نقشه يابي QTL هاي كنترل كننده تحمل به خشكي در گندم نان (Triticum aestivum)

QTL mapping for drought tolerant in bread wheat (Triticum aestivum)

Drought tolerance is a quantitative trait and immeasurable directly. Hence, for assessing drought tolerance related characters should be measured. Drought related characters such as root architecture and water use efficiency are quantitative traits and their phenotypic assessment, especially under filed conditions, is difficult. Consequently marker assisted selection is a superior tool for overcoming this problem. At this research genetic control of drought related characters was assessed using QTL analysis method. A set of 220 double haploid lines, derived from Kukri (drought sensitive) and RAC875 (drought tolerant), were used. Overall, 35 QTL on 11 chromosomes were identified. Ten QTL had R2>10. 63% of identified QTLs were located on B genome that shows the substance of this genome in drought tolerance. Root system and water use efficiency are two imperative drought tolerant mechanisms. But their phenotypic assessment under drought condition is either difficult or impossible. Hence these two worthwhile mechanisms are ignored at breeding programs. At this research 3 QTLs on chromosomes IB, 5A and 5B were identified for root number that explained 39.7 percent of phenotypic variations. Also 3 QTLs on chromosomes IB, 4B and 6D were responsible for genetic control of water use efficiency and explained 30 percent of phenotypic variation. Root number and water use efficiency have genotypic correlation, the genotypes with more root had more water use efficiency. Leaf width is the most important related character for early vigor. Five QTLs on chromosomes 2B, 2D, 3D, 5A and 6A were identified for leaf width that explained 41.6 percent of phenotypic variations. Selecting genotypes, using Marker assisted selection (MAS), for favorable alleles that has been identified in this study such as Gwm0304b and Barc0256 may allow to improve drought tolerant mechanisms, consequently yield at drought prone environments.