Search

Odd ploidy-level cytotypes in sexually reproducing species are considered a dead end due to absent or reduced fertility. If sterility is only partial, however, their contribution to the population gene pool can be augmented by longevity and clonal growth. To test this, we investigated the cytotype origin and spatial pattern, and pollen viability in three relict shrub species of the genus Daphne (Thymelaeaceae Juss.) in central Europe. Daphne cneorum subsp. cneorum is a widespread European species that has a broad ecological amplitude, whereas D. cneorum subsp. arbusculoides and D. arbuscula are narrow endemics of the western Pannonian Plain and the Western Carpathians, respectively. Our study confirmed that all three taxa are diploid. However, of more than a thousand analysed individuals of D. cneorum subsp. cneorum , five in four different populations were triploid. Our data indicate that these triploids most likely originate from recurrent autopolyploidization events caused by the fusion of reduced and unreduced gametes. High pollen viability was observed in all three taxa and in both diploid and triploid cytotypes, ranging from 65 to 100 %. Our study highlights the significant role of odd ploidy-level cytotypes in interploidy gene flow, calling for more research into their reproduction, genetic variability, and overall fitness. Interestingly, while the endemic D. arbuscula differs from D. cneorum based on genetic and genome size data, D. cneorum subsp. arbusculoides was indistinguishable from D. cneorum subsp. cneorum. However, our study reveals that the subspecies differ in the number of flowers per inflorescence. This is the first comprehensive cytogeographic study of this intriguing genus at a regional scale, and in spite of its karyological stability, it contributes to our understanding of genomic evolution in plant species with a wide ecological amplitude. [ABSTRACT FROM AUTHOR]

Female hemp plants are desired in floral hemp operations due to their higher cannabinoid contents. To produce feminized seeds, a critical step of inducing fertile male flowers on female plants is performed. In feminized seed production, freshly mixed STS (silver thiosulfate + sodium thiosulfate) is applied to female plants as an ethylene inhibitor to induce male flowers. However, the short-shelf stability of the STS buffer can cause difficulty in the application and inconsistent results. Alternative methods with improved accessibility and stable buffers will be beneficial for the hemp industry and hemp breeders. A commercially available floriculture product, Chrysal ALESCO®, contains silver nitrate, the same active ingredient as STS but with increased shelf stability. This study compares Chrysal ALESCO® to the traditional STS standard methods for male flower induction on female plants and their pollen quality. The two treatments were applied to six female hemp accessions with three replicates investigated, and the male flower counts and pollen quality were compared. No statistically significant difference was discovered in their male flower counts; the STS-treated plant produced an average of 478.18 male flowers, and the Chrysal ALESCO®-treated plant produced an average of 498.24 male flowers per plant. Fluorescein diacetate (FDA) and acetocarmine stains were used to investigate the pollen quality (non-aborted rate) of two chosen genotypes. FDA-stained pollen of Chrysal ALESCO® showed a significantly higher non-aborted rate than the pollen of traditional STS-treated plants (p < 0.001); however, only a marginally higher non-aborted rate was discovered by acetocarmine staining (p = 0.0892). In summary, Chrysal ALESCO® performed equally to traditional STS treatment at male flower counts and better or equally in pollen quality. With better shelf stability and easy application, ALESCO® can be a viable alternative option for stimulating male flowers on female hemp plants. [ABSTRACT FROM AUTHOR]

Euonymus americanus is a common understory shrub in mesic deciduous forests of eastern North America. Its inconspicuous greenish-white flowers appear in late April and May and are regularly visited by several species of ants and, by night, a species of cockroach. Because the species is self-compatible, these pollinators need not move between plants to effect fertilization and fruit-set. Flowers last for three days and are strongly protandrous with little if any overlap of male and female function. Based on a survey of five years of reports on iNaturalist in Georgia, Prenolepis imparis is the most commonly observed ant, followed by Camponotus pennsylvanicus and Crematogaster lineolata, though Camponotus castaneus was more common than the latter two species at our study sites. Each of these species was found to carry many viable pollen grains, as was a species of cockroach (Cariblatta lutea). Exclusion of ants from flowers resulted in near-zero fruit-set. Nevertheless, addition of pollen increased fruit-set significantly over open-pollinated levels, indicating pollen limitation. The upper limit in terms of potential seeds per fruit is 30, representing six seeds in each of the five locules of a mature capsule, but the average number of seeds per capsule was only 12. Seed viability was high, exceeding 95%. [ABSTRACT FROM AUTHOR]

The pollen viability of Siberian spruce (Picea obovata Ledeb.) has been studied on the border of the city Krasnoyarsk, as well as under unpolluted growth conditions. This study has discovered the variability and correlation between the functional characteristics of pollens, as well as a low rate of development anomalies. The viability of pollen growth in forest ecosystems of the middle mountains of the Eastern Sayans (the northeastern border of the Krasnoyarskie Stolby national park) have decreased under pollution press. The great variety of pollen viability characteristics of the Siberian spruce pollen makes the high degree of flexibility and adaptability of species reproductive processes evident. [ABSTRACT FROM AUTHOR]

Betula pendula Roth. is tolerant to technogenic air pollutants. However, the viability of pollen decreases under stress conditions, as well as under air pollution. This research was conducted in Middle Siberia on eight plots of motley birches near the industrial city of Krasnoyarsk. In each plot on the west side, the male twigs of 15–20 trees were cut at pollination time. Pollen was extracted from the male generative organs for size and viability (potential (by starch test) and actual (by in vitro germination)) determination. The results were analyzed by statistical methods. A reduction in pollen viability under technogenic pollution and reliable differences in pollen grain (PG) diameters under different growing conditions is revealed, but deformed PG is not. The variability of PGs in diameter in the biocenosis does not exceed 9.3–9.9%. The maximum number of sprouted PGs is observed under background conditions and the minimum is at the eastern border of the city in the main direction of the transfer of technogenic aerosols. The length of pollen tubes in trees growing under these conditions decreased by more than twice in comparison with the critical value (namely, PG diameter of 18–20 µm). Regression analysis has shown correlations between pollen germination and the accumulation of dust on foliage, as well as of lead and aluminum content in the foliage (r = − 0.1−0.3, р ≥ 0.05). Despite the tolerance of the species to air pollution, Betula pendula male generative structures are sensitive to contamination. Pollen viability can be used as a bioindicator of environmental pollution upon monitoring. [ABSTRACT FROM AUTHOR]

An in vitro pollen storage study was conducted using pollen from three seeded citrus plant genotypes, viz., ‘Mexican lime’, ‘W’. Murcott’ and ‘Mosambi’ and five seedlesscitrus genotypes, viz., ‘Lisbon lemon’, ‘Jaffa’, ‘Clementine’, ‘Hamlin’ and ‘Mukaku Kishu’. Pollen viability and germination percentage were evaluated at different storage temperature treatments, i.e., at room temperature (in anhydrous calcium chloride) (control), in a refrigerator at 4°C, in a freezer (-20°C), and in a freeze drier (-80°C). The viability of the pollen plants was tested with an acetocarmine stain (2%). Among all the tested sucrose concentrations (0, 5, 10, 15, 20, and 25%) for in vitro pollen germination, the 15% sucrose concentration had the highest effect on pollen germination. The results showed significant differences in pollen viability and germination under different storage temperature conditions. The pooled data revealed that, among the seeded genotypes, W. Murcotts showed the maximum mean viability and germination percentage (67.86% and 60.88%, respectively) after 48 weeks of storage at -80°C, and the minimum values were observed for Mexican lime (46.57% and 33.71%, respectively). However, in the low-seeded genotype, Mukaku Kishu had the maximum mean pollen viability and germination (71.52% and 64.07%, respectively) after 48 weeks of storage at -80°C, and the lowest values were observed in Jaffa (39.36% and 28.08%, respectively). The results indicate that the freeze drier storage temperature (-80°C) had the greatest effect on retaining pollen viability and germination in both the seeded and low-seeded genotypes. However, a progressive decrease in pollen viability and germination rate was observed with increasing duration at all storage temperatures, reaching a minimum at 48 weeks after storage. However, the reduction in pollen storage ability was greatest at room temperature and 40°C. Pollen grains stored at low temperatures (-80°C and -20°C) showed good viability and germination percentage compared with those stored at room temperature and 4°C.

The present study reports the chromosome number, meiotic behavior and its relation with pollen fertility and seed set of Arnebia euchroma (Royle ex Benth.) I.M.Johnst. The species shows a chromosome count of 2n = 2x = 14. The meiotic abnormalities such as chromatin stickiness, cytomixis, laggard formation, chromosomal bridges, were also observed in the Pollen Mother Cells (PMCs) of the target plant species. The linear model of regression showed a significant reduction of seed set with increasing meiotic abnormality and correlation analysis highlighted positive relationship between pollen viability and seed set. Meiotic abnormalities within the species hinder its reproductive process, causing a decline in reproductive efficiency. This study highlights the importance of addressing these intrinsic factors in future conservation programs to prevent a decline in the species population in nature.

The knowledge of pollen morphology, suitable storage condition, and species compatibility is vital for a successful grapevine improvement programme. Ten grape genotypes from three different species, viz., Vitis vinifera L., Vitis parviflora Roxb., and Vitis champini Planc., were studied for their pollen structure and pollen storage with the objective of determining their utilization in grape rootstock improvement programs. Pollen morphology was examined through the use of a scanning electron microscope (SEM). The viability of the pollen was assessed using 2,3,5-triphenyltetrazolium chloride (TTC). In vitro pollen germination was investigated using the semi-solid medium with 10 % sucrose, 100 mg/L boric acid, and 300 mg/L calcium nitrate. The results revealed variations in pollen micro-morphology in 10 genotypes, with distinct pollen dimensions, shapes, and exine ornamentation. However, species-wise, no clear difference was found for these parameters. Pollen of V. parviflora Roxb. and Dogridge was acolporated and did not germinate. The remaining eight genotypes exhibited tricolporated pollen and showed satisfactory in vitro pollen germination. Storage temperature and duration interactions showed that, at room temperature, pollen of most of the grape genotypes can be stored for up to 1 day only with an acceptable pollen germination rate (>30 %). However, storage for up to 7 days was successfully achieved at 4 °C, except for ‘Pearl of Csaba’. The most effective storage conditions were found to be at −20 °C and −196 °C (in liquid N2), enabling pollen storage for a period of up to 30 days, and can be used for pollination to overcome the challenge of asynchronous flowering. Four interspecific combinations were studied for their compatibility, among which V. parviflora Roxb. × V. vinifera L. (Pusa Navrang) and V. parviflora Roxb. × V. champini Planc. (Salt Creek) showed high cross-compatibility, offering their potential use for grape rootstock breeding. However, V. parviflora Roxb. × V. vinifera L. (Male Hybrid) recorded the lowest compatibility index among studied crosses. In the case of self-pollinated flowers from V. parviflora Roxb. and V. parviflora Roxb. × V. champini Planc. (Dogridge), pollen failed to germinate on the stigma due to male sterility caused by acolporated pollen. As a result, the flowers of these genotypes functioned as females, which means they are ideal female parents for grape breeding without the need for the tedious process of emasculation.

The genus Sphaeralcea belongs to the Malvaceae family and has native species from South America. Their attractive morphological characteristics with ornamental value have not yet been explored. The objective of this work was to know the viability of pollen, stigma receptivity, type of pollination and combining ability of four Sphaeralcea species (S. australis, S. bonariensis, S. crispa and S. mendocina), with the aim to develop new ornamental varieties. Fructification, fertility, seed germination and survival seedlings on intraspecific and reciprocal interspecific offspring were assessed. The highest values ​​of stigma receptivity and pollen viability were obtained at 2:00 pm for the four species. S. mendocina also showed high values ​​of pollen viability at 4:00 pm. The species proved to be self-incompatible and allogamous, with different degrees of reproductive compatibility. The interspecific crosses of S. mendocina and the intraspecific of S. crispa did not produce descendants. The crosses between S. australis and S. bonariensis as maternal parent presented the best combining ability with good fruit production, seed germination and survival. This research provides useful information for the formulation and implementation of breeding strategies, to improve pollination efficiency, and to breed new Sphaeralcea varieties with ornamental potential.

Abstract Due to global climate change, heat stress is increasingly harming the growth, development, overall biomass, and grain yield of numerous crops. Heat stress impairs pollen development and thus reduces seed set in Sorghum bicolor (L.) Moench; however, the effects of heat stress on anther development at specific stages and tiller formation remain incompletely understood. Here we report that exposure to heat stress [42°C/32°C (day/night)] at pollen mother cell (PMC) and booting stages profoundly disrupts tapetum and pollen development, resulting in a significant decrease in grain yield in sorghum. Sorghum plants subjected to 9 days or less of heat stress at the PMC stage exhibited normal pollen viability, but 12 days of heat stress caused almost complete loss of grain yield and the formation of nonviable pollen grains. Similarly, sorghum plants that were heat‐stressed for 3 days at the booting stage produced few seeds. Further analysis revealed that aberrant tapetum and pollen development contributed to the sterility of pollen in these heat‐stressed plants. Notably, in addition to inhibiting plant height, a 12‐day heat stress at the PMC stage promoted the formation of basal tillers, whereas a 3‐day heat stress at the booting stage stimulated the formation of apical tillers, which helped salvage seed yield under heat stress conditions. Moreover, the application of exogenous auxin promoted the formation of apical tillers and leaf numbers per apical tiller. Collectively, our findings suggest that sorghum is susceptible to heat stress during both early and late anther development, and auxin might be involved in governing the formation of apical tillers.

Potted miniature roses are popular indoor ornamental plants. Due to consumer demands, different varieties are introduced to the market every year. The most widely used method for the development of potted miniatures is cross breeding. Six divergent popular pot miniature roses as female parents and Rosa centifolia and Black Baccara as male parents as well as 190 of their F1 hybrids were studied to determine the extent of crossability and the heterosis effects for several quantitative and qualitative traits for determining miniature rose breeding potential. The percentage of pollen viability and the pollen germination rate differed between 48.61% and 61.27% and between 23.26% and 32.19%, respectively. All cultivars exhibited a strong correlation between the fruit set, the weight of fruit, the total set, the weight of seed, the number of seeds per fruit, and the seed germination rate. The cultivar Rosa White Star as a female parent exhibited a good fruit set and crossing success, whereas Juanita Kordana showed a poor crossing success rate. The maximum setting after the crossing was that of Rosa White Star x R. centifolia comprising 75% of fruits, 132 total seeds, and seed weight of 0.68 g. The highest number of seeds per fruit (12.63) was obtained from Rosa Bling Love Star x R. centifolia, and the Red Romance x Black Baccara had the maximum germination of seed rate (48%). The potential for heterobeltiosis and heterosis varied and exhibited a contrasting performance for various qualitative and quantitative traits between F1 progenies. The parents and F1 hybrids were sorted into three major groups by cluster analysis based on the phenotypic variation. [ABSTRACT FROM AUTHOR]

Summary: Global nocturnal temperatures are rising more rapidly than daytime temperatures and have a large effect on crop productivity. In particular, stomatal conductance at night (gsn) is surprisingly poorly understood and has not been investigated despite constituting a significant proportion of overall canopy water loss.Here, we present the results of 3 yr of field data using 12 spring Triticum aestivum genotypes which were grown in NW Mexico and subjected to an artificial increase in night‐time temperatures of 2°C.Under nocturnal heating, grain yields decreased (1.9% per 1°C) without significant changes in daytime leaf‐level physiological responses. Under warmer nights, there were significant differences in the magnitude and decrease in gsn, values of which were between 9 and 33% of daytime rates while respiration appeared to acclimate to higher temperatures. Decreases in grain yield were genotype‐specific; genotypes categorised as heat tolerant demonstrated some of the greatest declines in yield in response to warmer nights.We conclude the essential components of nocturnal heat tolerance in wheat are uncoupled from resilience to daytime temperatures, raising fundamental questions for physiological breeding. Furthermore, this study discusses key physiological traits such as pollen viability, root depth and irrigation type may also play a role in genotype‐specific nocturnal heat tolerance. [ABSTRACT FROM AUTHOR]

Cannabis sativa is a widely studied species and is currently accepted worldwide due to its medicinal properties, especially those conferred to the CBD phytocannabinoid, which is synthesized mainly in the globular trichomes of female flowers. Males are undesirable and rare in commercial plantations; however, they are necessary for breeding programs. This research aimed to evaluate sexual reversion methods in female cannabis plants as a preliminary stage of a plant breeding program. A completely randomized design with eight treatments and four repetitions was used. The treatments consisted of protocols for the sexual reversion of female plants through drip application and foliar spraying of Silver Thiosulfate (STS), Aminoethoxy-vinyl-glycine (AVG), 1-Methylcyclopropene (1-MCP), and Gibberellic acid (AG3), plus a control treatment without application. Male flower production was evaluated in female cannabis plants, and pollen viability in male flowers was determined. The AVG treatments applied to the apex by dripping, and the AG3 applied to the foliage in the form of a spray influenced the sexual reversion of female plants and produced a total of 132 and 32 male flowers, respectively, without difference between them (P=0.08383). For AVG dripping, only male flowers were observed at the apex, where the application was made directly. Moreover, STS and 1-MCP did not induce the production of male flowers. The pollen from male plants treated with AG3 in spray, and AVG dripping showed high viability (>50%), contrary to the low viability observed in plants treated with AGC applied in spray. The plants treated with AG3 (spray) were higher due to the elongation of the internodes. The AVG and AG3 compounds are effective in the sexual reversion of female cannabis and generate male flowers with viable pollen. [ABSTRACT FROM AUTHOR]

Bdallophytum americanum (Cytinaceae) is an endoparasitic plant species, meaning only the flowers emerge from the host during the reproductive season. Reports on the pollination biology of this species state that its primary pollinators are carrion flies attracted by the smell of the flowers and nectar as a reward. However, the functional role of one of the most outstanding attributes of B. americanum has been neglected. These are the staminal appendages formed by the apical overgrowth of connective tissue during anther development. To determine whether these staminal appendages play a role in pollination, we monitored a nectarless population of B. americanum. We described the inflorescence emergence, floral movements, and pollination and performed field experiments to test whether the absence of the staminal connective appendages affected the visitation frequency. Male inflorescences emerge early, and both male and female flowers open during the day and do not close. Hoverflies are the most frequent visitors to both floral sexes and carry the most pollen. Moreover, the movement of staminal appendages matching the pollen viability changes is reported for the first time. The staminal appendages are the structures where pollinators land before foraging. The field experiments showed that the visitation frequency decreased sharply without staminal appendages. As a landing platform, the staminal connective appendages in B. americanum are crucial for pollinator positioning and collecting viable pollen. [ABSTRACT FROM AUTHOR]

The success of rose breeding programs is low due to poor seed set and germination rate. Determining the combining ability of parents might increase breeding programs’ success. The study was conducted to determine the crossing success of ‘pot miniature rose × cut rose’ combinations. Four different pot miniature rose varieties as the seed parents, and four different cut roses as pollen parents were used as plant material. Eight cross combinations were formed, and 30 crosses were made in each combination. Pollen viability and germination rate, fruit set, seed number per fruit, fruit and seed weight, and seed germination rate were recorded. The pollen germination rate varied between 14.09% (‘Moonlight’) and 31.25% (‘Golden Gate’). Among cross combinations, the fruit set rate ranged from 0% to 83.33%, while the seed number was between 0 and 6.14, and the seed germination rate ranged from 0% to 47.5%. The best combinations were ‘Rosa Bling Love Star × Golden Gate’, ‘Rosa Bling Love Star x Magnum’, ‘Rosa Bling Love Star × Inferno’, and ‘Rosa Shining Star × Inferno’. Except for Hot Jewel as the seed parent, low values were obtained from the traits examined in all combinations where Moonlight was used as the pollen parent. There was a positive correlation between seed number, seed weight and fruit weight. There may be prepollination barriers in ‘pot miniature rose × cut rose’ crosses, but productive seeds and progenies are obtainable. The miniature roses can be successfully used as seed parents when combined with cut roses. [ABSTRACT FROM AUTHOR]

Background: Sweetpotato is an important vegetable and food crop that is bred through sexual crosses and systematic selection. The use of in vitro germination of sweetpotato pollen to test its viability has important theoretical and practical implications for improving the efficiency of sweetpotato crossbreeding by controlling pollination and conducting research on sweetpotato pollen biology. Results: In this study, we observed the morphological structure of sweetpotato pollen under a scanning electron microscope (SEM), developed an effective method for the in vitro germination of sweetpotato pollen, and examined the viability of sweetpotato pollen after treating plants at different temperatures before blossoming. Sweetpotato pollen grains are spherical, with an average diameter of 87.07 ± 3.27 μm (excluding spines), with multiple germination pores and reticulate pollen surface sculpture. We applied numerous media to sweetpotato pollen germination in vitro to screen the initial medium and optimised the medium components through single-factor design. The most effective liquid medium for in vitro sweetpotato pollen germination contained 50 g/L Sucrose, 50 g/L Polyethylene glycol 4000 (PEG4000), 100 mg/L Boric acid and 300 mg/L Calcium nitrate, with a pH = 6.0. The optimum growth temperature for pollen development in sweetpotato was from 25 to 30 °C. Neither staining nor in situ germination could accurately determine the viability of sweetpotato pollen. Conclusions: In vitro germination can be used to effectively determine sweetpotato pollen viability. The best liquid medium for in vitro germination of sweetpotato pollen contained 50 g/L Sucrose, 50 g/L Polyethylene glycol 4000 (PEG4000), 100 mg/L Boric acid and 300 mg/L Calcium nitrate, with the pH adjusted to 6.0. This study provides a reliable medium for the detection of sweetpotato pollen viability, which can provide a theoretical reference for sweetpotato genetics and breeding. [ABSTRACT FROM AUTHOR]

Global climate changes have led to frequent and recurrent heat stress, which has seriously affected the world maize production. The experiment presented in this paper was carried out during the maize‐growing season in 2021 and 2022 at the Huang–Huai–Hai Region Maize Science and Technology Innovation Center (36°09′N, 117°09′E) in Tai'an, Shandong province, China. The test site is located in the semi‐humid warm temperate continental monsoon climate zone, soil is brown loam. We selected different heat‐sensitive maize varieties: heat‐tolerant variety Zhengdan 958 (ZD958) and heat‐sensitive variety Xianyu335 (XY335) to study the stress effects of high temperature on the development of tassel in the key stage of its differentiation (the 12‐leaf stage, V12). We found that exposure to heat stress during the V12 stage significantly reduced the tassel size and the anther dehiscence area, making it difficult to disperse pollen, thus effectively reducing pollen production. In addition, heat stress had significant negative effects on pollen development, resulting in deformed pollen and lower pollen viability and germination rate. Our results also showed that heat stress significantly increased the activities of key reactive oxygen species‐scavenging enzymes including superoxide dismutase, peroxidase and catalase, and that the malondialdehyde and H2O2 content in tassels exposed to heat stress were significantly higher than those control group, where it should be noted that for the XY335, these effects were more pronounced than for the ZD958. The endogenous hormone content of tassels exhibited a variety of responses. After heat stress, the zeatin and salicylic acid content in tassels of both maize varieties were significantly lower than those in the respective control groups, while the abscisic acid and gibberellin acid content were significantly higher. With respect to the jasmonic acid and 3‐indoleacetic acid content, the two maize varieties exhibited opposite responses: in tassels from ZD958 plants subjected to heat stress were higher than those in the respective control group, while in tassels from XY335 plants, they were lower. The observed changes in protective enzyme activities and endogenous hormone contents induced by heat stress significantly affected the development of maize tassels and significantly reduced the amount, activity and germination rate of pollen. [ABSTRACT FROM AUTHOR]

Ogura cytoplasmic male sterility (CMS) is one of the important methods for hybrid seed production in cruciferous crops. The lack of a restorer of fertility gene (Rfo) in Brassica rapa L. restricts the development and utilization of its germplasm resources. In this research, Brassica napus with the Rfo gene was used to restore the fertility of Ogura CMS B. rapa with the golden heart trait. Through the distant cross of two B. rapa and four B. napus, six interspecific hybrid combinations received F1 seeds. The six combinations were different in seed receiving. By morphological observation and molecular marker-assisted selection (MAS), in F1, individuals containing the Rfo gene all appeared fertile, while those without it remained male-sterile. The pollen viability of the fertile individuals was measured, and the fertile lines of the six interspecific hybrid combinations were different (40.68–80.49%). Three individuals (containing both Rfo and GOLDEN genes) with the highest pollen vitality (≥60%) were backcrossed with fertile cytoplasmic B. rapa, resulting in a total of 800 plants. Based on the MAS, a total of 144 plants with GOLDEN but no Rfo were screened (18%). Moreover, through morphological investigation, one individual with normal cytoplasm, stable fertility but without the restoring gene Rfo, the GOLDEN gene, and morphological characteristics similar to those of B. rapa was obtained. These results increased the diversity of B. rapa germplasm and provided a new method for the utilization of CMS germplasm in Brassica crops. [ABSTRACT FROM AUTHOR]

Intergeneric and interspecific hybridization has been employed for the breeding of Phalaenopsis to transfer desirable traits between species, producing novel phenotypes with improved size, color, form, and flower-bearing ability. These characteristics are often enhanced; however, many of these hybrids are triploids and have reduced or complete sterility, for example, Phalaenopsis Queen Beer 'Mantefon', an important novelty-type cultivar in Asia, particularly in China, Japan, and Republic of Korea. Despite the increasing demand for the crop for ornamental purposes, little is known about its cytogenetics, which is essential for breeding and, consequently, crop improvement. In this study, karyotyping using fluorescence in situ hybridization, meiotic chromosome behavior analysis, pollen staining, and in vitro viability germination tests were performed to understand the cause of hybrid sterility and pollen abnormality in Phalaenopsis Queen Beer 'Mantefon' from a cytogenetic perspective. Viability tests revealed pollen infertility at all flower developmental stages, confirmed by the absence of pollen tube growth. Aberrant chromosomal behavior was observed in pollen mother cells (PMCs), frequently forming univalents, chromosomal bridges, and laggards during the entire meiotic process. PMCs were also divided irregularly into sporads with varying numbers of micronuclei, which may be responsible for pollen sterility in this cultivar. Altogether, the cytogenetic analyses provided insights into the pollen development of Phalaenopsis Queen Beer 'Mantefon' and the conceivable causes of its infertility. [ABSTRACT FROM AUTHOR]

The evolution and expression of floral traits are responsive to selection pressure from biotic and abiotic factors. Although floral traits significantly vary among environments, the flower remains unchanged. We aimed to understand the adaptation of Epimedium chlorandrum of floral traits to a frequently nocturnally rainy and wet environments and the roles of floral traits in pollination and reproduction. We observed flowering phenology, measured floral characteristics including the number of pollen grains and ovules per flower, measured pollen viability and stigma receptivity, tested the volume and sugar concentration of nectar and conducted flower-visit observations in this species. Different pollination treatments were performed to characterize the breeding system. The inner sepals and highly curved longer spurs of E. chlorandrum jointly formed an umbrella that shielded the anthers and stigma from rain wash and prevented nectar dilution. Epimedium chlorandrum was visited by six species, while Bombus trifasciatus was the only effective pollinator and fed on the nectar. One flower secreted approximately 17.06 µL of nectar with a 29.19 g/100 mL sugar concentration, and the pollination efficiency of B. trifasciatus was positively associated with the nectar sugar concentration. The self- and open-pollination treatments resulted in fewer fertile seeds than the cross-pollination treatment. In contrast, the autonomous self-pollination treatment failed to yield fertile seeds. In summary, pollen limitation caused by harsh weather and pollinator shortage occurred during the pollination process of E. chlorandrum , which was partially alleviated by self-compatibility. [ABSTRACT FROM AUTHOR]

A study was undertaken to evaluate the physiological and biochemical parameters and to quantify yield of twenty-two contrasting tomato genotypes when exposed to high temperature stress. Experiment was conducted in the Department of Plant Physiology, College of Agriculture, Vellayani during two growing seasons i.e., September to December, 2019 and March to June, 2020. The experiment was laid out in completely randomized design with two treatment levels i.e. control and high temperature stress (36+/-2oC) with three replications each under first season and 38+/-2oC during the second season. The high temperature stress was induced from flower initiation to maturity stage by keeping the pots in a temperature controlled green house facility for 45 days. The presence of stigma exertion, reduction in chlorophyll content and photosynthetic rate, reduced starch content and soluble sugar content, reduced chlorophyll fluorescence, low leaf membrane thermostabilty (LMT) were the major limitations for reproductive success and good yield. The correlation and regression analysis showed that yield under control conditions had strong positive correlation between LMT, pollen viability, photosynthetic rate, chlorophyll fluorescence, starch, soluble sugar and chlorophyll content. A negative correlation was observed between yield and stomatal conductance and transpiration rate. Under high temperature stress condition, all the parameters showed a positive correlation with yield. Based on the performances of various tomato genotypes under control and heat stress conditions, we were able to identify traits that could be manipulated to improve the high temperature tolerance in tomato. [ABSTRACT FROM AUTHOR]

Summary: Sporopollenin is one of the most structurally sophisticated and chemically recalcitrant biopolymers. In higher plants, sporopollenin is the dominant component of exine, the outer wall of pollen grains, and contains covalently linked phenolics that protect the male gametes from harsh environments. Although much has been learned about the biosynthesis of sporopollenin precursors in the tapetum, the nutritive cell layer surrounding developing microspores, little is known about how the biopolymer is assembled on the microspore surface.We identified SCULP1 (SKS clade universal in pollen) as a seed plant conserved clade of the multicopper oxidase family. We showed that SCULP1 in common wheat (Triticum aestivum) is specifically expressed in the microspore when sporopollenin assembly takes place, localized to the developing exine, and binds p‐coumaric acid in vitro.Through genetic, biochemical, and 3D reconstruction analyses, we demonstrated that SCULP1 is required for p‐coumaroylation of sporopollenin, exine integrity, and pollen viability. Moreover, we found that SCULP1 accumulation is compromised in thermosensitive genic male sterile wheat lines and its expression partially restored exine integrity and male fertility.These findings identified a key microspore protein in autonomous sporopollenin polymer assembly, thereby laying the foundation for elucidating and engineering sporopollenin biosynthesis. [ABSTRACT FROM AUTHOR]

Late blight disease caused by the fungus Phytophthora infestans is the main yield limiting factor amongst the diseases of potato in India and across the globe. Potato Cyst Nematode/PCN (Globodera spp.) is another biotic factor of economic importance and is a quarantine organism. Exploitation of genetic resistance is the most preferred management strategy. In the present study, indigenous potato genotypes collected from different parts of the country along with checks were evaluated for their resistance against late blight under natural epiphytotic field conditions and in laboratory under artificially inoculated conditions including detached leaf and tuber slice assays and PCN through Root ball technique during 2020-2023. The converted field scale values i.e. average AUDPC value ranged from 7 in highly resistant genotype Rangpuria to 1596 in susceptible accession AGR/56. The field blight response was comparatively more correlated (r =0.63) with susceptibility levels measured in the detached leaf assay compared to that with tuber slice assay (r =0.48). Genotypes Kanpuria Safed, JG-1, Rangpuria and Desi Aloo showed resistance to late blight both under laboratory and field conditions. For PCN, Garlentic, Jeevan Jyoti and JG-1 have combined resistance (0 female/root ball) over the years to both the species. Majority of the studied genotypes have medium to high pollen viability with desirable tuber traits and yield advantage. The identified resistant genotypes excel their usage as parental lines in breeding for biotic stress resistance specifically for late blight and PCN. [ABSTRACT FROM AUTHOR]

An experiment is conducted in bitter gourd cropping system at Coimbatore district in India, to study bitter gourd floral character, the foraging ecology of native pollinators and their modes of pollination. Bitter gourd is a monoecious plant bears separate male and female flowers. Male flower blooms early followed by female flowers. Stigma receptivity of pistillate flowers was confirmed on 4th day old flower showed yellowish-green stigma with shining stigmatic exudation. The stigma receptivity lasts up to 24 hours after anthesis. Pollen viability test done with 2 per cent acetocarmine solution indicated that pollen collected during morning hours (06:00 h) were more viable and were deeply stained, whereas pollens collected at evening hours (17:00 h) remained unstained and considered as nonviable. The foraging activities of Apis cerana indica Fabricius and Tetragonula iridipennis begin at 06:00 h and 06:30 h respectively and ceased by evening 17:00 h. T. iridipennis foragers spent more time in pollen collection (31.1 seconds/flower) and nectar collection (26.14 seconds/flower) whereas, A. cerana indica spent less time in pollen collection (8.62 seconds/flowers) and nectar collection (3.56 seconds/flower) respectively. A total of 17 pollinator species belongs to four orders viz., Hymenoptera, Diptera, Lepidoptera and Coleoptera have been documented and grouped based on their mode of foraging in bitter gourd flowers. [ABSTRACT FROM AUTHOR]

Prunus cerasoides have a high value in phytochemistry and pharmacology. It was classified as the Least Concern globally based on the IUCN red list due to its widespread distribution in eastern Asia. This research aims to evaluate the reproductive biology of P. cerasoides through the study of pollen morphology, pollen viability, stigma receptivity, and pollination in the Cibodas Botanical Garden, located in the Cibodas subdistrict of West Java, Indonesia. The pollen morphology was observed using SEM. Moreover, the pollen viability test was followed by the staining method (aceto-orcein 2%, I2KI 1%, TTC 1%) and in vitro pollen germination with thirteen treatments (aquadest [control]; 5-30% sucrose; and 5-30% sucrose + 5 ppm boric acid). Stigma receptivity was observed daily, from 7 days before anthesis until the anthesis stage. Furthermore, several types of pollination were evaluated, including open pollination, autogamy, geitonogamy, and allogamy. The results showed that the best staining method on P. cerasoides was aceto-orcein 2%, with pollen viability at 87.87%. The sucrose concentration of 25% at 72 hours of observation gave the highest pollen viability results, 52.48%. Stigma receptivity was optimal in the two days before anthesis until anthesis. The highest pollination efficiency was cross-pollination at 53.33%, with an average percentage of the total fruit set of 24.17%. [ABSTRACT FROM AUTHOR]

Androgenesis is reported in a few tree crops such as citrus and papaya; however, there is little information available about guava. Different modified Chu (N6) media and cold pretreatments of floral buds were tested to induce embryogenic calli in the anthers of two white flesh guava cultivars, 'Round' and 'Pyriform'. Four modified Chu (N6) media formulations, i.e., M1 (400 mgL-1 casein hydrolysate, 200 mgL-1 glutamine, 0.2 mgL-1NAA, 1.0 mgL-1 KIN, 0.5 mgL-1 6-BAP, 0.5 mgL-1 zeatin and 5% coconut water), M2 (400 mgL-1 casein hydrolysate, 200 mgL-1 glutamine, 0.2 mgL-1NAA, 1.0 mgL-1 KIN, 0.5 mgL-1 6-BAP), M10 (0.5 mgL-1 2,4-D), and M11 (0.5 mgL-1 2,4-D and 50 mgL-1 PVP) enhanced anther swelling and callus formation. Genotypic variability was found in pollen viability, phenolic exudation, and anther tissue browning after cold pretreatment for 0-72 hrs. intervals. Anthers of 'Round' showed more pollen viability across cold pretreatment intervals with less phenolic exudations and tissue browning than 'Pyriform'. On both M10 and M11 media, anthers with uni-nucleate microspores developed embryogenic calli; however, anthers of 'Pyriform' resulted in more calli induction (69.58%) on M10 media, whereas anthers of 'Round' developed more calli (66.60%) on M11 media. The proliferating calli in white flesh 'Round' and 'Pyriform' cultivars and pink flesh 'Round' cultivar formed more embryogenic masses upon transfer to growth hormone-free Chu (N6) media under light conditions; however, embryos showed delayed maturity with limited germination. More genotypes shall be explored to enhance embryo germination, and embryogenic media shall be further fine-tuned. This study provides the foundation for the generation of homozygous lines in guava using androgenesis. [ABSTRACT FROM AUTHOR]

When the sexual system of a rare plant species is complex, characterizing floral development, plant morphology, and subpopulation structure is essential for assessing reproductive potential. Availability of pollinator rewards and positioning of sexual morphs within inflorescences relates to outcrossing potential. We studied the complex sexual system of the recently discovered Euphorbia rosescens E.L. Bridges & Orzell, a rare species occurring in a single Florida county. Euphorbia rosescens has both monomorphic subpopulations of female plants and mixed subpopulations with male and andromonoecious plants. Most data on cyathia sex, inflorescence architecture, floral visitors, and fruit set came from one female subpopulation and one mixed subpopulation. Cyathia longevity, flowering phase, nectar secretion, pollen production, and viability were measured in female, male, and hermaphrodite cyathia. Female plants had fewer inflorescence levels and cyathia and significantly smaller cyathia than male and andromonoecious plants. Andromonoecious plants were larger and produced more cyathia relative to male plants. Within mixed populations, sex switching occurred in both directions between male and andromonoecious plants. Female plants did not switch sexes. Proximal to distal inflorescence levels transitioned from hermaphrodite to male cyathia on andromonoecious plants. Nectar secretion corresponded to initiation of staminate flowering, but in female cyathia stigmas were receptive approximately a day before nectar secretion. Pollen production and viability were similar in male and hermaphrodite cyathia. Fruit maturation was minimal, primarily observed on andromonoecious plants. Nectar availability, pollen rewards, trimorphic inequalities in inflorescence display, and low fruit set suggest high geitonogamy, thus limiting outcrossing potential for this species. [ABSTRACT FROM AUTHOR]

Banana (Musa spp.) is a major global economic fruit crop. However, cross-pollination from other Musa cultivars grown in nearby plantations results in seeded fruit that exceeds market demand. This study investigated pollen viability and germination and examined the expression profiles of pollen development-related genes across seven Musa genomes (AA, BB, AAA, BBB, AAB, ABB and ABBB). Twenty-three Musa cultivars were assessed for pollen viability using lacto-aceto-orcein and triphenyltetrazolium chloride staining methods. Results revealed that pollen viability obtained from both methods was significantly different among all the studied cultivars. Cultivars carrying BB (diploid) genomes had higher viability percentages than AA (diploid), AAA, BBB, AAB and ABB (triploid) and ABBB (tetraploid) genomes. Germination of the studied cultivars was also investigated on pollen culture medium, with results showing significant differences between the pollen of each cultivar. The best germinating cultivar was TKM (11.0 %), carrying BB genome. Expression profiles of pollen development-related genes by RT–qPCR indicated that both TPD1A and MYB80 genes were highly expressed in triploid Musa genomes but the PTC1 gene showed down-regulated expression, resulting in non-viable pollen. Pollen viability, pollen germination and pollen development-related genes differed across Musa cultivars. This knowledge will be useful for the selection of male parents for Musa cross-breeding programs. Pollen viability should also be considered when planning Musa production to avoid seeded fruit. [ABSTRACT FROM AUTHOR]

The common bean (Phaseolus vulgaris L.) is an important nutritional source globally but is sensitive to high temperatures and thus particularly vulnerable to climate change. Derived from a breeding program at CIAT (Colombia), a heat-tolerant breeding line, named heat-tolerant Andean-type 4 (HTA4), was developed by a series of crosses of parents with a small-bean tepary genotype (Phaseolus acutifolius L.) in their pedigree, which might be the donor of heat stress (HS) tolerance. Importantly, in HTA4, the large, commercially desirable Andean-type beans was restored. To assess underlying tolerance mechanisms, HTA4, together with a heat-sensitive Colombian variety (Calima), was exposed to HS (31 °C/24 °C HS vs. 26 °C/19 °C day/night) under controlled environment conditions. Vegetative growth and photosynthetic performance were not negatively impacted by HS in either genotype, although senescence was delayed in Calima. HS during the reproductive stage caused an increase in pod number in Calima but with few fully developed seeds and many pods aborted and/or abscised. In contrast, HTA4 maintained a similar filled pod number under HS and a higher seed weight per plant. Pollen showed high sterility in Calima, with many non-viable pollen grains (24.9% viability compared to 98.4% in control) with a thicker exine and fewer starch granules under HS. Calima pollen failed to adhere to the stigma and germinate under HS. In HTA4, pollen viability was significantly higher than in Calima (71.1% viability compared to 95.4% under control), and pollen successfully germinated and formed pollen tubes in the style under HS. It is concluded that HTA4 is heat tolerant and maintains a high level of reproductive output due to its ability to produce healthy pollen that is able to adhere to the stigma. [ABSTRACT FROM AUTHOR]

Paeonia ostii is an important woody oil crop mainly cross-pollinated. However, the low yield has become an important factor restricting the industrial development of P. ostii. Cross-pollination has become one of the important measures to increase the seed yield. Therefore, conservation of pollen with high vitality is crucial to ensure successful pollination of P. ostii. In this study, we found an effective methodological system to assess the viability, ability to germinate, and optimal storage conditions of P. ostii pollen grains. The optimal medium in vitro was 50 g/L sucrose, 100 mg/L boric acid, 50 g/L PEG6000, 100 mg/L potassium nitrate, 300 mg/L calcium nitrate, and 200 mg/L magnesium sulfate at pH 5.4. Optimal germination condition in vitro was achieved at 25 °C for 120 min, allowing easy observation of the germination percentage and length of the pollen tubes. In addition, the viability of pollen grains was assessed by comparing nine staining methods. Among them, MTT, TTC, benzidine-H2O2, and FDA were effective to distinguish between viable and non-viable pollen, and the results of the FDA staining method were similar to the pollen germination percentage in vitro. After evaluation of pollen storage, thawing and rehydration experiments showed that thawing at 4 °C for 30 min and rehydration at 25 °C for 30 min increased the germination percentage of pollen grains stored at low temperatures. The low-temperature storage experiments showed that 4 °C was suitable for short-term storage of P. ostii pollen grains, while −80 °C was suitable for long-term storage. This is the first report on the in vitro germination, viability tests, and storage of P. ostii pollen grains, which will provide useful information for P. ostii germplasm conservation and artificial pollination. [ABSTRACT FROM AUTHOR]

Satureja pilosa Velen., S. coerulea Janka and S. kitaibelii Wierzb. ex Heuff. are Balkan endemic species, and they are distributed in restricted territories, primarily found in dry grasslands, rocky slopes, and stony habitats. This study presents the results of the first embryological and micromorphological analyses of three Satureja species (S. pilosa, S. kitaibelii, and S. coerulea) from the Bulgarian flora. The aim of this study was to establish the features of the male and female reproductive sphere, as well as surface characteristics of leaves, stem, and calyx in order to understand the mode of reproduction, character, size and state of species populations and delimitation. For the embryological study, flowers and flower buds in different developmental stages were collected from plants of natural populations and treated with the classic paraffin method. Reproductive capacity was assessed using the following approaches: (1) acetocarmine test for pollen viability, (2) tetrazolium test (TTZ) for seed viability, and (3) germination test. The surfaces characteristics of leaves, stem, and calyx were analyzed by scanning electron microscopy (SEM). As a result, the study revealed the structures of the male (M) and female (F) generative spheres as well as the processes of gamete development, pollination, and endosperm and embryo formation. It was found that the three Satureja species exhibited a high pollen viability but low seed viability and germination. The SEM analysis showed both common and distinct micromorphology features regarding epidermis, calyx and stem surfaces among the three Satureja species. Notably, the S. coerulea surfaces (leaves, calyx, stem) were clearly distinguishable from the other two Satureja species. Regarding the nutlet surfaces, it was observed that the exocarp surfaces of S. coerulea and S. kitaibelii have a reticulate convex type surface and comprise two types of cells: (1) highly bulging, bubble-like cells; and (2) flat cells with numerous striations. On the other hand, the exocarp of S. pilosa displayed rectangular or polygonal shapes without bubble-like cells, and it had a tabular to slightly convex type surface. Additionally, nutlets (seeds) of both S. coerulea and S. pilosa exhibited distinct papilla formations resembling non-glandular trichomes seen on the ends of the nutlets for S. coerulea and over the entire surface for S. pilosa. The characteristics of the embryological structures and processes, along with the absence of apomixis, characterized the three studied Satureja species as sexually reproducing. The established balanced processes and stable structures contribute to their high reproductive potential and population stability. However, these traits may also decrease their adaptability to environmental changes. [ABSTRACT FROM AUTHOR]

Main conclusion: Arabidopsis GR1 and NTRA function in pollen tube penetrating the stigma into the transmitting tract during pollination. During pollination, recognition between pollen (tube) and stigma mediates the hydration and germination of pollen, as well as the growth of the pollen tube on the stigma. Arabidopsis glutathione reductase 1 (GR1) and NADPH-dependent thioredoxin reductase A (NTRA) are involved in regulating cell redox hemostasis. Both GR1 and NTRA are expressed in pollen, but their roles in pollen germination and the growth of the pollen tube need further investigation. In this study, we performed pollination experiments and found that the Arabidopsis gr1/ + ntra/– and gr1/– ntra/ + double mutation compromised the transmission of male gametophytes. Pollen morphology and viability of the mutants did not show obvious abnormalities. Additionally, the pollen hydration and germination of the double mutants on solid pollen germination medium were comparable to those of the wild type. However, the pollen tubes with gr1 ntra double mutation were unable to penetrate the stigma and enter the transmitting tract when they grew on the surface of the stigma. Our results indicate that GR1 and NTRA play a role in regulating the interaction between the pollen tube and the stigma during pollination. [ABSTRACT FROM AUTHOR]

This document is a correction notice for an article titled "Alternative use of miRNA-biogenesis co-factors in plants at low temperatures." The authors discovered errors in the published figures and have provided corrected versions. The errors include the inclusion of two photographs of the same pistil with different gain parameters in Figure 1B and the duplication of a blot in Figure 2B. The authors have reviewed the original images and created corrected figures. The errors do not impact the results and conclusions of the paper. [Extracted from the article]

This document is a correction notice for an article titled "Alternative use of miRNA-biogenesis co-factors in plants at low temperatures." The authors discovered errors in the published figures and have provided corrected versions. The errors include the inclusion of two photographs of the same pistil with different gain parameters in Figure 1B and the duplication of a blot in Figure 2B. The authors have reviewed the original images and created corrected figures. The errors do not impact the results and conclusions of the paper. [Extracted from the article]

Wheat pollen, which is characterized by its short lifespan, exhibits rapid germination after anthesis. The preservation of wheat pollen is contingent upon environmental factors including temperature, relative humidity, light, and wind. The aim is to explicate the process for efficiently storing wheat pollen, particularly with regard to breeding. The short longevity of wheat pollen grains renders it impractical to conduct tests for pollen viability and in vitro germination on a large scale. Herein, the impact of storage temperatures and duration was assessed on pollen viability and in vitro germination in order to optimize storage conditions for preserving pollen viability. Pollen grains from 50 diverse spring wheat genotypes, each with three replicates, were harvested and stored at temperatures of 22 °C, −20 °C, and 4 °C. Subsequently, pollen viability and in vitro germination rates were determined after storage for 1, 3, and 6 days. The results revealed that storage temperatures, durations, genotypes, and their interactions had a statistically significant impact on both pollen viability and in vitro germination. Notably, when pollen was kept at 22 °C, almost all genotypes exhibited a loss of pollen viability and in vitro germination after 1, 3, and 6 days of storage. Likewise, storage at −20 °C failed to extend pollen germination. However, at a storage temperature of 4 °C, the pollen of 36 wheat genotypes exhibited a range of 6–14% for in vitro pollen germination and even remained viable for 6 days. The ANOVA revealed a substantial variation in grain number per spike between wheat genotypes, thereby highlighting the significant influence of genetic variations on grain yield. Moreover, a slight positive association between the viability of wheat pollen and the number of grains was found in the current study, suggesting that a variety of factors affect the number of grains produced. Simple linear regression analysis further revealed a significant negative correlation between pollen viability, in vitro germination, and storage time and temperature. In conclusion, our findings underscore that 4 °C is the optimal temperature for preserving pollen viability and in vitro pollen germination in spring wheat for up to 6 days. The results of the present study suggests that the pollen viability of wheat is dependent on genotype, storage temperature, and storage duration. Thus, the 36 wheat genotypes identified during the present work could be efficiently maintained at 4 °C for short-term storage (6 days) and could be further used for genetic and breeding purposes.

Abstract High temperature at reproductive stage causes a decrease in seed set that ultimately results in yield loss in important crops. Limited research is available regarding the effect of high temperature on viability attributes of pollen grain in sunflower. This study was planned to reveal the effects of high temperature stress on pollen grains in sunflower. An experiment was laid out in a triplicated Completely Randomized Design with split-split plot arrangements at the Oilseeds Research Institute, Ayub Agricultural Research Institute Faisalabad during spring 2021. Two temperature treatments T1 = 45° C for 10, 20 and 30 minutes, and T2 = 50° C for 3, 5 and 10 minutes were used on 10 sunflower inbred lines. Normal (untreated) pollen grains were used as control (T0). Data were collected on pollen viability, pollen germination, and pollen tube length. Recorded data were subjected to analysis of variance, Tukey’s HSD mean comparison test, and correlation. According to the results, ORI-1 showed the highest mean for pollen viability, whereas, RL-86 had highest mean for pollen germination and pollen tube length under normal conditions. RL-86 and ORI-73 revealed their ability to withstand both heat stresses as all pollen traits were least affected under high temperature stresses. It is advised to incorporate these inbred lines in future breeding programs aimed at the development of heat tolerant sunflower hybrids. Moreover, correlation studies displayed a positive, strong and highly significant relation of pollen germination with pollen tube length under normal and heat stress conditions revealing their importance in pollen study and reproduction.

Maize grain yield is drastically reduced by heat stress (HTS) during anthesis and early grain filling. However, the mechanism of HTS in reproductive organs and kernel numbers remains poorly understood. From 2018 to 2020, two maize varieties (ND372, heat tolerant; and XY335, heat sensitive) and two temperature regimens (HTS, heat stress; and CK, natural control) were evaluated, resulting in four treatments (372CK, 372HTS, 335CK, and 335HTS). HTS was applied from the nine-leaf stage (V9) to the anthesis stage. Various morphological traits and physiological activities of the tassels, anthers, and pollen from the two varieties were evaluated to determine their correlation with kernel count. The results showed that HTS reduced the number of florets, tassel volume, and tassel length, but increased the number of tassel branches. HTS accelerates tassel degradation and reduces pollen weight, quantity, and viability. Deformation and reduction in length and volume due to HTS were observed in both the Nongda 372 (ND372) and Xianyu 335 (XY335) varieties, with the average reductions being 22.9% and 35.2%, respectively. The morphology of the anthers changed more conspicuously in XY335 maize. The number of kernels per spike was reduced in the HTS group compared with the CK group, with the ND372 and XY335 varieties showing reductions of 47.3% and 59.3%, respectively. The main factors underlying the decrease in yield caused by HTS were reductions in pollen quantity and weight, tassel rachis, and branch length. HTS had a greater effect on the anther shape, pollen viability, and phenotype of XY335 than on those of ND372. HTS had a greater impact on anther morphology, pollen viability, and the phenotype of XY335 but had no influence on the appearance or dissemination of pollen from tassel. [ABSTRACT FROM AUTHOR]

Rising daily temperatures and water shortage are two of the major concerns in agriculture.In this work, we analysed the tolerance traits in a tomato line carrying a small region of the Solanum pennellii wild genome (IL12‐4‐SL) when grown under prolonged conditions of single and combined high temperature and water stress.When exposed to stress, IL12‐4‐SL showed higher heat tolerance than the cultivated line M82 at morphological, physiological, and biochemical levels. Moreover, under stress IL12‐4‐SL produced more flowers than M82, also characterized by higher pollen viability. In both lines, water stress negatively affected photosynthesis more than heat alone, whereas the combined stress did not further exacerbate the negative impacts of drought on this trait. Despite an observed decrease in carbon fixation, the quantum yield of PSII linear electron transport in IL12‐4‐SL was not affected by stress, thereby indicating that photochemical processes other than CO2 fixation acted to maintain the electron chain in oxidized state and prevent photodamage. The ability of IL12‐4‐SL to tolerate abiotic stress was also related to the intrinsic ability of this line to accumulate ascorbic acid.The data collected in this study clearly indicate improved tolerance to single and combined abiotic stress for IL12‐4‐SL, making this line a promising one for cultivation in a climate scenario characterized by frequent and long‐lasting heatwaves and low rainfall. [ABSTRACT FROM AUTHOR]

Plants in the Gesneriaceae family are appreciated for their decorative leaves and flowers, ease of cultivation, and shade tolerance. Sexual hybridisation has long been carried out for producing novel hybrids. However, scientific knowledge is lacking on the correct timing of pollination in this family. This study was conducted to elucidate the optimal timing for pollination by screening pollen viability and stigma receptivity throughout the flowering period in eight gesneriad taxa. Pollen viability was evaluated by the in vitro germination test and stigma receptivity was based on stigma morphology and pistil length. The flowering duration varied from 10 days in Alsobia to 18 days in Streptocarpus. While the pollens of Episcia, Kohleria, Saintpaulia, Sinningia, and Smithiantha had totally lost viability 2–5 days before the flowers withered, a slightly contrasting situation was observed in the cases of Alsobia, Deinostigma, and Streptocarpus, where a small portion of pollen grains remained viable towards the end of the flowering period. The highest pollen germination rate was recorded from 1 day in Alsobia, Episcia, and Kohleria, to 9 days in Deinostigma. The reduction in pollen germination was rapid in Alsobia, Saintpaulia, and Smithiantha, and moderate in the remaining taxa. The greatest pollen tube growth occurred at 1–3 days after flower opening and decreased rapidly in all the taxa tested. The longest pistil of 2.03–3.50 cm was observed at 3–8 days of anthesis depending on the plant tested. The findings in this study suggest that higher pollination success may be achieved using pollen grains of newly opened flowers and stigmas of mature flowers in this family. [ABSTRACT FROM AUTHOR]

The nine Viola pilosa Blume populations studied from Pir Panjal contained 20 chromosomes. This count is not reported so far in Indian populations. Currently, comparison of tapetal and meiotic cells revealed the existence of synchrony in different developmental phases. Young tapetal cells at prometaphase co-occurred with the pollen mother cells (PMCs) at diakinesis to metaphase, mature tapetal cells with disintegrated chromatin material co-occurred with tetrads and no tapetal cells were found at mature pollen stage. Cytological studies in young tapetal cells revealed most of these to be endopolyploid, with each having 40 chromosomes. While outnumbering somatic cells contained clear 40 chromosomes which seemed to be the outcome of endomitosis, a sizeable number of cells possessed 40 sticky chromosomes at metaphase. Later chromosomes are likely to form restitution nucleus. Mature tapetal cells, occurring singly/cytomictically connected (3.2–26.31%) or showing coalescence (10.5–22.8%), did not contain recognizable chromosomes. Instead, they were characterized by disintegrated nuclear content. Further, meiotic studies revealed that the present population contained all/outnumbering euploid cells (2n=20); many of which exhibited nearly regular behaviour. However, 6.5–26.9% meiocytes of eight populations and 47% cells of P-Khe population depicted aneuploidy/contained quadri-octavalents, with per cent pollen viabilities of these ranging from 38.6 to 49.9. Going by the normal tapetal development in V. pilosa, existence of various chromosomal anomalies seems to have accounted for the reduction in gametic fertility of this taxon. [ABSTRACT FROM AUTHOR]

To study the effects of different soil water conditions on pollen fertility and cottonseed yield, cotton plants were grown under different soil water conditions (normal water regime, waterlogging, mild drought, and medium drought) induced by different groundwater depths. Results showed that compared to the normal water regime, cottonseed yield decreased under waterlogging, mild drought, or medium drought. The mild drought had little effect on seed number per boll (SNB) and seed index, but waterlogging and medium drought had significantly negative effects on them. Weak pollen fertility might be the main reason for the decrease of SNB under waterlogging and medium drought, and the decreased pollen fertility was caused by the inhibited synthesis of starch and adenosine triphosphate in anthers. Waterlogging downregulated the activity of soluble starch synthases (SSSase) and the expression level of GhSSSase gene, but medium drought down-regulated SSSase and adenosine diphosphate-glucose pyrophosphorylase (AGPase) activities and the expression of GhAGPase and GhSSSase genes to impede starch synthesis. Moreover, waterlogging increased anther sucrose content by inhibiting acid invertase activity while medium drought increased the accumulation of sucrose content by decreasing sucrose synthetase activity. Both waterlogging and medium drought down-regulated the expression level of GhHXK gene, resulting in higher glucose content in anthers. Furthermore, increased O2− and H2O2 contents also adversely affected the pollen fertility, and this increase was attributed to lesser activities of superoxide dismutase (SOD), peroxidase (POD), and catalase (CAT), and down-regulated gene expression of Cu/Zn SOD, Mn SOD, POD, and CAT. Compared to the medium drought, proline content effectively increased under waterlogging, and a large decrease in SOD activity and Mn SOD gene expression was observed under waterlogging. Our findings suggest that both medium drought and waterlogging affected the carbohydrate and antioxidant metabolism to vitiate pollen viability, ultimately affecting cottonseed development, however, their effects on starch biosynthesis, sucrose decomposition, and antioxidant metabolism were not entirely uniform. These results will improve our knowledge and give us a direction on the mechanism of the tolerance to drought and waterlogging for cotton. [ABSTRACT FROM AUTHOR]

The lack of pollinators in the oil tree peony field was a serious problem for the seed yield. In the preliminary studies, we found that the seed rate of oil tree peonies was significantly improved by supplementing bees during the flowering stages in the pollination net room. In addition, the performance of Apis mellifera L. was better than Bombus terrestris L. To understand the interaction relationship between flowering characteristics and the managed bees, and the pollen-collecting ability of different species of bees, the flowering traits and the pollen loaded on bees were measured in this study. We found that the bees visited flowers with preference and they prefer to forage the flowers having pollen with higher viability. The B. terrestris carried more pollen (27,000.00 ± 5613.70 grains) on the body surface than that of the A. mellifera (7690.00 ± 2873.26 grains). The A. mellifera outperformed B. terrestris both in pollen deposition per visit on the stigma and on the pollen transfer efficiency. The viability of pollen on the body surface (67.77% ± 19.06%) and hind legs (92.02% ± 10.74%) of A. mellifera were both significantly higher than that of B. terrestris (31.84% ± 4.84% and 83.77% ± 6.40%). Our study indicated that the quantity and quality of pollen loaded on stigma by A. mellifera were both better than B. terrestris, which provided evidence that the A. mellifera was the effective pollinator pollinating for the oil tree peony in the pollination net room. [ABSTRACT FROM AUTHOR]

Curcuma is extensively cultivated as a medicinal and ornamental plant in tropical and subtropical regions. Due to the bright bract color, distinctive inflorescence and long blooming period, it has become a new favorite in terms of the urban landscape, potted flowers and cut flowers. However, little research on breeding new cultivars using traditional plant breeding methods is available on the genus Curcuma. In the present study, pollen viability and stigma receptivity evaluation were performed, and the genetic relationship of 38 Curcuma accessions was evaluated, then 5 C. alismatifolia Gagnep. (Ca), 2 C. hybrid (Ch), 2 C. sparganiifolia Gagnep. cultivars and 4 Curcuma native species were selected as parents for subsequent interspecific cross-breeding. A total of 132 reciprocal crosses were carried out for interspecific hybridization, including 70 obverse and 62 inverse crosses. Obvious discrepancies among fruit-setting rates were manifested in different combinations and in reciprocal crosses. Results showed that the highest fruit-setting rate (87.5%) was observed in the Ca combinations. There were 87 combinations with a fruit-setting rate of 0%, which meant nearly 65.9% was incompatible. We concluded that C. alismatifolia 'Siam Shadow' (Ch34) was suitable as a male parent and C. petiolata Roxb. (Cpet) was suitable as a female parent to improve the fruit-setting rates. The maximum number of seeds per fruit (45.4) was obtained when C. alismatifolia 'Chiang Mai Pink' (Ca01) was used as a female parent followed by C. attenuata Wall. ex Baker (Catt) (42.8) and C. alismatifolia 'Splash' (Ca63) (39.6) as male parents. The highest germination rate was observed for the Ca group followed by Catt and C. sparganiifolia 'Maetang Sunrise' (Csms). The germination rates of Ca accessions ranged from 58.2% (C. alismatifolia 'Siam Scarlet' (Ca06) as a male parent) to 89.3% (C. alismatifolia 'Sitone' (Ca10) as a male parent) with an average value of 74.0%. Based on the results of hybrid identification, all the individuals from the four combinations exhibited paternal-specific bands, indicating that the true hybrid rates of crossings were 100%. Our results would facilitate the interspecific hybridization and introduction of genetic variation from wild species into the cultivars in Curcuma in the future, which could be helpful in realizing the sustainable application in urban green areas. [ABSTRACT FROM AUTHOR]

A current trend in climate comprises adverse weather anomalies with more frequent and intense temperature events. Heatwaves are a serious threat to global food security because of the susceptibility of crop plants to high temperatures. Among various developmental stages of plants, even a slight rise in temperature during reproductive development proves detrimental, thus making sexual reproduction heat vulnerable. In this context, male gametophyte or pollen development stages are the most sensitive ones. High-temperature exposure induces pollen abortion, reducing pollen viability and germination rate with a concomitant effect on seed yield. This review summarizes the ultrastructural, morphological, biochemical, and molecular changes underpinning high temperature-induced aberrations in male gametophytes. Specifically, we highlight the temperature sensing cascade operating in pollen, involving reactive oxygen species (ROS), heat shock factors (HSFs), a hormones and transcriptional regulatory network. We also emphasize integrating various omics approaches to decipher the molecular events triggered by heat stress in pollen. The knowledge of genes, proteins, and metabolites conferring thermotolerance in reproductive tissues can be utilized to breed/engineer thermotolerant crops to ensure food security. [ABSTRACT FROM AUTHOR]

Solanum melongena is susceptible to diverse diseases and parasites, in particular the wilts (bacterial, Fusarium and Verticillium), nematodes, and some insects. Solanum torvum is robust to Verticillium and some bacterial wilts and root-knot nematode. It was reported that interspecific hybrid plants originated out of the hybridization of these species were sterile. In our previous studies that have been carried out to overcome this interspecific hybridization barrier, only from Faselis F1 that was used as the female parent, many interspecific hybrid seeds were obtained and 9.07% of the seeds grew into plants in vitro. The percentage of pollen viability and germination of tetraploid interspecific hybrid (amphidiploid) genotypes that have been produced by in vitro colchicine treatment, were 6.8 and 3.4 fold of its source diploid genotype, respectively. However, the increment was not high enough to overcome the interspecific hybridization barrier between S. torvum and S. melongena. In this study, the changes in pollen fertility of diploid interspecific hybrids and tetraploid plants, which have grafted on Pala or Faselis F1, were investigated. Pollen viability and germination percentage in diploid genotypes were not affected by grafting, although they increased significantly (51.54% and 119.73%, respectively) in tetraploid genotypes by grafting. It was determined that the fertile diploid rootstock used for the tetraploid genotypes that produced by chromosome doubling from cultured eggplants could increase the number of seeds per fruit. It was concluded that some fertile diploid varieties can be used as rootstocks in order to increase pollen viability, germination rate and seed yield of tetraploid genotypes with low pollen yield obtained from cultivated eggplant by chromosome doubling. [ABSTRACT FROM AUTHOR]

Modern agricultural biotechnologies, such as those derived from genetic modification, are solutions that can enable an increase in food production, lead to more efficient use of natural resources, and promote environmental impact reduction. Crops with altered genetic materials have been extensively subjected to safety assessments to fulfill regulatory requirements prior to commercialization. The Brazilian National Technical Biosafety Commission (CTNBio) provides provisions for commercial release of transgenic crops in Brazil, including requiring information on pollen dispersion ability as part of environmental risk assessment, which includes pollen viability and morphology studies. Here we present the pollen viability and morphology of non-transgenic conventional materials, single-event genetically modified (GM) products, and stacked GM products from soybean, maize and cotton cultivated in Brazil. Microscopical observation of stained pollen grain was conducted to determine the percentage of pollen viability as well as pollen morphology, which is assessed by measuring pollen grain diameter. The pollen viability and diameter of GM soybean, maize and cotton, evaluated across a number of GM events in each crop, were similar to the conventional non-GM counterparts. Pollen characterization data contributed to the detailed phenotypic description of GM crops, supporting the conclusion that the studied events were not fundamentally different from the conventional control. [ABSTRACT FROM AUTHOR]