Department of Grassland Science, China Agricultural University, Beijing, China.
Beijing Vegetable Research Center (BVRC), Beijing Academy of Agricultural and Forestry Sciences, National Engineering Research Center for Vegetables, Beijing, China.
Plant Biotechnol J. 2019 Dec;17(12):2370-2383. doi: 10.1111/pbi.13154. Epub 2019 Jun 7.
Salinity-induced accumulation of certain microRNAs accompanied by gaseous phytohormone ethylene production has been recognized as a mechanism of plant salt tolerance. MicroRNA319 (miR319) has been characterized as an important player in abiotic stress resistance in some C3 plants, such as Arabidopsis thaliana and rice. However, its role in the dedicated biomass plant switchgrass (Panicum virgatum L.), a C4 plant, has not been reported. Here, we show crosstalk between miR319 and ethylene (ET) for increasing salt tolerance. By overexpressing Osa-MIR319b and a target mimicry form of miR319 (MIM319), we showed that miR319 positively regulated ET synthesis and salt tolerance in switchgrass. By experimental treatments, we demonstrated that ET-mediated salt tolerance in switchgrass was dose-dependent, and miR319 regulated the switchgrass salt response by fine-tuning ET synthesis. Further experiments showed that the repression of a miR319 target, PvPCF5, in switchgrass also led to enhanced ethylene accumulation and salt tolerance in transgenic plants. Genome-wide transcriptome analysis demonstrated that overexpression of miR319 (OE-miR319) down-regulated the expression of key genes in the methionine (Met) cycle but promoted the expression of genes in ethylene synthesis. The results enrich our understanding of the synergistic effects of the miR319-PvPCF5 module and ethylene synthesis in the salt tolerance of switchgrass, a C4 bioenergy plant.
盐诱导某些 microRNA 的积累伴随着气态植物激素乙烯的产生，这已被认为是植物耐盐性的一种机制。microRNA319（miR319）已被确定为一些 C3 植物（如拟南芥和水稻）中抗非生物胁迫的重要参与者。然而，它在专门用于生物质的植物柳枝稷（Panicum virgatum L.）中的作用，一种 C4 植物，尚未被报道。在这里，我们展示了 miR319 和乙烯（ET）之间的串扰，以提高盐耐受性。通过过表达 Osa-MIR319b 和 miR319 的靶标模拟形式（MIM319），我们表明 miR319 正向调节柳枝稷中的 ET 合成和盐耐受性。通过实验处理，我们证明了 ET 介导的柳枝稷耐盐性是剂量依赖性的，miR319 通过精细调节 ET 合成来调节柳枝稷的盐响应。进一步的实验表明，在柳枝稷中 miR319 靶标的抑制，即 PvPCF5，也导致转基因植物中乙烯积累和耐盐性增强。全基因组转录组分析表明，miR319 的过表达（OE-miR319）下调了蛋氨酸（Met）循环关键基因的表达，但促进了乙烯合成基因的表达。这些结果丰富了我们对 miR319-PvPCF5 模块和乙烯合成在柳枝稷耐盐性中的协同作用的理解，柳枝稷是一种 C4 生物能源植物。
