The reporter recently learned from the Chinese Academy of Agricultural Sciences that the rice molecular design technology and application innovation team of the Institute of Crop Sciences of the Academy, in cooperation with other domestic scientific research institutions, identified a new cytokinin signal component ppkl1 and found that it can interfere with the signal transmission efficiency by luring but not accepting the phosphate group on the cytokinin phosphate transfer protein ahp2, So as to inhibit the grain size of rice. Based on this, the team established a set of rice grain size accurate design system. Relevant research results are published online in molecular plants.
Tong Hongning, a team member and researcher of Institute of Crop Sciences, Chinese Academy of Agricultural Sciences, introduced that the classical cytokinin signal transduction in plants depends on the transfer of phosphate groups between histidine receptor kinase, histidine phosphate transfer protein and cytokinin response factor RR. However, the academic community still knows little about the molecular mechanism of the regulation of this phosphate relay process. On the other hand, in rice, cytokinins can significantly regulate the number of grains per panicle, and the regulation function of grain weight or grain size is not clear.
Through large-scale mutation, the team screened a large grain dominant mutant and cloned the mutant gene ppkl1. Similar to RR protein, ppkl1 can directly interact with ahp2 protein and compete with ahp2 phosphate group by imitating RR protein functional region, resulting in a significant reduction in phosphate relay efficiency. When this functional region site was mutated, the effect on signal transmission was lost and the grain increased significantly. They used the high-quality rice variety kongyu131 as the material to edit the gene in this functional region, and obtained a number of genotypes that can increase the grain in varying degrees, and some can increase the yield significantly.
The team also created rice materials with 1000 grain weight gradually distributed from 20g to 38g, thus establishing a set of rice grain size accurate design system. This study found that the inhibitory effect of ppkl family proteins on cytokinin signal may be an ancient function, and its functional site is hidden in the sterol hormone brassinolide signal component. It is of great application value to explore and use this gene to improve crop molecular design.
Source: Science and Technology Daily
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