Separated Transcriptomes of Male Gametophyte and Tapetum in Rice
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ABSTRACT: In flowering plants, the male gametophyte, the pollen, develops in the anther. Complex patterns of gene expression in both the gametophytic and sporophytic tissues of the anther regulate this process. The gene expression profiles of the microspore/pollen and the sporophytic tapetum are of particular interest. In this study, a microarray technique combined with laser microdissection (44K LM-microarray) was developed and used to characterize separately the transcriptomes of the microspore/pollen and tapetum in rice. Expression profiles of 11 known tapetum specific-genes were consistent with previous reports. Based on the spatiotemporal expression patterns and gene ontology (GO) categories of anther-expressed genes, some noteworthy expression patterns are discussed in connection with various important biological events of anther development. The separated transcriptomes of rice microspore/pollen and tapetum were measured at the premeiosis, meiosis, tetrad, uninuclear, bicellular, and tricelluar stages by using laser microdissection (LM)-mediated microarray.
Project description:In flowering plants, the male gametophyte, the pollen, develops in the anther. Complex patterns of gene expression in both the gametophytic and sporophytic tissues of the anther regulate this process. The gene expression profiles of the microspore/pollen and the sporophytic tapetum are of particular interest. In this study, a microarray technique combined with laser microdissection (44K LM-microarray) was developed and used to characterize separately the transcriptomes of the microspore/pollen and tapetum in rice. Expression profiles of 11 known tapetum specific-genes were consistent with previous reports. Based on the spatiotemporal expression patterns and gene ontology (GO) categories of anther-expressed genes, some noteworthy expression patterns are discussed in connection with various important biological events of anther development.
Project description:Highly coordinated pollen wall patterning is essential for male reproductive development. However, the regulatory mechanisms involved in these processes remain poorly understood. Here, we report the identification of Defective Microspore Development1 (DMD1), which encodes a nuclear-localized protein possessing transactivation activity. DMD1 is preferentially expressed in the tapetum and microspores during postmeiotic anther development. Mutations in DMD1 cause a male sterile phenotype with impaired microspore cell integrity. The mutants display abnormal callose degradation, and primexine thickening is inhibited in the newly released microspores. The expression levels of several genes associated with callose degradation and primexine formation are down-regulated in dmd1 anthers. Moreover, irregular Ubisch body morphology and discontinuous endexine is observed in dmd1, and the baculum is completely absent. DMD1 interacts with Tapetum Degeneration Retardation (TDR), a basic helix-loop-helix transcription factor required for exine formation. Taken together, our results suggest that DMD1 is responsible for microspore cell integrity, primexine formation, and exine pattern formation during rice microspore development, and is a potential approach for manipulating male fertility in hybrid rice breeding.
Project description:N-terminal acetylation of proteins is a key modification in eukaryotes; however, our understanding of its biological function in plants is limited. Naa50 is the catalytic subunit of the protein N-terminal acetyltransferase NatE complex. We previously showed that the absence of Naa50 led to sterility in Arabidopsis thaliana. In the present study, we show that a lack of Naa50 in Arabidopsis resulted in collapsed and sterile pollen grains. Further study revealed that the mutation of Naa50 accelerated programmed cell death in the tapetum. Expression pattern analysis showed that Naa50 was specifically expressed in tapetal cells from anthers at stages 9–11 of pollen development, when tapetal programmed cell death occurs. Reciprocal cross analyses indicated that the male sterility of naa50 plants was due to sporophytic effects. Transcriptome sequencing of closed buds showed that the deletion of Naa50 resulted in up-regulation of the cysteine protease-coding gene CEP1 and impaired the expression of several genes that function in pollen wall deposition and pollen mitosis. Our findings suggest that Naa50 regulates cell degradation in the tapetum during anther development and plays an important role in pollen development by affecting several pathways.
Project description:Pollen grains are coated with a pollen wall which protects the microspore from various biotic and abiotic stresses, as well as facilitates male-female interaction. During pollen wall development, many compounds are transported from the tapetum to the developing pollen wall via tapetum-specific membrane transporters, and male sterility is often observed when membrane transporter’s function or localization is altered. Here, we show that mutating AP1/2β1 and AP1/2β2, two homologous genes of AP1/2β which encodes a large subunit shared by adaptor protein 1 (AP-1) and adaptor protein 2 (AP-2) complexes in Arabidopsis, impair pollen exine formation and cause reduced pollen germination rate and slowed pollen tube growth. However, the shared theory of AP1/2β is not proved in Arabidopsis.
Project description:Tissue-specific transcriptional profiling of the abscission layer (AL) at the base of young flower in rice using laser micro-dissection: NIL(qSH1) vs. Nipponbare. We used two rice varieties, NIL(qSH1) and Nipponbare. NIL(qSH1) is a nearly isogenic line containing the seed shattering gene qSH1. Seed shattering is easy in NIL(qSH1), but it is not in Nipponbare. So, we used some stages of young flower in NIL(qSH1) and some in Nipponbare. Four regions: 1. abscission layer region of NIL(qSH1), 2. upper abscission region of NIL(qSH1), 3. lower abscission layer region of NIL(qSH1), and 4. abscission layer region of Nipponbare. Sample experiments: NIL(qSH1) AL vs. Nipponbare AL, NIL(qSH1) AL vs. NIL(qSH1) upper region of AL, and NIL(qSH1) AL vs. NIL(qSH1) lower region of AL.
Project description:Tomato pollen production and viability is highly vulnerable to higher temperature. Hot summers with temperature reaching above 32°C can disrupt production of viable pollens and fruit set, resulting in yield loss. In recent years, temperature above 35-38oC has become a norm during mid-summer with potential adverse impacts on the production of tomatoes and many other crop species. Pollens are developed through the microsporogenesis and micro-gametogenesis stages. The most heat sensitive period is from the meiotic process of the microsporocytes, at the young microspore stage (uninucleate stage of microspore) to during late pollen development (pollen mitosis). This project studied the heat-induced proteomes in microsporocyte, also called pollen mother cells (PMC). Homogenous PMC samples were collected from cross-sectioned frozen fresh anther tissues of tomato ‘Maxifort’ using laser capture microdissection (LCM). Tandem mass tag (TMT) proteomics analysis was conducted to identify proteomics changes related to heat tolerance during pollen development.
Project description:Transcriptomic analysis of single, double and triple mutant anthers of bhlh010, bhlh089 and bhlh091. We examine here three recently duplicated Arabidopsis bHLH genes, bHLH010, bHLH089 and bHLH091, using evolutionary, genetic, morphological and transcriptomic approaches, and uncover their redundant functions in anther development. These three genes are relatively highly expressed in the tapetum of the Arabidopsis anther; single mutants at each of the bHLH010, bHLH089 and bHLH091 loci are developmentally normal, but the various double and triple combinations progressively exhibit increasingly defective anther phenotypes (abnormal tapetum morphology, delayed callose degeneration, and aborted pollen development), indicating their redundant functions in male fertility. Note: Samples in SRA were assigned the same sample accession. This is incorrect as there are different samples, hence “Source Name” was replaced with new values. Comment[ENA_SAMPLE] contains the original SRA sample accessions.
Project description:Using microarray, the anther transcript profiles of the three indica rice CMS lines revealed 622 differentially expression genes (DEGs) in each of the three CMS lines. GO and Mapman analysis indicated that these DEGs were mainly involved in lipid metabolic and cell wall organization. Comprised with the gene expression of sporophytic and gametophytic CMS lines, 303 DEGs were differentially expressed and 56 of them were down-regulated in all the CMS lines. Co-expression network analysis suggested that many genes were significantly differentially expressed in the CMS lines. These down-regulated DEGs in the CMS lines were found to be involved in tapetum or cell wall formation and their suppressed expression might be related to male sterility. The present study will give some information for the nuclear gene regulation by different cytoplasmic genotypes and provide some candidate genes for pollen development in rice.
Project description:The CLAVATA3/ESR-RELATED (CLE) peptide hormones are required for numerous plant growth and developmental processes. However, little is known regarding the function and working mechanism of the CLEs in the anther. Here, using RNA in situ hybridization analyses, we identified 7 CLE genes that are specifically expressed in the tapetum and microsporocytes in the anther, and the dominant-negative mutant plants of each of these genes exhibited significantly reduced anther size, pollen number, and abnormal pollen wall formation. Further transcriptomic and proteomic studies on cle19, DN-CLE19, and CLE19-OX mutant lines revealed that CLE19 affected the expression of more than 1,000 genes at the RNA level and 595 at the protein level, including genes involved in pollen coat and pollen exine formation, lipid metabolism, pollen germination, and hormone metabolism processes. Phenotypic analyses of mutants of the CLE19 downstream genes GRP20, ACOS5 and MEE48 revealed that the formation of pollen exine was affected in these mutants, confirming that these genes function downstream of CLE19 in the regulation of pollen wall formation. These findings demonstrate the function and downstream genes of CLE19 and redundant genes, providing insights into working pathways of the peptide hormones in pollen development.
Project description:Transcriptomes from multiple pre-meiotic stages of wild type, mac1, and msca1 maize anthers were characterized by microarray hybridization. The goal was to characterize the developmental progression as the anther specifies five cell types and grows rapidly precedeing meiotic entry. The stages characterized were immature anther primordia (0.15 mm long in maize) containing just stem cells, through somatic and germinal cell fate specification (0.20 and 0.25 mm), mitotic proliferation (0.4 mm), and finally the birth of the middle layer and tapetum (0.7 mm). To obtain cell-type specific markers, at 0.7 mm we also compared whole anthers to collections of laser-microdissected anther cell types including the archesporial cells (pre-meiotic germinal cells), nutritive layers (middle layer and tapetum) and structural layers (endothecium and epidemis) of the anther lobe. keyword: anther development, maize, male-sterile Three loop designs covered the early stages (up to 0.7 mm) with two replicates for each comparison. The first loop had 0.2 mm long anthers and compared wild type versus mac1 mutant versus msca1 mutant in a three vertex loop design. The second loop had four vertices and compared 0.15 mm WT anther primordia, 0.25 mm WT anthers, 0.4 mm WT anthers and finally 0.4 mm mac1 mutant anthers. The third had 0.7 mm anthers in a three vertex loop with the nutritive layers (middle layer and tapetum) at one vertex, the germinal pre-meiotic cells at another vertex, and whole anthers at a third vertex. The whole anther samples were also, separately and outside of the loop, compared in four replicates to the structural layers (endothecium and epidermis).