Genetic mapping of diagnostic markers for the Lg 2 locus conferring ligules in Triticum aestivum L. and derived from Aegilops tauschii Coss.

Abstract

It has been suggested that the non-allelic lg 2 and Lg t alleles, that confer liguleless phenotypes, are present in chromosome 2D. We hypothesized that the naturally occurring liguleless phenotype present in polyploid wheat was a typical example of loss of dominant duplicated alleles, a process that has been described as genetic diploidisation. In the present study, we obtained the base sequence of the candidate of Lg 2 gene through a “blastn” query with the upstream region of HvLG, the candidate gene sequence for the ligule locus in barley (Hordeum vulgare), and developed deletion markers of the Lg 2 locus from Ae. tauschii. We applied the deletion markers to locate the Lg 2 locus in hexaploid wheat. The F2 progeny of ANK-33/SynW-5 segregated in a 3 liguled:1 liguleless ratio. The Lg 2 gene was completely linked to markers G3489_2DL12del and G3489_2DL11del and segregated in a 1:2:1 ratio. Liguleless Mutant, a liguleless mutant of Aegilops tauchii, was determined by the dominant Lg t gene. In Ae. tauschii, the F2 progeny of KU2126/Liguleless Mutant, marker Atlg_2DL19del segregated in a 1:2:1 ratio independently of the 3 liguleless:1 liguled segregation. The results indicate that three deletion markers can be used to mark the Lg 2 locus in chromosome 2D of synthetic and hexaploid wheat.