The rice YGL gene encoding an Mg 2+ -chelatase ChlD subunit is affected by temperature for chlorophyll biosynthesis

Leaf color-related mutants are important materials to study the chlorophyll biosynthesis and chloroplast development. Here, we isolated and characterized a thermosensitive yellow-green leaf mutant, ygl , through mutagenized Japonica rice cultivar Zhonghua11 by EMS. The mutant showed yellow-green leaves only at the seedling stage. Genetic and molecular analyses uncovered that YGL encode an Mg2+-chelatase ChlD subunit, which was a new allele of Chl1/YGL7 . Quantitative PCR and GUS staining showed that the YGL transcripts expressed in all tested organs and subcellular localization detected YGL protein in the chloroplasts. The mutant displayed yellow-green leaves at 20°C and normal green leaves at 34°C during the seedling stage. Transcript level of YGL in the ygl mutant was significantly reduced at 20°C, and increased at 34°C compared with the wild-type plant. Furthermore, the expression of chlorophyll biosynthesis and chloroplast development related genes were influenced by the mutation of YGL at different temperature. These findings suggested that the YGL gene not only play a key role in chlorophyll biosynthesis, but is affected at transcript level by temperature in rice.