Gene Mapping Of Rice Albino To Yellow Leaf Color Mutants

Rice is one of the most important food crops in the world today,and more than66%of the nutrients in the grain are accumulated through photosynthesis during the reproductive growth period.Chloroplast differentiation and development is an important process closely related to rice growth and yield formation.In this study,albino to yellow leaf color mutant ayl1 was identified in the chromosome segment substitution line population generated by Changhui 121 and Koshihikari as parents,and this mutant was used as research material to analyze during its growth and development.Its morphological characteristics,agronomic traits and physiological and biochemical characteristics,and analysis of genetic patterns,gene positioning and replacement genes and bioinformatics analysis.The main results are as follows:1.The mutant ayl1 showed white leaves in the front leaf of the third leaf stage,and the leaf color turned green after the third leaf stage from the midrib to the edge of the two ends,and finally showed the yellow leaf phenotype,this yellow leaf phenotype lasts until maturity.The plant height is lower than that of wild type,the content of chlorophyll a,chlorophyll b and carotene is significantly lower than that of wild type,the stomatal conductance is slightly higher than that of wild type.Wild type,and the concentration of carbon dioxide between cells is higher than wild type.NBT staining and DAB staining revealed that the accumulation of O₂^–and H₂O₂in ayl1leaves was higher than that of wild type.By observing the ultrastructure of the chloroplast,it was found that the mutant ayl1 cell had a simple internal structure,and the chloroplast showed dysplasia,which was specifically manifested in the small number of chloroplasts,the size of the volume,and the disorder of the thylakoids.2.In the F₂population where the mutant parent and substitution line background parent Changhui 121 overlapped,the ratio of normal green leaf and albino leaf plants was 3:1,which was in accordance with Mendelian single gene inheritance law,indicating that the ayl1 was subject to discrete hidden Sexual nuclear gene control.The ayl1 gene was located between the In Del marker R-4 and the SSR marker RM5302 with the physical distance of the short arm of chromosome 1 at 30.6 kb using BAS and map cloning.By searching the rice gene database,it was found that there are 4 open reading frames in this interval:LOC＿Os01g08400,LOC＿Os01g08410,LOC＿Os01g08420,LOC＿Os01g08430.The four open reading coding frames were cloned,combined,and sequence aligned,and it was found that the wild type and mutant had a string T mutated to G on LOC＿Os01g08420,resulting in the missense mutation of the encoded isoleucine to serine.So it is speculated that LOC＿Os01g08420 is a replacement gene for ayl1.Comparing the results of previous studies,it was found that LOC＿Os01g08420 is a predetermined gene of the SSG4gene that has been cloned to control the size of starch granules,and this gene also affects the development of plastids.No genes related to leaf color mutations have been reported in this region,so ayl1 is a new mutant material.3.The expression of LOC＿Os01g08420 in the leaves of the three-leaf stage and heading stage showed that the mutant was higher than that of the wild type,and the expression of the mutant and the wild type in glume husk was not different.At the same time,by analyzing the expression levels of related genes in the processes of rice chlorophyll synthesis,chloroplast development,chloroplast transcription/translation and photosynthesis,we found the expression levels of wild-type indexes,mutants involved in chloroplast development related genes V2 and SPP in both the three-leaf stage and the heading stage,it showed a downregulation,the expression levels of Rpo B and Rps12 genes involved in chloroplast transcription/translation are up-regulated in both the three-leaf stage and the heading stage,so it is speculated that the ayl1mutation may affect the development of chloroplasts,thus affecting photosynthesis.4.The predetermined gene LOC＿Os01g08420 has a genomic DNA length of6931bp and a CDS of 3069bp.It consists of 14 exons and 13 introns and encodes a protein consisting of 1022 amino acids;there are light-responsive elements and a few hormones in its promoter Related elements and related elements in response to stress are related to meristem expression,indicating that LOC＿Os01g08420 may be induced by light signals,hormones,and other abiotic environments,and is related to meristem expression;the physical and chemical properties of the LOC＿Os01g08420 sequence indicate that the expressed protein Under physiological conditions,it is negatively charged and belongs to a stable protein,showing hydrophilicity;using Prot Scale analysis of its hydrophilicity and hydrophobicity,the results show that it is hydrophilic.