College of Life Sciences, Hunan Normal University, Changsha, 410081, China.
Guangxi Subtropical Crops Research Institute, Nanning, 530001, China.
J Integr Plant Biol. 2020 Apr;62(4):470-486. doi: 10.1111/jipb.12792. Epub 2019 Apr 4.
MicroRNAs (miRNAs) are key regulators of gene expression in many important biological processes of plants. However, few miRNAs have been shown to regulate seed vigor. Here, we conducted microarray assays to analyze miRNA expression levels in seeds of the rice (Oryza sativa L.) cultivar ZR02. Results showed significant differences in the expression of 11 miRNAs between artificially aged and untreated control seeds. Among these, osa-miR164c was transcriptionally upregulated, while osa-miR168a was downregulated in artificially aged seeds; this was verified by quantitative real-time PCR analysis. Under the same aging condition, osa-miR164c overexpression in OE164c transgenic seeds and osa-miR168a silencing in MIM168a transgenic seeds of the rice cultivar Kasalath led to lower germination rates, whereas osa-miR164c silencing in MIM164c and osa-miR168a overexpression in OE168a resulted in higher seed germination rates compared with wild-type seeds. Meanwhile, changes in cytomembrane permeability of seeds and in the expression level of osa-miR164c target genes (OsPM27 and OsPSK5) and osa-miR168a target genes (OsAGO1 and OsPTR2) under aging conditions coincided with changes in seed vigor induced by osa-miR164c and osa-miR168a. Thus, genetic manipulation of miRNAs has important implications in the development of crop cultivars with high vigor and extended life span of seeds.
microRNAs (miRNAs) 是植物许多重要生物学过程中基因表达的关键调节剂。然而，目前已知很少有 miRNAs 调节种子活力。在这里，我们通过 microarray 分析了水稻（Oryza sativa L.）品种 ZR02 种子中的 miRNA 表达水平。结果表明，人工老化和未处理对照种子之间的 11 个 miRNA 的表达存在显著差异。其中，osa-miR164c 在人工老化种子中转录上调，而 osa-miR168a 下调；这通过定量实时 PCR 分析得到了验证。在相同的老化条件下，水稻品种 Kasalath 中 OE164c 转基因种子中 osa-miR164c 的过表达和 MIM168a 转基因种子中 osa-miR168a 的沉默导致发芽率降低，而 MIM164c 沉默和 OE168a 过表达在 MIM164c 和 OE168a 中导致种子发芽率高于野生型种子。同时，种子质膜通透性变化以及 osa-miR164c 靶基因（OsPM27 和 OsPSK5）和 osa-miR168a 靶基因（OsAGO1 和 OsPTR2）的表达水平在老化条件下的变化与 osa-miR164c 和 osa-miR168a 诱导的种子活力变化一致。因此，miRNA 的遗传操作对开发具有高活力和延长种子寿命的作物品种具有重要意义。
