Genetic dissection of heading date and yield under Mediterranean dry climate in barley (Hordeum vulgare L.)

Understanding the genetics of drought tolerance is a major goal of plant breeders, especially in the Mediterranean region due to its sensitivity to drought and climate changes. Here we investigated genomic regions associated with heading date and yield under rainfed (R) and irrigated (I) conditions, along with some drought tolerance indices derived from phenotypic data collected on a panel of 83 European barley cultivars evaluated in field trials in Foggia, southern Italy, for three growing seasons. A genome wide association analysis (GWAS) was carried out using gene-based SNPs incorporated in the Illumina iSELECT Chip with known map position. A total of 4169 polymorphic SNPs were considered after filtering out SNPs with >10 % missing data and <10 % minimum allele frequency. Heritability was high for heading date and moderate for yield. Principle components analysis partitioned the barley germplasm in three subgroups characterized by different row-type and growth habit. A significant association with heading date was detected on chromosome 2HS, where the different alleles of associated markers were able to significantly affect heading date in different cultivars. Moreover, GWAS uncovered a significant association with yield and relative yield under R conditions on chromosome 5HS. These results provide a clue for further analysis on genetic control of barley flowering time and production in response to water stress under Mediterranean dry climate.