Progress 06/01/08 to 05/31/11
Outputs
Progress Report Objectives (from AD-416) 1) Transfer resistance from P. coccineus into P. vulgaris using the advanced backcross method. 2) Discover markers associated with QTL for resistance. 3) Map candidate genes for resistance to determine if they co-segregate with WM resistance QTL. Approach (from AD-416) Sclerotinia resistant P. coccineus accessions are being used as donors of resistance genes to introgress into P. vulgaris. Backcross-inbred populations have been created, and these are being characterized for resistance with the straw and oxalate tests, and in field disease nurseries. Molecular markers are being mapped in these populations, and analysis of the phenotypic data is being used to identify quantitative trait loci associated with resistance. Germplasm with resistance will be used to create white mold resistant cultivars and will be shared with other bean breeders. This project was initiated on June 1, 2008, and research is ongoing. The overall objective is the transfer and characterization of white mold resistance from P. coccineus into P. vulgaris. ADODR monitoring activities to evaluate research progress included phone calls, meetings with the cooperator, and an annual meeting held each year in January. Our focus has been the transfer of the high levels of white mold resistance found in P. coccineus (runner bean) into common bean. We have analyzed three backcross-inbred populations: OR 91G/PI255956 (115 BC2F4-8 lines), OR 91G/PI433251B (256 BC2F4-7 lines), and M0162/PI433251B (119 BC2F4-7 lines), OR 91G/PI255956 results has been previously reported but briefly, composite interval mapping revealed QTL on B02, B03, B09 and an unlinked fragment that collectively explained 34.7% of the phenotypic variation. Fourteen backcross-inbred interspecific lines with common bean characteristics have shown white mold resistance similar to G122, NY6020, and Ex Rico. The two PI433251B populations were subjected to four and five straw tests, respectively; and two years of field trials. Of 254 markers screened, 119 were polymorphic between parents, but only 40 could be used for map construction in the OR 91G/PI433251B population. Joinmap produced nine linkage groups corresponding to Pv01, Pv02, Pv03, Pv04 (two independent groups), Pv05, Pv06, Pv07 and Pv10 covering 336.7 cM (approximately 28.1% of the estimate bean genome). Composite interval mapping revealed one QTL nearest marker BM153 located on Pv05 associated with field severity and accounting for 6.4% of the phenotypic variation. Single factor analysis (SFA) and Kruskall-Wallis analysis (KWA) revealed 26 and 45 markers, respectively, associated white reduced white mold severity in various tests. Of 254 markers screened in the M0162 x PI433251B population, 91 were polymorphic between parents, but only three linkage groups could be constructed, corresponding to Pv02, Pv03 and Pv04 and consisting of 11 markers covering 42.44 cM (approximately 3.5% of the estimated bean genome). One QTL closely linked to marker BMd17 and located on Pv02 was associated with field severity, and accounted for 9. 8% of the phenotypic variation. Thirty and 26 markers were significantly associated with white mold resistance for SFA and KWA, respectively. Additionally, because all three populations were characterized by many polymorphic but unlinked markers, and a high degree of segregation distortion (higher levels of residual heterozygosity and fewer homozygous donor alleles than expected), we constructed virtual maps using previously published linkage maps to order polymorphic SSRs (both linked and unlinked in our maps). In conjunction with SFA and KWA, probable locations of QTL were identified in absence of the QTL interval mapping.
Impacts
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Progress 10/01/09 to 09/30/10
Outputs
Progress Report Objectives (from AD-416) 1) Transfer resistance from P. coccineus into P. vulgaris using the advanced backcross method. 2) Discover markers associated with QTL for resistance. 3) Map candidate genes for resistance to determine if they co-segregate with WM resistance QTL. Approach (from AD-416) Sclerotinia resistant P. coccineus accessions are being used as donors of resistance genes to introgress into P. vulgaris. Backcross-inbred populations have been created, and these are being characterized for resistance with the straw and oxalate tests, and in field disease nurseries. Molecular markers are being mapped in these populations, and analysis of the phenotypic data is being used to identify quantitative trait loci associated with resistance. Germplasm with resistance will be used to create white mold resistant cultivars and will be shared with other bean breeders. This project was initiated on June 1, 2008, and research is ongoing. The overall objective is to develop white mold resistant dry and snap beans using highly resistant accessions of Phaseolus coccineus as a source. ADODR monitoring activities to evaluate research progress included phone calls, meetings with the cooperator, and an annual meeting held each year in January. Interspecific transfer of white mold resistance in common bean: Common beans such as pinto and kidney beans are highly susceptible to white mold. A related species, the scarlet runner bean has the highest levels of resistance to white mold, and can be crossed to common bean. Resistance in scarlet runner bean is controlled by several genes with strong environmental influence. We backcrossed runner bean twice to the common bean to recover lines with runner bean genes in a common bean background. These lines have been inbred to achieve genetic uniformity, and tested to determine which carry white mold resistance genes. From one cross, we have identified seven lines with high levels of white mold resistance. To increase our chances of transferring all of the resistance genes, we are identifying DNA markers that are associated with resistance genes. The impact of this research is that bean growers will need fewer (or no) applications of fungicide to control white mold.
Impacts
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Progress 10/01/08 to 09/30/09
Outputs
Progress Report Objectives (from AD-416) 1) Transfer resistance from P. coccineus into P. vulgaris using the advanced backcross method. 2) Discover markers associated with QTL for resistance. 3) Map candidate genes for resistance to determine if they co-segregate with WM resistance QTL. Approach (from AD-416) Sclerotinia resistant P. coccineus accessions are being used as donors of resistance genes to introgress into P. vulgaris. Backcross-inbred populations have been created, and these are being characterized for resistance with the straw and oxalate tests, and in field disease nurseries. Molecular markers are being mapped in these populations, and analysis of the phenotypic data is being used to identify quantitative trait loci associated with resistance. Germplasm with resistance will be used to create white mold resistant cultivars and will be shared with other bean breeders. Significant Activities that Support Special Target Populations This project was initiated on June 1, 2008, and research is ongoing. The overall objective is to develop white mold resistant dry and snap beans using highly resistant accessions of Phaseolus coccineus as a source. ADODR monitoring activities to evaluate research progress included phone calls, meetings with the cooperator, and an annual meeting held each year in January. Interspecific transfer of white mold resistance in common bean: White mold disease caused by Sclerotinia sclerotiorum is a serious disease of common bean (Phaseolus vulgaris) which has little physiological resistance. Scarlet runner bean (Phaseolus coccineus) is one of the best sources of resistance available as a secondary gene pool. Interspecific crosses were made between common bean and scarlet runner bean in attempt to introgress resistance from the scarlet runner bean into the common bean background. This project has been focused on characterizing the resistance in two backcross inbred interspecific populations: 91G/PI433251B and MO162/PI433251B. A total of 50 SSRs were screened on the entire population of 91G/PI433251B and 35 SSRs on the MO162/PI433251B. Markers for candidate genes for white mold resistance have been identified and amplification and polymorphism in parental lines has been confirmed for EIN2\EagI, PP2C (phosphatase-2-C), WRKY (transcription factor), CHIT (chitinase) and NPR1\AciI. Primers for CHI (chalcone isomerase), EST (esterase enzyme) and CHS (chalcone synthase) show potential for use as markers. Due to seed limitations, a single replicate � repeated checks experimental design field trial was planted during the summer of 2008. Both populations and all plots were scored for disease incidence (%) and severity (%). The 91G/PI433251B population was read a single time and MO162/PI433251B population was read twice (at the same time as the 91G/PI433251B lines and then eight days later) in order to capture differences among the lines that weren�t evident at the first reading. The results of the field trial showed that the 91G/PI433251B population distribution was skewed toward the greater susceptibility compared to the distribution of the MO162/PI433251B population, which was skewed towards resistance. Once molecular marker data is completed, it will be combined with the phenotypic data and QTL analysis will be performed to detect QTL present in the populations for white mold resistance. The impact of this research is that bean growers will need fewer (or no) applications of fungicide to control white mold. The National Sclerotinia Initiative contributes to the goals of ARS National Program 303 � Plant Diseases.
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