Grain size and shape are important components determining rice grain yield, and they are controlled by quantitative trait loci (QTLs). Here, we report the cloning and functional characterization of a major grain length QTL, qGL3, which encodes a putative protein phosphatase with Kelch-like repeat domain (OsPPKL1). We found a rare allele qgl3 that leads to a long grain phenotype by an aspartate-to-glutamate transition in a conserved AVLDT motif of the second Kelch domain in OsPPKL1. The rice genome has other two OsPPKL1 homologs, OsPPKL2 and OsPPKL3. Transgenic studies showed that OsPPKL1 and OsPPKL3 function as negative regulators of grain length, whereas OsPPKL2 as a positive regulator. The Kelch domains are essential for the OsPPKL1 biological function. Field trials showed that the application of the qgl3 allele could significantly increase grain yield in both inbred and hybrid rice varieties, due to its favorable effect on grain length, filling, and weight.
水稻的籽粒大小和形狀是重要的產(chǎn)量組分，它們是由數(shù)量性狀基因控制的。本文報道了對一個水稻粒長主效位點qGL3的克隆和功能分析，它編碼一個含有兩個Kelch功能域的蛋白磷酸酶（OsPPKL1）。我們發(fā)現(xiàn)，位于OsPPKL1中第二個Kelch功能域上保守的AVLDT區(qū)域的D364E的稀有等位變異qgl3導(dǎo)致長粒表型。水稻中含有其他兩個OsPPKL1同源蛋白：OsPPKL2和OsPPKL3。轉(zhuǎn)基因研究發(fā)現(xiàn)：OsPPKL1和OsPPKL3在水稻粒長調(diào)控中發(fā)揮負(fù)調(diào)節(jié)子的作用，而OsPPKL2是一個正調(diào)節(jié)子。Kelch功能域在OsPPKL1的負(fù)調(diào)節(jié)功能中是充分必要的。田間試驗表明：優(yōu)異等位基因qgl3的利用可以通過增加粒長、灌漿速率和粒重而顯著的提高常規(guī)的和雜交稻的產(chǎn)量。