The novel quantitative trait locus GL3.1 controls rice grain size and yield by regulating Cyclin-T1;3

摘要

Increased crop yields are required to support rapid population growth worldwide.Grain weight is a key component of rice yield,but the underlying molecular mechanisms that control it remain elusive.Here,we report the cloning and characterization of a new quantitative trait locus(QTL)for the control of rice grain length,weight and yield.This locus,GL3.1,encodes a protein phosphatase kelch(PPKL)family — Ser/Thr phosphatase.GL3.1 is a member of the large grain WY3 variety,which is associated with weaker dephosphorylation activity than the small grain FAZ1 variety.GL3.1-WY3 influences protein phosphorylation in the spikelet to accelerate cell division,thereby resulting in longer grains and higher yields.Further studies have shown that GL3.1 directly dephosphorylates its substrate,Cyclin-T1;3,which has only been rarely studied in plants.The downregulation of Cyclin-T1;3 in rice resulted in a shorter grain,which indicates a novel function for Cyclin-T in cell cycle regulation.Our findings suggest a new mechanism for the regulation of grain size and yield that is driven through a novel phosphatase-mediated process that affects the phosphorylation of Cyclin-T1;3 during cell cycle progression,and thus provide new insight into the mechanisms underlying crop seed development.We bred a new variety containing the natural GL3.1 allele that demonstrated increased grain yield,which indicates that GL3.1 is a powerful tool for breeding high-yield crops.