QTL for relative water content in field-grown barley and their stability across Mediterranean environments.

A quantitative genetics approach was developed to identify the genomic regions that control relative water content (RWC) in field-grown barley. The trait was previously demonstrated to be a relevant screening tool of drought-tolerance in cereals, as well as a good indicator of plant water-status. The trait was measured at the heading stage on flag leaves recorded from 167 recombinant inbred lines grown in several Mediterranean sites (Montpellier, France; Meknès, Morocco; Le Kef, Tunisia). The results obtained confirmed that several genomic regions are implicated in the total phenotypic variation of RWC. A total of nine chromosomal regions were identified. One region situated on the long arm of chromosome 6H contains the most-consistent QTL obtained in the present study. This region was previously identified as controlling RWC, as well as leaf osmotic potential under water stress and osmotic adjustment, from an experiment conducted in growth-chamber conditions with the same genetic background. The confirmation of the role of this region in the genetic control of water and turgor status underlined its interest for breeding purposes in the Mediterranean area. In addition, the presence of several dehydrin loci in the same chromosomal area reinforce its interest for genomics analyses to confirm, or not to confirm, the implication of these genes in the variation of RWC.