Annual Report: 2005

Validation and Pyramiding White Mold Resistance from P. vulgaris and P. coccineus into an Interspecific Recombinant Inbred Population

Investigators: Mark A. Brick, Patrick F. Byrne, and Howard F. Schwartz, Colorado State University, Fort Collins, CO

Publications Related to this Project: 
Maxwell, J.J., Brick, M.A.*, Byrne, P.F., Schwartz, H.F., Shan, X., and Ogg J.B. 2005. Identification of quantitative trait loci linked to white mold resistance in common bean.  Poster. Bean Improvement Cooperative Biennial Meeting, Newark, DE, Oct 31-Nov 3, 2005.

Brick, M.A., J.J. Maxwell, P.F. Byrne, H.F. Schwartz, and R. Henson. 2005. Validation and Introgression of White Mold Resistance from Andean Into Middle American Germplasm. 3rd Sclerotinia Initiative Annual Meeting, Jan. 18-20, 2005. Minneapolis, MN.

Maxwell, J.J., M.A. Brick, P.F.Byrne, H.F. Schwartz, X Shan, J.B. Ogg, and R. Henson. 2006. Identification of quantitative trait loci linked to white mold resistance in common bean. Annual Report Bean Improvement Cooperative 49:63-64.

Brick, M.A., J. J. Maxwell, P. F. Byrne, X. Shan, H.F. Schwartz, J.B. Ogg, and R. Henson. 2006. Quantitative trait loci linked to white mold resistance in common bean.  Abstracts Western Society of Crop Science, 19-21 June 2006. Torrington, WY.

Publications in preparation:
Maxwell, J.J., M.A. Brick, P.F.Byrne, H.F. Schwartz, X Shan, J.B. Ogg, and R. Henson. 2006. Identification of quantitative trait loci linked to white mold resistance in common bean. In preparation. To be submitted to Crop Science August, 2006.

There were no patent activities.

Technology Transfer efforts included:
Poster presentation at the Annual Meeting of the Bean Improvement Cooperative in Newark Delaware in 2005

Poster presentation at the 3rd Sclerotinia Initiative Annual Meeting, Jan. 18-20, 2005. Minneapolis, MN.

Accomplishments:
The long-term goal of this research is to validate the effects of a resistant QTL on linkage group B7 in the common bean, and to combine forms of genetic resistance using molecular markers linked to resistance genes found in Andean common bean line G 122 with resistance genes from the related species P. coccineus. Before our long-term goal could be achieved, we developed a recombinant inbred line population (CSU RIL population) from a cross between an elite pinto line and G 122 to produce 117 F5:6 recombinant inbred lines. Year 1 funding enabled us to screen the RIL population using the straw test and initiate identification of lines that possessed the quantitative trait locus (QTL) on linkage group B7 identified by Miklas et al. (2001). Year 2 funding allowed us to validate the effect of the B7 QTL, map the RIL population, identify lines that possessed high levels of resistance, and identify additional QTL for resistance. During year 2 we were able to: 1) Validate the utility of the Phs SCAR marker linked to the B7 QTL from the parent G 122 using field and greenhouse evaluations, 2) map the markers found in the RIL population, and identify new markers linked to resistance, and 3) evaluate genetic compatibility between several lines in the CSU RIL population and an accession of P. coccineus found to have high levels of resistance to white mold by Gilmore and Myers (2003).  During Year 3, we verified that two RIL had significantly higher resistance than G 122, including lines CSU RIL 31 and 67 which had a disease severity indicies (DSI) of 3.2 and 3.4, respectively, compared to 4.5 for the resistant parent G 122. One hundred twenty four molecular markers were used to map the CSU RIL population based on AFLP, SSR, RAPD and SCAR markers. A significant relationship (P < 0.01) was found between the B7 QTL and resistance to white mold based on both greenhouse, and field tests conducted in Carrington, ND in 2005. Based on composite interval mapping (CIM), strong evidence indicated that three additional QTL in the CSU RIL population influenced physiological resistance to white mold and each QTL accounted for between 8 and 17% of the resistance. These QTL were linked with marker loci on linkage groups B2, B6a, and B7, respectively. These results will provide plant breeders with a better understanding of resistance to white mold and molecular tools to enhance selection for resistance. In Year 3 we also initiated the development of an inbred backcross line (IBL) population between the two most resistance CSU RIL and the P. coccineus accession identified by Gilmore and Myers. One of the two crosses produced fertile hybrid F1 plants and will be used to develop the IBL population to validate markers (identified in our lab) linked to resistance in the G 122 source, and those identified by Gilmore and Myers (2003) from P. coccineus in the interspecific population. This procedure represents an important step in the long term approach to pyramid resistance genes from common bean with resistance from P. coccineus, and to facilitate the breeding process using marker assisted selection.  This is the only attempt to introgress sources from two Phaseolus species that have been previously mapped for makers linked to resistance loci.

Future Plans and Efforts:
In Year 4 (2006-2007) we will complete the advancement of the IBL population to the BC1F5.  This IBL population will allow us to characterize each line (~140 lines) for reaction to white mold in replicated straw tests, and determine the QTL composition of each line using molecular markers developed during the first three years at CSU and those developed by Gilmore and Myers for P. coccineus. To date we have determined that all the resistant QTL found in the CSU RIL population (P. vulgaris) are polymorphic to the P. coccineus parent used to develop the IBL population. Among the primers used by Gilmore and Myers for P. coccineus, we have been able to identify polymorphisms between the P. coccineus parent and the P vulgaris parents of the IBL for three of the six. We are currently modifying our PCR methods to attempt to identify all six of the resistant QTL identified by Gilmore and Myers.  We anticipate near completion of the initial screening and molecular characterization of the IBL population by July 1, 2006.