饭豆VuSTOP1调控植物酸铝耐性的结构功能解析

Proton (H+) and aluminum (Al) are two major rhizotoxicities limiting plant growth in acidic soil. STOP1-like zinc finger transcription factors play important roles in regulating downstream genes involved in resistant mechanism of either stress. However, the STOP1-like proteins of different plant species show differentially regulated patterns in response to H+ and Al stress. In our previous study, a STOP1-like gene, VuSTOP1 from rice bean (Vigna umbellate) was characterized to play major role in H+ resistance but minor role in Al resistance. By comparing functional similarities and differences among STOP1-like proteins with other species, the hypothesis that N and/or C termini outside of conserved zinc-finger domain and protein phosphorylation are responsible for deferentially regulation of H+ and Al resistance mediated by STOP1-like protein was proposed. In this project, the biochemical and molecular methods as well as in planta complementation assays will be adopted to resolve structure-function relationship of VusSTOP1 in differential regulation of H+ and Al resistance, and find out the functional domains and amino acid residues. The carry out of the project will help to illustrate differential mechanism mediated by STOP1-like proteins under H+ and Al stress, reveal the interrelation among STOP1-like protein structure, modification, and function, and also provide theoretical basis and ideas for improving varieties with high H+ and Al resistance though a directional transformation of STOP1-like genes.

质子(H+) 和铝 (Al) 毒是酸性土壤上共存的胁迫因子。STOP1-like锌指蛋白在调控下游基因参与酸Al耐性中扮演了重要角色。然而，不同物种的STOP1-like在调控两种耐性时却存在功能差异。前期对耐酸Al饭豆（Vigna umbellate）VuSTOP1研究时发现，VuSTOP1主要在H+耐性中起作用，而对Al耐性贡献较小。结合其它物种中STOP1-like在功能上的共性与差异，提出非保守结构域的氨基酸序列和蛋白磷酸化是造成STOP1-like调控酸Al耐性差异的主要原因的假说。本项目采用生化与分子学手段，结合转基因功能回复验证，对VuSTOP1调控酸Al耐性进行结构-功能解析，找到功能区域和作用位点，阐明STOP1-like差异调控的作用机制，揭示STOP1-like结构、修饰与功能的相互关系，为定向改造STOP1-like以培育更加耐酸Al的种质资源提供理论依据和思路。

质子(H+) 和铝 (Al) 毒是酸性土壤上共存的胁迫因子。STOP1-like锌指蛋白在调控下游基因参与酸Al耐性中扮演了重要角色。然而，不同物种的STOP1-like在调控两种耐性时却存在功能差异。前期对耐酸Al饭豆（Vigna umbellate）VuSTOP1研究时发现，VuSTOP1主要在H+耐性中起作用，而对Al耐性贡献较小。结合其它物种中STOP1-like在功能上的共性与差异，探明：1）STOP1对H+耐性的调控在物种间比较保守，而对Al耐性的调控作用在物种间差异较大。与拟南芥AtSTOP1相比，饭豆VuSTOP1不能较大程度调控Al耐性的功能主要与N端的氨基酸序列差异有关，且这一过程依赖于PSKR1蛋白激酶介导的磷酸化修饰；2）饭豆VuSTOP1通过调控VuMATE1和VuMATE2介导的柠檬酸分泌的来部分增加Al耐性，但这一过程独立于ABA介导的信号转导途径之外。在Al胁迫早期VuSTOP1主要激活VuMATE2 的转录，在Al胁迫晚期，VuSTOP1部分激活VuMATE1的表达。但由于对后期起作用的VuMATE1激活较弱，因此不能贡献更多的柠檬酸分泌，而激活较强的VuMATE2 主要介导早期柠檬酸分泌，因此调控作用也比较有限，从另一侧面解释了饭豆VuSTOP1具有部分调控Al耐性的功能。上述结果为定向改造STOP1-like以培育更加耐酸Al的种质资源提供理论依据和思路。