LAUSR

The yellow-green leaf color mutant (Ygm) is a spontaneous mutant derived from the common wheat (Triticum aestivum L.) cultivar Xinong1718. Genetic analysis has shown that a novel single incompletely dominant gene (Y1718) is responsible for the yellow leaf color phenotype. The progeny of Ygm exhibit three distinct leaf color phenotypes, i.e., yellow (Y), yellow-green (Yg), and normal green (G). Y plants have yellow-green leaves in the seedling stage, which become yellow or a strong gold-yellow in the booting stage, with dwarfism and thin tillers until the flowering stage, and underdeveloped thylakoid membranes without well-structured grana in the chloroplasts. Yg plants always have a yellow-green phenotype with a number of well-structured grana that are loosely connected with stroma lamellae in the chloroplasts, where their main agronomic traits are the same as Xinong1718 and G plants, but the seed yield is low. Compared with Xinong1718 and G plants, Y and Yg plants had much lower chlorophyll (Chl) a, Chl b, and carotenoid contents in the booting stage. Molecular analysis using an F2 population and F2:3 lines derived from a cross of Yg and Shannong1 indicated that the Y1718 gene is located on chromosome 2BS, where it is flanked by the simple sequence repeat marker Xwmc25 and expressed sequence tag-sequence tagged sites marker BE498358 at genetic distances of 1.7 and 4.0 cM, respectively. Our results facilitate the fine mapping and gene cloning of Y1718 to explore chlorophyll synthesis, metabolism, and development in wheat.