Submitted to: Molecular Breeding
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/2/2000
Publication Date: N/A
Interpretive Summary: In order for malting barleys to be agronomically competitive, they must have good malting quality and must also yield well. In this study, we used molecular techniques to prepare barley lines that have improved yield genes from the good-yielding, poor-malting barley Steptoe and malting quality genes from the good-malting, poor-yielding variety Morex. Some of these two gene types occur very near each other, and it was previously hard to get both of the optimized sets of genes into the same progeny. In addition, the improved yield traits were small and hard to measure. Using modern gene manipulation techniques, it was possible to create barleys that had genes for both high yield (three sets) and good malting quality (two sets). Testing of these lines in four locations showed that the genes for high yield increased different plant characteristics that should increase yields under stressful conditions. However, under the benign conditions that occurred in the breeders plots, no major yield increases were found. In one case, it seems likely that the barley line would benefit farmers by maintaining relatively high yields under stressful growing conditions; in the other two cases, it appears that the tested genes probably must interact with other genes before improved yields will be obtained. Overall, this work demonstrates that it is possible to combine both yield and malting quality genes in barley lines and that the good malting quality of the barleys will be maintained. While barley characteristics that should lead to improved yields can be bred into the barleys, this will not always lead to improved barley yields in farmers fields. These results will allow barley breeders to breed lines that will yield better under stressful conditions and still have good malting
Technical Abstract: Three previously identified grain yield quantitative trait loci (QTL) on chromosomes 2S(2HS), 3C(3HC)and 5L(1HL), designated QTL-2S, QTL-3 & QTL-5L respectively, were evaluated for their potential to increase yields of high-quality malting barley without disturbing their favorite malting quality profile. QTL mapping of yield related traits was performed and near-isogenic lines (NILs) were developed. QTL for plant height, head shattering, seed 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 reduced height, lodging and head shattering features of Steptoe without major changes in malting quality. The yield of NILs, measured by minimizing the losses due to lodging and head shattering, did not exceed that of Morex. Steptoe 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 interact with other genes for full expression. Alternatively, they may affect the harvestable yield through reduced lodging, head shattering, and/or altered flowering time.