LIM基因广泛分布于真核生物中, 在植物基因表达调节、细胞骨架动力学、信号转导、生物和非生物胁迫应答以及次生代谢等方面发挥重要作用。本研究鉴定了蒺藜苜蓿(Medicago truncatula) LIM (MtLIM)基因家族的13个成员。系统进化分析显示其分为5个亚家族。在进化过程中共有4个基因复制事件发生。对家族基因结构和蛋白质保守结构域分析发现, 不同的亚家族之间具有不同的基因结构和蛋白结构, 分化程度较大。实时荧光定量PCR (RT-qPCR)结果显示: MtLIM1在盐胁迫、干旱胁迫和低温胁迫下转录水平都显著下调; MtLIM9和MtLIM12的表达模式极为相似, 转录水平都是在盐胁迫和低温胁迫下显著上调、干旱胁迫下显著下调; MtLIM8在干旱胁迫下显著下调、低温胁迫下显著上调; 而MtLIM2转录水平只在盐胁迫下显著上调, MtLIM4只在干旱胁迫下显著上调, MtLIM6只在低温胁迫下显著上调; 其他LIM基因的转录水平在胁迫条件下没有明显变化。研究结果暗示MtLIM基因在蒺藜苜蓿的胁迫应答过程中有重要的调控作用, 功能上既有分工也有合作。本研究为深入研究MtLIM基因的功能和逆境胁迫应答机制提供参考。
关键词：蒺藜苜蓿; MtLIM基因; 胁迫应答; 生物信息学
Corresponding author: LI Lixin; E-mail: firstname.lastname@example.org
LIM genes are widely distributed in eukaryotes and play important roles in gene expression regulation, cytoskeleton dynamics, signal transduction, biotic and abiotic stress response and secondary metabolism. In this study, we identified 13 members of LIM gene family in Medicago truncatula (MtLIMs). Phylogenetic analysis indicates that they are divided into 5 subfamilies. Totally four gene duplication events occurs during evolution. The analysis of gene structure and protein conserved domains reveals that different subfamilies have different gene structures and protein structures, with greater differentiation. Real-time quantitative PCR (RT-qPCR) results indicates that the transcription level of MtLIM1 was significantly down-regulated under salt, drought and cold stresses. The expressional patterns of MtLIM9 and MtLIM12 were very similar, both were significantly up-regulated under salt and cold stresses, and significantly down-regulated under drought stress. The transcription level of MtLIM8 was significantly down-regulated under drought stress and significantly up-regulated under low-temperature stress. While, the transcription level of MtLIM2 was only significantly up-regulated under salt stress, of MtLIM4 was only significantly up-regulated under drought stress, and of MtLIM6 was only significantly up-regulated under cold stress. The transcription levels of other LIM genes did not change significantly under stress. Our results suggests that MtLIM genes play important regulatory roles in the stress responses and have functional division and cooperation. This study would provide information for further exploration of MtLIM gene functions and stress response mechanisms in M. truncatula.
Key words: Medicago truncatula; MtLIM genes; stress response; bioinformatics
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