拟南芥微丝结合蛋白AtADF9参与干旱调控叶面积减小的分子机制

叶面积减小是植物抵御干旱胁迫的第一道防线，铺板细胞形态建成与叶片发育密切相关，然而干旱胁迫调节叶面积减小的细胞和分子生物学机理仍不清楚。申请人前期研究发现，干旱胁迫诱导微丝结合蛋白基因AtADF9表达下调，AtADF9突变体植株在叶面积减小、铺板细胞形态和耐旱性方面均表现出对干旱不敏感；MYB52突变体中AtADF9表达上调且叶面积减小和铺板细胞形态对干旱处理更敏感，表明AtADF9可能受MYB52调节参与干旱胁迫调控叶面积减小过程。本项目计划通过研究干旱胁迫条件下AtADF9的表达模式；分析AtADF9过表达、突变体及恢复突变体植株在干旱胁迫下叶面积表型与微丝组织动态变化；并分析在干旱胁迫调控叶面积减小过程中转录因子MYB52对AtADF9的调控机制，从而阐明AtADF9在干旱胁迫调控叶面积减小过程中的作用机理，为深入解析干旱胁迫下微丝作用机理和干旱胁迫下叶面积减小的分子机理奠定基础。

Reduction in leaf area is considered the first line of defense against drought. Pavement cell morphogenesis is implicated in leaf development, however the molecular mechanism of drought regulation of leaf area reduction remains unclear. We examined the expression of AtADFs in Arabidopsis. The result showed that the expression of AtADF9 was down-regulated under drought stress. In addition, the leaf area reduction, pavement cell morphogenesis and drought resistance of Atadf9 mutants showed insensitivity to drought stress. We analyzed the promoter of AtADF9 and found the MYB-binding site was contained in the promoter. Moreover, the expression of AtADF9 was up-regulated in myb52 mutant seedlings, and the leaf area and pavement cell morphogenesis of myb52 mutants were hypersensitivity to drought. These results indicate that AtADF9 regulated by MYB52 involved in the drought regulation of leaf area reduction. In this proposal, the expression patterns of AtADF9 under drought stress will be analyzed. The leaf areas and MFs organization and dynamics will be observed in AtADF9 overexpression, mutant and compensation lines under drought stress. The mechanism of AtADF9 regulated by the upstream transcription factor MYB52 will be analyzed in drought regulation of leaf area reduction. These results will explain the mechanism of AtADF9 in drought regulation of leaf area reduction, and lay the foundation for deeply understanding the molecular mechanisms of MF and reduction in leaf area under drought stress.