miR171 belongs to a highly conserved and ubiquitously expressed microRNA gene family across species that play a critical role in controlling plant growth and development through the regulation of the miR171-SCL (scarecrow-like proteins) module. There is limited research available on the evolutionary relationship and functional diversification of miR171 members. In this study, we identified eight miR171 genes in the mulberry genome by bioinformatics analysis that were subsequently used to compare the evolutionary levels and explore abiotic stress mechanisms mediated by mno-miR171s (Morus notabilis miR171s). The results of phylogenetic analysis showed that the mature mno-miR171 sequences have strong sequence conservation, but their critical sites also exhibit high variation leading to functional diversification. Through quantitative real-time PCR, the expression profile of each mno-miR171 was analyzed under different stress treatments. All mno-miR171s, apart from mno-miR171h, were found to be significantly up-regulated under salt and drought stress conditions. The target genes of mno-miR171a namely, Morus020885 and Morus011800, were predicted and verified using the plural RNA method. 5′-rapid amplification of complementary DNA ends assays further to reveal that the target genes could be degraded by mno-miR171a post-transcriptionally. Overexpression of mno-miR171a in Arabidopsis improved the percentage of seed germination when the seeds were grown in NaCl- and mannitol-containing media. Transgenic plants were observed to grow better under drought conditions. The expression of various stress genes was significantly higher in transgenic plants than in wild type, except ERF11. Taken together, our study confirmed that mno-miR171a enhanced plant resistance to adverse stress environments via the regulation of the SCL targets.

miR171 属于高度保守且在物种间广泛表达的 microRNA 基因家族，通过调节 miR171 - SCL（稻草人样蛋白）模块在控制植物生长和发育中发挥关键作用。关于 miR171 成员的进化关系和功能多样化的研究有限。在这项研究中，我们通过生物信息学分析确定了桑树基因组中的 8 个 miR171 基因，随后用于比较进化水平并探索由 mno-miR171s 介导的非生物胁迫机制（Mor​​us notabilismiR171s）。系统发育分析结果表明，成熟的mno-miR171序列具有很强的序列保守性，但其关键位点也表现出高度变异，导致功能多样化。通过定量实时PCR，分析了每个mno-miR171在不同应激处理下的表达谱。除 mno-miR171h 外，所有 mno-miR171s 在盐分和干旱胁迫条件下均显着上调。mno-miR171a的靶基因，即Morus020885和Morus011800，采用复数RNA法进行预测和验证。5'-快速扩增互补 DNA 末端分析进一步揭示靶基因可在转录后被 mno-miR171a 降解。mno-miR171a 在拟南芥中的过表达当种子在含 NaCl 和甘露醇的培养基中生长时，提高了种子发芽率。观察到转基因植物在干旱条件下生长得更好。除ERF11外，转基因植物中各种胁迫基因的表达均显着高于野生型。总之，我们的研究证实，mno-miR171a 通过调节SCL靶标增强了植物对不利胁迫环境的抵抗力。