Background: MicroRNAs participate in many molecular mechanisms and signaling trans-duction pathways that are associated with plant stress tolerance by repressing expression of their target genes. However, how microRNAs enhance tolerance to low temperature stress in plant cells remains elusive. Objective: In this investigation, we demonstrated that overexpression of the rice microRNA528 (Os-miR528) increases cell viability, growth rate, antioxidants content, ascorbate peroxidase (APOX) activi-ty, and superoxide dismutase (SOD) activity and decreases ion leakage rate and thiobarbituric acid reac-tive substances (TBARS) under low temperature stress in Arabidopsis (Arabidopsis thaliana), pine (Pi-nus elliottii), and rice (Oryza sativa). Methods: To investigate the potential mechanism of OsmiR528 in increasing cold stress tolerance, we examined expression of stress-associated MYB transcription factors OsGAMYB-like1, OsMYBS3, OsMYB4, OsMYB3R-2, OsMYB5, OsMYB59, OsMYB30, OsMYB1R, and OsMYB20 in rice cells by qRT-PCR. Results: Our experiments demonstrated that OsmiR528 decreases expression of transcription factor OsMYB30 by targeting a F-box domain containing protein gene (Os06g06050), which is a positive regulator of OsMYB30. In OsmiR528 transgenic rice, reduced OsMYB30 expression results in in-creased expression of BMY genes OsBMY2, OsBMY6, and OsBMY10. The transcript levels of the OsBMY2, OsBMY6, and OsBMY10 were elevated by OsMYB30 knockdown, but decreased by Os-MYB30 overexpression in OsmiR528 transgenic cell lines, suggesting that OsmiR528 increases low temperature tolerance by modulating expression of stress response-related transcription factor. Conclusion: Our experiments provide novel information in increasing our understanding in molecular mechanisms of microRNAs-associated low temperature tolerance and are valuable in plant molecular breeding from monocotyledonous, dicotyledonous, and gymnosperm plants.

中文翻译：

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OsmiR528通过抑制植物细胞中胁迫反应相关转录因子基因的表达来增强冷胁迫耐受性

背景：MicroRNA 通过抑制其靶基因的表达参与了许多与植物胁迫耐受性相关的分子机制和信号转导途径。然而，microRNAs如何增强植物细胞对低温胁迫的耐受性仍然难以捉摸。目的：在这项研究中，我们证明了水稻 microRNA528 (Os-miR528) 的过表达提高了细胞活力、生长速率、抗氧化剂含量、抗坏血酸过氧化物酶 (APOX) 活性和超氧化物歧化酶 (SOD) 活性并降低了离子泄漏率拟南芥 (Arabidopsis thaliana)、松树 (Pi-nus elliottii) 和水稻 (Oryza sativa) 中低温胁迫下的硫代巴比妥酸反应物质 (TBARS)。方法：探讨OsmiR528提高冷胁迫耐受性的潜在机制，我们通过 qRT-PCR 检测了与胁迫相关的 MYB 转录因子 OsGAMYB-like1、OsMYBS3、OsMYB4、OsMYB3R-2、OsMYB5、OsMYB59、OsMYB30、OsMYB1R 和 OsMYB20 在水稻细胞中的表达。结果：我们的实验表明，OsmiR528 通过靶向一个含有 F-box 结构域的蛋白基因 (Os06g06050) 来降低转录因子 OsMYB30 的表达，该蛋白基因是 OsMYB30 的正调节因子。在 OsmiR528 转基因水稻中，降低 OsMYB30 的表达导致 BMY 基因 OsBMY2、OsBMY6 和 OsBMY10 的表达增加。在 OsmiR528 转基因细胞系中，OsBMY2、OsBMY6 和 OsBMY10 的转录水平因 OsMYB30 敲低而升高，但因 Os-MYB30 过表达而降低，这表明 OsmiR528 通过调节应激反应相关转录因子的表达来提高低温耐受性。结论：