Map-based Cloning Of A ’zebra Leaf’ Mutant Gene Zl2in Rice

A yellow and green zebra leaf mutant zebra leaf2(zl2) displayed a distinctive zebra leaf at seedling stage, and the leaves of the mutant gradually turned yellow after heading. Compared with wild type, the chlorophyll and carotenoid content of zl2were significantly reduced at trileaf stage, tillering stage, heading stage and mature stage. The seed setting rate, grain weight and plant height of zl2also decreased significantly. The ultrastructures of chloroplasts in the mesophyll cells of the yellow part of seedling of zl2have obvious differences from that of wild type. Genetic analysis showed that the phenotype of zl2was controlled by a single recessive nuclear gene. Total1607zebra leaf plants selected from the F2population generated by crossing between zl2and Nanjingl1were used to fine-map the mutant gene. Finally, zl2gene was narrowed to the164.3kb region on Chromosome11. There are13ORFs in this region, and a single base mutation was found in the ORF12which encode a carotenoid isomerase. And as a result, four bases were missed in cDNA of ORF12of zl2, leading to frame-shift and the amino acid premature termination at the395th. Compared with the wild type, the expression level of ZL2and the genes involved in the control of leaf color and photosynthesis, such as PORA, RbcL, RbcS, Cab1, Cab2, psaA,psbA and OsDVR decreased significantly in mutant, while those of HEMA1, YGL1, VI, V2, SPP and OsPPR increase significantly. The results suggested that ZL2act a very important role in chlorophyll biosynthesis, chloroplast development and photosynthesis in rice.