Localization of Quantitative Trait Loci for Dryland Characters in Barley by Linkage Mapping

Abstract

The success of breeding for yield stability in stressful environments has been limited due to the high variability, timing, duration and severity of a number of climatic stresses. In the northwest of Syria, these stresses include cold, terminal drought, and heat occurring during the rainfed barley (Hordeum vulgare L.)-growing season. With the advent of DNA-marker techniques, it has become feasible to develop linkage maps for agricultural crops. Together with statistical procedures, these linkage maps can be used to locate and estimate phenotypic effects of quantitative trait loci (QTL). A genetic linkage map has been developed for recombinant inbred lines of the cross ‘Arta’/Hordeum spontaneum 41-1. A total of 194 recombinant inbred lines randomly chosen from a population of 494 RILs were mapped with 189 markers including one morphological trait (brittle rachis locus). The linkage map extended to 890 cM. Agronomic traits such as grain yield, biological yield, days-to-heading, plant height, cold tolerance, and others were evaluated at the ICARDA’s research stations at Tel Hadya and Breda in the years 1996/1997 and 1997/1998 and QTLs for agronomic traits related to drought resistance were localized. For the most important character “plant height under drought stress”, QTLs on 2H, 3H, and 7H were detected. The “plant height” QTLs, especially the one on 3H, showed pleiotropic effects on traits such as days-to heading, grain yield, and biological yield. Cold tolerance on 5H, days to heading on 7H and 2H, kernel weight on 3H were QTLs identified and localized at similar locations as in other QTL studies. However, for a number of traits QTLs and locations have been described for the first time such as for tillering capacity on 3H, growth habit on 6H and 1H, early growth vigor on 6H. This should allow us to exploit the information for marker-assisted selection of lines better adapted to the Mediterranean drylands.