National Centre for Biological Sciences, Tata Institute of Fundamental Research, GKVK Campus, Bangalore, 560065, India.
Plant Reprod. 2020 Mar;33(1):59-73. doi: 10.1007/s00497-020-00386-w. Epub 2020 Mar 10.
In this manuscript, we show that Oryza sativa indica Argonaute protein AGO18 is required for male gametophyte development likely to through a small RNA-mediated mechanism. Monocots have evolved unique gene silencing pathways due to the presence of unique members of Dicer-like and Argonaute (AGO) family members. Among the monocot AGO homologs, AGO18 occupies a unique position. Previous reports have implicated this protein in viral resistance as well as in gametogenesis, likely through its competition with AGO1 clade members for micro(mi)RNAs and other small (s)RNAs. Although expression of rice AGO18 in specific stages of male gametogenesis has been documented, its major functions in plant development remain poorly understood. Here, we show that Oryza sativa indica AGO18 is involved in male gametophyte development. Knockdown (KD) of AGO18 in transgenic rice lines resulted in stunted plants that are male sterile, whereas their carpels were functional. Transcriptome analysis revealed downregulation of several pollen development-associated genes in KD lines. sRNA sequencing in vegetative and reproductive tissues of KD lines indicated reduction of miRNAs and phased secondary sRNAs implicated in male gametophyte development. Our results indicate a distinct role for rice AGO18 in male fertility.
在本文中，我们表明，水稻 indica Argonaute 蛋白 AGO18 可能通过小 RNA 介导的机制参与雄性配子体发育。单子叶植物由于存在独特的 Dicer-like 和 Argonaute (AGO) 家族成员，因此进化出了独特的基因沉默途径。在单子叶 AGO 同源物中，AGO18 占据独特的位置。先前的报告表明，该蛋白参与病毒抗性和配子发生，可能是通过与 AGO1 类成员竞争 micro(mi)RNAs 和其他小 (s)RNAs。尽管已经记录了水稻 AGO18 在雄性配子体发育的特定阶段的表达，但它在植物发育中的主要功能仍知之甚少。在这里，我们表明，水稻 indica AGO18 参与雄性配子体发育。在转基因水稻系中敲低（KD）AGO18 导致植株矮小，雄性不育，但它们的心皮是有功能的。转录组分析显示 KD 系中几个与花粉发育相关的基因下调。在 KD 系的营养组织和生殖组织中的 sRNA 测序表明，miRNAs 和参与雄性配子体发育的阶段性二级 sRNA 的减少。我们的结果表明，水稻 AGO18 在雄性育性中具有独特的作用。
