Identification And Gene Mapping Of Chlorophyll-Deficient Mutant B23 In Wheat

Leaf color mutants are important materials for studying photosynthesis,chlorophyll metabolism and chloroplast development in plants.The morphological characteristics,chloroplast ultrastructure,physiological characteristics,genetic rules and chromosomal location of a stable genetic wheat leaf color mutant B23 selected from the mutagenic progeny of shannong 33,a common wheat variety induced by sodium azide,were studied systematically in this paper.the main results are as follows:1.B23 showed chlorosis phenotype during the whole growth period,which was most obvious at seedling stage.With the development of growth period,the leaf color slightly turned green,and the heading stage was Significantly delayed than that of wild type.The plant height,panicle length,flag leaf length,panicle number,yield per plant and 1000-grain weight of B23 decreased significantly,while the effective panicle number per plant and seed setting rate did not change significantly.2.Chloroplast ultrastructure showed that the chloroplast structure in mesophyll cells was unchanged,but the chloroplast shape changed from normal oval shape to irregular shape.The arrangement order of lamellae in chloroplast inner sacs is relatively chaotic in the matrix.3.Photosynthetic pigment content of B23 in different periods was significantly lower than that of wild type,and the content of chlorophyll b was mainly decreased.Proto ?,the intermediate product of chlorophyll anabolism pathway,did not accumulate.The net photosynthetic rate decreased slightly and its photosynthetic capacity decreased.4.Genetic analysis showed that B23 mutant traits were controlled by a pair of recessive nuclear genes.5.The mutant gene on chromosome 7AL by BSA combined with wheat 660 K chip,the genetic distances between AX-10938813 and AX-110487260 KASP markers are 0.7cM and 0.3cM respectively,and they are separated from AX-94521626 and AX-111685929,and they are named cn-A1.The candidate genes of cn-A1 were preliminarily predicted in the target segment,and the functional annotation was magnesium ion chelate synthase gene.