Cloning And Functional Analysis Of LRR Gene YGL6 In Rice(Oryza Sativa L.)

Leaf color mutant of rice is a good entry point to explore the function of gene.A novel leaf-color mutant ygl6?yellowish-green leaf 6?obtained by ⁶⁰Co?-ray irradiation was analyzed in this study.Through the analysis of physiological characteristics,mapping,subcellular localization and transcriptome sequencing,the main conclusions were as follows:1.Compared with wild type,the mutant was phenotypically yellow under all growth stages,and ygl6 had decreased tillers and lower plant height under natural conditions.The content of photosynthetic pigments in the three-leaf stage suggested that the accumulation of pigments in the mutant was significantly down-regulated,and the phenotype of ygl6 was closely related to this variation.In addition,some immature and smaller chloroplasts,and some without clear inner capsule lamella structure were observed in ygl6 through the transmission electron microscopy.2.Genetic analysis of F₂ generation from cross of Pei'ai 64S and ygl6 revealed that this trait was controlled by a pair of recessive nuclear gene ygl6.3.The mutation gene was located in the region of 88kb on chromosome 6 of rice between molecular marker ID0906 and MM0917 by map-based cloning technique.All the genes in this region were sequenced and we found that the gene Os06g0237502 was mutated in the fourth exon.The deletion of an A base resulted in a frameshift mutation and early termination of protein translation.4.Conservative analysis on amino acid sequence and the characteristics of YGL6 protein revealed that it contained LRR domain and was highly conserved in different higher plants.Further analysis of the evolution relationship between more homologous proteins,YGL6 protein was found to be more closely related to monocotyledonous plants,but distant from dicotyledons.5.Quantitative analysis of the genes related to chlorophyll synthesis,photosynthesis and chloroplast development showed that the gene YGL6 affected the first and second stage of chloroplast development and photosynthesis in rice.6.Transcriptome analysis of wild-type and ygl6 suggested that YGL6 would affect the metabolism of nitrogen in rice.Nitrogen was an important component of chlorophyll,the disorder of nitrogen metabolism would affect the synthesis of chlorophyll and eventually lead to ygl6 etiolation.In addition,nitrogen played an important role in the synthesis of chloroplast proteins,such as the contents and functions of PS?and PS?.Therefore,the reasons of chloroplast developmental deficiency were the nitrogen deficiency and the down-regulation of genes associated with chloroplast development of ygl6 at the transcriptional level.By affecting the transcriptional expression of the related pathway genes,YGL6 also had a certain degree of impact on the photosynthesis and carbon dioxide fixation in rice.This study reported a LRR domain protein YGL6,which was involved in chlorophyll synthesis and chloroplast development in rice.Our research provided a new idea for future studies on the function of LRR proteins and photosynthetic metabolic regulation networks in plants.