Mao Xingxue, Zheng Xiaoyu, Sun Bingrui, Jiang Liqun, Zhang Jing, Lyu Shuwei, Yu Hang, Chen Pingli, Chen Wenfeng, Fan Zhilan, Li Chen, Liu Qing
Rice Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, 510640, China.
Key Laboratory of Genetics and Breeding of High Quality Rice in Southern China (Co-Construction By Ministry and Province), Ministry of Agriculture and Rural Affairs, Guangzhou, 510640, China.
Rice (N Y). 2024 Jan 3;17(1):2. doi: 10.1186/s12284-023-00679-4.
With the increasing frequency of climatic anomalies, high temperatures and long-term rain often occur during the rice-harvesting period, especially for early rice crops in tropical and subtropical regions. Seed dormancy directly affects the resistance to pre-harvest sprouting (PHS). Therefore, in order to increase rice production, it is critical to enhance seed dormancy and avoid yield losses to PHS. The elucidation and utilization of the seed dormancy regulation mechanism is of great significance to rice production. Preliminary results indicated that the OsMKKK62-OsMKK3-OsMPK7/14 module might regulate ABA sensitivity and then control seed dormancy. The detailed mechanism is still unclear.
The overexpression of OsMKK3 resulted in serious PHS. The expression levels of OsMKK3 and OsMPK7 were upregulated by ABA and GA at germination stage. OsMKK3 and OsMPK7 are both located in the nucleus and cytoplasm. The dormancy level of double knockout mutant mkk3/mft2 was lower than that of mkk3, indicating that OsMFT2 functions in the downstream of MKK3 cascade in regulating rice seeds germination. Biochemical results showed that OsMPK7 interacted with multiple core ABA signaling components according to yeast two-hybrid screening and luciferase complementation experiments, suggesting that MKK3 cascade regulates ABA signaling by modulating the core ABA signaling components. Moreover, the ABA response and ABA responsive genes of mpk7/14 were significantly higher than those of wild-type ZH11 when subjected to ABA treatment.
MKK3 cascade mediates the negative feedback loop of ABA signal through the interaction between OsMPK7 and core ABA signaling components in rice.
随着气候异常频率的增加，水稻收获期经常出现高温和长期降雨的情况，特别是热带和亚热带地区的早稻作物。种子休眠直接影响对穗发芽（PHS）的抗性。因此，为了提高水稻产量，增强种子休眠并避免因穗发芽造成产量损失至关重要。阐明和利用种子休眠调控机制对水稻生产具有重要意义。初步结果表明，OsMKKK62-OsMKK3-OsMPK7/14模块可能调节脱落酸（ABA）敏感性，进而控制种子休眠。具体机制仍不清楚。
OsMKK3过表达导致严重的穗发芽。在萌发阶段，ABA和赤霉素（GA）上调了OsMKK3和OsMPK7的表达水平。OsMKK3和OsMPK7均位于细胞核和细胞质中。双敲除突变体mkk3/mft2的休眠水平低于mkk3，表明OsMFT2在MKK3级联下游调节水稻种子萌发。生化结果表明，根据酵母双杂交筛选和荧光素酶互补实验，OsMPK7与多个核心ABA信号成分相互作用，表明MKK3级联通过调节核心ABA信号成分来调节ABA信号。此外，在ABA处理下，mpk7/14的ABA反应和ABA反应基因显著高于野生型中花11（ZH11）。
MKK3级联通过水稻中OsMPK7与核心ABA信号成分之间的相互作用介导ABA信号的负反馈环。
