Viable Pollen Grains Research Articles

Exploring the influences of resource limitation and plant aging on pollen development in Azorella nivalis Phil. (Apiaceae), a long-lived high-Andean cushion plant.

Angiosperm pollen, the male gametophyte, plays a crucial role in facilitating fertilization by protecting and transporting male sperm cells to the female pistil. Despite their seemingly simple structure, pollen grains undergo intricate development to produce viable sperm cells capable of fertilizing the egg cell. Factors such as resource limitation and plant aging can disrupt normal pollen development and affect pollen performance. We investigated the influence of plant resources and aging on pollen developmental failure in Azorella nivalis Phil., an exceptionally long-lived high-Andean species that grows in a stressful alpine environment. Leveraging the modular nature of plants, we aimed to identify intra-individual sources of variation in pollen developmental failure. By using pollen viability and variation in viable pollen grain size as indicators of pollen developmental performance, we assessed whether proxies of plant resource availability and aging influenced these pollen traits at the inter-individual, inter-flower and intra-flower levels. Our findings revealed decreased pollen viability in putative resource-depleted flowers and in shoots that experienced higher levels of meristematic divisions from the zygote (i.e., greater cell depth). Additionally, we observed increased variability in the size of viable pollen grains in resource-depleted anthers. Our study suggests that resource availability and shoot aging are critical determinants shaping pollen development in long-lived plants at the intra-individual level. These findings contribute to our understanding of how differences in male fitness can arise in plants, with implications for their evolutionary trajectory.

ICE1 interacts with IDD14 to transcriptionally activate QQS to increase pollen germination and viability.

In flowering plants, sexual reproductive success depends on the production of viable pollen grains. However, the mechanisms by which QUA QUINE STARCH (QQS) regulates pollen development and how transcriptional activators facilitate the transcription of QQS in this process remain poorly understood. Here, we demonstrate that INDUCER OF CBF EXPRESSION 1 (ICE1), a basic helix-loop-helix (bHLH) transcription factor, acts as a key transcriptional activator and positively regulates QQS expression to increase pollen germination and viability in Arabidopsis thaliana by interacting with INDETERMINATE DOMAIN14 (IDD14). In our genetic and biochemical experiments, overexpression of ICE1 greatly promoted both the activation of QQS and high pollen viability mediated by QQS. IDD14 additively enhanced ICE1 function by promoting the binding of ICE1 to the QQS promoter. In addition, mutation of ICE1 significantly repressed QQS expression; the impaired function of QQS and the abnormal anther dehiscence jointly affected pollen development of the ice1-2 mutant. Our results also showed that the enhancement of pollen activity by ICE1 depends on QQS. Furthermore, QQS interacted with CUT1, the key enzyme for long-chain lipid biosynthesis. This interaction both promoted CUT1 activity and regulated pollen lipid metabolism, ultimately determining pollen hydration and fertility. Our results not only provide new insights into the key function of QQS in promoting pollen development by regulating pollen lipid metabolism, but also elucidate the mechanism that facilitates the transcription of QQS in this vital developmental process.

Phenotypic characteristics of black apricot Prunus × dasycarpa cultivar ‘Shlor-Tsiran’ in Armenia

ABSTRACT ‘Shlor-Tsiran’ (literally called ‘Plum-Apricot’) is an old black apricot cultivar, which is traditionally cultivated in Armenia. Taxonomically, it belongs to Prunus × dasycarpa Ehrh., which is a spontaneous hybrid of apricot and cherry plum (P. armeniaca L. × P. cerasifera Ehrh.). Currently, ‘Shlor-Tsiran’ is considered to be very rare in Armenia and it occurs as single trees in old home orchards of the Ararat Valley. It is characterised by high frost and disease resistance, late flowering and fruiting compared with other cultivated apricots, and is of interest for the development of apricot cultivars displaying delayed fruit ripening and enhanced frost resistance. This study aims to phenotype the cv. ‘Shlor-Tsiran’ taking into consideration 67 quantitative and qualitative characteristics of vegetative and generative organs, growth and development. Morphological description of the cv. ‘Shlor-Tsiran’, comparing with its parent species, P. armeniaca and P. cerasifera, was performed. Data on fertility and viability of pollen grains, biochemical and nutritional properties of fruits and tree productivity are provided. The data obtained should contribute to a wider use and conservation of the black apricot cv. ‘Shlor-Tsiran’ gene pool, which can be used for breeding purposes as well. The article is illustrated with tables and original photographs.

How the tailings of the Fundão Dam impacted the photosynthetic metabolism and viability of pollen grains of Canavalia rosea

How the tailings of the Fundão Dam impacted the photosynthetic metabolism and viability of pollen grains of Canavalia rosea

Reproductive biology of Capparis decidua (Kair): A potential underutilized multipurpose plant of arid and semi arid region

Foliation and flowering of Capparis decidua occurs three times a year i.e. from January to November months. Flowers are bracteate, pedicellate, complete, hermaphrodite, zygomorphic, hypogynous with slender pedicel, usually light red, scarlet red and yellow in colour. Anthesis was maximum between 4.00 p.m. to 8.00 PM and 6.00 to 10.00 AM. Pollen grains are prolate, tricolporate, trilobed, with costae, colpal membrane sparsely granulated. Anther dehiscence takes place after 20–30 minutes of anthesis at 6.00 to 8.00 PM by the time the flowers starts antehsizing, the anthers are almost mature. The viability of pollen grains ranges from 38–52%, and starts decreasing in the stored pollen. The percentage fruit set decreases with the collection time of the pollen grains and plant type. According to visual observation stigmatic surface change in the appearance i.e. green coloured stigma was considered receptive while dull and brown was accounted non-receptive. Pollen germination in-vivo showed 80 per cent stigma receptive and 90 percent of fruit set in the flowers pollinated on the time of anthesis. Pollen grains per anther were ranging from 331–369, fully developed and mature anthers differing significantly among the plant types. The mean number of pollen grains per ovule was 4309 thus the pollen-ovule ratio was 431:1. There is 17–23% fruit set observed under self pollination (autogamy and geitonogamy) and 52–72% as a result of cross pollination. The cross pollinated nature of C. decidua is due to entomophilic nature of flowers, insect visitors which play the main role of pollination are from Apidae and Papilionidae.

Evaluation of viability and germination of pollen grains of three local caprifig cultivars and their effect on some characteristics of fig fruits (Ficus carica L.)

This research was carried out in fig fields in the village of Kafar-Jales, in the north of Syria. The analyses were conducted in the laboratories of the Faculty of Agriculture at Idlib University during the 2022 farming season, to evaluate the viability and germination of three local varieties of Caprifig (Bunduqi, Azraq, Panjani). The morphological characteristics, the date of the exodus of insects (Blastophaga psenes) from male fruits, the quantity of pollen, and the percentage of germination and viability were studied on four nutritive media at a temperature of 27°C. The measurements were taken after 24 h, 48 h, and 72 h. These three pollinators were used to pollinate three varieties of edible figs (white Satehi, Safrawi, and Habashi) to study the effect of pollen source on the productive characteristics of edible fig fruits. The result showed significant superiority of the Bunduqi cultivar over the rest of the cultivars in traits of the fruit’s early ripening, pollen quantity, and date of departure of insects. The Azraq cultivar is found to be superior to Bunduqi and Panjani cultivars in the germination rate of pollen at all stages of the experiment and in all used media. The addition of stigma flower extract in culture media increased germination percentage by 35% for all studied Caprifig cultivars. The addition of 10% sucrose in the cultivation environment increased the percentage of pollen germination by 20%. The cultivars that were inoculated with the Panjani pollinator outperformed the characteristics of the length, diameter, and weight, demonstrating that the fruit’s quality characteristics are affected by the genotype of the pollinator used. The results of this research can be beneficial for both fig growers and plant breeders, as they help to select the best pollinators and contribute to the development and improvement of the quality of the cultivated fig fruits.

Viability and conservation of genipap tree pollen grains

Viability and conservation of genipap tree pollen grains

Examining the Effects of Prunus Necrotic Ringspot Virus (PNRSV) and Prune Dwarf Virus (PDV) on Peach (Prunus persica) Pollen Health

Pollen health is a key determinant of successful plant reproduction and crop yield. Prunus necrotic ringspot virus (PNRSV) and prune dwarf virus (PDV) are pollen-borne viruses of stone fruits, including peaches, primarily transmitted through vegetative propagation (i.e., grafting) and pollen. Here, we investigated the effects of PNRSV and PDV infection on peach pollen morphology, viability, and germination. Our scanning electron microscopy on pollen morphology, as well as pollen viability and germination assays, showed that PNRSV has cultivar-specific effects on pollen health; compared with pollen from virus-negative trees, PNRSV infection resulted in distorted shape, reduced viability, and germination of pollen grains of peach cultivar Red Top, but no significant effects on viability or germination were detected on cultivar Zee Lady pollen grains. PDV infection affected pollen width and reduced pollen viability but did not affect pollen germination when compared between PDV-positive and PDV-negative pollen grains. We discuss our results in terms of potential evolutionary consequences and implications on virus epidemiology and disease management in orchards. Investigating the effects of viral infection on pollen health will ultimately enhance our understanding of the transmission of pollen-borne viruses. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Reproductive Biology of Solanum orbiculatum ssp. orbiculatum, an Australian Endemic Bush Tomato

The Australian tomato Solanum orbiculatum ssp. orbiculatum is an edible bush tomato endemic to the more arid areas of Western Australia, South Australia, and the Northern Territory. Breeding system data indicate that the plants are potentially self-compatible but are unable to carry out spontaneous autogamy or agamospermy. The flower is protogynous, as the stigma become receptive to pollen germination while still in bud condition and the anthers do not release pollen immediately after anthesis. This arrangement is a simple and common way to avoid too much self-pollination, favours cross pollination, and would allow forced bud pollination for hybrid development. The floral structure and morphology of this species can also encourage cross pollination, as the stigma is mostly exserted above the anther’s tips. In an attempt to examine the hypothesis of a positive correlation between pollen grain size and style length, we found a statistically significant difference between the pollen size of the long-styled and short-styled flowers. Pollen in vitro germination and viability tests have been optimised to facilitate effective breeding work on this species. A modified Brewbake and Kwack (BK) medium supplemented with 20% sucrose and 2.5% PEG 4000 has been found to be the most efficient media components for the in vitro germination of viable pollen grains. Alternatively, Alexander’s and acetocarmine (1%) stains have shown the highest positive correlation with the in vitro pollen germination test and, therefore, can be used as quick tests for checking pollen viability. Moreover, pollen grains stored for three months under 4 °C and dry conditions can be used efficiently to effect fertilisation in breeding programs, as it can maintain more than 50% of the original viability. This study will contribute to understanding the evolution and systematic relationships of species and for founding effective conservation programs. Furthermore, understanding the reproductive biology of this species is also of interest because of its potential for tomato breeding.

Optimization of In Vitro Germination, Viability Tests and Storage of Paeonia ostii Pollen.

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.

Stamen and pollen heteromorphism linked to the division of labour in Melastomataceae species

The occurrence of stamen heteromorphism within pollen flowers (or heteranthery) has been mostly explained by a division of labour hypothesis, which suggests that some anthers produce pollen for pollination (pollinating anthers) while others are specialized in attracting and rewarding floral visitors (feeding anthers). Despite more than 20.000 species presenting stamen heteromorphism, the morphological and functional traits associated with it have been poorly investigated, especially at the pollen level. Here we evaluated the structural and possible functional roles of stamen and pollen heteromorphism in 16 Melastomataceae species belonging to four tribes. We investigated how a number of traits associated with floral heteromorphisms - anther size, pollen quantity and quality, pollen volume and exine ornamentation - might interact with pollination efficacy and pollinator feeding behaviour. Our results showed morphological differences between anthers and pollen grains that might affect pollinating and feeding functions in the studied species. Pollinating anthers were larger and produced more numerous and more viable pollen grains than feeding anthers. Pollen grain volume between the anther sets was mostly similar in the analysed species, with the exception of three species. Three species of tribe Microlicieae and one from the Marcetieae presented differences in pollen exine ornamentation between pollinating and feeding anthers. Overall, our findings support the division of labour hypothesis for some, but not all, species included in our study. We showed that stamen heteromorphism on the 16 studied species may lead to subtle and specific differences in anthers and pollen morphology which may contribute to their functional role.

Peculiarities of the development of reproductive organs of ornamental crabapples (Malus spp.) depending on drought resistance

The current task for both pomiculture and ornamental horticulture is the formation of plant cultivars resistant to different environmental stress and maintaining their high productivity. Drought is one of the most significant environmental factors that inhibit plant growth and development and cause a set of morphological, physiological, and biochemical changes in plant organisms. The aim of our research was to discover the relationship between the development of the reproductive organs of ornamental crabapples and the physiological indicators determined by drought stress factors. The four species and three cultivars of the ornamental crabapples (Malus spp.) from the collection of the National Dendrological Park “Sofiyivka” of NAS of Ukraine were involved in the study: M. × floribunda Siebold ex Van Houtte, M. halliana Koehne, M. niedzwetzkyana Dieck, M. × purpurea (A. Barbier) Rehder, M. × purpurea ‘Ola’, M. × purpurea ‘Royalty’, and M. × purpurea ‘Selkirk’. Drought resistance was determined by the following quantitative indicators: leaf water content, relative turgidity, leaf water deficit, and excised leaf water retention capacity. The leaf water content ranged from 60.0% (M. × floribunda) to 67.2% (M. × purpurea), the relative turgidity ranged from 81.7% (M. × purpurea ‘Ola’) to 98.9% (M. halliana), and the leaf water deficit ranged from 6.8% (M. halliana) to 24.4% (of M. niedzwetzkyana). As a result, the leaves of M. halliana lost the smallest amount of water in 24 hours (50.2%), whereas M. × purpurea 'Ola' leaves lost the largest amount (77.4%). The development of the reproductive organs was estimated based on the fertility and viability of pollen grains, percentage of fruit and seed set. Pollen fertility ranged from 79.8% (of M. niedzwetzkyana) to 95.0% (M. × purpurea 'Ola'); its viability varied from 5.1% (M. niedzwetzkyana) to 51.5% (M. × floribunda). The highest fruit set percentages were recorded in M. floribunda (80.5%), while the lowest was in M. × purpurea 'Royalty' (16.4%). The average percentage of seed sets was 48.5%. The development of the reproductive organs of Malus specimens depended on their drought resistance. The fruit and seed set percentages had a strong negative correlation with the water deficit in leaves determined during the period of drought stress. The percentage of fruit set was also strongly correlated with relative turgidity. The leaf water deficit and relative turgidity were the most important physiological indicators in the drought resistance study, taking into account the need to maintain crop yield and the decorative effect of Malus plants.

High Temperature-Induced Spindle Destabilization Results in Aborted Pollen Production in Populus

High temperature can induce the production of 2n gametes and aborted pollen during microsporogenesis in Populus canescens. However, the mechanism by which high temperature induces pollen abortion remains unknown. Here, pollen abortion was induced by exposing male flower buds of P. canescens to 38 and 41 °C; pollen morphology, meiotic abnormalities, defects of the meiotic microtubular cytoskeleton, and tapetum development were characterized. We found that the dominant meiotic stage, temperature, and duration of treatment significantly affected the percentage of high temperature-induced aborted pollen. Damaged spindle microtubules and depolymerized microtubular cytoskeletons were observed, which resulted in many lagging chromosomes at anaphase I and II as well as aneuploid male gametes and micronuclei, thereby generating aborted pollen grains. Tapetum disintegration was also delayed. The anther dehisced normally, and some viable pollen grains were released. However, no sufficient evidence showed that the delayed degradation of the tapetum was responsible for pollen abortion.

Evaluation of Growth and Pollen Viability (Fertility) in Relation to Fruit Set among Five Varieties of Tomato

The evaluation of pollen viability and fruit setting capacity are two essential criteria for pollinator’s characterization. This study was carried out to evaluate pollen Fertility/ viability in five Varieties of Tomatoes. We analyzed the viability of pollen grains of five different varieties of tomatoes grown in ITM University, Gwalior, Madhya Pradesh, India. Aceto- carmine method is used to estimate pollen viability. The germination percentage, pollen viability and Fruit setting rate were recorded at different stages respectively. Pollen viability in relation to fruit set was analyzed while growth parameters and fruit yield per plant of each variety were also collected and analyzed. Results displayed that the highest pollen viability rate (100%) was obtained in SWEAKAR-448 Variety followed by Arka Vikas (95%), ARJUN-135 (93%), 9005-SIRI (90%) and PKM-1 (80%). The highest percentage of germination (95%) was shown by 9005-SIRI Variety and maximum fruit setting (15-20 Fruits per plant) was recorded in the SWEAKAR-448 Variety. The results showed significant vegetative growth variations and correlations between pollen viability and fruit setting characters. In addition, it was found a noticeable variation in Pollen viability/fertility, was not proportional to fruit setting percentage. In general Pollen viability was directly linked to fruit set, whereas formation and fruit set were not in the tomato varieties that were investigated. Pollen viability was high, which was accompanied through a reduction in the number of fruit sets, fruit size and pollen viability in the field is highly variable, indicating that differences in microenvironment may have a profound effect on fruit setting and pollen viability.

Potential Gene Flow Between <i>Gossypium hirsitum</i> and <i>Abelmoschus esculentus</i> Through Interspecific Hybridization

The introduction of transgenic varieties of cotton (<i>Gossypium hirsitum</i>) in Cameroon has posed numerous concerns. One of the most concern was the horizontal transfer of the <i>Bt</i> gene to related species such as <i>Abelmoschus esculentus</i>. The current study was conducted to assess the occurrence <i>Bt</i> gene transfer from <i>Gossypium hirsitum </i>to<i> Abelmoschus esculentus</i>. To achieve this, the stigma receptivity periods and the viability of pollen grains were evaluated. The fruit set rates of 675 controlled intra- and interspecific crosses were assessed. The results showed that stigma receptivity and pollen grain viability are optimal at anthesis in both species, with a longer duration over 24 hours in <i>G. hirsitum</i>. Intra-specific crosses within the two species have shown fruit set rates of nearly 60-80%. Interspecific crosses gave a fruit set rate close to 2%, especially when <i>A. esculentus</i> is used as the female parent, and zero results in reciprocal crosses. The finding of the study pointed out that the possibility of horizontal transfer of a transgene to cotton relatives. In future studies, it would be useful to monitor the fate of seeds from interspecific crosses between both species and assess the agro-morphological and molecular characteristics of these possible hybrids.

POLLEN GRAIN STRUCTURE AND POLLINATION IN THE &lt;i&gt;RIBES&lt;/i&gt; (GROSSULARIACEAE) REPRESENTATIVES

Currant is an important small-fruit crop that has long been used for medicinal purposes. The systematic position of the genus Ribes in the kingdom Plantae is perceived by researchers unambiguously. However, the internal taxonomy of the genus Ribes and the systematic position of some species in the genus remains a matter of debate.The study of the morphology, fertility and viability of pollen grains is also an important indicator in determining phylogenetic relationships in the genus Ribes. Comparative poral-colpus analysis of pollen makes it possible to determine the similarities and differences in different species and the degree of genetic relatedness of the compared forms. The processes of pollination and germination of pollen in the pistil style in the Grossulariaceae are poorly covered in the cited literature.These problems became the ground for the study, the purpose of which was to determine the characteristics of pollen grains, pollination and germination of pollen on both the pistil stigma and artificial nutrient medium in Ribes species in order to identify species characterized by pollen of maximum viability, suitable for breeding work in the conditions of St. Petersburg.The objects of the study were plants of the Ribes species from the open ground collection of the Komarov Botanical Institute RAS (R. sachalinense, R. sanguineum, R. rubrum, R. mandschuricum, R. spicatum, R. saxatile, R. aureum, R. alpinum, R. nigrum), as well as the species growing in nursery of the N.I. Vavilov All-Russian Institute of Plant Genetic Resources: R. dikuscha, R. hudsonianum, R. nigrum subsp. europeum, R. nigrum subsp. sibiricum, R. pauciflorum, R. ussuriense. Pollen was examined using a Zeiss EVO-40 scanning electron microscope at the Center for Collective Use of Atomic Force and Electron Microscopy, Herzen University.It was revealed that the studied Ribes plants have normally developed pollen grains of a spherical or elliptical shape, with concave lateral planes, the pollen is porate-colpate. Currant pollen is characterized by wide polymorphism both between different species and within the same species. In all studied species, there are deviations in morphological structure of pollen grains; such pollen does not germinate on an artificial nutrient medium. The most deformed pollen was observed in Ribes mandshuricum, R. ussuriense, R. alpinum, R. dikusha, and R. pauciflorum (12.7–6.7%). The pollen of medium size (21–49 μm) is the most suitable for fertilization. The largest share of the medium-sized pollen is found in Ribes sanguineum, R. ussuriense, R. saxatile and R. aureum (91.8–94.6%). The studied plants have a high percentage of morphologically formed (fertile) pollen (the share of stained pollen is 80.3–96.4%). At the same time, the pollen has a rather low viability when germinated on an artificial nutrient medium, with the pollen of Ribes sanguineum, R. spicatum, R. nigrum, R. ussuriense, R. aureum germinates germinating better than the others (45–29%). Often, the pollen grains germinate with disturbances, which is reflected in the direction of their growth. In some species of Ribes, pollen is able to germinate while still inside the anther. The percentage of pollen germination inside the anther is unequal in the flowers taken from different parts of the inflorescence; the best germination is found in the pollen from the flowers of the central zone of the inflorescence.The pollinators of the Ribes flowers in St. Petersburg are representatives of genera Apis, Bombus and a lacewing Chrysopa oculata. There are 2 peaks of pollinators’ activity: in the morning (10–11 a.m.) and in the evening (5–6 p.m.).The germination of pollen grains on the pistil stigma in the studied plants is active. At a relatively high air temperature, the passage of the pollen tube to the ovule takes 3–5 days. In the ovules on the first day of flowering, mature embryo sacs ready for fertilization are observed. On the walls of the ovary, 4 hemi-orthotropic ovules develop, arranged in 6–10 “levels”. The pollen enters the stigma in a two-celled state. The division of the generative cell into two spermia occurs in the pollen tube during the growth of the latter. The germination of the pollen tube in the canal of the pistil style often occurs with disturbances.The conducted studies allow to recommend the species Ribes sanguineum, R. spicatum, R. nigrum, R. aureum for use in Ribes breeding in the conditions of St. Petersburg.

Effectiveness of Pollen Germination Media for Improving Storage Potential in Pomegranate (Punica granatum) Germplasm

Viable pollen grains with the ability to germinate after fertilization are necessary for fruit and seed formation. Pollens are sensitive to environmental conditions and quickly lose their viability after anthesis. In vitro storage potential of pollen grains depends on species, genotype, flower type, and storage conditions. The present study's objective was to evaluate pomegranate germplasm's storage potential and to study germination media's influence on short-term stored pollen's germination percentage. Pollens of fifteen pomegranate genotypes were collected and stored at 4 °C for 30 days. Pollen viability was assessed using in vitro pollen germination by the agar-Petri method. The germination media was composed of different concentrations of sucrose, boric acid, and agar. The results showed that germination media (12.5% sucrose + 0.2% agar) supplemented with 10 ppm boric acid gave the highest germination among all cultivars. Among genotypes, maximum (58.3%) germination was observed in Desi and Kandhari red pollens, and minimum (16.3%) was observed in Sandhora. The concentration of boric acid in germination media influenced pollen germination. The highest pollen germination was found at 10 ppm, followed by 5 ppm, and the lowest germination was found in media with no boric acid. Conclusively genotypes show variation in storage potential, and germination media influences post-storage germination rate. The utilization of effective germination media can increase the pollen germination rate for pomegranate genotypes.

Жизнеспособность пыльцы некоторых видов древесных растений Донецкой агломерации

Data on the sterility and viability of woody plants pollen grains in the Donetsk urban agglomeration are presented. The study object was pollen samples of woody plant species used in landscaping in Donetsk such as black poplar (Populus nigra L.), white willow (Salix alba L.), horse chestnut (Aesculus hippocastanum L.), Silver birch (Betula pendula Roth). On the studied sites, it has been established that the sterility of pollen grains ranges from 16 to 44 %, and the viability ranges from 49 to 96%, which is a critical indicator indicating the inability to restore reproductive function in some of the studied species. It is statistically determined that the correlation of the studied parameters (selection points, sterility, viability) characterizes the Donetsk agglomeration as an unfavorable environment for plant life. The data obtained indicate a high degree of adaptation and resistance of tree species to technogenic impact. Indicative signs of atmospheric air pollution are determined, which are typical for the Donetsk agglomeration. Under conditions of intense technogenic load, a pattern appears in the quality change of pollen grains forming pollen anomalies. An indicator that characterizes the anatomical and morphological structure of pollen grains can be used in Donetsk conditions as a complement to other characteristics when a significant level of environmental pollution is detected.

Staggered arrangement and sequential dehiscence of anthers in didynamous stamens facilitate reproductive fitness of Brandisia hancei

AbstractDidynamous stamens are separated into two pairs of different length, and the implication of this arrangement has not been well understood. The functional advantages of didynamous stamens were investigated in Brandisia hancei. Change of stamens during floral aging was recorded; the quantity, viability, and siring ability of pollen grains were tested; the anther arrangement was manipulated into four types based on stamen category and number, and fruit set and number of seeds per fruit were measured. Didynamous stamens exhibited staggered anther arrangement, and pollen sacs dehisced gradually. There was no difference for quantity, viability, and siring ability of pollen grains between the two pairs of anthers. Seed production after the removal of one long and one short stamen was higher than that of two long or two short stamens. Through prolonging pollen presentation and promoting delayed self‐pollination, staggered arrangement and sequential dehiscence of anthers in didynamous stamens facilitate reproductive fitness of B. hancei.

Tomato POLLEN DEFICIENT 2 encodes a G-type lectin receptor kinase required for viable pollen grain formation.

Pollen development is a crucial biological process indispensable for seed set in flowering plants and for successful crop breeding. However, little is known about the molecular mechanisms regulating pollen development in crop species. This study reports a novel male-sterile tomato mutant, pollen deficient 2 (pod2), characterized by the production of non-viable pollen grains and resulting in the development of small parthenocarpic fruits. A combined strategy of mapping-by-sequencing and RNA interference-mediated gene silencing was used to prove that the pod2 phenotype is caused by the loss of Solanum lycopersicum G-type lectin receptor kinase II.9 (SlG-LecRK-II.9) activity. In situ hybridization of floral buds showed that POD2/SlG-LecRK-II.9 is specifically expressed in tapetal cells and microspores at the late tetrad stage. Accordingly, abnormalities in meiosis and tapetum programmed cell death in pod2 occurred during microsporogenesis, resulting in the formation of four dysfunctional microspores leading to an aberrant microgametogenesis process. RNA-seq analyses supported the existence of alterations at the final stage of microsporogenesis, since we found tomato deregulated genes whose counterparts in Arabidopsis are essential for the normal progression of male meiosis and cytokinesis. Collectively, our results revealed the essential role of POD2/SlG-LecRK-II.9 in regulating tomato pollen development.