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The formation of the anther wall and the development of pollen processes, central to rice fertility and yield, are highly dependent on the synthesis and accumulation of lipid polymers. Although several regulatory factors related to lipid biosynthesis during pollen wall development have been identified, the molecular mechanisms controlling these processes remain poorly understood. In this study, a male-sterile rice mutant, lap3 , was identified, characterized by normal vegetative growth but complete male sterility due to delayed programmed cell death (PCD) in tapetal cells and defects in anther cuticle and pollen exine formation. Map-based cloning revealed that OsLAP3 is a new allele of the strictosidine synthase-like gene, OsSTRL2. Functional analysis, including complementation and CRISPR/Cas9-based gene editing, confirmed that the 2-nucleotide deletion in the OsLAP3 is responsible for the male sterility phenotype. OsLAP3 is homologous to the maize ZmMS45 , the core recessive nuclear sterile gene of maize Seed Production Technology (SPT), and localizes to the endoplasmic reticulum and plays a conserved role in anther development and pollenformation. Gene expression analysis revealed a significant downregulation of key genes involved in anther development and sporopollenin biosynthesis in lap3 anthers. Furthermore, lipid profiling demonstrated a marked reduction in both wax and cutin content. These findings establish OsLAP3 as a critical regulator of fatty acid synthesis and highlight its role in anther cuticle formation and pollen exine development. The findings of this study provide valuable insights into the molecular regulation of lipid biosynthesis during rice male reproductive development and offer potential applications for hybrid rice breeding. [ABSTRACT FROM AUTHOR]

Key message: Enhanced antioxidant enzymes activity, particularly superoxide dismutase and catalase, along with autophagy process in reproductive organs, can improve the resilience of rapeseed to heat stress, thereby securing crop yield in the face of global warming. Climate change and global warming have increasingly influenced yield and quality of rapeseed (Brassica napus) almost all across the world. The response of reproductive organs to high-temperature stress was studied in two rapeseed varieties, SAFI5 and DH13 with contrasting levels of heat stress tolerance. Pollen germination, viability, and seed set showed a significant reduction in the heat-sensitive variety (DH13). Superoxide quantification revealed higher accumulation in heat-sensitive variety, leading to decreased seed formation and floret fertility most probably due to declined pollen viability and stigma receptivity. Further microscopic analysis of the anther and pistil demonstrated a significant overlay between the damaged areas and the location of O2− accumulation. The sensitive variety showed higher O2− accumulation and a wider damage area than the tolerant one, suggesting that superoxide could incapacitate anther and pistil due to structural injury. Moreover, the activity levels and expression of superoxide dismutase and catalase antioxidant enzymes were significantly higher in the anther and pistil of the tolerant variety. Histochemical analysis also indicated markedly higher autophagosome formation in tolerant variety’s anther and pistil. Consistently, the expression levels of autophagy and ubiquitin-proteasome system (UPS)-related genes including BnATG8d, BnEXO70B, BnATl1 4A, and BnNBR1, as well as ubiquitin-activating enzyme E1, were higher in both reproductive organs of the tolerant variety. Interestingly, the areas of autophagosome formation overlapped with the areas in which higher superoxide accumulation and structural changes happened, suggesting a specific role of autophagy in oxidative stress response. [ABSTRACT FROM AUTHOR]

Key message: A high-throughput sequencing identified 1283 lncRNAs in anthers at different stages in Arabidopsis and their relationship with protein-coding genes and miRNAs during anther and pollen development were analyzed. Long non-coding RNAs (lncRNAs) are important regulatory molecules involved in various biological processes. However, their roles in male reproductive development and interactions with miRNAs remained elusive. In this study, a high-throughput sequencing of anthers at different developmental stages in Arabidopsis identified 1283 lncRNAs including 524 differentially expressed lncRNAs (DELs). Most of these DELs exhibited positive correlations with the expression patterns of adjacent protein-coding genes. Weighted gene co‐expression network analysis (WGCNA) revealed that protein-coding genes targeted by DELs in four modules related to the tetrad stage were associated with functions such as pollen wall formation, pollen germination, or pollen tube growth, respectively. Furthermore, five, 10, and 11 lncRNAs were predicted as miRNAs’ endogenous target mimics (eTMs), precursors, and natural antisense transcripts of pri-miRNA, respectively. Remarkably, the lncRNA, host gene of ath-miR167a (ath-miR167aHG), predicted as the precursor of miR167a, was selected for function validation. Its overexpression resulted in the up-regulation of miR167a and the subsequent down-regulation of miR167a’s target genes ARF6 and ARF8, demonstrating a functional interaction between ath-miR167aHG and miR167a. The transgenic plants showed delayed flowering, shorter filaments, abnormal anther dehiscence, and undeveloped siliques ultimately, suggesting a role of ath-miR167aHG in male reproductive development. Collectively, our research shed new light on the functions of lncRNAs in male reproductive development and uncovered the unique interactions between lncRNAs and miRNAs. [ABSTRACT FROM AUTHOR]

• The genus Microdon is revised with seven species recognised. • Microdon lyperioides is a new species from Piketberg. • Full nomenclature and typification are provided. • All species are fully described and illustrated. The taxonomy of the genus Microdon Choisy (Scrophulariaceae: Limoselleae) is revised. It is a genus of ericoid or microphyllous shrubs separated from Selago L. and other uniovulate members in the tribe by a combination of characters, notably the calyx tube adnate for up to half its length to the bract, with the posticous ovary locule aborted. The entirely eglandular vestiture of the plants is also diagnostic. The plicate calyx is very shortly and sub-equally 5-lobed and glabrous or more usually with spinules on the lower ribs. The flowers are moderately long-tubed with lobes shorter than the tube, and the anticous stamens are shortly included with the posticous pair either exserted or lacking. The fruits are clearly adapted for wind-dispersal, the diaspores shed as a unit comprising the prominent, wing-like bract attached to the calyx that expands to partially or fully enclose the solitary coccus, which remains attached to the receptacle. We recognise seven species in the genus, segregated between sect. Microdon for four species with straight corolla tubes and four stamens with smaller anthers 0.5–1.0 mm long, and sect. Agathelpis for three species with arcuate or geniculate corolla tubes and two stamens with larger anthers ± 2 mm long. The new species M. lyperioides J.C.Manning & R.Maluleke from the Piketberg is distinguished from the sympatric M. dubius by the longer leaves, dense whitish pubescence on the stems, and the markedly patent flowers with longer corolla tube mm 3\0554 mm"?>13–14 mm long and longer corolla lobes 3–4 mm long. [ABSTRACT FROM AUTHOR]

The anther is the developmental housing of pollen and therefore the male gametes of flowering plants. The meiotic cells from which pollen are derived must differentiate de novo from somatic anther cells and synchronously develop with the rest of the anther. Anthropogenic control over another development has become crucial for global agriculture so as to maintain inbred lines and generate hybrid seeds of many crops. Understanding the genes that underlie the proper differentiation, developmental landmarks, and functions of each anther cell type is thus fundamental to both basic and applied plant sciences. We investigated the development of the somatic niche of the maize (Zea mays) anther using single-cell RNA-seq (scRNA-seq). Extensive background knowledge on the birth then pace and pattern of cell division of the maize anther cell types and published examples of cell-type gene expression from in situ hybridization allowed us to identify the primary cell types within the anther lobe, as well as the connective cells between the four lobes. We established the developmental trajectories of somatic cell types from pre-meiosis to post-meiosis, identified putative marker genes for the somatic cell types that previously lacked any known specific functions, and addressed the possibility that tapetal cells sequentially differentiate. This comprehensive scRNA-seq dataset of the somatic niche of the maize anther will serve as a baseline for future analyses investigating male-sterile genotypes and the impact of environmental conditions on male fertility in flowering plants. [Display omitted] • A developmental series of maize anther cells were isolated and analyzed via single-cell RNA-sequencing. • The transcriptional profiles of the tapetum, endothecium, epidermis, and connective cells were identified. • The tapetum undergoes a massive transcriptional change at the end of meiosis. • Differentially expressed genes for each of the cell types may serve as markers for investigations into anther biology. [ABSTRACT FROM AUTHOR]

Pseudosasa subsolida belongs to the Pseudosasa genus within the Poaceae family. Due to its unique flowering cycle and the physiological traits associated with asexual reproduction, acquiring floral material from P. subsolida is particularly challenging. To investigate the causes of the low seed set rate in P. subsolida, floral organs and the development of male and female gametes were examined using conventional paraffin sectioning. The results revealed that the spikelet of P. subsolida exhibited the characteristics of a pseudospikelet with a latent bud, while the inflorescence displayed traits of an infinite inflorescence. Each spikelet contained approximately 10–16 florets and was accompanied by two bracts at its base. The fundamental structure of the florets comprised one lemma, one palea, three lodicules, three stamens, and one pistil. At the later stages of anther development, some abnormalities were observed, including the failure of pollen grains to form, deformation and shrinkage of the cells in the anther sac and tapetum, loss of the cells in the middle layer, cavitation of the microspores, and no identifiable contents The study concluded that the primary factor contributing to the low seed setting rate of P. subsolida was the aberrant development of male gametophytes. The significance of this study lay in its pioneering exploration of the reproductive structure of P. subsolida, and provide a theoretical reference for the fundamental examination of flower structure. [ABSTRACT FROM AUTHOR]

Background: Chinese cabbage is a cross-pollinated crop with remarkable heterosis, and male-sterile line is an important mean to produce its hybrids. In this study, a male-sterile mutant msm7 was isolated from a Chinese cabbage DH line 'FT' by using EMS-mutagenesis. Results: Compared with the wild-type 'FT', the anthers of mutant msm7 were completely aborted, accompanied by the defects in leaf and petal development. Genetic analysis showed that a single recessive nuclear gene controlled the sterile phenotype of mutant msm7. Cytological observation indicated that the anther abortion of mutant msm7 was caused by the degenarated microspores and premature degradation of tapetum. MutMap and KASP analyses identified that BraA01g038270.3 C, encoding the large subunit of ribonucleotide reductase (RNR1) which involved in the biosynthesis of dNTPs, was the candidate gene, named BrRNR1. Compared with the wild-type 'FT', a G-A mutation occurred on the 4th exon of the BrRNR1 gene, leading to the premature termination of encoded amino acid in mutant msm7. Expression analysis indicated that the BrRNR1 gene was ubiquitously expressed in all organs and was significantly decreased in flower bud and anther of mutant msm7 compared with the wild-type 'FT'. Subcellular localization revealed that BrRNR1 was an endoplasmic reticulum localization protein. Conclusion: Our study is the first to characterize the function of BrRNR1 gene associated with male sterility and lays a foundation for exploring the molecular mechanism of anther abortion caused by the mutation in BrRNR1 gene of Chinese cabbage. [ABSTRACT FROM AUTHOR]

Petunia hybrida is an annual herb flower that is prevalently cultivated both in public landscaping and home gardening. Anthers are vital reproductive organs for plants, but the molecular mechanism controlling petunia anther development remains elusive. In this work, we combined DNA methylation, microRNAome, degradome and transcriptome data to generate a comprehensive resource focused on exploring the complex molecular mechanism of petunia anther development. This study shows that DNA methylation could have an important impact in repressing the anther-expressed genes in the late stages of anther maturation. A total of 8,096 anther-preferential genes and 149 microRNAs (miRNAs) were identified that highly expressed in the five typical petunia anther developmental stages. Gene Ontology enrichment analysis of differentially expressed genes as well as miRNAs target genes revealed that metabolic, cellular and single-organism processes were significantly activated during the anther maturation processes. Moreover, a co-expression regulatory network for five typical anther development stages was constructed based on transcriptomic data, in which two hub transcription factors, PhERF48 and PhMS1 , were demonstrated to be important regulatory genes for male fertility. Furthermore, two DNA demethylase proteins (PhDME and PhDML3) and three methyl-CpG-binding-domain proteins (PhMBD2, PhMBD3 and PhMBD4) were identified as potential critical DNA methylation regulators in petunia anther development. Our results provide new knowledge regarding the regulatory mechanism of petunia anther development, which will support the breeding of novel sterile petunia lines in the future. [ABSTRACT FROM AUTHOR]

Background: MicroRNA159 (miR159) is a conserved miRNA found in various plant species. By regulating GAMYB-like transcription factors, miR159 is involved in diverse biological processes. Cymbidium goeringii, a significant traditional Chinese orchid, has unique flower shape and elegant fragrance. However, its development has been several limited because of the low flower bud differentiation and the difficult reproduction. This research aims to provide guidance for the role of cgo-miR159 in reproductive organ development to enhance the ornamental and economic value of Cymbidium. Methods: In this study, miR159 was cloned and its expression was determined across different development stages and tissue types. The function of cgo-miR159 was identified using gene transformation in Arabidopsis and tobacco plants. Results: High expression levels of cgo-miR159 were detected in the leaves and stamens during reproductive growth and expression peaked during flower bud development when the flower was above 0.5 to 3 cm in length. In transgenic experiments, the ectopic expression of cgo-miR159 led to defective development in the stamens of model plants (Arabidopsis and tobacco), including earlier anther dehiscence and pollen deformity, which resulted in developmental abnormalities and reduced seeds count in fruits. Conclusions: In summary, cgo-miR159 affected the development of reproductive organs in model plants. This research complements previous studies on the function of miR159 and provide useful references for the genetic improvement of orchids. [ABSTRACT FROM AUTHOR]

Apocynaceae is one of the richest flowering plant families, and the complexity of their reproductive structures and morphological diversity of the flowers has been considered central to understanding its evolutionary success and diversification. However, the diversity of its embryological characters is poorly known, especially in taxa that are early diverging in the family, such as the Aspidospermateae tribe. Moreover, the knowledge gap on early divergent taxa forbids the reconstruction of evolutionary trends in Apocynaceae. Here, we investigated the anther wall and pollen development of five species of Aspidosperma using conventional plant anatomy techniques. We found that the primary conditions for the Aspidosperma species are fibrous endothecium, middle layer, and secretory tapetum having one-layered and uninucleate cells, besides simultaneous cytokinesis. We also found pollen grains 4–6 colporate, alternately with pseudocolporate in all the species, with ridges formed by the thickened inequal deposition of the infratectum layer in the exine that delimits aperture regions. The differentiated deposition of exine confers a distinctive appearance to pollen grains and appears to be associated with the hydration/dehydration process during pollination. Similar deposition patterns have been identified in other genera within the tribe Aspidospermateae, suggesting that it may constitute a synapomorphy for the tribe. [ABSTRACT FROM AUTHOR]

Mirror-image flowers (enantiostyly) involve a form of sexual asymmetry in which a flower's style is deflected either to the left or right side, with a pollinating anther orientated in the opposite direction. This curious floral polymorphism, which was known but not studied by Charles Darwin, occurs in at least 11 unrelated angiosperm families and represents a striking example of adaptive convergence in form and function associated with cross-pollination by insects. In several lineages, dimorphic enantiostyly (one stylar orientation per plant, both forms occurring within populations) has evolved from monomorphic enantiostyly, in which all plants can produce both style orientations. We use a modelling approach to investigate the emergence of dimorphic enantiostyly from monomorphic enantiostyly under gradual evolution. We show using adaptive dynamics that depending on the balance between inbreeding depression following geitonogamy, pollination efficiency, and plant density, dimorphism can evolve from an ancestral monomorphic population. In general, the newly emergent dimorphic population is stable against invasion of a monomorphic mutant. However, our model predicts that under certain ecological conditions, for example, a decline of pollinators, dimorphic enantiostyly may revert to a monomorphic state. We demonstrate using population genetics simulations that the observed evolutionary transitions are possible, assuming a plausible genetic architecture. [ABSTRACT FROM AUTHOR]

Heat stress at the flowering stage significantly impacts rice grain yield, yet the number of identified genes associated with rice heat tolerance at this crucial stage remains limited. This study focuses on elucidating the function of the heat‐induced gene reduced heat stress tolerance 1 (OsRHS). Overexpression of OsRHS leads to reduced heat tolerance, while RNAi silencing or knockout of OsRHS enhances heat tolerance without compromising yield, as assessed by the seed setting rate. OsRHS is localized in the cytoplasm and mainly expressed in the glume and anther of spikelet. Moreover, OsRHS was found to interact with the HSP protein cHSP70‐4, and the knockout of cHSP70‐4 resulted in increased heat tolerance. Complementation assays revealed that the knockout of cHSP70‐4 could restore the compromised heat tolerance in OsRHS overexpression plants. Additional investigation reveals that elevated temperatures can amplify the bond between OsRHS and cHSP70‐4 within rice. Furthermore, our findings indicate that under heat stress conditions during the flowering stage, OsRHS plays a negative regulatory role in the expression of many stress‐related genes. These findings unveil the crucial involvement of OsRHS and cHSP70‐4 in modulating heat tolerance in rice and identify novel target genes for enhancing heat resilience during the flowering phase in rice. Summary statement: Our results demonstrate that the novel protein OsRHS serves as a negative regulator of rice heat tolerance during the flowering stage by interacting with the HSP70 protein cHSP70‐4 which also exerts a negative influence on rice heat tolerance, and the interaction between OsRHS and cHSP70‐4 is strengthened under heat stress conditions. [ABSTRACT FROM AUTHOR]

Key message: DDP1, encoding a β-Ketoacyl-CoA Synthase, regulates rice anther dehiscence and pollen fertility by affecting the deposition of lipid on anther epidermis and pollen wall. Anther dehiscence and pollen fertility are crucial for male fertility in rice. Here, we studied the function of Defective in Dehiscence and Pollen1 (DDP1), a novel member of the KCS family in rice, in regulating anther dehiscence and pollen fertility. DDP1 encodes an endoplasmic reticulum (ER)-localized protein and is ubiquitously expressed in various organs, predominately in the microspores and tapetum. The ddp1 mutant exhibited partial male sterility attributed to defective anther dehiscence and pollen fertility, which was notably distinct from those observed in Arabidopsis thaliana and rice mutants associated with lipid metabolism. Mutations of DDP1 altered the content and composition of wax on anther epidermis and pollen wall, causing abnormalities in their morphology. Moreover, genes implicated in lipid metabolism, pollen development, and anther dehiscence exhibited significantly altered expression levels in the ddp1 mutant. These findings indicate that DDP1 controls anther dehiscence and pollen fertility to ensure normal male development by modulating lipid homeostasis in the tapetum, thereby enhancing our understanding of the mechanisms underlying rice anther dehiscence and pollen fertility. [ABSTRACT FROM AUTHOR]

Alfalfa (Medicago sativa L.), a prominent perennial forage in the legume family, is widely cultivated across Europe and America. Given its substantial economic value for livestock, breeding efforts have focused on developing high-yield and high-quality varieties since the discovery of CMS lines. However, progress is restricted by the limitations of existing CMS lines, necessitating the development of new lines and study of the molecular mechanisms underlying pollen abortion. This study investigates early-stage anther development in cytoplasmic male sterile (CMS) alfalfa lines (MSJN1A) in relation to the isotypic maintainer line (MSJN1B). Histological analyses revealed abnormal degradation of tapetal cells post-meiosis in the CMS line. Notably, during the early mononuclear stage, the central vacuoles in the microspores were absent, leading to evident pollen abortion. These findings suggest that pollen abortion in the CMS line is associated with the delayed disintegration of the tapetum and structural anomalies in microspore vacuoles. Non-targeted metabolome sequencing revealed 401 and 405 metabolites at late tetrad and early mononuclear stages of alfalfa, respectively. Among these, 39 metabolites were consistently upregulated, whereas 85 metabolites were downregulated. Differential analysis revealed 45 and 37 unique metabolites at each respective stage. These metabolites were primarily featured in pathways related to energy, phenylpropane, sucrose and starch, and fatty acid metabolism. Integrated analysis demonstrated that differentially expressed genes and differential metabolites were co-enriched in these pathways. Additionally, quantitative real-time PCR and physiological index analysis confirmed downregulation of key genes involved in anther development, illustrating that changes in upstream gene regulation could significantly impact downstream metabolite levels, ultimately influencing pollen fertility. Pollen abortion is related to abnormal phenylpropane metabolism, fatty acid metabolism and starch and sucrose pathway, which provides reference for further research on the causes of pollen abortion of alfalfa. [ABSTRACT FROM AUTHOR]

Background: Thermosensitive male sterility (TMS) is a heritable agronomic trait influenced by the interaction between genotype and environment. The anthers of plants are composed of various specialized cells, each of which plays different roles in plant reproduction. In rapeseed (Brassica napus L.), Polima (pol) temperature-sensitive cytoplasmic male sterility (TCMS) is widely used in two-line breeding because its fertility can be partially restored at certain temperatures. The pol-TCMS line exhibits abnormal anther development and pollen abortion at high (restrictive) temperatures (HT, 25 °C) compared to at low (permissive) temperatures (LT, 16 °C). However, the response of different anther cell types to HT and the dynamic regulation of genes under such conditions remain largely unknown. Results: We present the first single-cell transcriptomic atlas of Brassica napus early developing flower bud tissues in response to HT. We identified 8 cell types and 17 transcriptionally distinct cell clusters via known marker genes under LT and HT treatment conditions. Under HT conditions, changes in the gene expression patterns of different cell clusters were observed, with the number of down-regulated genes in various cell types exceeding that of up-regulated genes. Pseudotime trajectory analysis revealed that HT strongly affected the development of early stamen/anther tissue cells. In combination with the snRNA-seq, WGCNA, and bulk RNA-seq results, we found that many transcription factors play crucial roles in the response to HT, especially heat response family genes. Conclusions: Our study revealed the transcriptional regulatory network of floral bud tissue in the pol-TCMS line under HT/LT conditions and increased our understanding of high-temperature-induced anther developmental abnormalities, which may help researchers utilize TCMS in the two-line breeding of Brassica plants. [ABSTRACT FROM AUTHOR]

In flowering plants, callose (β-1,3-glucan) plays a vital role in pollen development, especially in the separation and development of microspores. However, the molecular mechanism of callose deposition during rice pollen development remains unclear. In this study, we isolated and characterized a novel rice pollen defective mutant, non-separated microspores 1 (nsm1), which produced "dyad" or "tetrad" pollen grains. Cytological analysis indicated disrupted interstitial callose deposition at the cell plate of dyads and tetrads in nsm1 pollens. This disruption caused sporopollenin to be massively deposited outside of the junction where the interstitial callose wall connected with the peripheral callose wall, or unevenly distributed on the interstitial pollen primexine at the late meiosis stage. Consequently, an excess tectum-like layer was formed outside of the junction, connecting with the tectum of two microspores during later developmental stages, which prevented the separation of microspores. Additionally, in the linkage area, the tectum of two microspores gradually fused or degenerated, resulting in a decreased contact area between microspores and the anther locule. Therefore, the defect in callose deposition resulted in unsuccessful separation of microspores, abnormal deposition of pollen exine, and also affected the accumulation of materials in microspores, resulting in pollen semi-sterility. NSM1, encoding a callose synthase located in the Golgi body, is ubiquitously expressed in anthers with its peak expression at the young microspore stage. The in vitro enzyme activity assay confirmed that NSM1 possesses callose synthase activity, and the enzyme activity in the nsm1 mutants was significantly reduced. Phylogenetic analysis indicated that NSM1 and its orthologs play a highly conserved role in callose biosynthesis among plant species. Taken together, we propose that NSM1 plays an essential role in male meiotic callose synthesis and later pollen wall development. [ABSTRACT FROM AUTHOR]

Crop yield depends on biomass, which is primarily associated with photosynthesis. We previously demonstrated that two photorespiratory bypasses, i.e., GOC (glycolate oxidase + oxalate oxidase + catalase) and GCGT (glycolate oxidase + catalase + glyoxylate carboligase + tartronic semialdehyde reductase), significantly increased photosynthesis, biomass, and grain yield, but decreased seed-setting rates in rice. This study explored the underlying mechanism of how elevated photosynthetic efficiency impacted the seed-setting. First, pollen germination assessed in vivo and in vitro, revealed a reduced germination rate in GCGT rice. Subsequent analysis found that photosynthates highly accumulated in the leaves and stems; sucrose and soluble sugar levels were increased but the starch level was reduced in the anthers. Uridine diphosphate glucose (UDP-Glc) was increased but uridine diphosphate galactose (UDP-Gal) was unaltered, thus causing an imbalance in the UDP-Glc/UDP-Gal ratio in GCGT anthers. Most anthers in GCGT plants had two locules in contrast to four in the wild-type (WT). Pollen tapetum was developmentally abnormal, and genes related to sucrose synthesis, transport, and tapetal programmed cell death (PCD) were upregulated, whereas those involved in starch synthesis and conversion were downregulated in GCGT anthers. Taken together, our results demonstrated that an increase in sugar content was the primary factor causing reduced seed-setting rates in high photosynthetic efficiency rice, during which metabolic disorder of sugars and UDP sugar imbalance in anthers lead to impaired pollen fertility. [ABSTRACT FROM AUTHOR]

The pollen quality of nine Anatolian chestnut (Castanea sativa Mill.) cultivar/genotypes and two hybrid (Castanea sativa × Castanea crenata) cultivars were evaluated in this study. Fort his aim, anther and pollen sizes, amounts of pollen produced in an anther, pollen viability rate and germination percentages were determined. Significant differences were found among the cultivars in terms of the examined characteristics. It was determined that the average amount of pollen per anther of the varieties/genotypes was 5111-8000 pieces, and pollen germination rates varied between 16.93% and 35.35% at 5% sucrose concentration and 23.01% to 36.63% at 10% sucrose concentration. Pollen viability of the cultivars was found to be over 60%. Overall, it has been concluded that the pollination potential of chestnut cultivars/genotypes is sufficient and that alternative options can be offered to producers based on their regional distributions. [ABSTRACT FROM AUTHOR]

Globba zwegabinensis sp. nov., under sect. Haplanthera (Zingiberaceae) is newly described and illustrated from the Zwegabin Mountain of Kayin State in southern Myanmar. G. zwegabinensis is morphologically allied to G. sessiliflora and G. lithophila but differs in having the leaves with a foetid smell, glabrous blade, completely yellow filament, glabrous ovary, larger cuneiform labellum with bifid apex, glabrous and oblong to ovate fruit, lack of bulbils and anther appendages. A description and photographic data, along with the comparative characteristics of the closely allied species, are provided. [ABSTRACT FROM AUTHOR]

Key message: ARID-HMG DNA binding protein, AtHMGB15, regulates pollen development and pollen germination in Arabidopsis. Previous studies have shown that ARID-HMG DNA binding protein, AtHMGB15 regulate pollen development and pollen germination in Arabidopsis. Here, we performed transcriptome and cytological studies to understand the role of AtHMGB15 in regulating pollen wall morphology and the pollen tube germination rate. Our result showed abnormal vacuolization in the tapetal cells during anther maturation and prolonged PCD in AtHMGB15 loss-of-function mutant. The tapetum has the ability to perform both secretory and biosynthetic activities critical for pollen maturation and pollen viability. Interestingly, expression of PCD executer genes CEP1, MC9 and RNS3 were significant down-regulation of in athmgb15-4. The growth of pollen tubes is regulated by the actin cytoskeleton dynamics. To address the defect in pollen tube growth of athmgb15, we monitored the actin network in growing pollen tubes of wildtype and athmgb15-4 using Rhodamine-phalloidin fluorescence. Our results indicate a highly fragmented actin distribution in athmgb15-4 pollen tubes with a lesser number of long actin fibers and significantly low f-actin concentration at the apex. q-RTPCR further indicates significant downy-regulation of actin regulatory proteins VLN2 and PRF4. Collectively, our results suggest that AtHMGB15 being a nuclear architectural protein orchestrates high-order chromatin organization to promote the transcription of genes responsible for pollen development and pollen germination. [ABSTRACT FROM AUTHOR]

Background and Aims Fertilization relies on pollen mother cells able to transition from mitosis to meiosis to supply gametes. This process involves remarkable changes at the molecular, cellular and physiological levels, including (but not limited to) remodelling of the cell wall. During the onset of meiosis, the cellulose content in the pollen mother cell walls gradually declines, with the concurrent deposition of the polysaccharide callose in anther locules. We aim to understand the biological significance of cellulose-to-callose turnover in pollen mother cells walls. Methods We carried out electron microscopic, aniline blue and renaissance staining analyses of rice flowers. Key Results Our observations indicate that in wild-type rice anthers, the mitosis-to-meiosis transition coincides with a gradual reduction in the number of cytoplasmic connections called plasmodesmata. A mutant in the Oryza sativa callose synthase GSL5 (Osgsl5-3), impaired in callose accumulation in premeiotic and meiotic anthers, displayed a greater reduction in plasmodesmata frequency among pollen mother cells and tapetal cells, suggesting a role for callose in maintenance of plasmodesmata. In addition, a significant increase in extracellular distance between pollen mother cells and impaired premeiotic cell shaping was observed in the Osgsl5-3 mutant. Conclusions The results suggest that callose-to-cellulose turnover during the transition from mitosis to meiosis is necessary to maintain cell-to-cell connections and optimal extracellular distance among the central anther locular cells. The findings of this study contribute to our understanding of the regulatory influence of callose metabolism during initiation of meiosis in flowering plants. [ABSTRACT FROM AUTHOR]

We investigated the anther culture (AC) efficiency of nine genotypes of winter bread wheat (Triticum aestivum L.). The genotype dependency was assessed during the induction of the androgenic callus, i.e., embryo-like structures (ELSs), green-, albino- and acclimatizated plantlets. The highest level of callus formation were shown for samples 120/20 (114.39 ELS per 100 anthers—ELS/100A) and 132/20 (16.26 ELS/100A). The number of green plantlets per 100 anthers (GP/100A) varied from 0 to 3.05 GP/100A with a mean of 0.71 GP/100A. The acclimatized plantlets (ADPs) per 100 regenerated green plantlets ranged in each combination, from 32.00 to 62.50 ADP/100GP with an average value of 35.92. Between 12.50 and 60.00 doubled haploid (DH) plants per 100 acclimatized plantlets (DH/100ADP), depending on the combination, with a mean of 29.41% were recovered. Fertile plants in the anthers culture 5 out of 9 studied genotypes were obtained. Seventeen dihaploid lines with complex rust resistance and common bunt (8–9 points) were obtained. Two clusters of complex resistance genes were identified in the ten studied DH lines: Lr26/Sr31/Pm8/Yr9 and Lr34/Yr18/Sr58/Pm38. [ABSTRACT FROM AUTHOR]

Abstract Anther development involves a series of important biological events that are precisely regulated by many genes. Although several important genes involved in rice anther development have been identified, the regulatory network involved in tapetal development and pollen wall formation is still largely unclear. PERSISTENT TAPETAL CELL 1 (PTC1) encodes a PHD-Finger protein, which plays a critical role in the regulation of tapetal cell death and pollen development in rice. Here, we report the isolation and characterization of a new allele ptc1-2 with 2-base deletion in the third exon, causing the absent of the PHD domain due to the sequence change. Cytological analysis revealed delayed tapetal PCD, defective pollen exine formation and abnormal ubisch bodies development. Transcriptome analysis revealed that genes related to pollen wall formation (secondary metabolism, phenylalanine synthesis, and cutin and wax biosynthesis pathways), cell death (cysteine and methionine metabolism and DNA repair pathways), and carbohydrate synthesis (starch and sucrose metabolism pathways) were significantly altered in ptc1-2 mutant. A total of 13 reported anther development genes exhibited significant expression changes in the ptc1-2 mutant. Yeast two-hybrid and BiFC analyses showed that PTC1 could interact with API5, an inhibitor of apoptosis, and the citrin-binding enzyme EDT1. This work is helpful in deepening the understanding of the regulatory network of male reproductive development in rice.

Pollen coat proteins (PCPs) are cysteine-rich small-molecule proteins, which exhibit high levels of polymorphism and are expressed in gametocytes. Previous investigations have revealed that PCP genes are involved in pollen wall synthesis, pollen-stigma recognition, and pollen development and germination. However, gene expression and function of PCP family in pollen development is not well understood in Wucai (Brassica campestris L.). In this study, genome-wide identification and expression analysis of the BcPCP gene family members were conducted, including their physical and chemical properties, chromosome localization, phylogenetic relationships, gene structure, and tertiary structure. A total of 20 BcPCP genes were identified and classified into three subfamilies showing high homology to Arabidopsis thaliana. Expression pattern analysis indicated that the BcPCP gene family exhibits higher expression levels in reproductive organs, suggesting their potential involvement in the reproductive development. Notably, BraA02g002400.3 C, potentially associated with male sterility, was identified through multiple transcriptomic and proteomic datasets. Subsequently, sequence analysis revealed its homology with the Arabidopsis GRP20 gene, and thus it was named BcGRP20. Functional analysis of this gene showed that overexpression of BcGRP20 gene in the Arabidopsis grp20 mutant could restore anther fertility. Overall, our findings indicate that BcGRP20 plays a critical role in pollen development and may be the causative gene for male sterility in Wucai. This study provides candidate genes for further functional identification of BcPCP genes in Wucai, which are crucial for anther development. [ABSTRACT FROM AUTHOR]

Garcinia dulcis (Roxb.) Kurz (Clusiaceae) is a medicinal plant native to Southeastern Asia, with a peculiar, precocious pollenkitt production in early microspore development. We aimed to find out whether different secretory activities of the tapetum or a premature sporoderm development provides additional evidence for our recent hypothesis for the precocious pollenkitt production. Histology, histochemistry and ultrastructure of tapetum and sporoderm development during pollenkitt secretion in Garcinia dulcis were conducted, based on light and electron microscopy analysis. The results showed that Garcinia dulcis possesses normal pollen development. The presence of two different pollen coating types, precocious pollenkitt (L1) and common pollenkitt (L2), in the anther tapetum indicate that they are produced in two different active stages of the secretory tapetum. The precocious pollenkitt production and transport to the locule takes place in early active tapetal cells at early tetrad to early microspore stage and is ongoing until late microspore stage. The production of the second type of pollenkitt (L2) starts shortly after the first active tapetum stage together with the formation of sporopollenin precursors. The sporoderm formation was completed at late microspore stage, when the tapetal cell walls start to disintegrate. Orbicules are lining the inner tapetum wall at middle to late microspore stage. ER (during early microspore stage) and plastids (during late microspore stage) were the two main sources of pollenkitt, which finally fused to pollenkitt droplets when the tapetal cells degenerated at mature bicellular pollen stage. [ABSTRACT FROM AUTHOR]

Previous studies have determined that Chloroluma gonocarpa (Sapotaceae), is a species that has cryptic dioecy. This type of sexual system is characterized by flowers that are morphologically perfect (both sexual whorls are present) but functionally pistillate or staminate (in each type of flower one of the sexual whorls is non-functional). In C. gonocarpa the pistillate flowers present well-developed stigma, functional ovules, and staminodes, while the staminate flowers present a poorly developed stigma, collapsed ovules, and pollen-producing anthers. In angiosperms, the abortion of sexual organs can occur at different stages of development (from pre-meiosis to post-meiosis), that is why we conducted an anatomical analysis of both flower types at various developmental stages. Using light microscopy, we described the processes of sporogenesis and gametogenesis to establish when the staminate flowers lose their pistillate function. To achieve this, we collected, fixed, and processed the flowers following conventional anatomical techniques for observation under a light microscope. Our findings reveal that pollen development occurs only in staminate flowers, while ovule development begins in both types of flowers but ceases in staminate flowers due to post-meiosis abortion. In contrast, normal development continues in pistillate flowers. These results suggest that dioecy in C. gonocarpa may have arisen from a gynodioecious pathway. [ABSTRACT FROM AUTHOR]

Efficient sucrose transport and metabolism are vital for seed and pollen development in plants. Cell wall invertases (CINs) hydrolyze sucrose into glucose and fructose, maintaining a sucrose gradient in the apoplast of sink tissues. In rice, two CIN isoforms, OsCIN1 and OsCIN2, were identified as being specifically expressed in the anthers but not in pollen. Functional analyses through genetic crosses and mutant characterization showed that oscin1/2 double mutants exhibit a sporophytic male-sterile phenotype and produce shrunken seeds. This suggests that CIN activity is essential for proper pollen development and seed formation in rice. Observation of the progeny genotypes and phenotypes from various genetic crosses revealed that the phenotype of oscin1/2 seeds is determined by the genotype of the maternal tissue, indicating the critical role of CIN function in the apoplast between maternal and filial tissues for sucrose transport and metabolism. The CIN activity in the anthers and seeds of wild-type rice was found to be significantly higher—over 500-fold in the anthers and 5-fold in the seeds—than in the leaves, highlighting the importance of CIN in facilitating the efficient unloading of sucrose. These findings suggest that the fine-tuning of CIN activity in the apoplast, achieved through tissue-specific expression and CIN isoform regulation, plays a key role in determining the carbohydrate distribution across different tissues. Understanding this regulatory mechanism could provide opportunities to manipulate carbohydrate allocation to sink organs, potentially enhancing crop yields. [ABSTRACT FROM AUTHOR]

The influence of the location of flower buds in the inflorescence on the size variation of the male flower sphere organs - stamens, anthers and connective - was studied in 50 seedless grapevine varieties. They were found to be characterized by a large biometric diversity. In the case of vertically located flower buds on the inflorescence branches of the variants base, middle and tip, there is a high variability and statistically proven differences between different varieties. At the base of the inflorescence, they are distributed in eight generalized clusters, in the middle - in ten and towards the tip - in eight. The morphological differences found between the flower elements in the male sphere are mathematically plausible only in the individual variants, and they are not proven when comparing them as a whole. The sizes of stamens, anthers, and connective do not depend on the location of the flower buds in the inflorescence. Biometric data reflecting the parameters of these organs are representative for each variety, regardless of which part of the inflorescence the flower buds are located. [ABSTRACT FROM AUTHOR]

Tapetal cells, like other parietal layer cells were small and oblong in the beginning. Shortly afterwards they incvcased in size and became binucleate, their cytoplasm being densely staincd with haematoxylin. Not a fow cells of the tapetum showed chromatin qranules in their nuclei. At the pollen tetrad stage, the tapetal cells had attained their maximum growth. The submicroscopic structure of the tapetal cells of the barley anthers has been investigated at the stages of a late tetrad and uninucleate pollen qrain before and after vacuolization. The tapetal cells of the barley as regards their structure and functions at these stages of development may be characterized as secretary ones. Their cytoplasm is abundant with cell organells. Numerous mitochondria and a Golgi apparatus are in close vicini ty with the cisterns of an endoplasmic reticulum. The presence of ribosomes on the onter cisternae of the stack relates the entire structure to the endoplasmic reticulum. Ocmiophilic substances apper in several places with respect to the tapetal cells. At the stage of an uninucleate pollen grain instead of the degenerated pr imary walls, surrounding every tapetal cell, a new wall is formed, which consists mainly of sporopollenin. [ABSTRACT FROM AUTHOR]

The article discusses strategies for applying RNA m6A modification in crop improvement, emphasizing the importance of precise gene expression manipulation for enhancing crop traits. It highlights the role of m6A modification in regulating gene expression in plants and presents examples of how manipulating m6A levels can enhance agronomic traits in crops like rice, potato, and strawberries. The article also outlines three proposed strategies for enhancing crop traits through m6A modification and provides steps for m6A editing to improve crop agronomic traits. [Extracted from the article]

Stamens are vital reproductive organs in angiosperms, essential for plant growth, reproduction, and development. The genetic regulation and molecular mechanisms underlying stamen development are, however, complex and varied among different plant species. MSL-lncRNAs, a gene specific to the Y chromosome of Populus deltoides, is predominantly expressed in male flower buds. Heterologous expression of MSL-lncRNAs in Arabidopsis thaliana resulted in an increase in both stamen and anther count, without affecting pistil development or seed set. To reveal the molecular regulatory network influenced by MSL-lncRNAs on stamen development, we conducted transcriptome sequencing of flowers from both wild-type and MSL-lncRNAs-overexpressing Arabidopsis. A total of 678 differentially expressed genes were identified between wild-type and transgenic Arabidopsis. Among these, 20 were classified as transcription factors, suggesting a role for these regulatory proteins in stamen development. GO enrichment analysis revealed that the differentially expressed genes were significantly associated with processes such as pollen formation, polysaccharide catabolic processes, and secondary metabolism. KEGG pathway analysis indicated that MSL-lncRNAs might promote stamen development by upregulating genes involved in the phenylpropanoid biosynthesis pathway. The top three upregulated genes, all featuring the DUF295 domain, were found to harbor an F-box motif at their N-termini, which is implicated in stamen development. Additionally, in transgenic Arabidopsis flowers, genes implicated in tapetum formation and anther development were also observed to be upregulated, implying a potential role for MSL-lncRNAs in modulating pollen development through the positive regulation of these genes. The findings from this study establish a theoretical framework for elucidating the genetic control exerted by MSL-lncRNAs over stamen and pollen development. [ABSTRACT FROM AUTHOR]

ABSTRACT The development of mapping populations and quantitative trait loci (QTL) analysis face constraints, in crops exhibiting male sterility and self‐incompatibility under field conditions. Addressing these challenges requires the integration of advanced techniques, including the temporal alteration or excision of centromere histone H3 (CENH3) protein and the use of gene editing tools such as MATRILINEAL (MTL) knockout. Specifically, this can be achieved through Cas9/gRNA‐mediated mutagenesis or Cas9/gRNA‐driven promoter expression systems. These technologies offer efficient means to advance mapping populations and QTL analysis in male sterile and self‐incompatible crops within controlled ecosystems. The doubled haploid (DH) mapping population, traditionally requiring 3 years of generation time via anther culture method, can now be expedited to 2–3 years of generation time using gene editing techniques within controlled environmental systems. Notably, DH mapping populations can be efficiently generated in various crops, including rice, wheat, maize, barley and oats by leveraging gene editing tools. Among these tools, the novel approach of CENH3 protein temporal alteration/excision emerges as highly efficient compared to MTL knockout using Cas9/gRNA‐mediated mutation or Cas9/gRNA promoter expression. However, further investigation is warranted to optimise the regeneration of double haploid populations and enhance QTL analysis in male sterile and self‐incompatible crops under controlled systems. [ABSTRACT FROM AUTHOR]

Boesenbergia kalakadensis (Zingiberaceae), a new species from Kalakad‐Mundanthurai Tiger Reserve (KMTR), Tirunelveli District of Tamil Nadu, India is described and illustrated. Boesenbergia kalakadensis is closely allied to B. rotunda Mansf., and B. tiliifolia (Baker) Kuntze, but differs from them in its rhizome, leaves, inflorescence, length of flowers, glabrous nature of bract and bracteoles, length of calyx and corolla tube, size and shape of the corolla lobes, size, colour and margins of lateral staminodes, broader, orbicular, flat labellum, sessile, glandular hairy, crested anther, and length of style. A key to species of Boesenbergia in Peninsular India is provided. [ABSTRACT FROM AUTHOR]

A newly discovered species, Stereochilus linearifolius (Vandeae, Orchidaceae), which was found in Maguan (Yunnan Province, China), is described and illustrated. Detailed morphological examination revealed that S. linearifolius exhibits similarities to S. dalatensis, however, it distinguishes itself in terms of plant size, leaf dimensions (length and width), sepal width, spur shape, midlobe shape, as well as the coloration of lip, anther cap and stigma. [ABSTRACT FROM AUTHOR]

Historically, traditional crossbreeding schemes have predominated in oat breeding. In vitro culture techniques seek to expedite the breeding process and enhance selection efficiency. Maximum yields are achieved from hybrid plants produced by crossing pure (homozygous) lines with the desired traits. Homozygous lines can be produced through conventional breeding methods, which are time-consuming and costly. Alternatively, the production of homozygous lines can be accelerated by producing doubled haploid (DH) plants derived from (haploid) male gametophytes or their microspores (androgenesis). This method condenses the various stages required for producing homozygous lines in a single generation, resulting in significant time and cost savings. These and other advantages render androgenic DHs the preferred choice in numerous important crops where any of the various in vitro experimental techniques (anthers culture or isolated microspores culture) are well-established. However, in the case of oat (Avena sativa L.), an efficient plant regeneration method remains not very effective compared to the most common cereals, possibly due to the known recalcitrance of this cereal to in vitro culture. This review presents the methods through anther and microspore cultures utilized in the production of oat DHs revealing the crucial factors influencing the efficiency of this method in oat (Avena sativa L.). [ABSTRACT FROM AUTHOR]

The emergence of new diseases is an urgent concern, but hosts can also vary in resistance to pathogens that are novel to them, facilitating evolutionary rescue. However, little is known about the genetic source for polymorphic resistance to novel pathogens or its relationship to defences against endemic diseases. With anther‐smut disease from wild plant populations, we used selection experiments and genetic analyses to show that resistances to novel and endemic pathogens are genetically independent, despite being positively correlated in nature. Moreover, novel‐pathogen resistance presented a much simpler genetic basis and more rapid response to selection. We demonstrate that polymorphic resistance to a newly introduced disease is genetically determined and not an extension of defences against the related endemic pathogen, challenging the conventional view of nonhost resistance. [ABSTRACT FROM AUTHOR]

A new species, Chiloschista breviseta (Orchidaceae: Epidendroideae: Aeridinae) from Northern Thailand is described and illustrated, and notes on ecology and conservation status are provided. Chiloschista breviseta is morphologically similar to C. usneoides but differs in having much shorter seta on each side of the anther cap. Previous records of C. usneoides from Thailand refer to C. breviseta. [ABSTRACT FROM AUTHOR]

Lysionotus cangyuanensis, a new species from Yunnan, China, is described and illustrated. This new species morphologically resembles L. sulphureoides and L. coccinus, but can be distinguished by its leaf blade size, bracts shape, corolla size and throat markings, and anthers shape. Detailed description is provided. [ABSTRACT FROM AUTHOR]

Cucumber (Cucumis sativus L.) is a genetically diverse group of vegetables with various cultivars having distinct traits. This study optimized somatic embryogenesis in anther-derived calli of selected commercial cucumber cultivars (Local Khera, Champion, and CP 001). Therefore, the experiment investigated the impact of 2,4-D and benzyl 6-aminopurine (BAP) treatments on embryo formation. The anthers collected from different-sized floral buds sustained culturing in various concentrations of 2,4-D and BAP (0, 0.5, 1, 1.5, 2, 3, and 4 mg L-1). It was evident that calli induction in cucumber cultivars received significant stimuli from 2,4-D and BAP concentrations and dark culture conditions during calli culture. The maximum calli induction (51%) was prominent in anthers of cv. CP 001 at a higher level of 2,4-D in small-sized floral buds. However, the anthers of cucumber cultivar Local Khera (59.72%) performed better for calli induction than Champion (57.14%) and CP 001 (51.43%). The highest embryogenesis appeared in anther-derived calli of cultivar Local Khera (12%) under light culture conditions in tiny flower buds. Meanwhile, maximum (8%) embryo formation observed at a higher level of 2,4-D (4 mg L-1) resulted in cultivars Champion and CP 001 under dark conditions. In conclusion, from the tested treatments, applying the highest level of 2,4-D and BAP at 4 mg L-1 was more effective than other treatments, including the control. However, more calli induction was noteworthy under dark culture conditions, and maximum embryo formation occurred under light culture conditions. [ABSTRACT FROM AUTHOR]

The small, unspecialized flowers of Jaltomata antillana (Solanaceae), typical of island species, are likely allochthonous in origin given similar congeneric close relatives in the Andes. Floral nectar, produced continuously during the life of the flower, is yellowish in color and is UV absorptive, in contrast with the white UV reflecting corolla. The day the flower opens flowers are pistillate (anthers not yet presenting pollen) for only a few hours and then become functionally hermaphroditic (anthers dehisce). Within each flower there is length variation among the stamens, size variation among anthers, and staggered anther dehiscence, collectively an apparent pollen-dispensing mechanism. Flowers close each night both when the flower will be functional the next day and at floral senescence. In a pollinator-free greenhouse, 100% of the flowers that were manually self-pollinated set fruits; however, 29% of the tagged unmanipulated flowers set fruit. Autonomous self-pollination takes place at the end of the corolla's life and allows fruit and seed production in the absence of pollinators but results in fruits that are lighter and contain fewer seeds than fruits resulting from manual self-pollinations. [ABSTRACT FROM AUTHOR]

[Objective] This study explored the cytological characteristics of different developmental stages of Prunus sibirica microspores and revealed the relationships between microspore periods and floral organ morphology to provide basis for reproductive biology research and germplasm innovation of Prunus sibirica. [Method] The flower buds of male sterile and fertile lines of Prunus sibirica were selected as the research subjects. The paraffin section technique and modified carmine acetate staining technique were used to observe morphology of microspores at various development stages. Phenotypic observation and analysis of flower organ morphology were also conducted during corresponding periods. [Result] The microspore development periods of Prunus sibirica included tetrad stage, microspore period and mature stage. The microspore period included uninucleate stage (early-uninucleate stage, mid-uninucleate stage, late-uninucleate stage) and binucleate stage (early-binucleate stage, middle-binucleate stage, late-binucleate stage) with distinct cytological features in each stage. In the early-binucleate stage, the microspores of the male sterile line were abnormal due to the failure to complete mitosis, but there was no abnormality in the development of floral organs. The bud transverse diameter, bud longitudinal diameter, anther transverse diameter and anther longitudinal diameter gradually increased with the advance of microspore development stage in Prunus sibirica. There were corresponding relationships between microspore periods and morphological characteristics of floral organs. The bud transverse diameter, anther transverse diameter and anther longitudinal diameter were utilized to differentiate microspores between various microspore stages ranging from early-binucleate stage to late-binucleate stage. The color of calyx was employed to differentiate microspores between mid-uninucleate stage and late-uninucleate stage. Additionally, microspore diameter distinguished different stages of microspores from early-uninucleate stage to early-binucleate stage. At the early-binucleate stage, bud transverse diameters of male sterile line and male fertile line in Prunus sibirica were 3.36 and 3.34 mm, respectively. The anther longitudinal diameters of male sterile line and male fertile line were 0.95 and 0.96 mm, respectively. The anther transverse diameters of male sterile line and male fertile line were both 0.73 mm. The microspore diameter of male sterile line and male fertile line were both 28.90 μm. [Conclusion] The microspore period of Prunus sibirica was correlated with bud transverse diameter, anther transverse diameter, anther longitudinal diameter, and calyx color, which could be used as an important basis for dividing microspore stages. [ABSTRACT FROM AUTHOR]

The floral biology of Hylocereus undatus Haw. and Hylocereus polyrhizus Haw. in relation to floral visitors for enhancing cross pollination was studied at farmer's field, Suradenupura, Yelahanka, Bengaluru during 2021-22. Totally, 61 parameters with respect to morphology and floral biology were recorded. The flowering period initiated during 3rd week of April and required 17.75 ± 0.96 and 19 ± 2.58 days from bud initiation to flower opening in H. undatus and H. polyrhizus, respectively. Anthesis started at 19:00 hrs, reached maximum between 01:30 to 03:40 hrs and closed completely on next day between 11:30 to 12:00 hrs, while, anther dehiscence (14:00 hrs) started 5 hrs before anthesis. Pollen grains were viable (17:00 hrs) after 3 hrs of anther dehiscence, but stigma receptivity (23:00 hrs) started 9 hrs after anther dehiscence, after 6 hrs of pollen viability and 4 hrs after anthesis. Longevity of flower was 16 hrs and 30 minutes. Cessation of flowering is on 2nd week of September in H. undatus and 3rd week of October in H. polyrhizus. Sepals of un-opened flower buds secreted nectar and pollen is major floral reward for floral visitors. Heterostyly and protandry nature of flowers needs external agents for pollination. 14 floral visitors were recorded on the flowers of two dragon fruit types of which A. mellifera L. abundance was maximum. [ABSTRACT FROM AUTHOR]

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This experiment used floral buds from watermelon genic male sterile dual-purpose lines as materials to explore the differentially expressed miRNAs (DEMs) between male fertile and sterile floral buds of watermelon. Paraffin sectioning technology was employed for a cytological analysis, and small RNA sequencing was used to explore miRNAs related to anther or pollen development. Cytological analysis indicated that the abnormal development of tapetal cells may cause microspore abortion. Small RNA sequencing identified a total of 314 miRNAs (29 known and 285 novel, which belonged to 12 and 61 miRNA families, respectively) in floral buds. Differential expression revealed 36 (5 known and 31 novel) DEMs between male fertile and sterile buds, 7 and 29 of which were up-regulated and down-regulated, respectively. Target genes analysis showed that the 36 DEMs were predicted to target 577 genes, and these targets might participate in various biological processes, such as response to metal ions, floral organ development, stamen development, anther development, pollen maturation, and programmed cell death. Moreover, pathway analysis indicated that these genes were mainly enriched in purine metabolism, starch and sucrose metabolism, RNA transport, and other pathways. In addition, the 55 miRNA–target modules, including 3 known and 16 novel miRNAs with 30 target genes, might be related to anther or pollen development in watermelon. Our findings provide important miRNA–target modules related to watermelon anther or pollen development and can lay the foundation for biological functional analysis. [ABSTRACT FROM AUTHOR]

Epigenetic modifications are crucial for plant development. EFD (ExineFormationDefect) encodes a SAM-dependent methyltransferase that is essential for the pollen wall pattern formation and male fertility in Arabidopsis. In this study, we find that the expression of DRM2, a de novo DNA methyltransferase in plants, complements for the defects in efd, suggesting its potential de novo DNA methyltransferase activity. Genetic analysis indicates that EFD functions through HB21, as the knockout of HB21 fully restores fertility in efd mutants. DNA methylation and histone modification analyses reveal that EFD represses the transcription of HB21 through epigenetic mechanisms. Additionally, we demonstrate that HB21 directly represses the expression of genes crucial for pollen formation and anther dehiscence, including CalS5, RPG1/SWEET8, CYP703A2 and NST2. Collectively, our findings unveil a double negative regulatory cascade mediated by epigenetic modifications that coordinates anther development, offering insights into the epigenetic regulation of this process. Epigenetic modifications are crucial for plant development. Here, the authors find an epigenetically mediated double negative cascade for pollen formation and anther dehiscence, offering new insights into epigenetic regulation of anther development. [ABSTRACT FROM AUTHOR]

The rice cultivar ‘JJ644wx’ was developed to improve disease resistance and lodging tolerance of Korean japonica glutinous rice cultivars. ‘JJ644wx’ was derived from a cross between ‘HR27814-B-47-1-1’ (‘Sinjinbaek’), a multiple disease-resistant mid-late maturing elite line, and ‘HR29676-AC29’, a medium-maturing glutinous line with lodging tolerance. To shorten the breeding period, an anther culture method was applied to F1 plants. ‘JJ644wx’ was selected through the pedigree method, yield trials, and local adaptability tests, with high selection pressure for disease resistance and lodging tolerance. The heading date of ‘JJ644wx’ was August 11th, four days later than that of ‘Sinseonchal’. ‘JJ644wx’ exhibited strong tolerance to lodging with a short culm length. The 1,000-grain weight of brown rice of ‘JJ644wx’ was heavier than that of ‘Sinseonchal’, and its yield was 553 kg/10a, which was 10% higher than that of ‘Sinseonchal’. ‘JJ644wx’ had a higher milling performance than ‘Sinseonchal’, but a lower head rice ratio due to a higher percentage of broken rice. ‘JJ644wx’ tended to be situated between ‘Sinseonchal’ and ‘Dongjinchal’ in terms of pasting and texture characteristics. ‘JJ644wx’ is the only Korean japonica glutinous rice cultivar resistant to the most virulent bacterial blight race, K3a; it also showed resistance to rice blast and stripe virus. ‘JJ644wx’ is expected to be a valuable resource that could contribute to improving the cultivation stability of Korean japonica glutinous rice in response to climate change (Registration No. 9606). [ABSTRACT FROM AUTHOR]