Wild bean populations as source of genes to improve the yield of cultivated Phaseolus vulgaris L.

摘要

Yield is a focus of many common bean breeding programs. Up to now, it has been difficult to obtain substantial yield increases in this crop, compared to advances in crops like corn and sorghum. The limited extent to which genetic diversity has been utilized in the development of common bean cultivars could be a major factor explaining this situation. In this study, a wild and a weedy accession were evaluated to determine their potential contribution to increase yield of an elite common bean cultivar. We developed recombinant inbred (RI) populations for the analysis of the inheritance of yield and yield components via quantitative trait loci (QTL) analysis. Inbred backcross (IB) line populations were also developed to assess the value of these wild and weedy accessions for yield improvement. Due to the plant morphology of wild and weedy parental lines, phenotypic evaluations presented field management challenges that were addressed during the course of this study. Two genetic linkage maps were developed in the RI populations. Approximately 140 markers (AFLPs, ISSRs, CAPS, and RFLPs) were assigned to each map. Genome coverage was about 500 cM per genetic map. At the phenotypic level, none of the IB progeny lines resulting from the cross with the wild accession had yields significantly higher than that of the elite cultivar. However, two QTLs from this accession had a positive effect on yield and/or yield components. Additionally, two IB lines in the progeny of the weedy accession had yields significantly higher than that of the elite cultivar. These results confirm the suitability of the IB method to evaluate the potential of wild and weedy accessions to increase the yield of elite cultivars. Furthermore, the QTL analyses revealed the presence of beneficial wild loci with no discernible undesirable effects that could be further evaluated and introgressed into the domesticated gene pool. The benefit of some of these wild QTLs would not have been detected by a purely phenotypic analysis of both RI and IB populations. These results demonstrate the potential that wild accessions have for improving the yield of domesticated common bean.