Marker-assisted analysis of three grain yield QTL in barley (Hordeum vulgare L.) using near isogenic lines

Three previously identified grain yield quantitative trait loci (QTL) on ch romosomes 2S(2HS), 3C(3HC) and 5L(1HL), designated QTL-2S, QTL-3 and QTL-5L , respectively, were evaluated for their potential to increase yields of hi gh-quality malting barley without disturbing their favorable malting qualit y profile. QTL mapping of yield related traits was performed and near-isoge nic lines (NILs) were developed. QTL for plant height, head shattering, see d weight and number of rachis nodes/spike were detected in the QTL-3 region . NILs developed by introgressing QTL-3 from the high-yielding cv. Steptoe to the superior malting quality, moderate-yielding cv. Morex acquired reduc ed height, lodging and head shattering features of Steptoe without major ch anges in malting quality. The yield of NILs, measured by minimizing the los ses due to lodging and head shattering, did not exceed that of Morex. Stept oe NILs, with the Morex QTL-2S region, flowered 10 days later than Steptoe but the grain yield was not changed. None of the 3 QTL studied altered the measured yield of the recipient genotype, per se, although QTL 2S and QTL-3 affected yield-related traits. We conclude that these yield QTL must inter act with other genes for full expression. Alternatively, they affect the ha rvestable yield through reduced lodging, head shattering, and/or altered fl owering time.