Biological Characteristics And Gene Mapping Of Leaf Color Mutants In Rice

Mutation of leaf color mostly caused changes in photosynthetic pigment content or abnormal chloroplast development in rice,resulting in reduced photosynthetic efficiency and impeded growth of rice.It has important theoretical value and practical significance for carrying out basic theoretical research and applied research of genetic breeding for leaf color mutants.In this study,ethyl methyl sulfonate(EMS)was used to mutate rice male thermo-sensitive male sterile line T91 S and rice inbreed line.i.e.Q64,F18,3038,4631,and 4607.This study screened leaf color mutants of obvious phenotype and genetic stability.The biological characteristics of leaf color mutants were studied.The genetic mapping population of a population analysis BSA(Bulked Segregant Analysis)was constructed and the gene mapping of leaf color mutant genes was performed with whole genome sequencing.The results were:1,25 leaf mutant strains with obvious phenotypes and genetic stability were screened by using 0.5% EMS solution to mutate the male thermosensitive male sterile line T91 S and rice inbreed line.i.e.Q64,F18,3038,4631,and 4607.These leaf color mutants were classified into 4categories according to the seedling phenotype: yellowing,yellow-green,zebra leaf and green-revertible albino.2,The mutant Q64m1 had yellow leaf during the whole growth period and the contents of photosynthetic pigment in mutants was significantly less than wild-type plants.Compared with wild-type plants,photosynthetic efficiency of the mutant flag leaves decreased.In maturity,the plant height,effective panicles,and total grains per panicle were significantly lower than wild-type plants.Genetic analysis showed that the mutant phenotype was controlled by a pair of recessive nuclear genes.By whole-genome sequencing analysis of BSA,there were 1 candidate genes on chromosome 5,8 and 11,respectively.3,The yellow-green mutant F18m2 maintained a yellow-green phenotype during the whole growth period,and the contents of photosynthetic pigment were reduced compared with wild type.Photosynthetic efficiency of the mutant was significantly lower than wild-type plants.Compared with wild-type plants,pupal length,plant height,total grains per ear,seed setting rate and thousand-grain weight of the mutant in maturity had significantly reduced.Genetic analysis showed that the mutant phenotype was controlled by a pair of recessive nuclear genes.By whole-genome sequencing analysis of BSA,there were 2,2,3,1,1and 2 candidate genes on chromosome 2,3,7,8,11,and 12,respectively.4,The zebra mutant named Q64m3 had yellow-green zebra stripes in the seedling stage,and the zebra leaf returned to normal in tilleringstage.The photosynthetic pigment content of mutant Q64m3 was lower than wild-type plants in seedling stage and tillering stage,and there was no significant difference in photosynthetic parameters of heading stage compared with wild-type plants.Compared with wild-type plants,agronomic traits of maturity reduced in respect of plant height and effective panicles.5,The mutant of green-revertible albino F18m3 has turned albino in seedling stage and turned green during tillering stage but failed to turn green completely.The photosynthetic pigment content of the mutant was lower than wild-type plants,and the photosynthetic efficiency of the mutant were significantly lower than wild-type plants.In mature stage,plant height of the mutant was lower and total grains per ear of the mutant was increased than wild-type plants.6,The mutation traits of mutant with old yellowing leaf and new light green leaf named 4607m1 were genetically analyzed and the separation ratio did not meet the 3:1 ratio.After genome-wide sequencing,there were 1 candidate genes located on chromosome 3 and 5,respectively.7,The mutant of green-revertible albino T91Sm1 was albino seedlings before the second leaf stage,and reverted green after the second leaf stage,but the immature leaf was still albino.The photosynthetic pigment content of immature leaf and mature leaf of the mutants inseedling stage were significantly lower than wild-type plants.In tillering stage,the immature leaf of the mutant were albino and the photosynthetic pigment content was significantly decreasing;the mature leaf was completely green,and the photosynthetic pigment content reverted to wild-type levels.Photosynthetic parameters of the mutants in heading stage were not significantly different from wild-type plants.Compared with wild-type plants,the agronomic traits of the mutants reduced plant height,total grains per panicle,and pupal length in the maturity stage.Heterosis analysis showed that the mutant T91Sm1 had heterosis in plant height.Genetic analysis showed that the mutant phenotype was controlled by a pair of recessive nuclear genes.There were 4 candidate genes located on chromosome 11 by whole genome sequencing and fine mapping.