Abstract: In flowering plants, pollen development is a key process that is essential for sexual reproduction and seed set. Molecular and genetic studies indicate that pollen development is coordinatedly regulated by both gametophytic and sporophytic factors. Tapetum, the somatic cell layer adjacent to the developing male meiocytes, plays an essential role during pollen development. In the early anther development stage, the tapetal cells secrete nutrients, proteins, lipids, and enzymes for microsporocytes and microspore development, while initiating programmed cell death to provide critical materials for pollen wall formation in the late stage. Therefore, disrupting tapetum specification, development, or function usually leads to serious defects in pollen development. In this review, we aim to summarize the current understanding of tapetum-mediated pollen development and illuminate the underlying molecular mechanism in Arabidopsis thaliana.

Abstract: Cytoplasmic male sterility (CMS) is the basis of heterosis exploitation. CMS has been used to hybrid production in cotton, but its molecular mechanism remains unclear. CMS is associated with advanced or delayed tapetal programmed cell death (PCD), and reactive oxygen species (ROS) may mediate this process. In this study, we obtained Jin A and Yamian A, two CMS lines with different cytoplasmic sources.Compared with maintainer Jin B, Jin A anthers showed advanced tapetal PCD with DNA fragmentation, producing excessive ROS which accumulated around the cell membrane, intercellular space and mitochondrial membrane. The activities of peroxidase (POD) and catalase (CAT) enzymes which can scavenge ROS were significantly decreased. However, Yamian A tapetal PCD was delayed with lower ROS content, and the activities of superoxide dismutase (SOD) and POD were higher than its maintainer. These differences in ROS scavenging enzyme activities may be caused by isoenzyme gene expressions. In addition, we found the excess ROS generated in Jin A mitochondria and ROS overflow from complex III might be the source in parallel with the reduction of ATP content.ROS accumulation or abrogation were mainly caused by the joint action of ROS generation and scavenging enzyme activities transformation, which led to the abnormal progression of tapetal PCD, affected the development of microspores, and eventually contributed to male sterility. In Jin A, tapetal PCD in advance might be caused by mitochondrial ROS overproduction, accompanied by energy deficiency. The above studies will provide new insights into the cotton CMS and guide the follow-up research ideas.

Abstract: Reprogramming of microspores development towards embryogenesis mediated by stress treatment constitutes the basis of doubled haploid production. Recently, compounds that alter histone post-translational modifications (PTMs) have been reported to enhance microspore embryogenesis (ME), by altering histones acetylation or methylation. However, epigenetic mechanisms underlying ME induction efficiency are poorly understood. In this study, the epigenetic dynamics and the expression of genes associated with histone PTMs and ME induction were studied in two bread wheat cultivars with different ME response. Microspores isolated at 0, 3 and 5 days, treated with 0.7M mannitol (MAN) and 0.7M mannitol plus 0.4µM trichostatin A (TSA), which induced ME more efficiently, were analyzed. An additional control of gametophytic development was included. Microspores epigenetic state at the onset of ME induction was distinctive between cultivars by the ratio of H3 variants and their acetylated forms, the localization and percentage of labeled microspores with H3K9ac, H4K5ac, H4K16ac, H3K9me2 and H3K27me3, and the expression of genes related to pollen development. These results indicated that microspores of the high responding cultivar could be at a less advanced stage in pollen development. MAN and TSA resulted in a hyperacetylation of H3.2, with a greater effect of TSA. Histone PTMs were differentially affected by both treatments, with acetylation being most concerned. The effect of TSA was observed in the H4K5ac localization pattern at 3dT in the mid-low responding cultivar. Three gene networks linked to ME response were identified. TaHDT1, TaHAG2, TaYAO, TaNFD6-A, TabZIPF1 and TaAGO802-B, associated with pollen development, were down-regulated. TaHDA15, TaHAG3, TaHAM, TaYUC11D, Ta-2B-LBD16 TaMS1 and TaDRM3 constituted a network implicated in morphological changes by auxin signaling and cell wall modification up-regulated at 3dT. The last network included TaHDA18, TaHAC1, TaHAC4, TaABI5, TaATG18fD, TaSDG1a-7A and was related to ABA and ethylene hormone signaling pathways, DNA methylation and autophagy processes, reaching the highest expression at 5dT. The results indicated that TSA mainly modified the regulation of genes related to pollen and auxin signaling. This study represents a breakthrough in identifying the epigenetic dynamics and the molecular mechanisms governing ME induction efficiency, with relevance to recalcitrant wheat genotypes and other crops.

Abstract: Haploid plants are of significant interest to crop breeders due to their ability to expedite the development of inbred lines. Chromosome-doubling of haploids, produced by either in vitro or in vivo methods, results in fully homozygous doubled haploids. For nearly five decades, in vitro methods of anther and microspore culture have been attempted in many crops. In rice, in vitro methods are used with some success in japonica cultivars, although indica types have remained recalcitrant to a large extent. This review aims to explore the reasons for the lack of success of in vitro methods in indica rice and discuss new advancements in in vivo haploid induction protocols in other cereals and their relevance to rice. In particular, the current level of understanding of in vivo haploid inducer systems that utilize MTL and CENH3 mutants is analyzed in detail. One notable advantage of in vivo haploid induction systems is that they do not require tissue culture competence. This makes these methods more accessible and potentially transformative for research, offering a pragmatic approach to improving indica rice cultivars. By embracing these in vivo methods and harnessing the power of gene editing technologies like CRISPR/Cas9 systems, breeders can reshape their approach to indica rice improvement.

Abstract: β-1,3-Glucanases are considered key regulators responsible for the degradation of callose in plants, yet little is known about the role and mode of action of their encoding genes in tomato (Solanum lycopersicum). In the present study, we identified the β-1,3-glucanase encoding gene β-1,3-GLUCANASE10 (SlBG10) and revealed its regulation in tomato pollen and fruit development, seed production, and disease resistance by modulating callose deposition. Compared to wild-type or SlBG10 overexpressing (SlBG10-OE) lines, knockout of SlBG10 caused pollen arrest and failure to set fruit with reduced male rather than female fecundity. Further analyses showed that SlBG10-knockout promoted callose deposition in anther at the tetrad-to-microspore stages, resulting in pollen abortion and male sterility. Moreover, loss-of-function SlBG10 delayed degradation of endosperm cell wall calloses during cellularization and impeded early seed development. We also uncovered that Botrytis cinerea infection induces SlBG10 expression in wild-type tomato, and the knockout lines showed increased callose accumulation in fruit pericarps, reduced susceptibility to B. cinerea and enhanced antioxidant capacity to maintain tomato fruit quality. However, expression of genes encoding cell wall hydrolases decreased in SlBG10-knockout tomatoes and thus led to an increase in pericarp epidermal thickness, enhancement in fruit firmness, reduction of fruit water loss and extension of tomato shelf life. These findings not only expand our understanding of the involvement of β-1,3-glucanases as callose regulators in multiple developmental processes and pathogen resistance, but also provide additional insight into the manipulation of multi-agronomic traits for targeted tomato breeding.

Abstract: Cytoplasmic male sterility (CMS) has long been used to produce seedless fruits in perennial woody crops like citrus. A male sterile somatic cybrid citrus (G1+HBP) was generated from protoplast fusion between a CMS callus parent ‘Guoqing No. 1’ Satsuma mandarin (Citrus unshiu, G1) and a fertile mesophyll parent Hirado Buntan pummelo (Citrus grandis, HBP). To uncover the male sterile mechanism of G1+HBP, we compared the transcriptome profiles of stamen organ and cell types at five stages between G1+HBP and HBP, including the initial stamen primordia, enlarged stamen primordia, pollen mother cells, tetrads and microspores captured by laser microdissection (LMD). The stamen organ and cell types showed distinct gene expression profiles. A majority of genes involved in stamen development were differentially expressed, especially CgAP3.2 that was downregulated in enlarged stamen primordia and upregulated in tetrads of G1+HBP compared with HBP. The jasmonic acid (JA) and auxin related biological processes were enriched among the differential expression genes (DEGs) of stamen primordia, and the content of JA biosynthesis metabolites was higher in flower buds and anthers of G1+HBP. In contrast, the content of auxin biosynthesis metabolites was lower in G1+HBP. The mitochondrial tricarboxylic acid (TCA) cycle and oxidative phosphorylation (OXPHOS) processes were enriched among the DEGs in stamen primordia, meiocytes and microspores, indicating the dysfunction of mitochondria in stamen organ and cell types of G1+HBP. Taken together, the malfunction of mitochondria-nuclear interaction might cause disorder in stamen development, and thus lead to male sterility in the citrus cybrid.

Abstract: Although zygotic embryogenesis is usually studied in the field of seed biology, great attention has been paid to the methods used to generate haploid embryos due to their applications in crop breeding. These mainly include two methods for haploid embryogenesis: in vitro microspore embryogenesis and in vivo haploid embryogenesis. Although microspore culture systems and maize haploid induction systems were discovered in the 1960s, little is known about the molecular mechanisms underlying haploid formation. In recent years, major breakthroughs have been made in in vivo haploid induction systems, and several key factors, such as the matrilineal (MTL), baby boom (BBM), domain of unknown function 679 membrane protein (DMP), and egg cell-specific (ECS) that trigger in vivo haploid embryo production in both the crops and Arabidopsis models have been identified. The discovery of these haploid inducers indicates that haploid embryogenesis is highly related to gamete development, fertilization, and genome stability in ealry embryos. Here, based on recent efforts to identify key players in haploid embryogenesis and to understand its molecular mechanisms, we summarize the different paths to haploid embryogenesis, and we discuss the mechanisms of haploid generation and its potential applications in crop breeding. Although these haploid-inducing factors could assist egg cells in bypassing fertilization to initiate embryogenesis or trigger genome elimination in zygotes after fertilization to form haploid embryos, the fertilization of central cells to form endosperms is a prerequisite step for haploid formation. Deciphering the molecular and cellular mechanisms for haploid embryogenesis, increasing the haploid induction efficiency, and establishing haploid induction systems in other crops are critical for promoting the application of haploid technology in crop breeding, and these should be addressed in further studies.

Abstract: Doubled haploid (DH) technology is an important approach to accelerate genetic gain via a shortened breeding cycle, which relies on the ability to generate haploid cells that develop into haploids or doubled haploid embryos and plants. Both in vitro and in vivo (in seed) methods can be used for haploid production. In vitro culture of gametophytes (microspores and megaspores) or their surrounding floral tissues or organs (anthers, ovaries, or ovules) has generated haploid plants in wheat, rice, cucumber, tomato, and many other crops. In vivo methods utilize pollen irradiation or wide crossing or in certain species leverage genetic mutant haploid inducer lines. Haploid inducers were widespread in corn and barley, and recent cloning of the inducer genes and identification of the causal mutations in corn have led to the establishment of in vivo haploid inducer systems via genome editing of orthologous genes in more diverse species. Further combination of DH and genome editing technology led to the development of novel breeding technologies such as HI-EDIT™. In this chapter, we will review in vivo haploid induction and new breeding technologies that combine haploid induction and genome editing.

Abstract: Pollen development, from unicellular microspores to anthesis, is a complex process involving the coordinated specification, differentiation and functions of different cell types. Key to understanding this development is identifying the genes expressed at precise stages of development. However, transcriptomic studies on pollen prior to anthesis are complicated by the inaccessible nature of pollen developing in the anther and the resistant pollen wall. To assist with understanding gene expression during pollen development we have developed a protocol to perform RNA-Seq on pollen isolated from a single anther (SA RNA-Seq). The protocol involves removing pollen from a single anther for analysis and viewing the remaining pollen to determine the developmental stage. The isolated pollen is chemically lysed and mRNA isolated from the lysate using an oligo-dT column before library preparation. Here, we report on the development and testing of our method and the generation of a transcriptome for three stages of pollen development from Arabidopsis (Arabidopsis thaliana) and two stages from male kiwifruit (Actinidia chinensis). This protocol enables the transcriptome of precise developmental stages of pollen to be analyzed, and uses a small number of plants, potentially facilitating studies that require a range of treatments or the analysis of the first generation of transgenic plants.

Abstract: Wheat, the most important cereal crop in the poaceae family, contributes around 30% of global grain production. It is a significant contributor to our country’s food security. Abiotic stress poses challenges to plant growth and development in terms of ecological impacts. During reproductive growth, abiotic stress induces redox imbalance. Plants create reactive oxygen species (ROS) as a by-product of cellular metabolism. Numerous environmental factors increase ROS production, which causes oxidative damage and eventual cell death. In developing anthers, excessive ROS production induces sterility by causing pollen abortion and programmed cell death (PCD) of microspores. Physiological, biochemical, and morphological development also hampers with the production of ROS in wheat as a result of excessive environmental stress.

Abstract: Abstract Phenylpropanoid metabolism and timely tapetal degradation are essential for anther and pollen development, but the underlying mechanisms are unclear. In the current study, to investigate this, we identified and analyzed the male-sterile mutant, osccrl1 ( cinnamoyl coA reductase-like 1 ), which exhibited delayed tapetal programmed cell death (PCD) and defective mature pollen. Map-based cloning, genetic complementation, and gene knockout revealed that OsCCRL1 corresponds to the gene LOC_Os09g32020 .2, a member of SDR (short-chain dehydrogenase/reductase) family enzyme. OsCCRL1 was preferentially expressed in the tapetal cells and microspores, and localized to the nucleus and cytoplasm in both rice protoplasts and Nicotiana benthamiana leaves. The osccrl1 mutant exhibited reduced CCRs enzyme activity, less lignin accumulation, delayed tapetum degradation, and disrupted phenylpropanoid metabolism. Furthermore, an R2R3 MYB transcription factor OsMYB103/OsMYB80/OsMS188/BM1, involved in tapetum and pollen development, regulates the expression of OsCCRL1 . Finally, the osmyb103 osccrl1 double mutants, exhibited the same phenotype as the osmyb103 single mutant, further indicating that OsMYB103/OsMYB80/OsMS188/BM1 functions upstream of OsCCRL1. These findings help to clarify the role of phenylpropanoid metabolism in male sterility and the regulatory network underlying the tapetum degradation.

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

Abstract: Ogura cytoplasmic male sterility (CMS) lines are widely used breeding materials in cruciferous crops and play important roles in heterosis utilization; however, the sterility mechanism remains unclear. To investigate the microspore development process and gene expression changes after the introduction of orf138 and Rfo, cytological observation and transcriptome analysis were performed using a maintainer line, an Ogura CMS line, and a restorer line. Semithin sections of microspores at different developmental stages showed that the degradation of tapetal cells began at the tetrad stage in the Ogura CMS line, while it occurred at the bicellular microspore stage to the tricellular microspore stage in the maintainer and restorer lines. Therefore, early degradation of tapetal cells may be the cause of pollen abortion. Transcriptome analysis results showed that a total of 1287 DEGs had consistent expression trends in the maintainer line and restorer line, but were significantly up- or down-regulated in the Ogura CMS line, indicating that they may be closely related to pollen abortion. Functional annotation showed that the 1287 core DEGs included a large number of genes related to pollen development, oxidative phosphorylation, carbohydrate, lipid, and protein metabolism. In addition, further verification elucidated that down-regulated expression of genes related to energy metabolism led to decreased ATP content and excessive ROS accumulation in the anthers of Ogura CMS. Based on these results, we propose a transcriptome-mediated induction and regulatory network for cabbage Ogura CMS. Our research provides new insights into the mechanism of pollen abortion and fertility restoration in Ogura CMS.

Abstract: The creation of homozygous plants is essential for both genetic studies and the production of hybrid seeds, particularly in plants that were pollinated by an alien species. Dihaploid (DH) technology is an important application in obtaining homozygous lines used to plant speed breeding programs. The generation of haploid embryos by pollen irradiation and pollination of female flowers with irradiated pollen has been successfully applied. The influence of irradiated pollen on the induction of haploids in sunflower (Helianthus annuus L.) has been evaluated on 16 different sunflower lines from Turkey’s National Sunflower Breeding Program. In this study, pollen grains were irradiated with varying dosages of Gamma rays (500-1000 Gy) to generate parthenogenetic haploid embryos in oilseed sunflowers. At a period of 12–20 days following the process of pollination, embryos were plated into modified MS culture media under a 16/8 h photoperiod and a temperature of 25◦C. Parthenogenetic 18457 embryos at different developmental stages were rescued in vitro and 650 were germinated. The ploidy analysis of regenerants was made with chromosome count and flow cytometry. Except for 500 Gy, all dosages were effective for inducing embryos and haploid plants. Obtained results indicate that parthenogenetic haploid embryos can be produced in K3AD SN:8, IMI 069, and IMI 044 sunflower genotypes by selecting the appropriate Gamma ray dose and embryonic developmental stage. This study was focused to recover sunflower doubled haploids to accelerate the production of non-segregating lines for breeding.

Abstract: Rapeseed is one of the most important oil crops in the world. Increasing demand for oil and limited agronomic capabilities of present-day rapeseed result in the need for rapid development of new, superior cultivars. Double haploid (DH) technology is a fast and convenient approach in plant breeding as well as genetic research. Brassica napus is considered a model species for DH production based on microspore embryogenesis; however, the molecular mechanisms underlying microspore reprogramming are still vague. It is known that morphological changes are accompanied by gene and protein expression patterns, alongside carbohydrate and lipid metabolism. Novel, more efficient methods for DH rapeseed production have been reported. This review covers new findings and advances in Brassica napus DH production as well as the latest reports related to agronomically important traits in molecular studies employing the double haploid rapeseed lines.

Abstract: The microspore can follow two different developmental pathways. In vivo microspores follow the gametophytic program to produce pollen grains. In vitro, isolated microspores can be reprogrammed by stress treatments and follow the embryogenic program, producing doubled-haploid embryos. In the present study, we analyzed the dynamics and role of endogenous auxin in microspore development during these two different scenarios, in Brassica napus. We analyzed auxin concentration, cellular accumulation, the expression of the TAA1 auxin biosynthesis gene, and the PIN1-like efflux carrier gene, as well as the effects of inhibiting auxin biosynthesis by kynurenine on microspore embryogenesis. During the gametophytic pathway, auxin levels and TAA1 and PIN1-like expression were high at early stages, in tetrads and tapetum, while they progressively decreased during gametogenesis in both pollen and tapetum cells. In contrast, in microspore embryogenesis, TAA1 and PIN1-like genes were upregulated, and auxin concentration increased from the first embryogenic divisions. Kynurenine treatment decreased both embryogenesis induction and embryo production, indicating that auxin biosynthesis is required for microspore embryogenesis initiation and progression. The findings indicate that auxin exhibits two opposite profiles during these two microspore developmental pathways, which determine the different cell fates of the microspore.

Abstract: Curly kale (Brassica oleracea L. convar. acephala var. sabellica), the most common type of edible kale, characterized by providing rich nutrition and health care functions, is sought after and has been listed as top of the healthiest vegetables in recent trends, and has aroused the interest of breeders in cultivating new varieties. However, it usually takes more than six years to obtain a homozygous kale inbred line for commercial seed production through conventional breeding procedures due to its long growth and development period. The isolated microspore culture (IMC) technique could be a time-saving alternative method for producing doubled haploid (DH) lines that are genetically homozygous. In this study, we successfully utilize the efficient cytokinin thidiazuron (TDZ) to promote microspore embryogenesis and plant regeneration in two curly kale cultivars (‘Winterbor F2’ and ‘Starbor F2’). Compared with the control (0 mg/L TDZ), all tested TDZ concentrations (0.1, 0.2, 0.3, 0.4 mg/L) had no adverse effects on embryogenesis, and 0.2 mg/L TDZ had an optimal effect on embryo survival and plant regeneration of the two genotypes. For ‘Starbor F2’, 0.2 mg/L TDZ treatment achieved the highest embryogenesis rate (1.83-fold higher than the control group) and direct seeding rate (1.61-fold increase), and the lowest mortality rate. Likewise, 0.2 mg/L TDZ increased the embryogenesis rate of ‘Winterbor F2’ by 1.62 times, the direct seeding rate by 1.61 times, and the mortality rate fell to the lowest. A 1/2 Murashige and Skoog (MS) medium with 0.2 mg/L 1-Naphthaleneacetic acid (NAA) can significantly promote the rooting of the regenerated seedlings. These results provide new insights into the practical application of the IMC technique in shortening the breeding cycle of kale.

Abstract: Background: Okra [Abelmoschus esculentus (L.) Moench.] is a nutrient-rich vegetable crop widely grown in the tropics and sub-tropics mainly for its edible pods. The haploid technique has been used in plant breeding for the improvements of plants and to develop new varieties in relatively a short time. Hence, we have optimized several factors such as plant growth regulators (PGR), sucrose concentration, cold treatment, type of media and culture conditions for callus induction from the anther and ovary of okra (557 F1 hybrid). Methods: The flower buds of different sizes were collected to determine various stages of development and then subjected to cold pre-treatments. The explants were then cultured on various combinations of PGRs i.e., naphthyloxy acetic (NOA), Indole acetic acid (IAA), 2, 4-Dichlorophenoxy acetic acid (2, 4-D), Benzyl amino purine (BAP), isopentenyl adenine 2iP, Kinetin (KIN) and Thidiazuron (TDZ). Result: The optimum developmental stage of microspore for callus initiation was achieved from flower buds of okra and its size was about 11 mm long. Flower buds that emerged one week after the flowering showed significantly higher percentage of callus induction. The optimum stage for ovary and ovule culture were one or two days prior to anthesis and the flower buds stage was 35±1mm. In conclusion, our study investigated the effect of several factors that affects callus induction in okra and optimized cultured conditions for future haploid development for okra.

Abstract: In view of the scarce cytoembryological knowledge of Lessingianthus and in order to understand the contribution of polyploidy to the evolution of the genus we perform a developmental survey of anthers with the main objective of study if the different ploidy level affect the anther and pollen development in Lessingianthus species and infer the male fertility of diploid and polyploid species. Our results showed that diploid and polyploid species have normal anther development, thus polyploidy did not affect the anther wall development. The following male embryological traits are conserved among the species: tetrasporangiate anthers, four-layered anther wall of dicotyledonous development, with uniseriate persistent epidermis, invasive tapetum, tetrahedral or isobilateral tetrads, and 3-celled pollen grains. Diploid and polyploid species had high male fertility: both presented relatively high meiotic regularity and therefore formed normal viable spores independently of the ploidy level. Lessingianthus argenteus, the only species with high irregular behavior, might be a neopolyploid species. The eight studied species of the genus presented different percentages of meiotic irregularity at the different phases observed. In diploid specimens the irregularities were concentrated in anaphase of meiosis I, whereas in polyploid specimens the irregularities were dispersed through the phases of meiosis II. The main abnormal behavior identified, and therefore the main mechanisms of unreduced microspore formation, were chromosomes out of plate, bridges without fragments and asynchrony of meiosis I and II. These features broadened the male cytoembryological knowledge of the genus, confirming the suggestion that embryological characters related to male gametophyte development are conserved among the studied species. The results contribute to understand the mechanisms of polyploid formation which is an important process during the evolution of the genus.

Abstract: Pollen tube (PT) growth towards the micropyle is critical for successful double fertilization. However, the mechanism of micropyle-directed PT growth is still unclear in Brassica napus. In this study, two aspartate proteases, BnaAP36s and BnaAP39s, were identified in B. napus. BnaAP36s and BnaAP39s were localized to the plasma membrane. The homologues of BnaAP36 and BnaAP39 were highly expressed in flower organs, especially in the anther. Sextuple and double mutants of BnaAP36s and BnaAP39s were then generated using CRISPR/Cas9 technology. Compared to WT, the seed-set of cr-bnaap36 and cr-bnaap39 mutants was reduced by 50% and 60%, respectively. The reduction in seed-set was also found when cr-bnaap36 and cr-bnaap39 were used as the female parent in a reciprocal cross assay. Like WT, cr-bnaap36 and cr-bnaap39 pollen were able to germinate and the relative PTs were able to elongate in style. Approximately 36% and 33% of cr-bnaap36 and cr-bnaap39 PTs, respectively, failed to grow towards the micropyle, indicating that BnaAP36s and BnaAP39s are essential for micropyle-directed PT growth. Furthermore, Alexander's staining showed that 10% of cr-bnaap39 pollen grains were aborted, but not cr-bnaap36, suggesting that BnaAP39s may also affect microspore development. These results suggest that BnaAP36s and BnaAP39s play a critical role in the growth of micropyle-directed PTs in B. napus.The online version contains supplementary material available at 10.1007/s11032-023-01377-1.

Abstract: The study is aimed to the study of the peculiarities of the induction of morphogenesis pathways in vitro of morphogenetically competent anther cells - microspores in the isolated anther culture of a number of spring soft wheat genotypes, recommended for cultivation in the climatic conditions of the Republic of Bashkortostan. The content of IAA in seedlings of the studied genotypes of spring sof wheat was analyzed to determine the class of the genotype – characterized by high or low auxin content. Such morphogenesis pathways in vitro as embryoidogenesis, polyembryoidogenesis and callusogenesis have been identified and studied. Morpho-histological assessment of androclinic structures is given. It was established that the induction of a certain morphogenesis pathway in vitro is determined mainly by the balance between the content of endogenous auxin IAA in anthers before inoculation on a nutrient medium and the concentration of exogenous synthetic auxin 2,4-D in the composition of the nutrient medium. The fundamental possibility of regulation of morphogenesis pathways in vitro in isolated anther culture of wheat by selecting for each genotype an adequate balance of endogenous and exogenous auxins for the induction of a specific pathway has been shown.

Abstract: For evaluation of environmental chemicals we need competent monitoring and indication.1 The best tools are bioindicators because characterization of ecotoxicology factors through chemical analysis is limited.2 Higher plants have already shown their ability to fulfill all requisite conditions for the bioindication of genotoxicity of environmental chemicals.3,4 Nevertheless nearly all methods were in vivo tests.5-9 There is no doubt that in this condition they could hardly compete with routine methods of testing mutagens and/or carcinogens using bacterial and mammalian materials, although plant tests are cheaper and approximately 60 to 70% of hazardous chemicals have the same effects on plant tests as on bacterial and mammalian tests.3,10

Abstract: Background: The microspores of five tropical japonica and five indica rice genotypes were subjected to androgenic studies. The effect of growth regulators on callus induction were studied to improve the anther culture efficiency. Methods: The cold pre-treatment of panicles at 10°C were done at different days of intervals viz., 5, 8, 10 and 12 days. The microspores at uninucleate stage were selected and dusted after pre-treatment. The anthers were cultured in N6 basal media supplemented with casein hydrolysate (250 mg/L), proline (250 mg/L), silver nitrate (100 mg/L), maltose (50 g/L) and growth regulators. Result: The 8 days of cold pre-treatment initiated calli in most of the ten genotypes. The days taken for callus induction varied with genotype from 32-55 days. The callus induction frequency ranged from 1.41 to 5.12%. The responsive genotypes (Azucena, Palawan, Nira) on callus induction were studied for their regeneration potential. Background: The microspores of five tropical japonica and five indica rice genotypes were subjected to androgenic studies. The effect of growth regulators on callus induction were studied to improve the anther culture efficiency.