He Yuchi, Wu Jingjing, Lv Bing, Li Jia, Gao Zhiping, Xu Weifeng, Baluška František, Shi Weiming, Shaw Pang Chui, Zhang Jianhua
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China School of Life Sciences and State Key Laboratory of Agrobiotechnology, the Chinese University of Hong Kong, Hong Kong Hubei Collaborative Innovation Center for Green Transformation of Bio-Resources, Hubei University, Wuhan 430062, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
J Exp Bot. 2015 Apr;66(8):2271-81. doi: 10.1093/jxb/erv149. Epub 2015 Apr 6.
Plant 14-3-3 proteins are phosphoserine-binding proteins that regulate a wide array of targets via direct protein-protein interactions. In this study, the role of a 14-3-3 protein, GRF9, in plant response to water stress was investigated. Arabidopsis wild-type, GRF9-deficient mutant (grf9), and GRF9-overexpressing (OE) plants were treated with polyethylene glycol (PEG) to induce mild water stress. OE plant showed better whole-plant growth and root growth than the wild type under normal or water stress conditions while the grf9 mutant showed worse growth. In OE plants, GRF9 favours the allocation of shoot carbon to roots. In addition, GRF9 enhanced proton extrusion, mainly in the root elongation zone and root hair zone, and maintained root growth under mild water stress. Grafting among the wild type, OE, and grf9 plants showed that when OE plants were used as the scion and GRF9 was overexpressed in the shoot, it enhanced sucrose transport into the root, and when OE plants were used as rootstock and GRF9 was overexpressed in the root, it caused more release of protons into the root surface under water stress. Taken together, the results suggest that under PEG-induced water stress, GRF9 is involved in allocating more carbon from the shoot to the root and enhancing proton secretion in the root growing zone, and this process is important for root response to mild water stress.
植物14-3-3蛋白是一类磷酸丝氨酸结合蛋白，通过直接的蛋白质-蛋白质相互作用调节多种靶标。在本研究中，对一种14-3-3蛋白GRF9在植物对水分胁迫的响应中的作用进行了研究。用聚乙二醇（PEG）处理拟南芥野生型、GRF9缺陷型突变体（grf9）和GRF9过表达（OE）植株，以诱导轻度水分胁迫。在正常或水分胁迫条件下，OE植株的整体生长和根系生长均优于野生型，而grf9突变体的生长则较差。在OE植株中，GRF9有利于地上部碳向根部的分配。此外，GRF9增强了质子外排，主要在根伸长区和根毛区，并在轻度水分胁迫下维持根系生长。野生型、OE和grf9植株之间的嫁接表明，当以OE植株为接穗且GRF9在地上部过表达时，它增强了蔗糖向根中的运输；当以OE植株为砧木且GRF9在根中过表达时，在水分胁迫下它导致更多质子释放到根表面。综上所述，结果表明在PEG诱导的水分胁迫下，GRF9参与将更多的碳从地上部分配到根部，并增强根生长区的质子分泌，这一过程对根系对轻度水分胁迫的响应很重要。
