Map-based Cloning Of Two Young Leaf Chlorosis Genes In Rice

Rice is one of the most important food crops in the world. It is a very important strategic significance to solve the problem of future global food for the improvement of its production. The sequencing of rice genome, a important crop, and constructing of mutant pools have provided good conditions for rice functional genomics. Leaf coloration mutants are very important materials for photosynthesis research. These works are beneficial for learning the genetics of agricultural characters.In this study, two rice young leaf chlorosis mutants were obtained, named ylc2and ylc3.The ylc2mutant develops etiolation leaves and the ylc3mutant develops albino leaves before the three-leaf stage, but the mutants gradually turns green and recovers to normal green at the six-leaf stage. Further investigation showed that the change in leaf color in the mutants is associated with changes in chlorophyll content and abnormal chloroplast development.The YLC2and YLC3genes were isolated via map-based cloning. It revealed that YLC2gene encode a serine hydroxymethyltransferase that takes part in photorespiration process. There is a single nucleotide mutation (GGC-CGC) in the YLC2gene, which results in an amino acid change from Gly-Arg. Thus the mutant ylc2exhibited young leaf etiolation phenotype. The YLC3gene encodes a kinase belonging to the pfkB family. It is a very high homology with fructokinase that affects the glycolysis process and the process of photosynthesis. There is a single nucleotide mutation (TCT-TTT) in the YLC3gene, which results in an amino acid change from Ger-Phe. Thus the mutant ylc3exhibited young leaf albino phenotype. The YLC2and YLC3genes are constitutively expressed in all tissues, and their expression is not significantly affected in the mutants by a single nucleotide mutation. But this mutation affected the chlorophyll biosynthesis and chloroplast development.