Mature Anthers Research Articles

ORBICULES IN SOUTH AMERICAN BALANOPHORACEAE: ANALYSIS OF ITS POSSIBLE ROLE AND ITS TAXONOMIC VALUE IN THE FAMILY

Balanophoraceae are root parasites, lacking both chlorophyll and typical cormophytic organization. There have been few studies of pollen dispersal mechanisms in Balanophoraceae, and no studies on structures accompanying pollen, such as orbicules. Anthers were analyzed in five South American taxa of Balanophoraceae (Langsdorffia hypogaea, Lophophytum pyramidale, L. mirabile. subsp. bolivianum, Ombrophytum subterraneum and Helosis cayennensis), in order to: (1) determine the presence of orbicules, characterize them and relate their presence with the tapetum type, characteristics of the anther wall and dehiscence, and the pollination mode; (2) and analyze its possible taxonomic value in relation to the phylogeny of the family Balanophoraceae. In three genera (Lophophytum, Langsdorffia and Ombrophytum), the anthers were found to be dithecous, tetrasporangiate with longitudinal dehiscence. In these taxa the endothecium is present and is responsible for dehiscing the anthers. In Helosis the pollen sacs are welded in a synandrium with apical groves and lacking an endothecium. In all species, a secretory tapetum is responsible for nourishing the pollen grains during their formation. The presence of orbicules is variable among the species studied: it is found in Lophophytum and Langsdorffia, and is absent in Ombrophytum and Helosis. In Lophophytum the orbicules appear as small and spheroidal corpuscles with smooth surfaces. In Langsdorffia hypogaea the orbicules are conspicuous spherical, ellipsoid to ovoid forms. This study shows that there is no relationship between layers present in mature anthers, dehiscence type, pollination mode and orbicules presence. We report for the first time the presence of orbicules in the holoparasitic family Balanophoraceae belonging to the order Santalales, in which there is scarce information available regarding the presence of orbicules. Given the intergeneric variations and the consistency at generic level observed in the taxa here analyzed, orbicules may have predictive value and potential for systematically oriented research questions.

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.

Redundant role of OsCNGC4 and OsCNGC5 encoding cyclic nucleotide-gated channels in rice pollen germination and tube growth

In staple crops, such as rice (Oryza sativa L.), pollen plays a crucial role in seed production. However, the molecular mechanisms underlying rice pollen germination and tube growth remain underexplored. Notably, we recently uncovered the redundant expression and mutual interaction of two rice genes encoding cyclic nucleotide-gated channels (CNGCs), OsCNGC4 and OsCNGC5, in mature pollen. Building on these findings, the current study focused on clarifying the functional roles of these two genes in pollen germination and tube growth. To overcome functional redundancy, we produced gene-edited rice plants with mutations in both genes using the CRISPR-Cas9 system. The resulting homozygous OsCNGC4 and OsCNGC5 gene-edited mutants (oscngc4/5) exhibited significantly lower pollen germination rates than the wild type (WT), along with severely reduced fertility. Transcriptome analysis of the double oscngc4/5 mutant revealed downregulation of genes related to receptor kinases, transporters, and cell wall metabolism. To identify the direct regulators of OsCNGC4, which form a heterodimer with OsCNGC5, we screened a yeast two-hybrid library containing rice cDNAs from mature anthers. Subsequently, we identified two calmodulin isoforms (CaM1-1 and CaM1-2), NETWORKED 2 A (NET2A), and proline-rich extension-like receptor kinase 13 (PERK13) proteins as interactors of OsCNGC4, suggesting its roles in regulating Ca2+ channel activity and F-actin organization. Overall, our results suggest that OsCNGC4 and OsCNGC5 may play critical roles in pollen germination and elongation by regulating the Ca2+ gradient in growing pollen tubes.

The PPO family in Nicotiana tabacum is an important regulator to participate in pollination

Polyphenol oxidases (PPOs) are type-3 copper enzymes and are involved in many biological processes. However, the potential functions of PPOs in pollination are not fully understood. In this work, we have screened 13 PPO members in Nicotiana. tabacum (named NtPPO1-13, NtPPOs) to explore their characteristics and functions in pollination. The results show that NtPPOs are closely related to PPOs in Solanaceae and share conserved domains except NtPPO4. Generally, NtPPOs are diversely expressed in different tissues and are distributed in pistil and male gametes. Specifically, NtPPO9 and NtPPO10 are highly expressed in the pistil and mature anther. In addition, the expression levels and enzyme activities of NtPPOs are increased after N. tabacum self-pollination. Knockdown of NtPPOs would affect pollen growth after pollination, and the purines and flavonoid compounds are accumulated in self-pollinated pistil. Altogether, our findings demonstrate that NtPPOs potentially play a role in the pollen tube growth after pollination through purines and flavonoid compounds, and will provide new insights into the role of PPOs in plant reproduction.

Haploids can be induced in knockout mutants of OsPLA1, but not OsDMP3 or OsDMP6, in rice

Doubled haploid (DH) technology is an important tool in crop breeding because it can significantly accelerate the breeding process. ZmPLA1/MATL/NLD and ZmDMP are two key genes controlling haploid induction (HI) in maize, exhibiting a synergistic effect. However, it is unknown whether knock out of ZmDMP orthologs can stimulate HI in rice. In this study, a ZmPLA1 ortholog (OsPLA1) and two ZmDMP orthologs (OsDMP3 and OsDMP6) were identified in rice. All three genes encode plasma membrane-localized proteins and were highly expressed in mature anthers. Knockout of OsPLA1 in both Minghui 63 and Nipponbare resulted in reduced seed setting rate (SSR) and caused HI. The osdmp3, osdmp6 and the double mutant failed to trigger HI independently, nor increased the haploid induction rate (HIR) when combined with ospla1. Repeated pollinations operations of QX654A with the ospla1 mutant significantly improve SSR, while reducing HIR. RNA-seq profiling of mature ospla1 mutant anthers indicated that a large number of differentially expressed genes (DEGs) were enriched in redox homeostasis and lipid metabolic GO terms, plant hormone signal transduction, and MAPK signaling pathways. These findings provide important insights towards construction of an efficient DH breeding technology and study of the molecular mechanism of HI in rice.

Genome-wide identification and expression analyses of the pectate lyase (PL) gene family in Fragaria vesca

BackgroundPectate lyase (PL, EC 4.2.2.2), as an endo-acting depolymerizing enzyme, cleaves α-1,4-glycosidic linkages in esterified pectin and involves a broad range of cell wall modifications. However, the knowledge concerning the genome-wide analysis of the PL gene family in Fragaria vesca has not been thoroughly elucidated.ResultsIn this study, sixteen PLs members in F. vesca were identified based on a genome-wide investigation. Substantial divergences existed among FvePLs in gene duplication, cis-acting elements, and tissue expression patterns. Four clusters were classified according to phylogenetic analysis. FvePL6, 8 and 13 in cluster II significantly contributed to the significant expansions during evolution by comparing orthologous PL genes from Malus domestica, Solanum lycopersicum, Arabidopsis thaliana, and Fragaria×ananassa. The cis-acting elements implicated in the abscisic acid signaling pathway were abundant in the regions of FvePLs promoters. The RNA-seq data and in situ hybridization revealed that FvePL1, 4, and 7 exhibited maximum expression in fruits at twenty days after pollination, whereas FvePL8 and FvePL13 were preferentially and prominently expressed in mature anthers and pollens. Additionally, the co-expression networks displayed that FvePLs had tight correlations with transcription factors and genes implicated in plant development, abiotic/biotic stresses, ions/Ca2+, and hormones, suggesting the potential roles of FvePLs during strawberry development. Besides, histological observations suggested that FvePL1, 4 and 7 enhanced cell division and expansion of the cortex, thus negatively influencing fruit firmness. Finally, FvePL1-RNAi reduced leaf size, altered petal architectures, disrupted normal pollen development, and rendered partial male sterility.ConclusionThese results provide valuable information for characterizing the evolution, expansion, expression patterns and functional analysis, which help to understand the molecular mechanisms of the FvePLs in the development of strawberries.

Genome-Wide Identification, Phylogenetic and Expression Analysis of the B-Box Gene Family in the Woodland Strawberry (Fragaria vesca)

The strawberry (Fragaria × ananassa Duch.) is an important horticultural crop that is widely grown all over the world. Its sweetness, aroma, nutritional value and bright color make it popular. The woodland strawberry (Fragaria vesca) is a model plant for studying non-climacteric fruits because its respiration rate does not change significantly during fruit ripening. The B-box (BBX) protein family is made up of zinc-finger transcription factors important in plant growth and development. In this study, we identified 22 FveBBX genes from the newly released woodland strawberry genome database by comprehensive bioinformatics analysis. Phylogenetic analysis divided these FveBBX genes into five subfamilies. A promoter cis-acting element analysis detected 29 elements related to plant development, light response, abiotic stress and hormone response in the promoter of FveBBX genes. According to transcriptome data, relatively few BBX genes had tissue-specific expression, with examples including FveBBX12, which was expressed only in pre-fertilization cortex and pitch, and FveBBX19, which was specifically expressed in mature anthers. During fruit ripening, the expressions of eight FveBBX genes decreased by more than two-fold, and three FveBBX gene expressions increased more than two-fold both in “Ruegen” and “Yellow Wonder”. After cold and heat stresses, around half of the FveBBX genes displayed altered expression, especially FveBBX16 which showed an 8.3-fold increase in expression after heat treatment, while FveBBX14 showed at least an 11-fold decrease in expression after cold treatment. According to the result of quantitative real-time PCR (qRT-PCR), FveBBX genes’ expression differed depending on the photoperiod. Notably, FveBBX7 gene expression was the opposite during the first 16 h of the long-day (LD) and short-day (SD) conditions. This study provides helpful information for further research on BBX gene activity of the woodland strawberry in plant growth and development and adaptation to temperature and photoperiod environmental conditions.

Changes in the content of pollen total lipid and TAG in Arabidopsis thaliana DGAT1 mutant as11.

In mature pollen grains, lipids are primarily stored in the form of lipid droplets that provide energy and act as a carbon source for normal pollen development and germination. Triacylglycerol (TAG) is the major form of stored plant lipids. Diacylglycerol transferase, which is encoded by DGAT1 in Arabidopsis thaliana, is an important enzyme regulating triacylglycerol synthesis. Within the seeds of the DGAT1 mutant as11, the content of TAG is significantly decreased and the fatty acid composition also differs from the wild type. Transcriptome data of mature anthers showed that the genes involved in the TAG synthesis pathway were downregulated in as11. Analysis of gene expression patterns via transcriptome data also revealed that the expression of PDAT1, which functions in a manner complementary to the DGAT1 gene, was significantly decreased in as11, whereas the amylopectin synthase genes SS1 and SS2 were upregulated in mutant as11. We also detected lower total lipid, TAG and fatty acid contents in mature as11 pollen, with palmitic acid (C16:0) and linolenic acid (C18:3) being the major fatty acids in mature pollen. The cytological results showed that the lipid droplet content was reduced in mature as11 pollen. In the binuclear pollen grain II stage, WT pollen contained lipid droplets that were primarily accumulated around the generative nucleus, whereas the pollen in the mutant as11 was rich in starch grains that were primarily distributed around the vegetative nucleus. Ultrastructural analysis indicated that during pollen development in as11, the amount of endoplasmic reticulum in tapetal cells and pollen grains decreased, whereas the Golgi body content increased, which directly or indirectly led to a decrease in the levels of lipidosomes and an increase in the starch content in as11. Changes in the lipid content and fatty acid composition of the mutant as11 differ from those in the wild type during pollen development.

Heat-induced proteomic changes in anthers of contrasting rice genotypes under variable stress regimes.

Heat stress drastically affects anther tissues resulting in poor plant fertility, necessitating an urgent need to determine the key proteome regulation associated with mature anther in response to heat stress. We identified several genotype - specific protein alterations in rice anthers of Moroberekan (Japonica, heat sensitive), IR64 (Indica, moderately heat tolerant), and Nagina22 (Aus, heat tolerant) in the short-term (ST_HS; one cycle of 42°C, 4 hours before anthesis) and long-term (LT_HS; 6 cycles of 38°C, 6 hours before anthesis) heat stress. The proteins upregulated in long-term heat stress in Nagina22 were enriched in biological processes related to unfolded protein binding and carboxylic acid metabolism, including amino acid metabolism. In short-term heat stress, Nagina22 anthers were enriched in proteins associated with vitamin E biosynthesis and GTPase activator activity. In contrast, downregulated proteins were related to ribosomal proteins. The expression of different Hsp20 and DnaJ was genotype specific. Overall, the heat response in Nagina22 was associated with its capacity for adequate metabolic control and cellular homeostasis, which may be critical for its higher reproductive thermotolerance. This study improves our understanding of thermotolerance mechanisms in rice anthers during anthesis and lays a foundation for breeding thermotolerant varieties via molecular breeding.

Genome-Wide Identification of the Cytochrome P450 Superfamily Genes and Targeted Editing of BnCYP704B1 Confers Male Sterility in Rapeseed.

The cytochrome P450 (CYP450) monooxygenase superfamily, which is involved in the biosynthesis pathways of many primary and secondary metabolites, plays prominent roles in plant growth and development. However, systemic information about CYP450s in Brassica napus (BnCYP450) was previously undiscovered and their biological significance are far from understood. Members of clan 86 CYP450s, such as CYP704Bs, are essential for the formation of pollen exine in plant male reproduction, and the targeted mutagenesis of CYP704B genes has been used to create new male sterile lines in many crops. In the present study, a total of 687 BnCYP450 genes were identified in Brassica napus cultivar "Zhongshuang 11" (ZS11), which has nearly 2.8-fold as many CYP450 members as in Arabidopsis thaliana. It is rationally estimated since Brassica napus is a tetraploid oil plant with a larger genome compared with Arabidopsis thaliana. The BnCYP450 genes were divided into 47 subfamilies and clustered into nine clans. Phylogenetic relationship analysis reveals that CYP86 clan consists of four subfamilies and 109 BnCYP450s. Members of CYP86 clan genes display specific expression profiles in different tissues and in response to ABA and abiotic stresses. Two BnCYP450s within the CYP704 subfamily from CYP86 clan, BnCYP704B1a and BnCYP704B1b, display high similarity to MS26 (Male Sterility 26, also known as CYP704B1). These two BnCYP704B1 genes were specifically expressed in young buds. We then simultaneously knocked-out these two BnCYP704B1 genes through a clustered regularly interspaced short palindromic repeats/CRISPR-associated protein 9 (CRISPR/Cas9) genome engineering system. The edited plants displayed a pollenless, sterile phenotype in mature anthers, suggesting that we successfully reproduced genic male sterility (GMS, also known as nuclear male sterility) lines in Brassica napus. This study provides a systemic view of BnCYP450s and offers a strategy to facilitate the commercial utility of the CRISPR/Cas9 system for the rapid generation of GMS in rapeseed via knocking-out GMS controlling genes.

Biological features of Crocus speciosus M. Bieb. (Iridaceae family)

The paper presents the results of studying the decorative species Crocus speciosus. Some features of the formation and development of male and female generative spheres are presented. It is shown that the formed anther wall is generated by the epidermis, endothecium, middle layer and tapetum. The wall of the mature anther is formed by the epidermis, fibrous endothecium with fibrous thickening, and a tapetal spathella with sporopollenin orbicles. Analysis of mature pollen grains showed a rather high proportion of normal pollen grains (80%), which under favorable conditions indicates a high ability to effectively pollinate. The characteristics of the female generative sphere are also shown: three-celled ovary; anatropic, bitegmal, funicular, crassinucellate ovule; linear tetrad of megaspores; Polygonum-type of embryonic sac development. The processes of flowering, pollination and seed formation are described.

Transcriptome Analysis of Triple Mutant for OsMADS62, OsMADS63, and OsMADS68 Reveals the Downstream Regulatory Mechanism for Pollen Germination in Rice (Oryza sativa).

The MADS (MCM1-AGAMOUS-DEFFICIENS-SRF) gene family has a preserved domain called MADS-box that regulates downstream gene expression as a transcriptional factor. Reports have revealed three MADS genes in rice, OsMADS62, OsMADS63, and OsMADS68, which exhibits preferential expression in mature rice pollen grains. To better understand the transcriptional regulation of pollen germination and tube growth in rice, we generated the loss-of-function homozygous mutant of these three OsMADS genes using the CRISPR-Cas9 (clustered regularly interspaced short palindromic repeats-CRISPR associated protein 9) system in wild-type backgrounds. Results showed that the triple knockout (KO) mutant showed a complete sterile phenotype without pollen germination. Next, to determine downstream candidate genes that are transcriptionally regulated by the three OsMADS genes during pollen development, we proceeded with RNA-seq analysis by sampling the mature anther of the mutant and wild-type. Two hundred and seventy-four upregulated and 658 downregulated genes with preferential expressions in the anthers were selected. Furthermore, downregulated genes possessed cell wall modification, clathrin coat assembly, and cellular cell wall organization features. We also selected downregulated genes predicted to be directly regulated by three OsMADS genes through the analyses for promoter sequences. Thus, this study provides a molecular background for understanding pollen germination and tube growth mediated by OsMADS62, OsMADS63, and OsMADS68 with mature pollen preferred expression.

Allergenicity of Bet v 1 in wheat pollen after exposure to drought stress as a model for climate change

In the 21st century, climate changes and global warming have become critical concerns, in that they can affect many of the natural phenomena. It is reported that aeroallergen sensitization is influenced by changes in climate. Bet v 1 is an important birch pollen respiratory allergen and a prototype for the PR-10 protein family, which has been reported in wheat pollen. Two wheat genotypes were exposed to water deficit at the meiosis stage of anthers to investigate the effect of drought stress changes on wheat pollen Bet v 1 expression. Then, mature anthers of wheat underwent molecular experiments in the anthesis stage. Expression analysis was carried out, using Real-time PCR, on the Bet v 1 gene that encodes allergens. The results indicated the induction of Bet v 1 in both genotypes in the water deficit condition. The genotype which had been improved by breeders for tolerating drought more than the other genotype revealed more increase in Bet v 1 expression. Given the great spread of wheat, especially improved genotypes worldwide as a pivotal and crop plant and regarding wheat pollen effect on provoking allergy in humans, Bet v 1 can cause new distress in human society. Therefore, this finding is considered as a new verification of concerns of climate change on human health, which emphasizes the importance of efforts to alleviate climate changes to avoid the risk of public health.

A Rapid Pipeline for Pollen- and Anther-Specific Gene Discovery Based on Transcriptome Profiling Analysis of Maize Tissues.

Recently, crop breeders have widely adopted a new biotechnology-based process, termed Seed Production Technology (SPT), to produce hybrid varieties. The SPT does not produce nuclear male-sterile lines, and instead utilizes transgenic SPT maintainer lines to pollinate male-sterile plants for propagation of nuclear-recessive male-sterile lines. A late-stage pollen-specific promoter is an essential component of the pollen-inactivating cassette used by the SPT maintainers. While a number of plant pollen-specific promoters have been reported so far, their usefulness in SPT has remained limited. To increase the repertoire of pollen-specific promoters for the maize community, we conducted a comprehensive comparative analysis of transcriptome profiles of mature pollen and mature anthers against other tissue types. We found that maize pollen has much less expressed genes (>1 FPKM) than other tissue types, but the pollen grain has a large set of distinct genes, called pollen-specific genes, which are exclusively or much higher (100 folds) expressed in pollen than other tissue types. Utilizing transcript abundance and correlation coefficient analysis, 1215 mature pollen-specific (MPS) genes and 1009 mature anther-specific (MAS) genes were identified in B73 transcriptome. These two gene sets had similar GO term and KEGG pathway enrichment patterns, indicating that their members share similar functions in the maize reproductive process. Of the genes, 623 were shared between the two sets, called mature anther- and pollen-specific (MAPS) genes, which represent the late-stage pollen-specific genes of the maize genome. Functional annotation analysis of MAPS showed that 447 MAPS genes (71.7% of MAPS) belonged to genes encoding pollen allergen protein. Their 2-kb promoters were analyzed for cis-element enrichment and six well-known pollen-specific cis-elements (AGAAA, TCCACCA, TGTGGTT, [TA]AAAG, AAATGA, and TTTCT) were found highly enriched in the promoters of MAPS. Interestingly, JA-responsive cis-element GCC box (GCCGCC) and ABA-responsive cis-element-coupling element1 (ABRE-CE1, CCACC) were also found enriched in the MAPS promoters, indicating that JA and ABA signaling likely regulate pollen-specific MAPS expression. This study describes a robust and straightforward pipeline to discover pollen-specific promotes from publicly available data while providing maize breeders and the maize industry a number of late-stage (mature) pollen-specific promoters for use in SPT for hybrid breeding and seed production.

FLA14 is required for pollen development and preventing premature pollen germination under high humidity in Arabidopsis

BackgroundAs an important subfamily of arabinogalactan proteins (AGPs), fasciclin-like AGPs (FLAs) contribute to various aspects of growth, development and adaptation, yet their function remains largely elusive. Despite the diversity of FLAs, only two members, Arabidopsis FLA3 and rice MTR1, are reported to be involved in sexual reproduction. In this study, another Arabidopsis FLA-encoding gene, FLA14, was identified, and its role was investigated.ResultsArabidopsis FLA14 was found to be a pollen grain-specific gene. Expression results from fusion with green fluorescent protein showed that FLA14 was localized along the cell membrane and in Hechtian strands. A loss-of-function mutant of FLA14 showed no discernible defects during male gametogenesis, but precocious pollen germination occurred inside the mature anthers under high moisture conditions. Overexpression of FLA14 caused 39.2% abnormal pollen grains with a shrunken and withered appearance, leading to largely reduced fertility with short mature siliques and lower seed set. Cytological and ultramicroscopic observation showed that ectopic expression of FLA14 caused disruption at the uninucleate stage, resulting in either collapsed pollen with absent intine or pollen of normal appearance but with a thickened intine.ConclusionsTaken together, our data suggest a role for FLA14 in pollen development and preventing premature pollen germination inside the anthers under high relative humidity in Arabidopsis.

Overexpression Populusd-Type Cyclin Gene PsnCYCD1;1 Influences Cell Division and Produces Curved Leaf in Arabidopsis thaliana.

d-type cyclins (CYCDs) are a special class of cyclins and play extremely important roles in plant growth and development. In the plant kingdom, most of the existing studies on CYCDs have been done on herbaceous plants, with few on perennial woody plants. Here, we identified a Populus d-type cyclin gene, PsnCYCD1;1, which is mainly transcribed in leaf buds and stems. The promoter of PsnCYCD1;1 activated GUS gene expression and transgenic Arabidopsis lines were strongly GUS stained in whole seedlings and mature anthers. Moreover, subcellular localization analysis showed the fluorescence signal of PsnCYCD1;1-GFP fusion protein is present in the nucleus. Furthermore, overexpression of the PsnCYCD1;1 gene in Arabidopsis can promote cell division and lead to small cell generation and cytokinin response, resulting in curved leaves and twisted inflorescence stems. Moreover, the transcriptional levels of endogenous genes, such as ASs, KNATs, EXP10, and PHB, were upregulated by PsnCYCD1;1. Together, our results indicated that PsnCYCD1;1 participates in cell division by cytokinin response, providing new information on controlling plant architecture in woody plants.

КАЧЕСТВО ПЫЛЬЦЕВЫХ ЗЁРЕН В ЗРЕЛЫХ ПЫЛЬНИКАХ ПШЕНИЦЫ В УСЛОВИЯХ IN PLANTA (НА ПРИМЕРЕ СОРТА ЖНИЦА)

Biotechnological and selection investigations for making of wheat high-yielding resistant varieties require a significant amount of high-quality mature pollen. It is important to assess It is important to assess the quality of pollen grains in mature anthers in planta of the wheat genotypes included in the experiments. In the course of research the analysis of the histological status of mature anthers was carried out and qualitative cytological evaluation inside them pollen grain of spring soft wheat Zhnitsa cultivar was done in in planta conditions. It was shown that the structure of the wall locule anther presented by exothecium and endothecium is typical for cereals. It was established that 3-cell mature pollen grains are fertile (87-92%) and viable (75–80%) in general. At the same time in every mature anther abnormal pollen grains were observed and the cellular, nuclear, cytoplasmic and architectonic deviations from the norm were revealed. On the base of literature date the analysis of the reasons for the formation of abnormal pollen grains in planta was done and the classification of anomalies of plant pollen grains and the terminology used in this field of research were discussed.

Full-length transcriptome analysis reveals the differences between floral buds of recessive genic male-sterile line (RMS3185A) and fertile line (RMS3185B) of cabbage.

Starch and sucrose metabolism and plant-pathogen interaction pathways play a dominate role in recessive genic male sterility (RGMS) of cabbage (Brassica oleracea L. var. capitata). RGMS is common in plants and has been widely applied as an effective and economic system for hybrid seed production in many crops. However, little is known regarding the molecular mechanisms of RGMS in cabbage. Hence, full-length transcriptomic and physiological analysis were performed in the spontaneous RGMS mutant RMS3185A and its near-isogenic fertile line (NIL) RMS3185B of small (< 1.6mm in diameter), medium (~ 2.5mm in diameter), and large floral buds (~ 3.4mm in diameter) to identify the differentially expressed genes (DEGs) associated with RMGS. The pollen abnormalities between RMS3185B and RMS3185A appeared at the large floral bud stage. In contrast with RMS3185B, the mature anthers and stamens of RMS3185A were shorter than those of RMS3185B, and the anthers did not dehiscent. The concentrations of glucose, fructose, trehalose, starch, and cellulose in RMS3185A were all significantly lower than those in large floral buds of RMS3185B. PacBio sequencing results showed that DEGs were mainly concentrated in large floral bud stage. In combination with the KEGG enrichment analysis of DEGs in GO terms related to cell wall, pollen and anther, pentose and glucuronate interconversions (ko00040), starch and sucrose metabolism (ko00500), and plant-pathogen interaction (ko04626) were significantly enriched. Among which, cell-wall/pectin-related genes of eighteen PEI, twenty-two PEL, three PG, and fifteen PGL involved in ko00040, and one UGDH, one SPS, four CWINV, four TPP/TPS, and four EGL involved in ko00500, as well as plant-pathogen interaction genes, including sixteen calcium-dependent protein kinase (CDPK), one cyclic nucleotide-gated ion channel (CNGC), and twenty-three calcium-binding protein CML (CML), were significantly down-regulated in RMS3185A relative to that in RMS3185B. Besides, genes involved in ko04626, including two CML and one transcription factor WRKY33, were up-regulated in RMS3185A relative to that in RMS3185B. In conclusion, we hypothesized that the expression alterations of these genes were responsible for calcium signaling and sugar metabolism, thus affecting the occurrence of RGMS in cabbage.

Androecium anatomy of Isertia laevis, a polysporangiate species of Rubiaceae

In this study, we performed an anatomical analysis of the polysporangiate anthers and the development of pollen in Isertia laevis (Rubiaceae) with the aim to elucidate the internal structure of these atypical anthers. For this purpose, flowers in successive stages of development were dissected and the anthers were processed for conventional anatomical analysis. The material was examined using light microscopy and scanning electron microscopy. The present study shows that the anthers of Isertia laevis have two thecae divided into multiple microsporangia. This division is due to the presence of transverse and longitudinal septa formed of parenchyma and idioblasts with crystals. The septa appear together with the microsporangia and remain in the mature anther, even developing fibrous thickening. As the anther matures, the idioblasts in the septa accumulate crystals until they break, facilitating the separation of the septa from the outer wall of the theca, and thus apparently assisting the process of dehiscence. The mature anther opens through the longitudinal dehiscence of each theca. In addition to the anatomy of the anther, the development and morphology of the pollen, and the presence of orbicules are described. The structure of the anthers of I. laevis is discussed with other polysporangiate species in the Rubiaceae and angiosperms.

Structural anomalies in pollen grains of Dyckia racinae L.B.Sm. (Bromeliaceae)

The development of the pollen grains is a complex and regulated process. However, failures in sporogenesis and gametogenesis are common and include cell division errors and multiple structural modifications, culminating usually in abortions or, less frequently, in formation of anomalous pollen grains. These anomalies include altered morphology and functionality and are reported in several species, but are still unexplored in Bromeliaceae, a diverse neotropical family. Thus, this work structurally describes anomalous pollen grains in anthers of Dyckia racinae L.B. Sm., a Bromeliaceae species endemic to Southern Brazil. Mature anthers were processed and analyzed using standard methods for light microscopy. In addition to structurally normal pollen grains, unicellular, geminate, voluminous and aborted pollen grains were structurally described. These morphological alterations include differences in developmental destination, pollen grains with varied sizes, fusions with cytoplasmic communications, morphological alterations in exine and intine and variations in the cytoplasmic content. These anomalies are normally related to developmental disruptions, such as altered programmed cell death in tapetum, associated with cytoplasmic male sterility, for example, which usually leading to extensive abortion of the pollen grains in the anther locules. The structural anomalies described in this study, however, occur in anthers with apparently normal development and were first described for Bromeliaceae. Our results suggest a partial male sterility for this species, an unexplored embryological aspect of pollen grains in this family. Future investigations of ultrastructure and development of the anomalous pollen grains should contribute to a better understanding of the reported anomalies.