Cytological and microsatellite mapping of the genes determining liguleless phenotype in durum wheat

Abstract

Liguleless phenotypes of wheat lack ligule and auricle structures on all leaves of the plant. Two recessive genes principally control the liguleless character in tetraploid wheat. The F2 progenies of k17769 (liguleless mutant)/Triticum dicoccoides and k17769/T. dicoccum segregated in a 15:1 ratio, whereas the F2 progenies of k17769/T. durum and k17769/T. turgidum segregated in a 3:1 ratio. A new gene, lg 3, was found on chromosome 2A. Segregation of F2 progenies between k17769 and chromosome substitution lines for homoeologous group 2 chromosomes suggested that the liguleless genotype had occurred by mutation at the lg 3 locus on chromosome 2A, and then by mutation at the lg 1 locus on chromosome 2B, in the process of domestication of tetraploid wheat. The gene (lg 1) was linked to Tc 2 (11.9 cM), which determines phenol colour reaction of kernels, on the long arm of chromosome 2B. The distance of lg 1 to the centromere was found to be 60.4 cM, and microsatellite mapping established the gene order, centromere – Xgwm382 – Xgwm619 – Tc 2 – lg 1 on the long arm of chromosome 2B.