College of Agronomy and Biotechnology, Hexi University, Zhangye, 734000, China.
College of Agronomy, Gansu Agricultural University, Lanzhou, 730070, China.
BMC Plant Biol. 2018 Mar 27;18(1):52. doi: 10.1186/s12870-018-1242-4.
Low temperature is a major abiotic stress affecting the production of rapeseed in China by impeding plant growth and development. A comprehensive knowledge of small-RNA expression pattern in Brassica rapa under cold stress could improve our knowledge of microRNA-mediated stress responses.
A total of 353 cold-responsive miRNAs, 84 putative novel and 269 conserved miRNAs, were identified from the leaves and roots of two winter turnip rape varieties 'Longyou 7' (cold-tolerant) and 'Tianyou 4' (cold-sensitive), which were stressed under - 4 °C for 8 h. Eight conserved (miR166h-3p-1, miR398b-3p, miR398b-3p-1, miR408d, miR156a-5p, miR396h, miR845a-1, miR166u) and two novel miRNAs (Bra-novel-miR3153-5p and Bra-novel-miR3172-5p) were differentially expressed in leaves of 'Longyou 7' under cold stress. Bra-novel-miR3936-5p was up-regulated in roots of 'Longyou 7' under cold stress. Four and five conserved miRNAs were differentially expressed in leaves and roots of 'Tianyou 4' after cold stress. Besides, we found two conserved miRNAs (miR319e and miR166m-2) were down-regulated in non-stressed roots of 'Longyou 7' compared with 'Tianyou 4'. After cold stress, we found two and eight miRNAs were differentially expressed in leaves and roots of 'Longyou 7' compared with 'Tianyou 4'. The differentially expressed miRNAs between two cultivars under cold stress include novel miRNAs and the members of the miR166 and miR319 families. A total of 211 target genes for 15 known miRNAs and two novel miRNAs were predicted by bioinformatic analysis, mainly involved in metabolic processes and stress responses. Five differentially expressed miRNAs and predicted target genes were confirmed by quantitative reverse transcription PCR, and the expressional changes of target genes were negatively correlated to differentially expressed miRNAs. Our data indicated that some candidate miRNAs (e.g., miR166e, miR319, and Bra-novel-miR3936-5p) may play important roles in plant response to cold stress.
Our work indicates that miRNA and putative target genes mediated metabolic processes and stress responses are significant to cold tolerance in B. rapa.
低温是影响中国油菜生产的主要非生物胁迫因素，它会阻碍植物的生长和发育。全面了解低温胁迫下油菜中小 RNA 的表达模式，可以提高我们对 microRNA 介导的胁迫响应的认识。
从冬油菜品种‘龙游 7 号’（耐低温）和‘天龙 4 号’（低温敏感）的叶片和根系中，分别鉴定到 353 个冷响应 miRNA，其中包括 84 个假定的新 miRNA 和 269 个保守 miRNA，这两个品种在 -4°C 下处理 8 小时。8 个保守 miRNA（miR166h-3p-1、miR398b-3p、miR398b-3p-1、miR408d、miR156a-5p、miR396h、miR845a-1、miR166u）和 2 个新 miRNA（Bra-novel-miR3153-5p 和 Bra-novel-miR3172-5p）在低温胁迫下叶片中差异表达。Bra-novel-miR3936-5p 在低温胁迫下‘龙游 7 号’的根中上调表达。4 个和 5 个保守 miRNA 在‘天龙 4 号’的叶片和根中差异表达。此外，我们发现两个保守 miRNA（miR319e 和 miR166m-2）在非胁迫条件下，与‘天龙 4 号’相比，‘龙游 7 号’的根中下调表达。低温胁迫后，与‘天龙 4 号’相比，‘龙游 7 号’的叶片和根中分别有 2 个和 8 个 miRNA 差异表达。两个品种在低温胁迫下差异表达的 miRNA 包括新 miRNA 和 miR166 和 miR319 家族的成员。通过生物信息学分析预测了 15 个已知 miRNA 和 2 个新 miRNA 的 211 个靶基因，主要涉及代谢过程和应激反应。通过定量反转录 PCR 验证了 5 个差异表达 miRNA 和预测的靶基因，靶基因的表达变化与差异表达的 miRNA 呈负相关。我们的数据表明，一些候选 miRNA（如 miR166e、miR319 和 Bra-novel-miR3936-5p）可能在植物对低温胁迫的响应中发挥重要作用。
本研究表明，miRNA 和假定的靶基因介导的代谢过程和应激反应对油菜的耐寒性很重要。
