The DROOPING LEAF (DR) Gene Encoding GDSL Esterase Controls Leaf Morphology in Rice (Oryza sativa L.)

Abstract Background: Leaf morphology is one of the most important agronomic traits in rice breeding because of its contribution to crop yield. Although many studies related to leaf phenotypes in rice have been identified, our understanding of the mechanism of grain development is still limited. Results: The drooping leaf (dr) mutant was developed from the Ilpum rice cultivar by ethyl methanesulfonate (EMS) mutagenesis. Compared with the wild-type, the dr mutant exhibited drooping leaves accompanied by a small midrib, short panicle, and reduced plant height. The phenotype of the dr mutant was caused by a mutation within a single recessive gene on chromosome 2, dr (LOC_Os02g15230), which encodes a GDSL esterase. Analysis of wild-type and mutant sequences revealed that the dr allele carried a single nucleotide substitution, glycine to aspartic acid. RNAi targeted to LOC_Os02g15230 produced the same phenotype as the dr mutation, confirming LOC_Os02g15230 as the dr gene. Microscopic observations and nutrient analysis of SiO2 revealed that silica was less abundant in mutant leaves than in wild-type leaves. Conclusions: This study suggests that the dr gene is involved in the regulation of silica deposition and that disruption of silica processes lead to all drooping leaf phenotypes.