Fine mapping of a novel yellow-green leaf 14 (ygl14) mutant in rice

As the primary organ for photosynthesis, the leaf color is crucial for plant growth and development. In this study, we isolated a yellow green leaf 14 (ygl14) mutant from Xinong 1B, an indica restorer line of rice (Oryza sativa L.), which was treated with ethyl methane sulfonate. The mutant not only showed a yellow-green leaf phenotype for the entire life cycle, the flag leaf is significantly longer and the total leaf area is increased, which resulted in an increase in photosynthetic area. Leaf pigment (chlorophyll and carotenoids) contents were significantly lower in ygl14 than those in the wild type (WT). Compared with WT, stomatal conductance, photosynthetic rate, and transpiration rate of ygl14 were significantly reduced, whereas the intercellular CO2 concentration was significantly increased. Anatomical observation revealed that a portion of the chloroplasts in mesophyll cells of ygl14 were structurally impaired compared with those of WT. YGL14 was fine-mapped to a 70.7kb region on chromosome 5, covered includes 15 open reading frames, no other yellow-green leaf related mutants have ever been reported within this region in rice. Quantitative real-time PCR analysis showed that the expression levels of genes associated with chlorophyll metabolism and photosynthesis were significantly altered in the ygl14 mutant. These results provide a foundation for cloning and functional analysis of the yellow-green leaf gene YGL14.