ZFP6和GIS3调控拟南芥根毛细胞形成的分子作用机制

The occurrence, differentiation and elongation of root hair cells are controlled by multiple transcription factors, plant hormones and environmental signals. In recent years, progress had been made in the uncovering molecular mechanism of root cell development. However, the detailed molecular mechanism, in particular how transcription factors control root hair development throught plant hormone and nutrient stress, has hardly been reported. We have recently cloned two ZFP5 homologous genes, ZFP6 and GIS3. Our results had shown that they are mainly expressed in root and the mutants of these two genes showed significant reductions on the number and length of root hairs. Different from ZFP5 which plays a key role in contorling root hair initiaion, ZFP6 and GIS3 may mainly regulate root hair differetiation and root hair elongation. More importantly, our prelimenary results also had shown the expression of ZFP6 and GIS3 were induced by P and K starvation. P and K starvation could significantly increase the root hair length of wild type, but could not significantly increase the root hair length of zfp6 and gis3 mutants. These results incdicate that ZFP6 and GIS3 might control root hair elongation through low P and low K stress. That zinc finger protoin contorls root hair elongation through nutrient stress signal has not yet reported before. This project will use molecular techniques, such as the application of exogenous hormone and nutrient stress, genetic analysis of mutants in related to the key genes contorling the root hair initiation, differentiation and elongation, and use RNA-seq and ChIP to study the molecular mechanisms of the ZFP6 and GIS3 genes controling root hair development in Arabidposis.

植物根毛细胞的发生、分化和伸长主要受转录因子、植物激素和环境信号的调控。近年来对植物根毛发育的分子遗传机理研究虽取得了很大进展，但转录因子通过植物激素和营养胁迫控制根毛形成的报道甚少。最近，我们从刚结题的一年期国家自然科学基金项目研究中克隆拟南芥ZFP5的2个同源基因ZFP6和GIS3，这2个基因突变体的根毛数量和长度显著减少。与ZFP5基因不同，这2个基因主要参与根毛细胞命运决定后的分化和伸长。更为重要的是，这2个基因的表达受P和K饥饿胁迫所诱导，P和K饥饿胁迫能显著增加野生型的根毛细胞长度，但不能显著增加zfp6和gis3突变体根毛细胞长度，这揭示ZFP6和GIS3基因可能通过P和K信号调控根毛细胞的伸长。本项目将应用外源激素和营养胁迫实验、突变体遗传学分析、RNA-seq和染色体免疫共沉淀等技术，进一步研究ZFP6和GIS3基因通过植物激素和营养胁迫调控根毛形成和发育的分子作用机制。

根毛是植物吸收水分和营养的主要器官，培育具有较多和较长的根毛是作物高效利用养分和水分，提高作物产量的基础和关键。本项目主要研究ZFP5的同源基因ZFP6和GIS3是否通过植物激素信号和营养胁迫调控根毛的形成和伸长。突变体分析和分子遗传学实验结果证实了ZFP6和GIS3是根毛发育过程中的关键功能基因。遗传学和分子生物学实验揭示了GIS3通过调控其直接作用靶点基因RHD2和RHD4的表达量，来调控根毛伸长的分子机理 《Plant Physiology，小修中》。同时，我们还发现ZFP5及其同源基因ZFP6和GIS3能够响应低磷、低钾信号调控根毛的伸长。低磷、低钾处理不能恢复其3个突变体短根毛的表型，RT-PCR和GUS染色结果表明, 低磷、低钾处理能够在转录水平和蛋白水平增加ZFP5及其同源基因的表达。遗传学和分子生物学实验表明，在低磷、低钾胁迫下，ZFP5、ZFP6和GIS3能够协同乙烯共同调控根毛的伸长，相关研究结果于2019年11月发表在《Plant Molecular Biology》。此外，我们还揭示了生长素、乙烯、细胞分裂素和RHD6，可以通过协同调控相同的根毛特异性基因RSL4和EXP7等的表达量来促进根毛形成的分子作用机理《Journal of Experimental Botany 2016》。我们在研究乙烯信号和营养非生物胁迫互作的同时，也发现乙烯信号也参与其他非生物胁迫（如ZnO NPs和Cr），乙烯介导ZnO NPs和Cr并诱导它们的毒性从而抑制植物生长，相关研究成果发表在《Environmental Science-Nano，2019》和《Plant Cell Environment，2018》等期刊上。以上研究结果，进一步完善了植物激素和营养胁迫通过锌指蛋白调控根毛细胞形成的作用机制及其基因调控网络，对于如何培育具有较高根系生理活性，特别是具有较多和较长根毛的作物，从而提高作物根系吸收养分和水分的效率，提高作物产量，具有重要的理论意义和实际应用价值。本项目全面完成了课题的所有目标和任务，揭示了ZFP5、ZFP6和GIS3 通过细胞分裂素、乙烯及低磷和低钾的信号调控拟南芥根毛形成的分子作用机制。本项目在国际刊物发表SCI论文10篇，其中5年影响因子6.0以上论文5篇，培养硕博研究生8名，顺利完成项目各项任务和3篇论文的考核指标。

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