Genetics and mapping of the novel leaf-colour mutant gene

Abstract

Leaf colour plays an important role in plant growth and development. In this study, a stably inherited yellow–green leaf mutation, temporarily designated yglw-1, was initially isolated from progenies of wheat (Triticum aestivum L.) cross Bainong58409/Caifumai. The yellow-leaf phenotype could be observed in the yglw-1 mutant during the seedling stage, and then the yellow leaves gradually progressed from the bottom to the top throughout development. Compared with its sister line Cf5019-21 with a normal leaf-colour phenotype, the main agronomic traits of the yglw-1 mutant including spike length, number of kernels per spike and 1000-kernel weight were significantly decreased. Measurement of chlorophyll contents showed that chlorophylls a and b in the third top leaf at the jointing stage and the penultimate leaf and third top leaf at the heading stage were obviously lower in yglw-1 than in Cf5019-21. Genetic analysis indicated that the yellow–green leaf trait was controlled by a single recessive gene. Bulked segregant analysis found that two published simple sequence repeat (SSR) markers and four expressed sequence tag-sequence tagged site (EST-STS) markers were linked to the yglw-1 gene, and BE494262 was the most closely linked marker to yglw-1, at a genetic distance of 2.3 cM. To increase the density of the genetic map, 135 novel SSR markers at a certain distance near the marker BE494262 were developed according to SSR loci detected in the Chinese Spring reference sequence. Of these, nine SSR markers detected polymorphic fragments between the two parents as well as between the contrasting DNA bulks. Finally, the yglw-1 gene was mapped between SSR markers Xhwm1 and Xhwm43 and showed genetic distances 1.9 cM and 23.9 cM on chromosome 2BS. These findings can facilitate candidate-gene prediction and map-based cloning of the yglw-1 gene.