|TRAPP, JENNIFER - Seneca Foods|
|URREA, CARLOS - University Of Nebraska|
|Miklas, Phillip - Phil|
Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/13/2015
Publication Date: 7/1/2015
Citation: Trapp, J., Urrea, C., Cregan, P.B., Miklas, P.N. 2015. QTL for yield under multiple stress and drought conditions in a dry bean population. Crop Science. 55:1596-1607.
Interpretive Summary: Dry edible beans are an important component of cropping systems in the U.S. and globally. In addition, dry beans are a critical source of protein and income for small-holder resource-poor farmers in Africa and Latin America. Dry bean yields plummet when grown under ever-increasing limited water conditions worldwide. Our project is responsible for improving yield of dry bean under drought conditions using conventional breeding techniques. Some bean cultivars exhibit high levels of tolerance to drought – but the genetic control or inheritance of this tolerance is unknown. Our goal was to gain a better understanding of the high yield maintained by Roza pink bean under drought compared to Buster pinto which performs poorly. Both cultivars are high yielding in growing environments with ample water. A hybridization performed between Roza and Buster generated a population of segregating progeny that was tested under drought and non stress environments for multiple years in Washington and Nebraska. The field performance of the progeny lines combined with genotypic marker information was used to identify two major genes on chromosomes 1 and 2 which influenced more that 50% of the yield performance of Roza pink bean under drought stress. This is the first report of major genes for yield under drought stress in dry bean. These genes are also important because they were consistently expressed across years and locations. These findings will assist breeders with development of drought tolerant cultivars for dry land production in the U.S., and contribute to US breeding efforts geared toward developing cultivars for sustainable bean production in Feed the Future countries.
Technical Abstract: Terminal and intermittent drought limits dry bean (Phaseolus vulgaris L.) production worldwide. Tolerance to drought exists but is difficult to breed for because of inconsistent expression across environments. Our objective was to identify quantitative trait loci (QTL) conditioning yield in a recombinant inbred line (RIL) population with consistent expression across multiple drought stress environments. We tested 140 RILs from ‘Buster’ pinto (susceptible)/’Roza’ pink (tolerant) for yield under multiple stress (intermittent drought, compaction, and low fertility) across three years and terminal drought across four location-years. A genetic linkage map (953 cM) was generated using SNP markers. Two QTL with major effect were detected on chromosomes Pv01 and Pv02. The Pv01 QTL, defined by the closest marker SNP50809 (47.7 Mb), explained up to 37% of the phenotypic variance for seed yield under multiple stress (including intermittent drought) and was consistently expressed each year. The Pv02 QTL, nearest SNP40055 (11.8 Mb), was expressed (33%) for seed yield under drought stress and was also detected under multiple stress. Phenological traits cosegregated with the yield QTL and affirmed importance of phenological plasticity in adaptation to drought stress. Late maturity contributed to increased yield under multiple and non stress and early maturity to increased yield under terminal drought. Given major and consistent effect, further investigation of the potential for the Pv01 and Pv02 QTL in breeding for drought tolerance in common bean is warranted.