Beijing Vegetable Research Center, Beijing Academy of Agriculture and Forestry Sciences, Key Laboratory of Biology and Genetic Improvement of Horticultural Crops (North China), Ministry of Agriculture, Beijing, China.
PLoS One. 2018 Mar 12;13(3):e0193462. doi: 10.1371/journal.pone.0193462. eCollection 2018.
Cabbage (Brassica oleracea L. var. capitata), an important vegetable crop in the Brassicaceae family, is economically important worldwide. In the process of hybrid seed production, Ogura cytoplasmic male sterility (OguCMS), controlled by the mitochondrial gene orf138, has been extensively used for cabbage hybrid production with complete and stable male sterility. To identify the critical genes and pathways involved in the sterility and to better understand the underlying molecular mechanisms, the anther of OguCMS line R2P2CMS and the fertile line R2P2 were used for RNA-seq and iTRAQ (Isobaric Tags for Relative and Absolute Quantitation) proteome analysis. RNA-seq analysis generated 13,037,109 to 13,066,594 SE50-clean reads, from the sterile and fertile lines, which were assembled into 36,890 unigenes. Among them, 1,323 differentially expressed genes (DEGs) were identified, consisting of 307 up- and 1016 down-regulated genes. For ITRAQ analysis, a total of 7,147 unique proteins were identified, and 833 were differentially expressed including 538 up- and 295 down-regulated proteins. These were mainly annotated to the ribosome, spliceosome and mRNA surveillance pathways. Combined transcriptomic and proteomic analyses identified 22 and 70 genes with the same and opposite expression profiles, respectively. Using KEGG analysis of DEGs, gibberellin mediated signaling pathways regulating tapetum programmed cell death and four different pathways involved in sporopollenin synthesis were identified. Secretion and translocation of the sporopollenin precursors were identified, and the key genes participating in these pathways were all significantly down-regulated in R2P2CMS. Light and transmission electron (TE) microscopy revealed fat abnormal tapetum rather than vacuolization and degradation at the tetrad and microspore stages of the OguCMS line. This resulted in the failed deposition of sporopollenin on the pollen resulting in sterility. This study provides a comprehensive understanding of the mechanism underlying OguCMS in cabbage.
甘蓝（ Brassica oleracea L. var. capitata ），十字花科的一种重要蔬菜作物，在全球范围内具有重要的经济价值。在杂交种子生产过程中，Ogura 细胞质雄性不育（OguCMS）已被广泛应用于具有完全和稳定雄性不育的甘蓝杂种生产，其受线粒体基因 orf138 控制。为了鉴定与不育相关的关键基因和途径，更好地理解其潜在的分子机制，本研究以雄性不育系 R2P2CMS 和可育系 R2P2 的花药为材料，进行了 RNA-seq 和 iTRAQ（Isobaric Tags for Relative and Absolute Quantitation）蛋白质组分析。RNA-seq 分析产生了来自不育系和可育系的 13,037,109 到 13,066,594 条 SE50 清洁读段，组装成 36,890 条非冗余基因。其中，鉴定到 1,323 个差异表达基因（DEGs），包括 307 个上调和 1,016 个下调基因。对于 iTRAQ 分析，共鉴定到 7,147 个独特的蛋白质，其中 833 个差异表达，包括 538 个上调和 295 个下调蛋白。这些蛋白主要注释到核糖体、剪接体和 mRNA 监测途径。转录组和蛋白质组联合分析鉴定到 22 个和 70 个具有相同和相反表达谱的基因。对 DEGs 进行 KEGG 分析，鉴定到调控绒毡层程序性细胞死亡的赤霉素介导的信号通路和参与几丁质合成的 4 种不同途径。鉴定到了几丁质前体的分泌和转运，并且在 R2P2CMS 中，这些途径的关键基因均显著下调。光镜和透射电镜（TE）显示，OguCMS 系四分体和小孢子阶段的绒毡层异常堆积脂肪，而非空泡化和降解，导致几丁质无法沉积在花粉上，从而导致不育。本研究为甘蓝 OguraCMS 不育机制提供了全面的认识。
