Location: Tropical Crops and Germplasm Research
Project Number: 6090-21000-054-000-D
Project Type: In-House Appropriated
Start Date: May 19, 2013
End Date: May 8, 2018
1. Identify and map important abiotic (heat and drought) and biotic traits for disease and pest resistance in common bean, and develop useful molecular markers that will help accelerate the breeding process. 1a: Map drought and heat tolerance traits, derived from common bean and tepary, respectively, using bi-parental and association mapping populations and develop markers. 1b: Elucidate the genetics of resistance to pathogen Macrophomina phaseolina, causing ashy stem blight. 2. Develop and release common bean germplasm with higher levels of abiotic stress tolerance, and with multiple resistance, including disease and insect resistance, in important U.S. market classes. 2a: Develop heat and drought tolerant common bean in new market classes, including great northern and cranberry. 2b: Develop germplasm of medium seed size tolerant to multiple root rot pathogens; and to leaf-hoppers. 3. Introgress useful genes from tepary bean into common bean and develop tepary bean as a new crop with superior heat and drought stress tolerance and with improved agronomic and quality traits for areas where bean production is not practical due to severe abiotic stress.
Identification and mapping of important abiotic (heat and drought) and biotic traits will be completed using bi-parental and association mapping populations. Drought and heat tolerance traits, derived from common bean and tepary, respectively, will be evaluated using yield components and stress-response traits. For genotyping, the BeanCAP 6,000 SNP chip will be employed using the Illumina Infinium system that was developed through the BeanCAP project. In order to analyze these complex traits, both quantitative trait loci (QTL) and association mapping (AM) analyses will be employed. The genetics of resistance to the pathogen Macrophomina phaseolina, causing ashy stem blight, will also be elucidated. Controlled trials, using inoculation with M. phaseolina in the field, will be completed. Green house screening techniques for M. phaseolina will be further refined, as greenhouse methods producing more consistent results are needed. Development and release of common bean germplasm with higher levels of abiotic stress tolerance will focus on the great northern and cranberry market classes. Parental crosses will be performed during the shortest photoperiods (winter) in order to ensure flowering of exotic parents and reduced temperature stress during hybridization. About 100-400 F2 progeny will be planted in the field in Juana Diaz for selection for high temperature tolerance in May, or for drought tolerance in December. For root rot and Empoasca resistance, the ARS Isabela Research Farm, PR will be used as the selective environment and the focus will be on general germplasm improvement. Due to differences in genetic control and genetic distance between different germplasm, varied breeding approaches are often required for gene introgression, including recurrent selection, congruity backcrossing, bridging parents or inbred backcross approaches. Useful traits from tepary will be introgressed from inter-specific lines generated at CIAT and at the U. of Saskatchewan. Populations developed from intercrossing will be selected in the F2 under heat stress at the UPR Ag. Substation in Juana Diaz, PR in FY13 based on heat tolerance, plant habit and seed type. In order to take advantage of the superior abiotic stress tolerance of the tepary bean, a concurrent effort will focus on improving agronomic characteristics and virus resistance in tepary bean. The goal is to develop tepary bean germplasm that is capable for use as a crop in areas with high levels of heat and drought stress, such as in arid zones and in areas marginalized by climate change. Although challenging due to genetic distance between the species, crosses between tepary bean and common bean lines with virus resistance genes (e.g., I, bc3) will be completed in order to transfer BCMV and BCMNV virus resistance to tepary. The lines generated will serve as important germplasm for future tepary bean breeding efforts.