Characterization and fine mapping of a leaf yellowing mutant in common wheat

Creation of leaf color mutants is the options in the study of photosynthesis, chloroplast development and Chlorophyll biosynthesis. In this study, a leaf color mutant NAU31 was identified from tissue culture of common wheat. In general, the mutant exhibited whole plant yellowing, fewer tillering, dwarfing and interestingly, improved resistance to wheat powdery mildew. Photosynthetic physiological analysis showed that the chloroplast inner structure varied in the mesophyll cells of the mutant, and this may lead to reduced chlorophyll content (chlorophyll “a”, Chlorophyll “b”, total chlorophyll and carotenoid), as well as decreased maximum quantum efficiency of photosystem II (Fv/Fm) and net photosynthetic rate. Transcriptome analysis indicated that the impairing of photosynthesis may be responsible for plant yellowing of NAU31. Inheritance analysis showed that NAU31 was a gain-of-function mutant and the yellowing trait was controlled by a dominant gene, namely Taymg (yellow mutant gene). SSR markers analysis preliminarily mapped Taymg to the distal short arm of chromosome 2D using an F2 population from the cross between NAU31 and W7984, a synthesized wheat. The mapping result was confirmed by BSA using a 55 K wheat SNP array. Through recombinants screening, the Taymg was finely mapped to the terminal region of 2DS, flanked by markers ZH47 and gwm296 and corresponding to a physical interval of 0.76 Mb. The cloning of Taymg will facilitate the dissection of the mechanism involved in chloroplast development of wheat and the coordinating of plant development and disease resistance.