Project description:Environmental conditions, such as photoperiod and temperature, can affect male fertility in plants. While this feature is heavily exploited in rice to generate male-sterile lines for hybrid breeding, the underlying molecular mechanisms remain largely unknown. In this study, we use a transcriptomics approach to identify key genes and regulatory networks affecting pollen maturation in rice anthers in response to different day lengths.This work provides a new understanding on photoperiodsensitive pollen development in rice, and our gene expression database will provide a new, comprehensive resource to identify new environmentally sensitive genes regulating male fertility for use in crop improvement.
Project description:Background: Pepper (Capsicum annuum L.) is a major cash crop throughout the world. Male sterility is an important characteristic in crop species that leads to a failure to produce functional pollen, and it has crucial roles in agricultural breeding and the utilization of heterosis. Objectives: In this study, we identified many crucial factors and important components in metabolic pathways in anther and pollen development, and elucidated the molecular mechanism related to pollen abortion in pepper. Methods: Pepper pollen was observed at different stages to detect the characteristics associated with male sterility and fertility. The phytohormone and oxidoreductase activities were detected in spectrophotometric and redox reaction assays, respectively. Proteins were extracted from male sterile and fertile pepper lines, and identified by TMT/iTRAQ (Tandem mass tags/isobaric tags for relative and absolute quantitation) and LC-MS/MS (liquid chromatograph-mass spectrometer) analysis. Differentially abundant proteins (DAPs) were analyzed based on Gene Ontology annotations and the Kyoto Encyclopedia of Genes and Genomes database according to |fold change)| > 1.3 and P value < 0.05. DAPs were quantified in the meiosis, tetrad, and binucleate stages by parallel reaction monitoring (PRM). Results: In this study, we screened and identified one male sterile pepper line with abnormal cytological characteristics in terms of pollen development. The peroxidase and catalase enzyme activities were significantly reduced and increased, respectively, in the male sterile line compared with the male fertile line. Phytohormone analysis demonstrated that the gibberellin, jasmonic acid, and auxin contents changed by different extents in the male sterile pepper line. Proteome analysis screened 1645 DAPs in six clusters, which were mainly associated with the chloroplast and cytoplasm based on their similar expression levels. According to proteome analysis, 45 DAPs were quantitatively identified in the meiosis, tetrad, and binucleate stages by PRM, which were related to monoterpenoid biosynthesis, and starch and sucrose metabolism pathways. Conclusions: We screened 1645 DAPs by proteomic analysis and 45 DAPs were related to anther and pollen development in a male sterile pepper line. In addition, the activities of peroxidase and catalase as well as the abundances of phytohormones such as gibberellin, jasmonic acid, and auxin were related to male sterility. The results obtained in this study provide insights into the molecular mechanism responsible for male sterility and fertility in pepper.
Project description:Formation of functional pollen and successful fertilisation relies upon the spatial and temporal regulation of anther and pollen development. This process responds to environmental cues to maintain optimal fertility despite climatic changes. Arabidopsis transcription factors bHLH10,-89,-91 were previously thought to be functionally redundant in their control of male reproductive development, however here we show that they play distinct roles in the integration of light signals to maintain pollen development under different environmental conditions. Combinations of the double and triple bHLH10,-89,-91 mutants were analysed under normal (200μmol/m2/s) and low (50μmol/m2/s) light conditions to determine the impact on fertility. Transcriptomic analysis of a new conditionally sterile bhlh89,91 double mutant shows differential regulation of genes related to sexual reproduction, hormone signal transduction and lipid storage and metabolism under low-light. Here we have shown that bHLH89 and bHLH91 play a role in regulating fertility in response to light, suggesting they function in mitigating environmental variation to ensure fertility is maintained under environmental stress.
Project description:Global temperature increase poses a serious challenge for agricultural production worldwide, affecting yield in many crops including vegetable crops. While most crop plants can survive temperature increases during their vegetative growth periods, the reproduction phase is highly heat-stress (HS)-sensitive. Impaired pollen development and functioning under HS is implicated as the major cause for yield reduction. To better understand HS effect on pollen and identify pollen thermotolerance mechanisms, we established conditions that enable developing pollen grains to acquire thermotolerance (ATT conditions), using tomato as a model system. High-throughput sequencing at cDNA level was performed by Massive Analysis of 3’cDNA using Illumina HiSeq 2000 technology, generating a total of 6430 and 4660 transcripts differentially expressed (p ≤ 1e-05) during pollen development/maturation and following response of developing pollen to ATT, respectively. Gene Onthology functional analysis showed that transcripts related to maintenance of protein homeostasis (translation, proteolysis, protein folding) were enriched during pollen maturation and following the ATT treatment in our study, highlighting these processes as central for enabling pollen maturation and maintenance of pollen functioning under HS. The transcriptomic data was compared to available pollen proteomic data based on the same experimental setup and an overlap of 47% was detected between differentially expressed proteins and transcripts following ATT conditions, highlighting genes/proteins involved in protein folding, oxidation-reduction and translation, and validating transcriptomic results. Involvement of mitochondria and endoplasmic reticulum in pollen heat acclimation, and activation of several HSPs including sHSPs and HSP101, for protecting pollen cellular components including the translational machinery, are indicated. The results of this study can serve as a valuable resource of genes for future research on improving pollen thermotolerance.
Project description:Jasmonates are well known signaling components required for diverse processes ranging from wound and pathogen responses to regulation of developmental processes. A prominent feature of jasmonate biosynthesis or signaling mutants is the loss of fertility. In contrast to the male sterile phenotype of Arabidopsis mutants, the loss of the co-receptor protein COI1 in the tomato mutant jai1-1 results in female sterility with additional severe effects on stamen and pollen development. While a general model of jasmonate effects on male gametophyte development has been proposed to involve the regulation of water transport, the molecular details of this response are scarce. Here we show an extensive temporal profiling of the development, hormone content, transcriptome and metabolome of tomato stamen in six distinct stages of flower development in wild type and jai1-1. We found that the premature stamen desiccation of jai1-1 stamens and the preponed pollen maturation coincide with an accumulation of desiccation-related metabolites. The wild type shows a transient increase of jasmonates up to mid-flowering that is absent in jai1-1. This finding coincides with an early increase of the ethylene precursor ACC in jai1-1 that is similarly reflected in the increased expression of ethylene biosynthesis and response genes. Our data suggests an essential role of jasmonates in the temporal inhibition of ethylene production to prevent premature desiccation of stamens and to ensure proper timing in flower development.
Project description:Illumina sequencing was employed to examine the expression profiles of rice anther miRNAs from the a non-pollen male sterile line Wuxiang S (WXS), one of photo-thermo sensitive genical male sterile (PTGMS) line rice, during in the fertility transition stage. A total of 493 known miRNAs and 273 novel miRNAs were identified during rice anther development. Based on the number of sequencing reads, a total of 26 miRNAs were discovered to be significant difference expression between WXS(S, Sterility) and WXS(F, Fertility), and the results were partially validated by qRT-PCR. Among these, 11 miRNAs were decreased and 15 miRNAs were increased in WXS(S) compared with WXS(F). The expression patterns for targets of osa-miR156a-j, osa-miR3879, osa-miR159c/d/e, osa-miR171a/c/e/i, osa-miR398b, osa-miR164d, osa-miR528 and osa-miR408 were selectively examined, and the results showed that there was a negative correlation on the expression patterns between miRNAs and their targets. These targets have previously been reported to be related with pollen development and male sterility, suggesting that miRNAs might act as regulators of rice anthers. Furthermore, miRNA editing events were observed. The U-to-C and U-to-A editing phenomenon was validated by molecular cloning and sequencing. Examine small RNA profiles change of four tissues of the rice non-pollen male sterile line Wuxiang S under two different environments.
Project description:We employed a microarray-based transcriptomic status comparison of rice cytoplasmic male sterile (CMS) lines in order to categorize the nuclear gene expressions upon cytoplasmic substitution. In anthers at the uninucleate and bicellular pollen stages, we found that 8,199 genes significantly changed their expression in at least one of the CMS lines. We categorized the genes into 100 clusters by k-means clustering, and common obvious expression patterns were observed in W11, LD and BT.