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Virginia Walbot - One of the best experts on this subject based on the ideXlab platform.
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pre meiotic Anther development
Current Topics in Developmental Biology, 2019Co-Authors: Karina Van Der Linde, Virginia WalbotAbstract:Abstract Most genetic and molecular analyses of Anther development utilize Arabidopsis thaliana, Oryza sativa (rice), and Zea mays (maize). Especially in maize, early stages of Anther development are easy to study because: (1) Maize has unisex flowers. (2) Compared to rice or A. thaliana, maize Anthers are relatively large, making dissection for molecular and biochemical analyses easy. (3) Anther developmental stage is strongly correlated with maize Anther length. Besides these technical advantages, understanding Anther and pollen development in maize is of significant agricultural importance. Today maize is a worldwide cereal crop: approximately 25% of all consumed food contains maize. Yield stability or even increases depend on maintenance of hybrid vigor, and production of hybrid seed requires manual detasseling or genetic control of pollen development. Knowledge of pollen development can also be used to manage transgene containment. In the first section of this chapter, we will describe the current model for sequential cell fate specification in maize Anther lobes, with reference to rice and A. thaliana to point out similarities and differences. In the second section of this chapter, we will review what is known about the individual cell types in Anther lobes. The diversity of Anther organization is addressed to a limited extent by cytological studies of Anthers, often directed to clarify taxonomic relationships. In the third section, we will comment on how new lines of investigation could clarify questions remaining in our current appreciation of Anther development.
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chloroplasts in Anther endothecium of zea mays poaceae
American Journal of Botany, 2015Co-Authors: Katherine M Murphy, Rachel L Egger, Virginia WalbotAbstract:PREMISE OF THE STUDY: Although Anthers of Zea mays, Oryza sativa, and Arabidopsis thaliana have been studied intensively using genetic and biochemical analyses in the past 20 years, few updates to Anther anatomical and ultrastructural descriptions have been reported. For example, no transmission electron microscopy (TEM) images of the premeiotic maize Anther have been published. Here we report the presence of chloroplasts in maize Anthers. METHODS: TEM imaging, electron acceptor photosynthesis assay, in planta photon detection, microarray analysis, and light and fluorescence microscopy were used to investigate the presence of chloroplasts in the maize Anther. KEY RESULTS: Most cells of the maize subepidermal endothecium have starch-containing chloroplasts that do not conduct measurable photosynthesis in vitro. CONCLUSIONS: The maize Anther contains chloroplasts in most subepidermal, endothecial cells. Although maize Anthers receive sufficient light to photosynthesize in vivo and the maize Anther transcribes >96% of photosynthesis-associated genes found in the maize leaf, no photosynthetic light reaction activity was detected in vitro. The endothecial cell layer should no longer be defined as a complete circle viewed transversely in Anther lobes, because chloroplasts are observed only in cells directly beneath the epidermis and not those adjacent to the connective tissue. We propose that chloroplasts be a defining characteristic of differentiated endothecial cells and that nonsubepidermal endothecial cells that lack chloroplasts be defined as a separate cell type, the interendothecium.
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male reproductive development gene expression profiling of maize Anther and pollen ontogeny
Genome Biology, 2008Co-Authors: David S Skibbe, John Fernandes, Virginia WalbotAbstract:During flowering, central Anther cells switch from mitosis to meiosis, ultimately forming pollen containing haploid sperm. Four rings of surrounding somatic cells differentiate to support first meiosis and later pollen dispersal. Synchronous development of many Anthers per tassel and within each Anther facilitates dissection of carefully staged maize Anthers for transcriptome profiling. Global gene expression profiles of 7 stages representing 29 days of Anther development are analyzed using a 44 K oligonucleotide array querying approximately 80% of maize protein-coding genes. Mature haploid pollen containing just two cell types expresses 10,000 transcripts. Anthers contain 5 major cell types and express >24,000 transcript types: each Anther stage expresses approximately 10,000 constitutive and approximately 10,000 or more transcripts restricted to one or a few stages. The lowest complexity is present during meiosis. Large suites of stage-specific and co-expressed genes are identified through Gene Ontology and clustering analyses as functional classes for pre-meiotic, meiotic, and post-meiotic Anther development. MADS box and zinc finger transcription factors with constitutive and stage-limited expression are identified. We propose that the extensive gene expression of Anther cells and pollen represents the key test of maize genome fitness, permitting strong selection against deleterious alleles in diploid Anthers and haploid pollen. Because flowering plants show a substantial bias for male-sterile compared to female-sterile mutations, we propose that this fitness test is general. Because both somatic and germinal cells are transcriptionally quiescent during meiosis, we hypothesize that successful completion of meiosis is required to trigger maturation of Anther somatic cells.
B Buter - One of the best experts on this subject based on the ideXlab platform.
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The improvement in regenerated doubled haploids from Anther culture of wheat by Anther transfer
Plant Cell Tissue and Organ Culture, 2000Co-Authors: A. Redha, B Buter, S.m.s. Islam, P. Stamp, J E SchmidAbstract:This study was conducted to determine the most suitable method of regeneration by comparing two approaches: transfer of Anthers (with and without embryo-like structures) to regeneration conditions after a period of two to four weeks on induction medium (= Anther-transfer treatment) and transfer of embryo-like structures to regeneration conditions after five to eight weeks on induction medium. The early transfer of Anthers brought about a significant reduction in the number of embryos formed, but nevertheless significantly improved the frequency of plant regeneration. Combining an optimal date of Anther transfer with the early addition of colchicine to the induction medium (100 mg l^−1 for 1 and 3 days) led to an increase in the number of doubled haploid regenerants. The results indicate that transferring the Anthers after 28 days and adding 100 mg l^−1 colchicine to the induction medium on one day only caused a significant improvement in the ability of green plants to regenerate (7.0 compared to 0.50) as well as in chromosome doubling (success index: 4.0 compared to 0.33).
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colchicine mediated chromosome doubling during Anther culture of maize zea mays l
Theoretical and Applied Genetics, 1996Co-Authors: S Saisingtong, J E Schmid, Peter Stamp, B ButerAbstract:Efficient methods of chromosome doubling are critical for the production of microspore-derived, doubled-haploid (=DH) plants, especially if, as in maize Anther culture, spontaneous chromosome doubling occurs infrequently. In the present study, colchicine (5–1000 mg/l) was added to the induction medium and maize Anthers were incubated in the colchicine-containing medium for different durations (1–7 days). In order to improve overall Anther culture response, the culture temperature was adjusted to 14°C during the first 7 days. Colchicine applied at low concentration, i.e. 5 mg/l (7 days), or for short duration, i.e. 1–3 days (250 mg/l), showed beneficial effects on the formation of embryolike structures (=ES) and thus led to increased plant production, but was comparatively ineffective regarding chromosome doubling. Optimal doubling effects were observed when Anthers had been exposed to culture medium containing 250 and 1000 mg/l of colchicine (7 days); in these treatments the doubling index (=DI), defined as the quotient of the number of DH plants and the number of totally regenerated plants in a specific treatment, rose to 0.56 and 0.53, respectively, compared to 0.20 in the untreated control. However, colchicine administered at concentrations higher than 250 mg/l seemed to be detrimental to general plant production; thus, in spite of a high DI, the overall DH plant production was even lower than in the control treatment. Maximum DH plant production for three different genotypes was accomplished with culture medium containing 250 mg/l of colchicine (7 days). With the best-responding genotype (ETH-M 36) a DH plant production of 9.9 DH plants/100 Anthers was accomplished, i.e. a 7-fold increase compared to the non-treated Anthers. This is the first report on efficient chromosome doubling in Anther culture by subjecting Anthers to colchicinecontaining induction medium during a post-plating cold treatment. Chromosome doubling as described here becomes an integral part of the maize Anther culture protocol and thus represents a rapid and economical way to produce DH plants.
Gynheung An - One of the best experts on this subject based on the ideXlab platform.
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wax deficient Anther1 is involved in cuticle and wax production in rice Anther walls and is required for pollen development
The Plant Cell, 2006Co-Authors: Kihong Jung, Lukas Schreiber, Rochus Franke, Andrea Faust, Alexander Yephremov, Heinz Saedler, Inhwan Hwang, Gynheung AnAbstract:In vegetative leaf tissues, cuticles including cuticular waxes are important for protection against nonstomatal water loss and pathogen infection as well as for adaptations to environmental stress. However, their roles in the Anther wall are rarely studied. The innermost layer of the Anther wall (the tapetum) is essential for generating male gametes. Here, we report the characterization of a T-DNA insertional mutant in the Wax-deficient Anther1 (Wda1) gene of rice (Oryza sativa), which shows significant defects in the biosynthesis of very-long-chain fatty acids in both layers. This gene is strongly expressed in the epidermal cells of Anthers. Scanning electron microscopy analyses showed that epicuticular wax crystals were absent in the outer layer of the Anther and that microspore development was severely retarded and finally disrupted as a result of defective pollen exine formation in the mutant Anthers. These biochemical and developmental defects in tapetum found in wda1 mutants are earlier events than those in other male-sterile mutants, which showed defects of lipidic molecules in exine. Our findings provide new insights into the biochemical and developmental aspects of the role of waxes in microspore exine development in the tapetum as well as the role of epicuticular waxes in Anther expansion.
J E Schmid - One of the best experts on this subject based on the ideXlab platform.
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The improvement in regenerated doubled haploids from Anther culture of wheat by Anther transfer
Plant Cell Tissue and Organ Culture, 2000Co-Authors: A. Redha, B Buter, S.m.s. Islam, P. Stamp, J E SchmidAbstract:This study was conducted to determine the most suitable method of regeneration by comparing two approaches: transfer of Anthers (with and without embryo-like structures) to regeneration conditions after a period of two to four weeks on induction medium (= Anther-transfer treatment) and transfer of embryo-like structures to regeneration conditions after five to eight weeks on induction medium. The early transfer of Anthers brought about a significant reduction in the number of embryos formed, but nevertheless significantly improved the frequency of plant regeneration. Combining an optimal date of Anther transfer with the early addition of colchicine to the induction medium (100 mg l^−1 for 1 and 3 days) led to an increase in the number of doubled haploid regenerants. The results indicate that transferring the Anthers after 28 days and adding 100 mg l^−1 colchicine to the induction medium on one day only caused a significant improvement in the ability of green plants to regenerate (7.0 compared to 0.50) as well as in chromosome doubling (success index: 4.0 compared to 0.33).
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colchicine mediated chromosome doubling during Anther culture of maize zea mays l
Theoretical and Applied Genetics, 1996Co-Authors: S Saisingtong, J E Schmid, Peter Stamp, B ButerAbstract:Efficient methods of chromosome doubling are critical for the production of microspore-derived, doubled-haploid (=DH) plants, especially if, as in maize Anther culture, spontaneous chromosome doubling occurs infrequently. In the present study, colchicine (5–1000 mg/l) was added to the induction medium and maize Anthers were incubated in the colchicine-containing medium for different durations (1–7 days). In order to improve overall Anther culture response, the culture temperature was adjusted to 14°C during the first 7 days. Colchicine applied at low concentration, i.e. 5 mg/l (7 days), or for short duration, i.e. 1–3 days (250 mg/l), showed beneficial effects on the formation of embryolike structures (=ES) and thus led to increased plant production, but was comparatively ineffective regarding chromosome doubling. Optimal doubling effects were observed when Anthers had been exposed to culture medium containing 250 and 1000 mg/l of colchicine (7 days); in these treatments the doubling index (=DI), defined as the quotient of the number of DH plants and the number of totally regenerated plants in a specific treatment, rose to 0.56 and 0.53, respectively, compared to 0.20 in the untreated control. However, colchicine administered at concentrations higher than 250 mg/l seemed to be detrimental to general plant production; thus, in spite of a high DI, the overall DH plant production was even lower than in the control treatment. Maximum DH plant production for three different genotypes was accomplished with culture medium containing 250 mg/l of colchicine (7 days). With the best-responding genotype (ETH-M 36) a DH plant production of 9.9 DH plants/100 Anthers was accomplished, i.e. a 7-fold increase compared to the non-treated Anthers. This is the first report on efficient chromosome doubling in Anther culture by subjecting Anthers to colchicinecontaining induction medium during a post-plating cold treatment. Chromosome doubling as described here becomes an integral part of the maize Anther culture protocol and thus represents a rapid and economical way to produce DH plants.
Xianlong Zhang - One of the best experts on this subject based on the ideXlab platform.
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promoters of arabidopsis casein kinase i like 2 and 7 confer specific high temperature response in Anther
Plant Molecular Biology, 2018Co-Authors: Yaoyao Li, Qin Hu, Yuanlong Wu, Lin Zhang, Jie Li, Xianlong ZhangAbstract:(1) We systematically analyze the promoter activities of AtCKLs in various tissues; (2) AtCKL2 and AtCKL7 were expressed in early developmental Anthers under high temperature (HT) conditions; (3) AtMYB24 may function as a positive regulator of AtCKL2 and AtCKL7 expression under HT. High temperature (HT) can seriously impede plant growth and development, causing severe loss of crop production. In Arabidopsis, AtCKL genes show high similarity to GhCKI, a gene reported to disrupt tapetal programmed cell death in cotton. However, most of AtCKL genes are not well characterized. Here, we systematically analyzed the expression patterns of AtCKLs in various tissues. The expression of AtCKL2 and AtCKL7 was induced in early Anther development under HT, which is similar to the case of GhCKI. In silico analysis of AtCKL2 and AtCKL7 promoters indicated that four types of transcription factors (TFs) (MADS, NAC, WRKY and R2R3-MYB) might bind to AtCKL2 and AtCKL7 promoters. Furthermore, three MADS, three NAC, one WRKY, and three R2R3-MYB TFs were up-regulated in stage 1–8 Anthers and three R2R3-MYB TFs were up-regulated in stage 9–10 Anthers under HT, implying the important roles of R2R3-MYB genes in the response of Anthers to HT. Among the R2R3-MYB genes, AtMYB24 showed the similar expression as AtCKL2 and AtCKL7 in the Anthers under HT. Additionally, yeast one-hybrid and dual-luciferase reporter system assays verified that AtMYB24 could bind to AtCKL2 and AtCKL7 promoters and activate the expression of these two genes. In brief, this study provides the overall expression profiles of AtCKLs, useful information for unraveling the molecular mechanism of AtCKL2 and AtCKL7 gene expression in early Anther development under HT, and important clues for elucidating the mechanism of transcriptional regulation of CKI genes in plant Anther under HT, which are critical to the reduction of crop yield loss resulting from HT.
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sugar and auxin signaling pathways respond to high temperature stress during Anther development as revealed by transcript profiling analysis in cotton
Plant Physiology, 2014Co-Authors: Yaoyao Li, Qin Hu, Yuanlong Wu, Yuanhao Ding, Xiyan Yang, Xianlong ZhangAbstract:Male reproduction in flowering plants is highly sensitive to high temperature (HT). To investigate molecular mechanisms of the response of cotton (Gossypium hirsutum) Anthers to HT, a relatively complete comparative transcriptome analysis was performed during Anther development of cotton lines 84021 and H05 under normal temperature and HT conditions. In total, 4,599 differentially expressed genes were screened; the differentially expressed genes were mainly related to epigenetic modifications, carbohydrate metabolism, and plant hormone signaling. Detailed studies showed that the deficiency in S-ADENOSYL-l-HOMOCYSTEINE HYDROLASE1 and the inhibition of methyltransferases contributed to genome-wide hypomethylation in H05, and the increased expression of histone constitution genes contributed to DNA stability in 84021. Furthermore, HT induced the expression of CASEIN KINASEI (GhCKI) in H05, coupled with the suppression of starch synthase activity, decreases in glucose level during Anther development, and increases in indole-3-acetic acid (IAA) level in late-stage Anthers. The same changes also were observed in Arabidopsis (Arabidopsis thaliana) GhCKI overexpression lines. These results suggest that GhCKI, sugar, and auxin may be key regulators of the Anther response to HT stress. Moreover, PHYTOCHROME-INTERACTING FACTOR genes (PIFs), which are involved in linking sugar and auxin and are regulated by sugar, might positively regulate IAA biosynthesis in the cotton Anther response to HT. Additionally, exogenous IAA application revealed that high background IAA may be a disadvantage for late-stage cotton Anthers during HT stress. Overall, the linking of HT, sugar, PIFs, and IAA, together with our previously reported data on GhCKI, may provide dynamic coordination of plant Anther responses to HT stress.
