黄花苜蓿小G蛋白基因MfARL1的抗逆功能研究

Medicago falcata is an important native legume pasture plant that widely occurs naturally in grassland of northern China. M. falcata is distinguished by its superior tolerance to environmental stress such as cold, drought and salinity. However, the molecular mechanism by which M. falcata tolerates the stress is hardly known due to its complex gentic background and lack of genomic information. We isolated a gene encoding a small GTPase in response to drought, cold and salt, designed MtARL1, from suppression subtractive hybridization library. Transgenic Arabidopsis expressing MfARL1 was more tolerant to drought and salt stress than wild-type. The proposed project aims to further functionally characterize MfARL1 by genetating transgenic Medicago with altered expression level of MfARL1, and elucidate the signaling network associated with MfARL1 in response to abiotic stress, in terms of property of protein, expression pattern and regulatory network by yeast-two-hybridization, transcriptome analysis and determination of physiology indexes. The outcome of this project will advance our knowledge on the function of Arf small GTPases in response and adaption to abiotic stress.

黄花苜蓿 (Medicago falcata) 是一种广泛分布于我国北方的豆科牧草，具有耐旱、抗寒、耐盐碱等优良特性，但由于其遗传背景复杂，抗逆的分子机理研究较少。申请人从黄花苜蓿抑制性差减杂交文库中筛选到了一个响应干旱、低温、盐的小G蛋白基因MfARL1,转基因拟南芥表现出较强的抗旱、耐盐特性。本项目将在此基础上以MfARL1超表达和RNAi苜蓿株系为研究对象，从蛋白特性、表达模式、网络调控三个层面，通过酵母双杂交、转录组分析、生理指标测定等手段，研究MfARL1感受逆境胁迫信号和调控下游基因表达的网络，解析MfARL1调控苜蓿适应逆境胁迫的生理和分子机制。本项目的实施将填补Arf类小G蛋白在植物应答逆境胁迫研究中的空白，拓展我国优异野生牧草资源黄花苜蓿的抗逆分子机理研究，带动我国苜蓿抗逆分子生物学的发展。

黄花苜蓿 (Medicago falcata) 是一种广泛分布于我国北方的豆科牧草，具有耐旱、抗寒、耐盐碱等优良特性，但由于其遗传背景复杂，抗逆的分子机理研究较少。申请人从黄花苜蓿抑制性差减杂交文库中筛选到了一个响应干旱、低温、盐的小G蛋白基因MfARL1,转基因拟南芥表现出较强的抗旱、耐盐特性。又通过苜蓿遗传转化获得了该基因的超表达植株，并购得了该基因的TNT1插入突变体。通过盐胁迫存活率试验表明超表达植株表现出较强的抗盐性，而突变体则对盐超敏。进一步试验证明该基因可能调控了苜蓿盐胁迫相关的HKT基因的表达。此外，我们还分析了苜蓿中响应渗透和盐胁迫的长非编码RNA，预测了其靶基因，探讨其在植物抗逆中的作用；并在基因组水平阐明了蒺藜苜蓿生态型J. A17与R108抗逆能力差异的机制。本项目的研究成果发表在BMC Plant Biology等刊物上，研究结果拓展了人们对于苜蓿抗逆机理的理解，为苜蓿抗逆育种奠定了基础。