Pollen Pistil Research Articles

An insight into the reproductive success in an interspecific cross of sesamum

Sesame viz., Sesamum indicum (CO 1) and Sesamum alatum. The wild species are the potential source for biotic and abiotic stress-resistant genes and therefore high crossability with the cultivated variety is very essential for the transfer of genes through a conventional breeding programme. The pollen images obtained and the number of colpi counted from Light Microscope and Scanning Electron Microscope assisted in differentiating the pollen of Sesamum indicum from Sesamum alatum. The pollen fertility assessment by Acetocarmine test proved that Sesamum indicum (CO 1) was more fertile than Sesamum alatum and hence the former was presumed to be the better pollen-producing parent in terms of fertility. The pollen pistil interaction by aniline blue technique between direct and reciprocal crosses of two species of Sesamum reported higher and lower germination per cent at 2 HAP and 8 HAP, respectively. The mean pollen germination per cent of the direct and reciprocal cross was observed to be 69.99 and 58.59, respectively. In the direct cross, the pollen tube managed to reach the ovary but did not set seeds and hence is claimed to possess a post-zygotic fertilization barrier. In the reciprocal cross, the growth of the pollen tube stopped before reaching the ovary apparently, no seed set was observed and therefore designated to have pre zygotic fertilization barriers. Direct and reciprocal crosses were compared and ways to mitigate fertilization barriers are discussed. Key words: Sesame, interspecific cross, pollen pistil interactions, aniline blue technique, fertilization barriers

Reproductive Biology and Pollination Ecology of Berberis lycium Royle: A Highly Valued Shrub of Immense Medicinal Significance.

Study of reproductive biology and pollination ecology helps in understanding the life history patterns of species. Such a study brings to light the bottlenecks, if any, on account of which the individuals of the species are not able to reproduce in nature and ultimately helps in planning appropriate conservation strategies for the species under threat. The present study was aimed at examining the morphological and reproductive variance in Berberis lycium, a threatened ecological specialist growing within shrubberies and open hillsides of the North-Western Himalayas in India. B. lycium displays three different variants. Flowering period ranges from February to September. Pollen viability as reported on fluorescein diacetate and acetocarmine treatments was highest for variant I, while maximum pollen output was obtained for variant III. Pollen pistil interaction is brought by the movement of anther towards stigma. Fluorescence microscopy of hand pollinated club shaped stigma shows that the germinating pollen form a ring over the receptive adaxial surface. Pollination syndrome is entomophily. Variant II attracts a significantly large number of pollinators from diverse insect families. Breeding experiments reflect that plants are self-compatible and cross fertile. Reproductive output (% fruit set) was highest for variant II followed by III and I, respectively. This investigation helped to understand the effect of different biotic and abiotic constraints on the phenology and reproductive biology of the plant. The information generated so will enable conservationists to design appropriate strategies for its long-term survival and sustenance in nature.

Intraspecific crossability and compatibility within Solanum aethiopicum

Understanding hybridization barriers is relevant for germplasm conservation and utilization. The prezygotic barriers to hybridization include floral morphological differences like pistil and stamen length, pollen characteristics and pollen-pistil interactions. This study sought to elucidate the reproductive biology of Solanum aethiopicum; its mating systems and compatibility barriers. Eight genotypes of Solanum aethiopicum were examined for differences in floral morphology, phenology and cross compatibility in a full diallel mating design, with assessment of fruit set, seed set and seed viability. In-vivo pollen tube growth was observed for failed crosses at 24, 48 and 72 h after pollination. All genotypes had heterostyly flowers, with predominantly small white petals. Incompatibility was observed in five out of 39 combinations. All selfed genotypes displayed compatibility implying the genotypes are self-compatible. Pollen–pistil incompatibility, which was exhibited in four out of the five failed cross combinations, occurred on the stigma, upper style and lower style, a phenomenon typical in Solanaceae. Solanum aethiopicum is self-compatible and majorly self-pollinating but has features that support cross-pollination.

Application of Pollen Germination Media on Stigmas during Pollination Increases Seed Set in East African Highland Cooking Bananas (Musa spp.)

Seed set in East African Highland Cooking bananas (EAHBs) is extremely low and therefore hampers breeding. Pollen–pistil interaction is a key contributing factor. We assessed the effect of pollen germination media (PGM) on seed set in EAHBs. Five EAHB cultivars were pollinated with pollen from the wild banana ‘Calcutta 4’. Glucose-based PGM sprayed on freshly emerged stigmas significantly increased seed set per 100 fruits per bunch. Increases were 73.5% in ‘Enzirabahima’, 39.9% in ‘Mshale’, and 302.4% in ‘Nshonowa’. However, PGM did not increase seed set in the female sterile ‘Mlelembo’ and ‘Nakitembe’. As larger bunches were more fertile, good field management practices are also recommended to get more seed to improve breeding efficiency.

Turgor regulation defect 1 proteins play a conserved role in pollen tube reproductive innovation of the angiosperms.

Sexual reproduction in angiosperms is siphonogamous, and the interaction between pollen tube and pistil is critical for successful fertilization. Our previous study demonstrated that mutation of the Arabidopsis turgor regulation defect 1 (TOD1) gene leads to reduced male fertility, a result of retarded pollen tube growth in the pistil. TOD1 encodes a Golgi-localized alkaline ceramidase, a key enzyme for the production of sphingosine-1-phosphate (S1P), which is involved in the regulation of turgor pressure in plant cells. However, whether TOD1s play a conserved role in the innovation of siphonogamy is largely unknown. In this study, we provide evidence that OsTOD1, which is similar to AtTOD1, is also preferentially expressed in rice pollen grains and pollen tubes. OsTOD1 knockout results in reduced pollen tube growth potential in rice pistil. Both the OsTOD1 genomic sequence with its own promoter and the coding sequence under the AtTOD1 promoter can partially rescue the attod1 mutant phenotype. Furthermore, TOD1s from other angiosperm species can partially rescue the attod1 mutant phenotype, while TOD1s from gymnosperm species are not able to complement the attod1 mutant phenotype. Our data suggest that TOD1 acts conservatively in angiosperms, and this opens up an opportunity to dissect the role of sphingolipids in pollen tube growth in angiosperms.

Ovary Signals for Pollen Tube Guidance in Chalazogamous Mangifera indica L.

Most flowering plants show porogamy in which the pollen tubes reach the egg apparatus through the micropyle. However, several species show chalazogamy, an unusual pollen tube growth, in which the pollen tubes reach the embryo sac through the chalaza. While ovary signals for pollen tube growth and guidance have been extensively studied in porogamous species, few studies have addressed the process in chalazogamous species such as mango (Mangifera indica L.), one of the five most important fruit crops worldwide in terms of production. In this study, we characterize pollen–pistil interaction in mango, paying special attention to three key players known to be involved in the directional pollen tube growth of porogamous species such as starch, arabinogalactan proteins (AGPs), and γ-aminobutyric acid (GABA). Starch grains were observed in the style and in the ponticulus at anthesis, but their number decreased 1 day after anthesis. AGPs, revealed by JIM8 and JIM13 antibodies, were homogenously observed in the style and ovary, but were more conspicuous in the nucellus around the egg apparatus. GABA, revealed by anti-GABA antibodies, was specifically observed in the transmitting tissue, including the ponticulus. Moreover, GABA was shown to stimulate in vitro mango pollen tube elongation. The results support the heterotrophic growth of mango pollen tubes in the style at the expense of starch, similarly to the observations in porogamous species. However, unlike porogamous species, the micropyle of mango does not show high levels of GABA and starch, although they were observed in the ponticulus and could play a role in supporting the unusual pollen tube growth in chalazogamous species.

Chemical composition and reproductive functionality of contrasting faba bean genotypes in response to water deficit

Water deficit (WD), a major contributor to yield reductions in faba bean (Vicia faba), is a complex phenomenon that varies across daily to seasonal cycles. Several studies have identified various morphological and physiological indicators of WD tolerance, which generally show limited water use during WD. Limited information is available on the impact of WD on nutrient content and reproductive biology of the faba bean. We studied carbohydrates, amino acids, mineral nutrients and the abundance of naturally occurring carbon isotopes (δ13 C) in leaf and grain tissues of faba bean genotypes grown under well-watered (WW) and WD conditions. δ13 C of leaf tissues were found to indicate changes in water use due to WD but this was not reflected in grain tissues. Nutrient concentrations with regard to amino acids and minerals were not influenced by WD. However, carbohydrate accumulation was found to be significant for WD, specifically through the presence of a higher concentration of myo-inositol in WD leaf tissues. Alternatively, sucrose concentration in grain tissues was reduced under WD treatment. WD hampered reproductive functionality by reducing pollen viability and germination with the severity and duration of stress and this reduction was less prominent in the drought-tolerant genotype (AC0805#4912) compared to the sensitive one (11NF010c-4). It was also demonstrated that WD caused developmental impairment in the stamen and pistil, where the pistil appeared more sensitive than stamen. These findings suggest that WD impairs pollen viability and pistil function reducing yield volume, but the nutrient content of the resulting yield is not significantly affected.

Two subgroups of receptor-like kinases promote early compatible pollen responses in the Arabidopsis thaliana pistil.

In flowering plants, cell-cell communication between the compatible pollen grain/growing pollen tube and the pistil is an essential component for successful sexual reproduction. In Arabidopsis thaliana, the later stages of this dialogue are mediated by several peptide ligands and receptors that guide pollen tubes to the ovules for the release of sperm cells. Despite a detailed understanding of these processes, a key gap remains regarding the nature of the regulators that function at the earlier stages which are essential steps leading to fertilization. Here, we report on new functions for A. thaliana Receptor-Like Kinase (RLK) genes belonging to the LRR-II and LRR-VIII-2 RLK subgroups in the female reproductive tract to regulate compatible pollen hydration and the early stages of pollen tube growth. Mutant pistils for the A. thaliana RKF1 gene cluster were observed to support reduced wild-type pollen hydration and, when combined with the SERK1 and SERK3/BAK1 mutations, reduced pollen tube travel distances occurred. As these mutant pistils displayed a wild-type morphology, we propose that the observed altered compatible pollen responses result from an impaired pollen-pistil dialogue at these early stages.

Relationship between interspecific pollen transfer and pistil length in sympatric congeners, Clerodendrum trichotomum and C. izuinsulare

AbstractInterspecific pollen transfer (IPT) often leads to reproductive interference. Although character displacement of reproductive traits in plants is often considered a consequence of reproductive interference, few studies have tested whether intraspecific variation in floral morphology changes the intensity of reproductive interference among pollinator‐sharing plants. We investigated whether intraspecific variation in pistil length changes the proportion of IPT (interspecific pollen transfer) in sympatric populations of Clerodendrum trichotomum and C. izuinsulare on the two islands. On Toshima Island, C. izuinsulare flowers with shorter pistils were significantly less likely to receive C. trichotomum pollen, and there was a slight tendency for longer pistiles of C. trichotomum flowers to receive less C. izuinsulare pollen, suggesting that IPT has caused character displacement in pistil length in these congeneric plants. In contrast, we did not detect any relationship between pistil length and the proportion of IPT for the two species on Niijima Island. The discrepancy between the islands may reflect differences in pollinator assemblages.

Effect of Boron on Pollen Attributes in Different Cultivars of Malus domestica L.

The effect of varying boron concentrations on in vivo pollen germination and tube penetration in four different apple cultivar crosses among ‘Golden Delicious,’ ‘Red Delicious,’ ‘Gala’ and ‘Fuji’ was evaluated. Boric acid (H3BO3) with two different concentrations: 1000 and 2000 mg L−1, was sprayed on the foliage long before the onset of flowering. Pollen–pistil interaction vis-a-vis pollen germination and tube penetration was evaluated using fluorescence microscopy technique, 72 and 120 h after manual pollination. Among different crosses, ♀Golden delicious × Red delicious♂ treated at 1000 mg L−1 concentration of boric acid showed maximum (27.39%) pollen germination and pollen tubes at different levels inside the style. In control without boron, only 6.49% germination was observed. Interaction of boron conc. × time depicted maximum pollen germination and tube number 120 hap. The present study demonstrates that foliar application of boron beyond 1000 mg L−1 on different apple cultivars reduces germination of pollen and development of pollen tubes down the style.

Temperature-Dependent Compatible and Incompatible Pollen-Style Interactions in Citrus clementina Hort. ex Tan. Show Different Transglutaminase Features and Polyamine Pattern.

In clementine, failure of fertilization can result in parthenocarpic fruit development, which has several advantages, such as seedless fruit, longer shelf-life, and greater consumer appeal. Recently, S-RNases have been identified in Citrus grandis, thus revealing that the self-incompatibility (SI) reaction relies on the S-RNase gametophytic mechanism. The fundamental role of environmental factors, mostly temperature, in determining the numbers of pollen tubes reaching the ovary is also well established in Citrus. In the present work, temperature-dependent pollen–pistil interactions in C. clementina were analyzed, focusing on several morphological aspects, as well as on polyamine (PA) content and the activity and distribution of transglutaminase (TGase), both reported to be involved in the SI response in pear and in pummelo. Results clearly indicate that temperature contributed to a different activation of the SI response, which occurs at optimal temperature of 25°C but was by-passed at 15°C. TGase activity was stimulated during the SI response, and it localized differently in the compatible and incompatible interaction: in compatible pollinated styles, TGase localized inside the style canal, while it was detected all around it in incompatible crosses. TGase localization and activity were congruent with the levels of soluble and insoluble conjugated PAs and with morphological evidences, which highlighted cell wall modification occurring as a result of SI.

Stigma receptivity with pollen in sunflower accompanies novel histochemical and biochemical changes in both male and female reproductive structures

Pollen–pistil interaction is one of the widely studied cell–cell communication events in angiosperms. Pollination of the receptive pistil with compatible pollen and the subsequent steps that determines the success of fertilization depend on the cooperative events between pollen and pistil. Before the onset of these interactive events between pollen and pistil, both the participants prepare themselves for the upcoming complex cellular events. Receptive surface of stigma is characterized by the accumulation of reactive oxygen species and expression of specific biomolecules and enzymes, such as non-specific esterases and peroxidases. Pollen grains produce nitric oxide that scavenge reactive oxygen species generated on stigma surface after pollination and just prior to pollen germination. Present work reports accumulation of glycoproteins, lipids and phospholipids at the base of stigmatic papillae in mature receptive stigma. A 31 kDa glycoprotein has been detected in stigma homogenate. Stigma exhibit enhanced expression of peroxidase isoforms relative to buffer soluble fractions of pollen, i.e. intact pollen, internal pollen and tryphine fractions. A 54 kDa protease is expressed in pollen grains as well as stigma. Biochemical analyses of these biomolecules in pollen and stigma relative to other vegetative (corolla of ray and disc floret, bracts, young leaves) and reproductive (anther wall and ovary) parts highlight the implications of these biomolecules in pollen–stigma interaction.

Boosting autophagy in sexual reproduction: a plant perspective.

The key process of sexual reproduction is the successful fusion of the sperm and egg cell. Distinct from dynamic and flagellated animal sperm cells, higher flowering plant sperm cells are immotile. Therefore, plants have evolved a novel reproductive system to achieve fertilization and generate progenies. Plant sexual reproduction consists of multiple steps, mainly including gametophyte development, pollen-pistil recognition, pollen germination, double fertilization and postfertilization. During reproduction, active production, consumption and recycling of cellular components and energy are critically required to achieve fertilization. However, the underlying machinery of cellular degradation and turnover remains largely unexplored. Autophagy, the major catabolic pathway in eukaryotic cells, participates in regulating multiple aspects of plant activities, including abiotic and biotic stress resistance, pathogen response, senescence, nutrient remobilization and plant development. Nevertheless, a key unanswered question is how autophagy regulates plant fertilization and reproduction. Here, we focus on comparing and contrasting autophagy in several key reproductive processes of plant and animal systems to feature important distinctions and highlight future research directions of autophagy in angiosperm reproduction. We further discuss the potential crosstalk between autophagy and programmed cell death, which are often considered as two disconnected events in plant sexual reproduction.

Self-sterility May Be Due to Prezygotic Late-acting Self-incompatibility and Early-acting Inbreeding Depression in Chinese Chestnut

Chinese chestnut (Castanea mollissima), which is native to China, has been cultivated as a nontimber forest tree species for 4000 years. This species has been found to display self-sterility, which results in a significantly lower seed set following self-pollination (SP) compared with that following cross-pollination (CP). Self-sterility can be induced by prezygotic or postzygotic late-acting self-incompatibility (LSI) or early-acting inbreeding depression (EID). To elucidate the causes of self-sterility in chestnut, we investigated pollen–pistil interactions, fertilization, and early ovule development following SP and CP by using a paraffin section technique and fluorescence microscopy. The fruit set percentage and seed characteristics also were evaluated among different pollination treatments. The results show that there were no significant differences in pollen tube behavior following SP vs. CP, regardless of the stigmatic or stylar level. Double fertilization was significantly greater following CP (18.09%) than SP (2.58%). The significantly lower percentages of ovule penetration and double fertilization in the selfed vs. crossed ovules support a prezygotic LSI mechanism in C. mollissima. The fruit set resulting from chase-pollination (CHP; 53.85% to 63.64%) was greater than that resulting from SP (12.12% to 14.00%). In addition, the distribution of aborted seed sizes after SP showed a widely clumped pattern. Abortion occurred at different stages during seed development rather than at a uniform stage, which supported the idea that EID was operating in C. mollissima. Levels of self-sterility in the chinese chestnut trees ranged from 88.2% to 90.5%. Thus, partial prezygotic LSI and EID contributed to self-sterility in the C. mollissima ‘Yanshanzaofeng’, with prezygotic LSI rejecting part of the self-pollen in the ovary and EID aborting part of the self-fertilized seeds.

Insights into secrets along the pollen tube pathway in need to be discovered.

The process of plant fertilization provides an outstanding example of refined control of gene expression. During this elegant process, subtle communication occurs between neighboring cells, based on chemical signals, that induces cellular mechanisms of patterning and growth. Having faced an immediate issue of self-incompatibility responses, the pathway to fertilization starts once the stigmatic cells recognize a compatible pollen grain, and it continues with numerous players interacting to affect pollen tube growth and the puzzling process of navigation along the transmitting tract. The pollen tube goes through a guidance process that begins with a preovular stage (i.e. prior to the influence of the target ovule), with interactions with factors from the transmitting tissue. In the subsequent ovular-guidance stage a specific relationship develops between the pollen tube and its target ovule. This stage is divided into the funicular and micropylar guidance steps, with numerous receptors working in signalling cascades. Finally, just after the pollen tube has passed beyond the synergids, fusion of the gametes occurs and the developing seed-the ultimate aim of the process-will start to mature. In this paper, we review the existing knowledge of the crucial biological processes involved in pollen-pistil interactions that give rise to the new seed.

Calcium: A Critical Factor in Pollen Germination and Tube Elongation.

Pollen is the male gametophyte of higher plants. Its major function is to deliver sperm cells to the ovule to ensure successful fertilization. During this process, many interactions occur among pollen tubes and pistil cells and tissues, and calcium ion (Ca2+) dynamics mediate these interactions among cells to ensure that pollen reaches the embryo sac. Although the precise functions of Ca2+ dynamics in the cells are unknown, we can speculate about its roles on the basis of its spatial and temporal characteristics during these interactions. The results of many studies indicate that calcium is a critical element that is strongly related to pollen germination and pollen tube growth.

Xenia in bahiagrass: gene expression at initial seed formation

AbstractXenia is the direct effect of pollen genotype on the development and characteristics of the seed and fruit in the period that spans from fertilization to seed germination. Xenia effects cause phenotypic variations in the seed and fruit, which have importance for seed and fruit production but are not heritable to the progeny. Two hypotheses have been proposed as a mechanism for xenia: the hormonal hypothesis and the mobile mRNAs hypothesis. Although xenia effects have been studied in seeds and fruits in many crops, its effects and mechanism have been poorly studied at the molecular level. The aim of this work was to perform an initial screening of the xenia effect in the hybrid endosperm at the molecular level by differential gene expression among different pollen genotype sources from Paspalum notatum Flüggé. In order to characterize xenia effects and mechanisms, crosses were made between an emasculated mother plant with donors from two different pollen genotypes. RNA was isolated from ovaries 3 h after pollination. Some of the 24 differentially expressed transcript-derived fragments (DETDFs) provided relevant information. Four of those DETDFs were related to germination, pollen tube growth and pollen–pistil interaction. Seven DETDFs were associated with seed development and production. Finally, four DETDFs were predicted to encode for mobile mRNAs. These DETDFs might be involved in xenia effects and mechanisms in P. notatum.

Comparative pollen–pistil interactions and insect pollination in two Hypoxis species (Hypoxidaceae) in China and North America

We compared the floral ecology and pollen–pistil interactions in Hypoxis hirsuta (L.) Coville from North America and Hypoxis aurea Loureiro from China. Both species are vernal-flowering herbs, with yellow perianths, providing pollen as their only reward. In H. hirsuta, hand self-pollinated, emasculated and bagged control flowers failed to set fruit. When cross-pollinated, 77% of the pistils produced seed-filled capsules while 72% of open, insect-pollinated flowers set seed. Epifluorescence showed that most germinating grains failed to penetrate the stigmatic surface > 24 h after hand self-pollination suggesting early-acting self-incompatibility (SI). The majority of pollinators of H. hirsuta were female bees representing 21 species distributed in four families. Pollen load analyses indicated that most bees were polylectic and carried grains of H. hirsuta mixed with pollen of co-blooming, nectariferous species. In contrast, capsule production of H. aurea was 60% for open, insect-pollinated flowers. Pollen tubes of H. aurea also entered ovules within 24 h, and SI of this species was partial. Evidence of a late-acting rejection in this species following self-pollination included abnormal growth of pollen tubes in styles with fewer tubes penetrating ovules. In contrast, abnormal tube growth was not observed in styles of H. hirsuta. Hypoxis aurea received fewer insect visitations. Pollen was dispersed primarily by hoverflies (Syrphidae) followed by bees. Floral presentation, generalist pollination and two modes of SI found in these two Hypoxis species contribute to our understanding of floral evolution for congeners isolated on different continents.

The Molecular and Cellular Regulation of Brassicaceae Self-Incompatibility and Self-Pollen Rejection.

In flowering plants, sexual reproduction is actively regulated by cell-cell communication between the male pollen and female pistil, and many species possess self-incompatibilitysystems for the selective rejection of self-pollen to maintain genetic diversity. The Brassicaceae self-incompatibility pathway acts early on when pollen grains have landed on the stigmatic papillae at the top of the pistil. Extensive studies have revealed that self-pollen rejection in the Brassicaceae is initiated by an S-haplotype-specific interaction between two polymorphic proteins: the pollen S-locus protein 11/S cysteine-rich (SP11/SCR) ligand and the stigma S receptor kinase (SRK). While the different S-haplotypes are typically codominant, there are several examples of dominant-recessive interactions, and a small RNA-based regulation of SP11/SCR expression has been uncovered as a mechanism behind these genetic interactions. Recent research has also added to our understanding of various cellular components in the pathway leading from the SP11/SCR-SRK interaction, including two signaling proteins, the M-locus protein kinase (MLPK) and the ARM-repeat containing 1 (ARC1) E3 ligase, as well as calcium fluxes and induction of autophagy in the stigmatic papillae. Finally, a better understanding of the compatible pollen responses that are targeted by the self-incompatibility pathway is starting to emerge, and this will allow us to more fully understand how the Brassicaceae self-incompatibility pathway causes self-pollen rejection. Here, we provide an overview of the field, highlighting recent contributions to our understanding of Brassicaceae self-incompatibility, and draw comparisons to a recently discovered unilateral incompatibility system.

Investigation of Differences in Fertility among Progenies from Self-Pollinated Chrysanthemum.

Most chrysanthemum cultivars are self-incompatible, so it is very difficult to create pure lines that are important in chrysanthemum breeding and theoretical studies. In our previous study, we obtained a self-compatible chrysanthemum cultivar and its self-pollinated seed set was 56.50%. It was interesting that the seed set of its ten progenies ranged from 0% to 37.23%. Examination of the factors causing the differences in the seed set will lead to an improved understanding of chrysanthemum self-incompatibility, and provide valuable information for creating pure lines. Pollen morphology, pollen germination percentage, pistil receptivity and embryo development were investigated using the in vitro culture method, the paraffin section technique, scanning electron microscopy and transmission electron microscopy. Moreover, RNA sequencing and bioinformatics were applied to analyzing the transcriptomic profiles of mature stigmas and anthers. It was found that the self-pollinated seed set of “Q10-33-1①”,”Q10-33-1③”,”Q10-33-1④” and “Q10-33-1⑩” were 37.23%, 26.77%, 7.97% and 0%, respectively. The differences in fertility among four progenies were mainly attributable to differences in pollen germination percentage and pistil receptivity. Failure of the seed set in “Q10-33-1⑩” was possibly due to self-incompatibility. In the transcriptomic files, 22 potential stigma S genes and 8 potential pollen S genes were found out.