水稻R2R3-MYB转录因子OsFLP参与气孔发育及干旱和盐胁迫多效性功能的研究

Drought and salt stresses are major restrained factors for crop production and quality. How to improve crop resistance to drought and salt stresses is a big challenge for agricultural development. Arabidopsis R2R3-MYB transcription factor FOUR LIPS (FLP, MYB124) play important roles in stomatal development and in response to environmental stress. Here we cloned a homologous gene of AtFLP in rice, named as OsFLP. When introduce OsFLP in flp mutant, it can partially complement stomatal defect in flp mutant. And the rice OsFLP-RNAi plants showed abnormality in stomatal development. Overexpressing OsFLP in Arabidopsis wild type plants can improve plant tolerance to salt stress. Rice OsFLP overexpression lines had higher resistant ability to drought stress compared to non-transgenic rice plants. In this research, theories and methods of cell biology, molecular biology, bioinformatics and biochemistry were used to study the roles of OsFLP and its regulatory genes in stomatal development and in response to drought and salt stresses. Our results will clarify the regulatory network of OsFLP and its regulatory genes in drought and salt stresses and will provide some theoretical basis for the improvement of crop resistance to drought and salt stresses through molecular breeding technique.

干旱和盐胁迫是影响作物产量和品质的重要限制因素，如何提高作物的抗旱和耐盐能力是目前农业生产面临的巨大挑战。拟南芥R2R3-MYB转录因子FOUR LIPS (FLP, MYB124)不仅参与气孔发育过程，而且参与了对逆境胁迫的响应。我们在水稻中已成功克隆与AtFLP同源的基因OsFLP，前期的研究结果表明OsFLP能部分互补flp突变体的气孔发育缺陷，所获得的水稻OsFLP-RNAi株系表现为气孔发育异常。同时也初步发现在拟南芥中异源过量表达OsFLP提高了转基因植株的耐盐能力。相对于水稻对照材料，OsFLP的过量表达水稻株系抗旱能力明显提高。本项目将在此基础上进一步利用细胞生物学、分子生物学、生物信息学及生物化学理论与方法，研究OsFLP参与气孔发育调控的作用模式，揭示OsFLP与下游调控基因参与干旱和盐胁迫的网络调控途径，为通过分子育种技术提高作物抗旱或抗盐能力提供新的理论依据和手段。

拟南芥R2R2 MYB类转录因子FOUR LIPS（FLP, MYB124）在调节气孔发育和响应干旱和盐胁迫响应过程中发挥重要作用。本项目中完成了水稻中拟南芥AtFLP同源基因OsFLP克隆，并验证了OsFLP可互补拟南芥flp-1气孔表型，表明水稻OsFLP与拟南芥AtFLP在调控气孔发育过程中存在一定的进化保守性。通过对水稻OsFLP的RNAi和Tilling突变体表型观察和互补实验，确定OsFLP参与水稻气孔发育过程中GMC（guard mother cell）细胞分裂及随后的GC（guard cell）成熟过程调控。过量表达OsFLP提高了转基因水稻的耐旱性和耐盐能力，OsFLP通过直接调控的下游靶基因为NAC类转录因子的表达参与逆境胁迫响应过程。同时还发现水稻中的OsCDKB1;1与拟南芥AtCDKB1在功能上存在一定的保守性，OsCDKB1;1能够与细胞周期蛋白OsCYCA2;1结合，OsCDKB1和OsCYCA2;1的RNAi突变体提高了耐盐性能。OsCYCA2;1的表达下调影响细胞分裂和细胞内复制过程。综上所述，我们的研究结果阐明了OsFLP与拟南芥AtFLP在调控气孔发育过程中存在保守性及多样性，为进一步理解单子叶植物气孔发育过程奠定了基础。另一方面，研究结果还阐明了OsFLP在干旱和盐胁迫调控过程的的功能多效性和分子机制，为深入理解气孔发育通路与植物逆境胁迫关系提供了新的数据。