Jung Hyun Ju, Kang Hunseung
Department of Plant Biotechnology, Agricultural Plant Stress Research Center and Biotechnology Research Institute, College of Agriculture and Life Sciences, Chonnam National University, 300 Yongbong-dong, Buk-gu, Gwangju 500-757, Republic of Korea.
Plant Physiol Biochem. 2007 Oct-Nov;45(10-11):805-11. doi: 10.1016/j.plaphy.2007.07.015. Epub 2007 Aug 6.
MicroRNAs (miRNAs) are 20-25 nucleotides-long RNA transcripts that are capable of suppressing target gene expression by either mRNA cleavage or translational repression. Although many recent reports propose that miRNAs play diverse roles in growth, development, morphogenesis, and stress responses of plants, the biological roles of many miRNAs remain to be verified. Here, we investigated stress-responsive expression patterns and functional roles of miRNA417 in seed germination and seedling growth of Arabidopsis thaliana under various abiotic stress conditions. miRNA417 was expressed constantly throughout the entire growth stages and ubiquitously in all organs including stems, roots, leaves, and flowers. The expression of miRNA417 was regulated by salt stress, dehydration stress, or abscisic acid treatment. To examine the biological roles of miRNA417 in stress responses, the transgenic Arabidopsis plants that constitutively overexpress miRNA417 under the control of cauliflower mosaic virus 35S promoter were generated, and their phenotypes were analyzed under stress conditions. Results showed that seed germination of the transgenic plants was retarded compared with the wild-type plants in the presence of high salt or abscisic acid. These results imply that miRNA417 plays a role as a negative regulator of seed germination in Arabidopsis plants under salt stress conditions.
微小RNA（miRNA）是长度为20 - 25个核苷酸的RNA转录本，能够通过mRNA切割或翻译抑制来抑制靶基因表达。尽管最近许多报道表明miRNA在植物的生长、发育、形态发生和应激反应中发挥着多种作用，但许多miRNA的生物学作用仍有待验证。在此，我们研究了拟南芥在各种非生物胁迫条件下，miRNA417在种子萌发和幼苗生长中的胁迫响应表达模式及功能作用。miRNA417在整个生长阶段持续表达，并且在包括茎、根、叶和花在内的所有器官中普遍存在。miRNA417的表达受盐胁迫、脱水胁迫或脱落酸处理的调控。为了研究miRNA417在胁迫反应中的生物学作用，构建了在花椰菜花叶病毒35S启动子控制下组成型过表达miRNA417的转基因拟南芥植株，并在胁迫条件下分析其表型。结果表明，在高盐或脱落酸存在的情况下，转基因植株的种子萌发比野生型植株延迟。这些结果表明，在盐胁迫条件下，miRNA417在拟南芥植株中作为种子萌发的负调控因子发挥作用。
