The Kernel Size-Related Quantitative Trait Locus <i>qKW9</i> Encodes a Pentatricopeptide Repeat Protein That Aaffects Photosynthesis and Grain Filling

Abstract

In maize (<i>Zea mays</i>), kernel weight is an important component of yield that has been selected during domestication. Many genes associated with kernel weight have been identified through mutant analysis. Most are involved in the biogenesis and functional maintenance of organelles or other fundamental cellular activities. However, few quantitative trait loci (QTLs) underlying quantitative variation in kernel weight have been cloned. Here, we characterize a QTL, <i>qKW9</i>, associated with maize kernel weight. This QTL encodes a DYW motif pentatricopeptide repeat protein involved in C-to-U editing of <i>ndhB</i>, a subunit of the chloroplast NADH dehydrogenase-like complex. In a null <i>qkw9</i> background, C-to-U editing of <i>ndhB</i> was abolished, and photosynthesis was reduced, resulting in less maternal photosynthate available for grain filling. Characterization of <i>qKW9</i> highlights the importance of optimizing photosynthesis for maize grain yield production.