Phenotypic and genotypic variation in flowering time in Ethiopian barleys

Abstract

A set of 192 barley genotypes of wide eco-geographic origin were evaluated for flowering time (FT), the major adaptive trait in Ethiopian barleys. Morphological, functional and DArT markers were used to explore trait-marker associations, population structure, genetic diversity and extent of pair-wise linkage disequilibrium (LD). A wide magnitude of variation in FT was detected within and across environments and spanned at least 50–60 days with clear G × E interactions (GEI). The average DArT polymorphism estimated by gene diversity and polymorphic information content (PIC) was 0.33 and 0.27 respectively. Four distinct subpopulations, with one outlying group were identified which indicated that the populations were structured. The genome-wide LD extended up to 25 cM, with extensive variation at chromosome level. Markers associated with FT were found close to known QTLs for FT such as VRN-H1, VRN-H3, Ppd-H1, Ppd-H2 and earliness per se (Eps-2S), but also in regions known for FT-like and CO-like genes working under short days. In some QTLs the magnitudes and directions of the effects varied with environments. It is proposed that genes conditioning tolerance to drought and/or waterlogging interact with FT genes and modify the phenotype. A non-random association of alleles on different chromosomes—vrs1 (2H), BYDV resistance (3H) and srh (5H) associated with altitude and FT indicated a co-adapted gene complex. A set of 95 genotypes were selected to represent the Ethiopian section of the Barley Core Collection.