Gene Mapping And Characteristics Analysis Of Yellow Green Leaf Mutant Ygl205 In Rice

The color of the leaves in rices is not only controlled by its own genes,but also affected by environmental conditions.The abnormal development of chloroplast or the change of chlorophyll content and proportion will lead to the mutation of the leaves’ color,which will affect the light energy absorption and electron energy transfer of chloroplast,and then affect the growth and development of rice.In this study,the yellow-green Leaf mutant ygl205(Yellow-green Leaf 205)was used as the main material,which was obtained by mutagenesis of SN9816 with ethyl methyl sulfonate chemical.The indexes of wild type SN9816 and yellow-green leaf mutant ygl205 were determined and analyzed,including morphological indices,important agronomic traits,ultrastructure of the chloroplast,content of the photosynthetic pigment in leaves,the related parameters of photosynthesis,the activities of antioxidant enzymes,the quality traits of rice.Genetic analysis and gene mapping of the mutant gene were also carried out.In order to further enrich the theory of chlorophyll metabolism and photosynthesis in rice,it will lay a foundation for cloning and functional studies of this gene in the future.The results are as follows:1.Compared with the wild-type SN9816,the yellow-green mutant ygl205 showed a yellow-green phenotype from the seedling stage,which existed throughout the whole growth period.The plant height and tillering number of the yellow-green leaf mutant ygl205 were significantly lower than those of the wild-type SN9816,indicating that the mutation of the gene affected not only the development of plant height but also the tillering ability of rice.2.Compared with the wild-type SN9816,the area of the sword leaf,the inverted second leaf and the inverted three leaf of yellow-green leaf mutant ygl205 was significantly reduced,suggesting that the mutation of the gene affected the establishment of functional leaf morphology in rice.3.The chlorophyll content of the yellow-green mutant ygl205 was significantly lower than that of the wild-type SN9816,but the chla/chlb was significantly increased at different periods.Compared with the wild-type SN9816,the chloroplast structure of yellow-green leaf mutant ygl205 was abnormal,the internal matrix was significantly reduced,the number of thylakoid grana lamella and stack layer was also significantly reduced,the starch grains were generally smaller,and osmophilic grains were increased.4.Compared with the wild-type SN9816,the stomatal conductance of the yellow-green leaf mutant ygl205 was significantly decreased,the actual efficiency of photochemical conversion was significantly increased,the coefficient of non-photochemical quenching was significantly decreased,and the transfer rate of apparent electron was significantly increased.The photosynthetic system of the mutant was not completely destroyed and the PSII reaction center still had a complete function.5.Compared with the wild-type SN9816,the data in 2020 and 2021 showed that the1000-grain weight and grains per panicle of yellow-green leaf mutant ygl205 had no significant differences,but the seed setting rate was significantly reduced,and the milling,appearance and taste quality of rice were also decreased to varying degrees.6.Genetic analysis showed that the color phenotype of yellow-green leaf mutant ygl205 was controlled by a pair of recessive nuclear genes.The yellow and green leaf mutant gene was located between 43.2cm-64.9cm on chromosome 1 by map-based cloning,and the gene was located between Indel-6 and Indel8 about 146 kb by expanding the population and designing encrypted primers.