gibberellic acid (GA3) caused defects in meiotic cytokinesis by interfering with radial microtubule array formation resulting in meiotic restitution and 2n pollen production in Populus. A protocol for inducing 2n pollen in Populus with GA3 was established by investigating the effects of the dominant meiotic stage, GA3 concentration, and injection time. The dominant meiotic stage (F = 41.882, P < 0.001) and GA3 injection time (F = 172.466, P < 0.001) had significant effects on the frequency of induced 2n pollen. However, the GA3 concentration (F = 1.391, P = 0.253) did not have a significant effect on the frequency of induced 2n pollen. The highest frequency of GA3-induced 2n pollen (21.37%) was observed when the dominant meiotic stage of the pollen mother cells was prophase II and seven injections of 10 µM GA3 were given. Eighteen triploids were generated from GA3-induced 2n pollen. Thus, GA3 can be exploited as a novel mutagen to induce flowering plants to generate diploid male gametes.Our findings provide some new insight into the function of GAs in plants. [ABSTRACT FROM AUTHOR]

Societal Impact Statement: Many economically, culturally, and historically important apple cultivars are triploids, which have three copies of each chromosome instead of the more typical two copies in diploids. Despite their prevalence and importance, there have been conflicting reports regarding their origin and their ability to beget diploids. New genetic analysis methodologies outlined in this study have clarified the genetic origin of triploid apple cultivars and suggest that triploidy has been a dead end in historic apple pedigrees. The specific results of this study have resolved the pedigrees of many cultivars, including the famous English cultivar Cox's Orange Pippin and the oldest known US cultivar Roxbury Russet. Summary: In apple (Malus × domestica), most cultivars are diploid, though a sizeable number are triploids, which tend to be stronger growing, more robust, and bear larger fruit. However, triploidy is also associated with strongly reduced fertility. Some recorded pedigrees for historical apple cultivars include triploids as parents of diploids, despite this reputation of poor fertility. This information, coupled with some initiatives using triploids in breeding efforts, result in confusion about how possible or common it is for triploids to be parents of diploid offspring. To date, no studies have systematically evaluated and identified pedigrees of triploid apple cultivars to resolve these contradictions.Here, we describe a method to make triploid genotype calls using Illumina Infinium single nucleotide polymorphism (SNP) array data through a novel Python script: ploidyClassifier. SNP data for 219 unique triploids was compared alongside 2498 unique diploid apple accessions to conduct pedigree reconstruction.Unreduced gamete‐donating parents were identified for over half of the triploid accessions. From those, reduced gamete‐donating parents were identified for nearly half. Full or partial pedigrees for many classic triploids were uncovered, including that of the oldest known American cultivar, 'Roxbury Russet'. All tested pedigrees from literature that listed triploids as parents of diploids were deemed false, including that of the well‐known 'Cox's Orange Pippin', whose previously unreported second parent was also identified here as 'Rosemary Russet'.These results together suggest that historic triploids are mostly or solely the product of diploid parentage and that triploidy has been a dead end in historic apple pedigrees. [ABSTRACT FROM AUTHOR]

Background and Aims Oil palms showing exceptional vigour and dubbed as 'giant palms' were identified in some progeny during breeding. A panel of phenotypical traits were studied to characterize these trees. The hypothesis that gigantism and other anomalies might be linked to polyploidy was investigated. Methods Twenty sib pairs of palms from different crosses, each comprising a giant and a normal oil palm, were studied by flow cytometry with rice 'Nipponbare' as standard reference. In parallel, palms were assessed in the field using 11 phenotypic traits. A principal component analysis (PCA) was conducted to define relationships between these phenotypical traits, and a linear discriminant analysis (LDA) to predict ploidy level and giant classification. Finally, a co-dominant molecular marker study was implemented to highlight the sexual process leading to the formation of 2 n gametes. Key Results The first group of oil palms presented an oil palm/rice peak ratio of around 4.8 corresponding to diploid oil palms, whereas the second group presented a ratio of around 7, classifying these plants as triploid. The PCA enabled the classification of the plants in three classes: 21 were normal diploid palms; ten were giant diploid palms; while 11 were giant triploid palms. The LDA revealed three predictors for ploidy classification: phyllotaxy, petiole size and circumference of the plant, but surprisingly not height. The molecular study revealed that triploid palms arose from 2 n gametes resulting from the second division restitution of meiosis in parents. Conclusions This study confirms and details the process of sexual polyploidization in oil palm. It also identifies three phenotypical traits to assess the ploidy level of the giant oil palms in the field. In practical terms, our results provide a cheap scientific method to identify polyploid palms in the field. [ABSTRACT FROM AUTHOR]

In this study, the cold shock treatment was used to induce triploid yellow drum (Nibea albiflora) and the ploidy was determined. The histology and gene expression analysis of reproduction-related genes were further used to characterize the gonadal development in triploid yellow drum. Firstly, the fertilized eggs were subjected to the cold shock treatment implemented at 3 °C for a period of 10 min commencing at post-fertilization 2.5min, and the fertilization rate and hatching rate in the cold shock treatment groups were (70.31±4.49)% and (21.5±6.63)%, respectively, which were significantly lower than that of diploid. Secondly, we found that the DNA relative content of triploid was 1.5 times larger than that of diploid by flow cytometer analysis, and the number of the chromosome in the triploid was 72, whereas the number of the chromosome in the diploid was 48 shown by karyotype analysis. The rate of the triploid was 100% in the present study. Thirdly, the gonadosomatic indexes of the triploids were significantly lower than that of the diploids. Histological results showed that the gonadal development of the triploids was slower than that of the diploids. At the age of 12 months, the testis and ovary of the diploids were both at the stage V, while the testis and ovary of the triploids were at stage III and stage I, respectively. Fourthly, the dmrt1 and vasa expression in the triploid testis and cyp19a expression in the triploid ovary were significantly lower than those in the diploid gonads (P<0.05), and the vasa expression in the triploid ovary was also lower than that in the diploids (P>0.05). The results indicated that the triploid yellow drum could be successfully induced by the cold shock treatment, and the gonadal development of the triploids was retarded. The results of present study will lay a basis for the application of the triploid in germ cell transplantation and the genetic improvement of yellow drum. [ABSTRACT FROM AUTHOR]

High temperature is considered to be one of the important causes of mass mortality of diploid and triploid oysters in summer. In order to compare the tolerance adaptability of diploid and triploid oysters to heat stress, the activities of superoxide dismutase activity (SOD), catalase activity (CAT) and contents of malondialdehyde (MDA) and the expression of Hsp70 and metallothionein (MT) genes in diploid and triploid oysters under acute and chronic heat stress were studied. The results showed that the survival rate of diploid oysters was significantly higher than that of triploid oysters under acute and chronic heat stress (p < 0.05). Under acute heat stress, the SOD levels in gills of both diploid and triploid oysters increased significantly from hour 3 (p < 0.05), but there was no significant difference in SOD levels between diploid and triploid oysters at all time points. The SOD level in hepatopancreas of triploid oysters was significantly higher than that of diploid oysters at all time points except 48 h (p < 0.05). The CAT level of diploid and triploid oysters decreased sharply at 48 h and that of diploid oysters was significantly higher than that of triploid oysters (p < 0.05). Under acute heat stress, the increase in MDA content in triploid oysters was significantly higher than that in diploid oysters (p < 0.05). Under acute heat stress, the expression levels of Hsp70 in the gills and hepatopancreas were significantly increased in diploid and triploid oysters (p < 0.05), but increased varies between gills and hepatopancreas. The expression levels of MT in the gills and hepatopancreas were significantly decreased in diploid and triploid oysters (p < 0.05). The results obtained in this study provide physiological and immunological evidence to explain differences in high‐temperature tolerance between diploid and triploid oysters and help us better understand the mass mortality of oysters that occurs during high temperatures in summer. [ABSTRACT FROM AUTHOR]

Simple Summary: The jumping plant louse Cacopsylla ledi (Flor, 1861) (Hempitera: Psylloidea) is a triploid apomictic parthenogenetic species. Occasionally, so-called rare males and diploid females that can interbreed with each other are found in the populations. If these bisexuals were able to move to a new area and establish a new population, this could eventually lead to the formation of a new bisexual species through a founder event. By using cytological and molecular approaches, we were able to find a bisexual lineage occurring together with triploid females in northern Fennoscandia and originating from rare males and diploid females, as evidenced by a shared haplotype with triploid parthenogenetic females. An independent bisexual population of parthenogenetic origin was found in the Kola Peninsula. By contrast, another bisexual lineage in southern Fennoscandia carried a different haplotype than the triploids in the same population. This lineage appeared to represent the ancestral bisexual C. ledi, which had moved postglacially northwards along with the triploid parthenogenetic females. As these lineages are well separated from each other, the population in the Kola Peninsula has the potential to develop into a new bisexual species refuting the view that parthenogenesis is an evolutionary dead end. A widely accepted hypothesis is that parthenogenesis is an evolutionary dead end since it is selectively advantageous in the short term only but results in lowered diversification rates. Triploid apomictic parthenogenesis might represent an exception, as in favorable environments, triploid females are able to produce rare males and diploid females. The aim of the present study was to analyze the modes of reproduction and their evolutionary implications in the parthenogenetic psyllid Cacopsylla ledi (Flor, 1861) from Fennoscandia. The cytogenetic assessment of ploidy levels and the analysis of the COI haplotype revealed two geographically separated bisexual lineages implying genuine bisexual populations. The southern lineage occurring south of latitude 65° N in Finland showed a COI haplotype different from that of parthenogenetic triploids in the same population but identical to the haplotype of specimens in a genuine bisexual population in the Czech Republic. This allows us to suggest that bisexuals in southern Fennoscandia represent the original bisexual C. ledi. By contrast, in the northern bisexual lineage north of latitude 65° N, rare males and diploid females carried the same haplotype as triploids in the same population, having been produced by the triploids. In the Kola Peninsula, a genuine bisexual population of presumably rare male/diploid female origin was discovered. As this population is geographically isolated from populations of the ancestral bisexual C. ledi, it can develop into a new bisexual species through peripatric speciation during evolution. Our findings demonstrate that apomictic triploid parthenogenesis is not necessarily an evolutionary dead end but is able to lead to the emergence of a new bisexual species of parthenogenetic origin. [ABSTRACT FROM AUTHOR]

Premise of research. Polyploidy and hybridization are prevalent and widespread phenomena in plants. The genetic consequences of genome duplication are numerous, but we understand very little about the comparative ecology of polyploids. In particular, the ways in which hybrid and polyploid offspring differ in ecology relative to their parents and relatives are poorly known. Among angiosperms, the triploid bridge is hypothesized to accrue some marginal fitness benefit to parent species from mostly sterile hybrid offspring. Because of the complexities of the fern life cycle, involving two free-living life stages, the ability to backcross via a triploid bridge should be more limited. If the triploid sporophyte offspring provide no fitness benefit to parents via subsequent generations, this raises the question about whether triploids further compete with parents by occupying similar ecological niches. We investigated comparative ecophysiology across light and wetness gradients of five members of the hybrid wood fern complex, Dryopteris. Methodology. We selected two related triads. Each triad consisted of a triploid and its diploid and tetraploid progenitor species: the D. × triploidea (3n) triad, with the parents D. carthusiana (4n) and D. intermedia (2n), and the D. × bootii (3n) triad, with the parents D. cristata (4n) and D. intermedia (2n). We sampled the temperature and relative humidity, population abundance and relative frequency, photosynthetic parameters, and hydraulic conductivity of populations to examine the extent of shared ecological niche space. Pivotal results. We found that triploids varied in habitat space relative to their parents. In the case of the triploid D. × bootii , this taxon occupied habitats similar to those of its parents at similar abundances and frequencies. In the case of D. × triploidea , the hybrid occurred across a more diverse range of habitats, which was more similar to its diploid parent. In both triads, the triploid's photosynthetic rate was intermediate between those of its parents, and the majority of the photosynthetic parameters were similar to those of the parents. There were some differences in hydraulic conductivity: xylem-specific hydraulic conductivity of the triploid D. × bootii was significantly higher than that of its diploid parent. Conclusions. Our results show that related triploids, diploids, and tetraploids substantially overlap in morphological and physiological niche space. The high relative frequency of triploids in habitats and the lack of clear niche partitioning within triads suggest that in addition to not contributing to parental reproductive fitness, the triploids could also negatively impact their progenitors by potentially competing for space and light resources in similar ways. [ABSTRACT FROM AUTHOR]

The impact that escaped farmed fish may have on wild populations is of major concern for Atlantic salmon (Salmo salar) farming. Triploid fish, being infertile, were originally introduced to mitigate the genetic impact of escaped fish. In the recent years, an increase in the number of infectious salmon anaemia (ISA) outbreaks in Norway has been observed, mainly in the northern parts, which is also where farming of triploid fish has been licensed. The present study investigated the susceptibility of triploid Atlantic salmon to ISA both by field observations and experimental infections. Based on field observations, we found an increased susceptibility, with 9.4 increased odds to primary ISA outbreaks in triploid fish versus diploid fish at production‐site level, and a tendency of increased odds (3.4) of ISA in triploid fish at individual cage level at sited with primary outbreaks. At some sites, ISA outbreaks were only diagnosed in cages with triploid fish and not in cages with diploid fish. Primary ISA outbreaks are the source for further spread of the disease, and it is noteworthy that in an experimental trial we found significantly more viral RNA in non‐ISA‐vaccinated triploid than in non‐ISA‐vaccinated diploid fish at the peak of the infection. Interestingly, the notable differences of susceptibility to ISA for non‐ISA vaccinated diploid and triploid fish observed in field were not repeated experimentally. The possible increased risk of ISA should be considered when evaluating the costs and benefits of triploid salmon in farming. It is recommended to keep triploid and diploid fish in biosecure separated sites, or that triploid fish are not farmed at all. [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 flowering, vigor, and monopodial plant structure, all of which may be useful in breeding for mechanical harvest in blueberry. In this study, tetraploid V. meridionale was successfully hybridized as both female and male with 2x Vaccinium vitis-idaea (section Vitis-idaea, lingonberry). The resultant F1 hybrids with lingonberry were both 3x and 4x, respectively. These hybrids were intermediate in morphology and notably vigorous. Most appear to be evergreen, with small, red-colored fruit. The 4x F1 hybrids displayed good fertility as females in backcrosses to both lingonberry and V. meridionale. Pollen production and quality were evaluated as an indicator of male fertility. Most clones had good pollen shed and high frequencies of well-formed tetrads. The overall fertility suggests that these hybrids, despite being derived from intersectional crosses, might be conventionally used for breeding without substantial difficulty.

Triploids have received increasing attention in the industrialization of oysters due to their fast growth rate, tolerance, and their sterility to be marketed year-round. Cultivating varieties or lines with special colors could be crucial for germplasm enrichment as well as traceability and intellectual property protection during the commercialization process. However, triploids and tetraploids with special colors have not been studied in the Fujian oyster Crassostrea angulata , which has seriously limited their commercialization and scalability. In this study, diploid and tetraploid C. angulata with normal, golden and black shell colors were used as parents and their corresponding triploids were constructed. The growth and survival of the nine groups were comprehensively evaluated during the larval and grow-out stages. Sex ratio, ploidy composition and thermotolerance were also statistically compared. All three triploid groups (NDT, GDT and BDT) exhibited significant advantages in growth and survival, compared to their diploid (NDD, GDD and BDD) and tetraploid (NTT, GTT and BTT) counterparts in all three sites. The triploid advantages in survival rate among NDT, GDT and BDT were 38.36%, 40.38% and 36.00%, respectively, at Jiaonan at day 480. Moreover, higher thermotolerances were exhibited in NDT, BDT and GDT, with the values of LT 50 at 41.77 °C, 42.28 °C and 42.13 °C, respectively. On the contrary, the three tetraploid C. angulata lines (NTT, GTT and BTT) exhibited poor growth, survival and thermotolerances. The values of LT 50 for GTT and NTT were comparable and lower than this of BTT (GTT: 39.85 °C; BTT: 41.05 °C; NTT: 39.57 °C). It is encouraging to note that the tetraploid rates also remained above 80% at day 480 in all three tetraploid lines. Based on our study, the three triploid C. angulata lines with normal, black, and golden shell colors showed great potential and can be industrialized as new varieties to improve the oyster industry. However, the inferior performance of tetraploids should not be overlooked and demands extra concern in the future breeding process. • We firstly constructed diploid, triploid and tetraploid Crassostrea angulata with normal, golden and black shell colors. • Significant triploid advantages in survival, growth and thermotolerance were observed among all three triploid lines. • The tetraploid rates also remained above 80% at day 480 in all three tetraploid lines. • The significant advantages of triploids and the inferior performance of tetraploids cannot be overlooked in the breeding process. [ABSTRACT FROM AUTHOR]

It is known that laccase genes are involved in lignin synthesis. Eucalyptus is an important timber species; functional studies of specific laccase members and their upstream regulatory factors in Eucalyptus are incomplete, and the mechanism of lignin content variation in polyploid plants remains unclear. Therefore, in this study, we investigated the function of EuLAC17 by overexpressing it in tobaccos and the result showed the lignin content in transgenic tobacco increased significantly. Further, yeast one hybrid sequencing was used to identify a series of potential regulatory factors of EuLAC17 , among which EuMYB308 showed the most significant correlation with EuLAC17. Yeast one hybrid, dual-luciferase reporter gene assay and electrophoretic mobility shift assay jointly verified that EuMYB308 could directly target the EuLAC17 promoter and repress its expression. In addition, overexpression of EuMYB308 resulted in significant reductions in plant growth, xylem cell lumen area, cell wall thickness and lignin content. Transcriptome sequencing showed that lignin biosynthesis genes including laccase genes were significantly differential expression in transgenic plants compared with wild-type plants. In triploid Eucalyptus urophylla , the expression of EuMYB308 was significantly upregulated, which may enhance the inhibition of EuLAC17 and thus reduce its expression level in triploid, which is one possible reason for the reduced lignin content in triploid E. urophylla. This study provides important insights into transcriptional regulation of lignin biosynthesis in Eucalyptus , and also contributes to revealing the genetic mechanism of lignin content variation in polyploid plants, which are of great significance for promoting the improvement of wood quality in forest trees and polyploid breeding. • EuMYB308 has an important influence on the regulation of lignin content in Eucalyptus urophylla. • A mode of negative regulation of lignin content by EuMYB308 targeting EuLAC17 was identified. • Differential expression of EuMYB308 may be an important reason for the reduced lignin content in triploid Eucalyptus. [ABSTRACT FROM AUTHOR]

Recent advances in genetic manipulation such as triploid breeding and artificial selection, have rapidly emerged as valuable hatchery methodologies for enhancing seafood stocks. The Pacific oyster Magallana gigas is a leading aquaculture species worldwide and key ecosystem engineer that has received particular attention in this field of science. In light of the growing recognition of the ecological effects of intraspecific variation, oyster polyploids provide a valuable opportunity to assess whether intraspecific diversity affects physiological responses to environmental stressors. While the responses of diploid and triploid oysters to climate change have been extensively investigated, research on their sensitivity to environmental pollution remains scarce. Here, we assess whether genotypic (i.e., ploidy) variation within Magallana gigas affects physiological responses to microplastic pollution. We show that diploid and triploid M. gigas have similar clearance rates and ingest similar amounts of microplastics under laboratory-controlled condition. In addition, they exhibited similar heart rates after prolonged exposure to microplastic leachates. Our findings suggest that intraspecific variations within M. gigas ploidy does not affect oyster responses to microplastic pollution. However, regardless of ploidy, our work highlights significant adverse effects of microplastic leachates on the heart rate of M. gigas and provides evidence of microplastic ingestion in the laboratory. [Display omitted] • We tested whether ploidy affects oyster responses to microplastic pollution. • We focused on diploid and triploid juvenile oyster, Magallana gigas. • Diploid and triploid ingested similar amount of polyester microfibre. • Diploid and triploid heart rate was similar but decreased after leachates exposure. • Oyster ploidy did not affect physiological responses to microplastic pollution. [ABSTRACT FROM AUTHOR]

The demands on aquaculture for high-value products, like the eastern oyster (Crassostrea virginica), continue to rise. To aid commercial production, hatcheries mate diploid females with tetraploid males to produce triploid offspring, which, in many instances, exhibit faster growth than diploid oysters and maintain meat quality during the reproductive season. Many factors limit triploid production by hatcheries, including low gamete quality. While it is known that abiotic factors can influence gamete performance in eastern oyster, the effects of salinity on triploid production are not well understood. To investigate these effects on gametogenesis and gamete quality, adult tetraploids and diploids were held in recirculating aquaculture systems (RAS) at 10, 20, and 30 PSU for 30 days. Each treatment contained six 140 L tanks with 15 oysters per ploidy. All morphometric measurements were recorded and the genotypic sex of the oysters was determined. Sperm density was quantified from tetraploid males. Sperm motility and velocity from tetraploid males was also analyzed by Computer Assisted Sperm Analysis, while their viability was determined using flow cytometry. ATP and lipid peroxidation were quantified for tetraploid sperm via bioluminescence and fluorescence, respectively. Eggs from diploid females were assessed for fecundity and size. For tetraploid males and diploid females, lipids from gonadal tissues were analyzed by gas chromatography. Results showed that survival, shell morphometrics, and sperm density were unaffected by salinity. However, variability in sperm density increased when tetraploids were held at 10 PSU. In general, sperm motion was suppressed for oysters held at 10 PSU, relative to the other salinity treatments. Sperm membrane viability was lowest and variability highest in oysters held at 30 PSU. Salinity did not impact the quantity of ATP in sperm. Lipid peroxidation was higher in oysters held at 30 PSU compared to 10 PSU, while those at 20 PSU demonstrated no significant difference compared to other treatments. Variation in lipid peroxidation was highest at 10 PSU. Oocyte irregularities were more prevalent when diploids were held at 10 and 30 PSU. Developmentally crucial lipids from females, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), were highest when oysters were held at 10 PSU, compared to 30 PSU, while the amount of these lipids from either salinity treatment was statistically different from 20 PSU. Fatty acid concentrations within the sperm from tetraploid males did not differ between salinities. In conclusion, gametes collected from both ploidies held at 20 PSU, performed as well or better than those from the other salinities for every hatchery and gamete-quality metric measured. • Identify how salinity (10, 20, 30 PSU) impacts gamete quality in Eastern oyster. • Generally, tetraploid sperm kinematics were suppressed at 10 PSU. • Oxidative stress in males increased at 30 PSU, while sperm viability decreased • Oocyte irregularities were more prevalent when diploids were held at 10 and 30 PSU • Crucial lipids (e.g., EPA, DHA) from females decreased as salinity increased. [ABSTRACT FROM AUTHOR]

Populus is a genus of 25−30 species of deciduous flowering plants in the family Salicaceae, which are primarily planted in short-rotation planations for producing timber, pulpwood, wooden products as well as bioenergy feedstock; they are also widely planted in agricultural fields and along roadsides as shelter forest belts for windbreak, decoration, and reduction of pollutants and noise. Moreover, their fast-growth and good adaptation to marginal lands enable them to provide some critical ecosystem services at various phytoremediation sites for land restoration and reclaimation. Thanks to their important roles, breeding for fast growing poplar trees has been one of the most important objectives for nearly a century. One of the most demonstrated, documented achievements in this aspect is polyploid breeding, especially triploid breeding. This paper critically reviews the various techniques used in inducing triploid plants, including natural 2n formation, artificial induction of 2n male and female gemmates through chemical or physical treatments, trait characterization of the triploid and tetraploid breeding populations, unveiling the molecular mechanisms underpinning the significantly improved traits, and identification and selection of the best triploid progenies. This review also recapitulated the challenges and strategies facing the future of triploid breeding in Populus, including amelioration of 2n gamete induction techniques and efficiency, selection of the best parents and identification of the best progrenies, utilization of the huge amount of genomic, transcriptomic, proteomic, metabolomic, and other omics data for selecting parents for improving target traits.

Triploid fish show significant growth heterosis compared to their parents, but its underlying molecular mechanisms are still largely unknown. In this study, Sequential Window Acquisition of All Theoretical Mass Spectra‐based quantitative proteomic profiling was performed on the liver tissues from triploid crucian carp (TCC) and its parents red crucian carp (RCC) and allotetraploid (4nAT). Comparative proteomics analysis revealed that several causal proteins were differentially regulated between TCC and its parents. Particularly, proteins eno3 (p = 1.18E‐3, ratio = 2.86 between TCC and RCC; p = 4.76E‐4, ratio = 4.92 between TCC and 4nAT) and glud1a (p = 4.4E‐7, ratio = 9.21 between TCC and RCC; p = 7.59E‐7, ratio = 4.57 between TCC and 4nAT) were significantly upregulated in triploid fish. Multiple bioinformatics analysis including functional enrichment, pathway analysis and protein–protein interaction network construction further suggested that these candidate proteins play crucial roles in regulating growth heterosis by mediating important metabolic pathways including 'carbohydrate metabolic process', 'glycolytic process' and 'glycolysis/gluconeogenesis' and 'carbon metabolism'. They may accelerate the processes of substrate and energy metabolism to meet the requirement of body growth. The identified candidate proteins such as eno3, glud1a in this study may serve as significant target indicators for further research involved in hybrid breeding and variety improvement. [ABSTRACT FROM AUTHOR]

Cultivated caladium (Caladium × hortulanum; 2n = 2x = 30) is an important ornamental aroid for the environmental horticulture industry. A better understanding of its genetic diversity is needed for continued improvement of caladium. The caladium germplasm maintained in the University of Florida's caladium breeding program were surveyed for potential variation in chromosome number and nuclear DNA content to gain a better understanding of caladium genetic diversity at the cytogenetic level. For the first time caladium triploidy was discovered in two breeding lines, UF-15-414 and UF-4407 with 2n = 3x = 45 chromosomes and a nuclear DNA content of 13.86 pg·2C21. In addition, a new chromosome number (2n = 2x = 34) was found in one cultivar, 'White Wing'. Compared with their diploid parents or grandparents, the triploids showed a distinct, attractive leaf morphology with rounder and thicker leaves. The pollen stainability of UF-15-414 and UF-4407 was 63% and 73%, respectively, indicating potential male fertility, which was unexpected. Analysis of simple sequence repeat (SSR) marker banding patterns confirmed that UF-15-414 was a direct progeny of UF-4407 through hybridization with the diploid cultivar Aaron, whereas UF-4407 might result from fusion of an unreduced (female or male) gamete with a reduced gamete. Chromosome counting and SSR marker analysis of 'White Wing' and its progeny cultivars 'White Wonder' and 'White Delight' suggested that 'White Wing' possibly transmitted its 34 chromosomes to progeny during sexual reproduction. The discovery and characterization of these triploids revealed the occurrence of natural sexual polyploidization in caladium and indicated good potential for creating and selecting new triploids for future caladium breeding. The observed new chromosome number in 'White Wing' and its progeny cultivars implies that other chromosome variations may be present among cultivated caladiums. In summary, these results revealed two male-fertile triploid caladiums and a new chromosome number that can enrich the cytogenetic diversity in future caladium cultivar development. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Cultivated caladium (Caladium × hortulanum; 2n = 2x = 30) is an important ornamental aroid for the environmental horticulture industry. A better understanding of its genetic diversity is needed for continued improvement of caladium. The caladium germplasm maintained in the University of Florida’s caladium breeding program were surveyed for potential variation in chromosome number and nuclear DNA content to gain a better understanding of caladium genetic diversity at the cytogenetic level. For the first time caladium triploidy was discovered in two breeding lines, UF-15-414 and UF-4407 with 2n = 3x = 45 chromosomes and a nuclear DNA content of 13.86 pg·2C−1. In addition, a new chromosome number (2n = 2x = 34) was found in one cultivar, ‘White Wing’. Compared with their diploid parents or grandparents, the triploids showed a distinct, attractive leaf morphology with rounder and thicker leaves. The pollen stainability of UF-15-414 and UF-4407 was 63% and 73%, respectively, indicating potential male fertility, which was unexpected. Analysis of simple sequence repeat (SSR) marker banding patterns confirmed that UF-15-414 was a direct progeny of UF-4407 through hybridization with the diploid cultivar Aaron, whereas UF-4407 might result from fusion of an unreduced (female or male) gamete with a reduced gamete. Chromosome counting and SSR marker analysis of ‘White Wing’ and its progeny cultivars ‘White Wonder’ and ‘White Delight’ suggested that ‘White Wing’ possibly transmitted its 34 chromosomes to progeny during sexual reproduction. The discovery and characterization of these triploids revealed the occurrence of natural sexual polyploidization in caladium and indicated good potential for creating and selecting new triploids for future caladium breeding. The observed new chromosome number in ‘White Wing’ and its progeny cultivars implies that other chromosome variations may be present among cultivated caladiums. In summary, these results revealed two male-fertile triploid caladiums and a new chromosome number that can enrich the cytogenetic diversity in future caladium cultivar development.

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.

Populus ussuriensis Kom. is a valuable forest regeneration tree species in the eastern mountainous region of Northeast China. It is known that diploid P. ussuriensis (CK) performed barely satisfactorily under salt stress, but the salt stress tolerance of polyploid (i.e., triploid (T12) and tetraploid (F20)) P. ussuriensis is still unknown. In order to compare the salt stress tolerance and salt stress response mechanism between diploid and polyploid P. ussuriensis, phenotypic observation, biological and biochemistry index detections, and transcriptome sequencing (RNA-seq) were performed on CK, T12, and F20. Phenotypic observation and leaf salt injury index analysis indicated CK suffered more severe salt injury than T12 and F20. SOD and POD activity detections indicated the salt stress response capacity of T12 was stronger than that of CK and F20. MDA content, proline content and relative electric conductivity detections indicated CK suffered the most severe cell-membrane damage, and T12 exhibited the strongest osmoprotective capacity under salt stress. Transcriptome analysis indicated the DEGs of CK, T12, and F20 under salt stress were different in category and change trend, and there were abundant WRKY, NAM, MYB and AP2/ERF genes among the DEGs in CK, T12, and F20 under salt stress. GO term enrichment indicated the basic growth progresses of CK, and F20 was obviously influenced, while T12 immediately launched more salt stress response processes in 36 h after salt stress. KEGG enrichment indicated the DEGs of CK mainly involved in plant–pathogen interaction, ribosome biogenesis in eukaryotes, protein processing in endoplasmic reticulum, degradation of aromatic compounds, plant hormone signal transduction, photosynthesis, and carbon metabolism pathways. The DEGs of T12 were mainly involved in plant–pathogen interaction, cysteine and methionine metabolism, phagosomes, biosynthesis of amino acids, phenylalanine, tyrosine and tryptophan biosynthesis, plant hormone signal transduction, and starch and sucrose metabolism pathways. The DEGs of F20 were mainly involved in plant hormone signal transduction, plant–pathogen interaction, zeatin biosynthesis, and glutathione metabolism pathways. In conclusion, triploid exhibited stronger salt stress tolerance than tetraploid and diploid P. ussuriensis (i.e., T12 > F20 > CK). The differences between the DEGs of CK, T12, and F20 probably are the key clues for discovering the salt stress response signal transduction network in P. Ussuriensis. [ABSTRACT FROM AUTHOR]

This study examined the impact of rearing temperature (10.5, 13.5 or 16.5°C) on the hepatic transcriptome of AquAdvantage Salmon (growth hormone transgenic female triploid Atlantic salmon) at an average weight of 800 g. Six stranded PE libraries were Illumina-sequenced from each temperature group, resulting in an average of over 100 M raw reads per individual fish. RNA-sequencing (RNA-seq) results showed the greatest difference in the number of differentially expressed transcripts (1750 DETs), as revealed by both DESeq2 and edgeR (q < 0.05; fold-change > |1.5|), was between the 10.5 and 16.5°C temperature groups. In contrast, 172 and 52 DETs were found in the 10.5 vs. 13.5°C and the 13.5 vs. 16.5°C comparisons, respectively. Considering the DETs between the 10.5 and 16.5°C groups, 282 enriched gene ontology (GO) terms were identified (q < 0.05), including "response to stress", "immune system process", "lipid metabolic process", "oxidation-reduction process", and "cholesterol metabolic process", suggesting elevated temperature elicited broad effects on multiple biological systems. Pathway analysis using ClueGO showed additional impacts on amino acid and lipid metabolism. There was a significant positive correlation between RNA-seq and real-time quantitative polymerase chain reaction (RT-qPCR) results for 8 of 9 metabolic-related transcripts tested. RT-qPCR results also correlated to changes in fillet tissue composition previously reported in these salmon (e.g., methionine and lysine concentrations positively correlated with hsp90ab1 transcript expression), suggesting that rearing temperature played a significant role in mediating metabolic/biosynthetic pathways of AquAdvantage Salmon. Many transcripts related to lipid/fatty acid metabolism (e.g., elovl2 , fabpi , hacd2 , mgll , s27a2 , thrsp) were downregulated at 16.5°C compared to both other temperature groups. Additionally, enrichment of stress-, apoptosis- and catabolism-relevant GO terms at 16.5°C suggests that this temperature may not be ideal for commercial production when using freshwater recirculating aquaculture systems (RAS). This study relates phenotypic responses to transcript-specific findings and therefore aids in the determination of an optimal rearing temperature for AquAdvantage Salmon. With approval to grow and sell AquAdvantage Salmon in the United States and Canada, the novel insights provided by this research can help industry expansion by promoting optimal physiological performance and health. [ABSTRACT FROM AUTHOR]

Purpose: Human trophoblast stem cells (hTSCs) are counterparts of the precursor cells of the placenta and are valuable cell models for the study of placental development and the pathogenesis of placental diseases. The aim of this work was to establish a triploid human TSC (hTSC3PN) derived from the tripronuclear embryos, which are clinically discarded but readily available, for potential applications in basic placental research and disease modeling. Methods: Eighteen tripronuclear human zygotes from IVF were collected and cultured for 5–6 days. Five high-quality blastocysts were harvested and were individually cultured in hTSC medium. Finally, two hTSC lines were established after 10 days and could be passaged stably. Results: The karyotyping analysis showed that hTSC3PN contained three sets of chromosomes. And the hTSC3PN exhibited typical features of hTSCs, with the ability to differentiate into two trophoblast lineages: extravillous cytotrophoblasts (EVTs) and syncytiotrophoblasts (STs). In addition, the hTSC3PN can mimic some vital features of trophoblast, including hormone secretion and invasion. Further studies showed that the proliferation and differentiation of hTSC3PN were reduced compared with normal hTSCs, which may be related to the disturbed metabolic signaling in hTSC3PN. Conclusions: We established the triploid hTSC lines derived from tripronuclear embryos, which provides a potentially useful research model in vitro to study human placental biology and diseases. [ABSTRACT FROM AUTHOR]

After polyploidization, plants usually undergo some morphological and physiological changes, including the lignin content of polyploids usually becoming lower than that of diploids. However, the regulatory mechanism of the variation of lignin content in polyploid plants remains unclear. Therefore, in this research, we used full-sib poplar triploids and diploids to explore the molecular regulatory basis of lignin content in poplar triploid leaves through the determination of lignin content, the observation of xylem cells, and transcriptome sequencing. The results showed that the lignin content of triploid leaves was significantly lower than that of diploid leaves. The xylem cells of triploid leaves were significantly larger than those of diploids. Transcriptome sequencing data show that most lignin biosynthesis genes were significantly downregulated, and genes related to cell growth were mostly upregulated in triploid leaves compared with diploid leaves. In addition, co-expression network analysis showed that several transcription factors might be involved in the regulation of lignin biosynthesis. Consequently, the altered expression of genes related to lignin might lead to the reduced lignin content in triploids. These results provide a theoretical basis for further exploring the molecular mechanism of the variation of polyploid lignin content and the utilization of polyploid lignocellulosic resources. [ABSTRACT FROM AUTHOR]

Based on the allodiploid lineage (WR, 2n ​= ​100, F1–F5) of white crucian carp (Carassius cuvieri, WCC, 2n ​= ​100) (♀) ​× ​red crucian carp (Carassius auratus red var., RCC, 2n ​= ​100) (♂) and the diploid hybrid fish (WR-II, 2n ​= ​100) derived from WR-F1 (♀) ​× ​WCC (♂), in this research, we obtain a new type of triploid fish (WR-III) by the distant hybridization of WR-II (♀) and autotetraploid fish (4nAU, 4n ​= ​200) (♂). We investigate the morphological traits, chromosomal numbers, DNA content, growth rates and 5S rDNA in the WR-III. The results show that the WR-III is triploid fish with 150 chromosomes and they have no barbel and have a gray body color. All the measurable traits of WR-III show hybrid characteristics; and there is a significant difference in the body length/body height between WR-III and 4nAU, which indicating that WR-III has a smaller head and higher body compared with 4nAU; furthermore, the WR-III has a fast growth rate, the average body weights of eight months old WR-III is 487g. The 5s rDNA of the WR-III inherits the 5s rDNA of its parents and has some mutant bases or chimeric sequences, which revealed heredity, variability and heterozygosity in WR-III. The successful production of this triploid fish is of great significance in fish genetic breeding.

China has the highest oyster yield in the world, with Crassostrea gigas and C. angulata being the two most productive oysters species. The hybrid triploid of Crassostrea gigas and C. angulata exhibits good heat resistance and can mitigate the plight of mass mortality of Crassostrea gigas in northern China caused by high temperature and spawning during the summer. Additionally, triploid oysters have reduced fecundity, which allows the energy typically used for gonad development to be redirected to somatic cell growth, resulting in better taste and lower mortality during the reproductive season. Therefore, it is essential to study the detailed gonad development of hybrid triploid oysters. This study compared the gonad development between autotriploids (TGG-diploid C. gigas ♀ × tetraploid C. gigas ♂) and allotriploids (TAG-diploid C. angulata ♀ × tetraploid C. gigas ♂) during the breeding season. Results showed that the female proportion of TGG increased gradually with rising temperature, reaching a peak of 57.1% in August, whereas the proportion of females in TAG was lower, with males accounting for >50% from June to August 2023. Histological analysis revealed that the proportion of female α (producing many oocytes) increased with gonad development, peaking for TGG female α in July and for TAG female α in September. Moreover, the number of sperm in male TAG gonadal tubules was less than in male TGG, and more apoptotic cells were observed in the ultrastructure of male TAG gonad, which was confirmed by apoptosis experiment. Based on these results, it is suggested that the gonad development of female and hermaphrodite TAG were delayed compared with TGG, and the level of sterility in male TAG should be higher than in male TGG. • First comparative histological analysis of gonad development of triploid Crassostrea gigas and hybrid triploid of C. gigas and C. angulata (TAG). • TAG had higher male proportion during the breeding season. • Gonad development of female and hermaphrodite TAG were delayed compared with triploid C. gigas. • Male TAG sterility was higher compared with male triploid C. gigas. [ABSTRACT FROM AUTHOR]

This study examined the impact of rearing temperature (10.5, 13.5 or 16.5°C) on the hepatic transcriptome of AquAdvantage Salmon (growth hormone transgenic female triploid Atlantic salmon) at an average weight of 800 g. Six stranded PE libraries were Illumina-sequenced from each temperature group, resulting in an average of over 100 M raw reads per individual fish. RNA-sequencing (RNA-seq) results showed the greatest difference in the number of differentially expressed transcripts (1750 DETs), as revealed by both DESeq2 and edgeR (q < 0.05; fold-change > |1.5|), was between the 10.5 and 16.5°C temperature groups. In contrast, 172 and 52 DETs were found in the 10.5 vs. 13.5°C and the 13.5 vs. 16.5°C comparisons, respectively. Considering the DETs between the 10.5 and 16.5°C groups, 282 enriched gene ontology (GO) terms were identified (q < 0.05), including “response to stress”, “immune system process”, “lipid metabolic process”, “oxidation-reduction process”, and “cholesterol metabolic process”, suggesting elevated temperature elicited broad effects on multiple biological systems. Pathway analysis using ClueGO showed additional impacts on amino acid and lipid metabolism. There was a significant positive correlation between RNA-seq and real-time quantitative polymerase chain reaction (RT-qPCR) results for 8 of 9 metabolic-related transcripts tested. RT-qPCR results also correlated to changes in fillet tissue composition previously reported in these salmon (e.g., methionine and lysine concentrations positively correlated with hsp90ab1 transcript expression), suggesting that rearing temperature played a significant role in mediating metabolic/biosynthetic pathways of AquAdvantage Salmon. Many transcripts related to lipid/fatty acid metabolism (e.g., elovl2, fabpi, hacd2, mgll, s27a2, thrsp) were downregulated at 16.5°C compared to both other temperature groups. Additionally, enrichment of stress-, apoptosis- and catabolism-relevant GO terms at 16.5°C suggests that this temperature may not be ideal for commercial production when using freshwater recirculating aquaculture systems (RAS). This study relates phenotypic responses to transcript-specific findings and therefore aids in the determination of an optimal rearing temperature for AquAdvantage Salmon. With approval to grow and sell AquAdvantage Salmon in the United States and Canada, the novel insights provided by this research can help industry expansion by promoting optimal physiological performance and health.

Tetraploid oysters hold a significant position in the global oyster industry, particularly as core germplasm resources for the production of triploids. Triploids exhibit desirable characteristics such as reduced gonadal development, larger adult size, and superior flesh quality compared with diploids. However, tetraploids often face challenges of slow growth and chromosomal instability during the breeding process, and the mechanisms underlying the formation of these polyploid characteristics remain unclear. This study aimed to elucidate these mechanisms by constructing a polyploid oyster system and comparing the differences in growth-related phenotypes and gene expression among diploids, triploids, and tetraploids. We identified 1404 differentially expressed genes (DEGs) between diploids and triploids, 1814 DEGs between triploids and tetraploids, and 933 DEGs between diploids and tetraploids. Furthermore, we observed distinct gene expression patterns related to innate immunity response and biomineralization between different ploidy levels. Through trend analysis, we clustered genes with similar expression level changes across different ploidy levels and conducted gene ontology (GO) enrichment analysis on genes with different expression profiles. The results indicated that genes associated with the innate immunity response exhibited significantly upregulated expression with increasing ploidy, while genes related to biomineralization showed higher or lower expression levels in triploid oysters. As biomineralization is closely linked to oyster shell growth, this highlights the crucial role of genes associated with biomineralization in regulating the rapid shell growth observed in triploid oysters. Confronted with environmental challenges, tetraploid oysters may display a stronger innate immune response than diploids and triploids. Our study provides valuable resources for investigating the functional aspects of genes related to polyploid phenotype differences and offers new insights into the molecular mechanisms of existing issues in tetraploid oyster breeding. • Triploid oysters show enhanced calcium transport, regulation, and protein degradation. • Chromosomal duplication affects polyploid oysters' growth and adaptability. • Gene replication exhibits detrimental dosage effects following duplication. [ABSTRACT FROM AUTHOR]

Sterility caused by triploidization holds promising commercial implications in aquaculture. In this study, we conducted a thorough investigation into the spermatogenesis of triploid male oysters (Crassostrea gigas) to evaluate their fertility. Histological analysis and immunostaining revealed the presence of numerous immature spermatocytes and a markedly low abundance of mature spermatozoa in triploid males, indicating a robust blockade in spermatogenesis. Ultrastructural analysis and apoptosis analysis demonstrated that triploid males underwent normal spermatogonial mitosis during early spermatogenesis, like diploids. Analysis of phosphorylated histone H2AX (γ-H2AX) displayed heightened γ-H2AX staining in developed triploid male gonads, with a significantly higher number of apoptotic cells confirmed by the TUNEL assay compared to diploid counterparts. These findings suggest a potential arrest at the zygotene stage, preventing the completion of the zygotene-pachytene transition and ultimately leading to cell apoptosis. Flow cytometry results confirmed aneuploidy in spermatozoa from triploid oysters, containing approximately 1.5 times the DNA content of spermatozoa from diploid oysters. Notably, the sperm head size and flagella length in triploid oysters surpassed those in their diploid counterparts. Occasional observations of two-tailed spermatozoa in triploid males were noted. This study provides novel insights into the blocked spermatogenesis in triploid oysters, emphasizing the sterility of triploid male oysters and its relevance in aquaculture practices. • Spermatogenesis in triploid oysters undergoes meiotic prophase I arrest, failing to progress beyond the zygotene stage. • The meiotic arrest induces cell apoptosis and restricts the growth of gonadal tubules. • Triploid males generate a small number of abnormal aneuploid spermatozoa, which may lead to failed fertilization outcomes. [ABSTRACT FROM AUTHOR]

Eucommia ulmoides is a temperate gum source plant that produces trans-polyisoprene (TPI), also known as Eucommia rubber. The structural configuration and function of TPI offer a new material with important potential for industrial development. In this study, we detected the TPI content in the leaves of diploid and triploid E. ulmoides plants. The average TPI content in the leaves of triploid E. ulmoides was significantly higher than that of diploid. Transcriptome data and weighted gene co-expression network analyses identified a significant positive correlation between the EuFPS1 gene and TPI content. Overexpression of EuFPS1 increased the density of rubber particles and TPI content, indicating its crucial role in TPI biosynthesis. In addition, the expression of EuHDZ25 in E. ulmoides was significantly positively correlated with EuFPS1 expression. Yeast one-hybrid and dual-luciferase assays demonstrated that EuHDZ25 mainly promotes TPI biosynthesis through positive regulation of EuFPS1 expression. The significantly up-regulated expression of EuHDZ25 and its consequent upregulation of EuFPS1 during the biosynthesis of TPI may partially explain the increased TPI content of triploids. This study provides an important theoretical foundation for further exploring the molecular mechanism of secondary metabolites content variation in polyploids and can help to promote the development and utilization of rubber resources. [ABSTRACT FROM AUTHOR]

The triploid Pacific abalone (Haliotis discus hannai) has significant economic value and promising application prospects. However, the optimal cultural conditions that maximize the advantages of triploidy in the abalone have yet to be determined. This study examined the properties of triploid Pacific abalone after 3 months of culture under three constant temperatures (18 °C, 22 °C, and 26 °C) to fill up this information gap. The results showed that the survival rate of triploids in the 26 °C group was significantly higher than that of diploids (P < 0.05), while the survival rate of triploids in the other two groups was similar to that of diploids (P > 0.05). Except for the shell width of the 22 °C group and the shell length of the 26 °C group, triploid Pacific abalone exhibited significantly superior growth traits compared to diploids at all temperatures (P < 0.05). The most notable improvement was observed in the foot muscle weight trait, where there were triploid advantage rates of 81.44% (18 °C), 76.21% (22 °C), and 54.96% (26 °C). The specific growth rate and the ratio of shell length and body weight indicated that triploids grew the fastest in the 22 °C group. Furthermore, the thermal resistance of diploids and triploids was evaluated through the Arrhenius break temperature (ABT) of cardiac performance. The results demonstrated that the ABT of triploids was significantly higher than that of diploids (P < 0.05, ABT 2N = 30.81 ± 0.43 °C, ABT 3N = 31.38 ± 0.72 °C). Both diploid and triploid foot adhesion forces were measured, and the results showed that triploid foot adhesion force was stronger than that of diploids (P < 0.05). Additionally, there was a significant positive correlation between foot adhesion force and meat yield traits (foot muscle weight, fullness index (FI) and foot muscle-soft tissue index (FMSI)) (P < 0.05). In summary, this study confirmed the triploid advantage in meat yield of Pacific abalone and identified a temperature range that maximizes their growth rate. Moreover, triploids exhibited improved thermal resistance and adhesion capacity compared to diploids, with an increase in meat yield. The results of this study could serve as a reference for identifying a culture model suitable for triploid Pacific abalone and thus could promote the development of the triploid aquaculture industry. • Growth performance of triploids in the three temperature groups was better than that of their diploid counterparts. • The highest growth rate of triploid abalone was observed at the 22 °C group. • The most notable triploid advantages were observed in meat yield traits. • Water temperature appeared to be an important abiotic factor in the grow-out phase of triploid Pacific abalone. [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.

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.

Polyploidy, the expression of more than two sets of chromosomes, is common in plants, and is thought to influence plant trait expression and drive plant species evolution. The degree to which polyploidy influences interactions among physiological processes such as growth and defense in natural populations through its effect on phenotypic variability is poorly understood. We link broad plant genotypic features (including polyploidy) to phenotypic expression of growth and chemical defense in natural populations of quaking aspen (Populus tremuloides) to examine patterns in resource allocation that might drive growth-defense tradeoffs. Quaking aspen are capable of rapid growth, and are also a primary food plant for a large range of herbivores, including insects and ungulates. While often diploid, aspen can exhibit polyploidy as triploid clones. We tested for the effect of genotype, cytotype (ploidy level, divided between diploids and triploids), and ramet age on relationships between growth and leaf chemistry across natural aspen clones in northern Utah. Substantial genotype variability in growth and leaf chemistry occurred across both cytotypes. Phenolic glycosides, but not condensed tannins, were negatively related to growth. Ramet age was also negatively related to growth. Phenolic glycosides were negatively related to condensed tannins, but only for the diploid clones. Triploid clones exhibited ~ 20% higher levels of phenolic glycosides than diploids. Growth in quaking aspen was likely sacrificed for the production of phenolic glycosides. Our study underscores the importance of considering polyploidy, genetic variability, and ramet age in understanding growth-defense tradeoffs in natural populations of clonal organisms, such as quaking aspen. [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 flowering, vigor, and monopodial plant structure, all of which may be useful in breeding for mechanical harvest in blueberry. In this study, tetraploid V. meridionale was successfully hybridized as both female and male with 2x Vaccinium vitis-idaea (section Vitis-idaea, lingonberry). The resultant F1 hybrids with lingonberry were both 3x and 4x, respectively. These hybrids were intermediate in morphology and notably vigorous. Most appear to be evergreen, with small, red-colored fruit. The 4x F1 hybrids displayed good fertility as females in backcrosses to both lingonberry and V. meridionale. Pollen production and quality were evaluated as an indicator of male fertility. Most clones had good pollen shed and high frequencies of well-formed tetrads. The overall fertility suggests that these hybrids, despite being derived from intersectional crosses, might be conventionally used for breeding without substantial difficulty. [ABSTRACT FROM AUTHOR]

Pumpkin rootstock affects watermelon scion growth, fruit yield, and quality, but the mechanisms of related key enzymes and photosynthesis remain unclear. In this study, net photosynthetic rate (PN), chlorophyll (Chl) fluorescence parameters, fruit mass and sugar accumulation, and related key enzyme activities were determined during the fruit development stage in diploid and triploid watermelon lines and corresponding pumpkin rootstock-grafted lines. The results showed that pumpkin rootstock increased PN and Chl fluorescence parameters of diploid and triploid watermelon, indicating that pumpkin rootstock could increase photosynthesis, the utilization efficiency of light energy of diploid and triploid watermelon lines. Pumpkin-grafted lines had higher alkaline α-galactosidase activity and lower activities of insoluble acid invertase, sucrose phosphate synthase, and sucrose synthase than corresponding own-root lines in diploid and triploid watermelon. It indicates that pumpkin rootstock could increase the unloading of photoassimilates and reduce the conversion of photoassimilates into sucrose in diploid and triploid watermelon fruits.

Background Coral reefs house about 25% of marine biodiversity and are critical for the livelihood of many communities by providing food, tourism revenue, and protection from wave surge. These magnificent ecosystems are under existential threat from anthropogenic climate change. Whereas extensive ecological and physiological studies have addressed coral response to environmental stress, high-quality reference genome data are lacking for many of these species. The latter issue hinders efforts to understand the genetic basis of stress resistance and to design informed coral conservation strategies. Results We report genome assemblies from 4 key Hawaiian coral species, Montipora capitata, Pocillopora acuta, Pocillopora meandrina , and Porites compressa. These species, or members of these genera, are distributed worldwide and therefore of broad scientific and ecological importance. For M. capitata , an initial assembly was generated from short-read Illumina and long-read PacBio data, which was then scaffolded into 14 putative chromosomes using Omni-C sequencing. For P. acuta, P. meandrina , and P. compressa , high-quality assemblies were generated using short-read Illumina and long-read PacBio data. The P. acuta assembly is from a triploid individual, making it the first reference genome of a nondiploid coral animal. Conclusions These assemblies are significant improvements over available data and provide invaluable resources for supporting multiomics studies into coral biology, not just in Hawaiʻi but also in other regions, where related species exist. The P. acuta assembly provides a platform for studying polyploidy in corals and its role in genome evolution and stress adaptation in these organisms. [ABSTRACT FROM AUTHOR]

To study pollen characteristics of triploid Salvia miltiorrhiza(tetraploid S. miltiorrhiza f. alba × diploid S. miltiorrhiza)hybrid, morphological variation of triploid pollen during the triploid process was examined. Triploid and diploid pollen were observed at microscopic and ultra-microscopic level using light and scanning electron microscopes. Pollen size and shape data were analyzed to determine statistical significance. The results were as follows:(1)Compared to typical 6-colpate diploid pollen grains, triploid S. miltiorrhiza are 6- or 8-colpate, with increased number of colpi and heterogenous granules on colpus membranes, and abnormal colpate.(2)Exine sculpturing of triploid pollen was reticulate like the diploid. Both 6- and 8-colpate triploid pollen had no perforation or a few small perforations, whereas diploid pollen had many large polygonal perforations in each lumen.(3)In terms of size, mean of the polar axis(P)and equatorial axis(E)in triploid pollen were significantly smaller than that of diploid pollen. The pollen size of triploid hybrid followed a skewed normal distribution, and the coefficient of variation(CV)in P*E value of triploid was greater than that of diploid and existed extreme values. Comparison data revealed variance in colpi and sculpture between triploid and diploid, however no significant differences in pollen shape is found. Overall, the triploid S. miltiorrhiza pollen has more morphological variations due to genetic effect of both ploidy level and heterozygosity. [ABSTRACT FROM AUTHOR]

The spermatozoa of triploid gynogenetic crucian carp (Carassius auratus) (3nDTCC) possess a spermatogenesis process with a normal genetic background. However, the genetic materials of these spermatozoa do not completely inherit gynogenetic progeny in general. Understanding the intrinsic mechanism may be helpful for developing breeding strategies of gynogenetic fishes. In this study, the spermatozoa ultrastructure was systematically studied in diploid red crucian carp and 3nDTCC to demonstrate their cytological structural differences. In addition, the artificial breeding tests of 3nDTCC(♀) with different ploidy spermatozoa were performed to verify the contributions of genetic materials from 3nDTCC spermatozoa to the gynogenesis progeny. Furthermore, the mRNA expression of centriole-related genes (i.e., cep57 , cetn1 , rootletin , and nek2) involved in spermatozoa packaging was also determined by quantitative real-time PCR (qPCR) to illustrate the molecular expression characteristics of the spermatozoa packaging process in 3nDTCC. The results reveal the adaptive features of spermatozoa in 3nDTCC, including the loose midpiece structure, abnormal head structure, and abnormal expression of centriole-related genes, which may influence the motility of spermatozoa and make it not involved normally in the genetic composition of the gynogenesis offspring. [ABSTRACT FROM AUTHOR]

Chromosomal ploidy manipulation is one of the means to create excellent germplasm. Triploid fish could provide an ideal sterile model for searching of a underlying mechanism of abnormality in meiosis. The complete understanding of the coding and noncoding RNAs regulating sterility caused by meiosis abnormality is still not well understood. By high-throughput sequencing, we compared the expression profiles of gonadal mRNA, long non-coding RNA (lncRNA), and microRNA (miRNA) at three different developmental stages between the diploid (XX) and triploid (XXX) female rainbow trout. These stages were gonads before differentiation (65 days post fertilisation, dpf), at the beginning of morphological differences (180 dpf) and showing clear difference between diploids and triploids (600 dpf), respectively. A majority of differentially expressed (DE) RNAs were identified, and 22 DE mRNAs related to oocyte meiosis and homologous recombination were characterized. The predicted miRNA-mRNA/lncRNA networks of 3 developmental stages were constructed based on the target pairs of DE lncRNA-miRNA and DE mRNA-miRNA. According to the networks, meiosis-related gene of ccne1 was targeted by dre-miR-15a-5p_R + 1, and 6 targeted DE lncRNAs were identified. Also, qRT-PCR was performed to validate the credibility of the network. Overall, this study explored the potential interplay between coding and noncoding RNAs during the gonadal development of polyploid fish. The mRNA, lncRNA and miRNA screened in this study may be helpful to identify the functional elements regulating fertility of rainbow trout, which may provide reference for character improvement in aquaculture. • miRNA-mRNA/lncRNA interaction networks of gonadal development in triploid fishes. • 22 genes were related to oocyte meiosis and homologous recombination. • 6 lncRNAs regulate meiosis as the target of miR-15a-5p. • Polyploidy-associated effects on fertility of fish. [ABSTRACT FROM AUTHOR]

Meiosis is the key process for producing mature gametes. A natural fertile triploid Carassius auratus population (3nDTCC) and an artificially derived sterile triploid crucian carp (3nCC) have been previously observed, providing suitable model organisms for investigating meiosis characteristics in triploid fish. In the present study, the microstructures and ultrastructures of spermatogenesis were studied in these fishes. TdT-mediated dUTP nick end labeling detection was performed to investigate the apoptosis of spermatocytes. Fluorescence in situ hybridization was employed to trace chromatin pairing. In addition, the mRNA expressions of cell cycle-related genes (i.e., cell division control 2 and cell cycle protein B) were determined by quantitative realtime polymerase chain reaction to illustrate the molecular mechanism of abnormal meiosis in the 3nCC. The results showed that the 3nCC undergoes an irregular prophase I, with the chromosomes distributed in a unipolar radial manner and exhibiting partial pairing, hindered metaphase I, and degenerated cells in the subsequent stages. Meanwhile, the 3nDTCC presented a relatively regular meiotic prophase I with complete conjugate chromosome pairs and chromosomes distributed along the karyotheca, which were presented as a ring structure by slicing. Only the spreads with 130–150 irregular chromosomes can be easily detected in the 3nDTCC, suggesting that it may undergo an abnormal metaphase I. This study provides new insights into the meiosis of fertile and sterile triploid cyprinid fish. [ABSTRACT FROM AUTHOR]