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Gerardine Mukeshimana, Amy L. Lasley, Wayne H. Loescher, and James D. Kelly

response to drought in the field. Nine genotypes from the Mesoamerican race of the Middle American gene pool ( Singh et al., 1991 ) were chosen to maintain genetic similarity among genotypes so that drought response can be monitored easier and not be

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R.S. Balardin and J.D. Kelly

Sixty-two genetically diverse modern and traditional Phaseolus vulgaris L. cultivars from Brazil, the Dominican Republic, Honduras, Mexico, the Netherlands, and the United States, representative of the Andean and Middle American gene pools, were selected to study the interaction with distinct races of Colletotrichum lindemuthianum (Sacc. & Magnus) Lams.-Scrib. Principal component and phenetic analyses were conducted on the disease reaction to inoculation with 34 races of C. lindemuthianum from Argentina, Brazil, Colombia, Costa Rica, the Dominican Republic, Honduras, Mexico, Peru, and the United States. The principal component analysis revealed four clusters in which only one cluster consisted of cultivars from both gene pools. Bean genotypes clustered based on the gene pool origin of the resistance genes present, regardless of the actual gene pool of the host genotype. Middle American genotypes in cluster A carried Andean resistance genes. Further grouping of genotypes based on overall level of resistance within each gene pool was observed. Clusters A and C consisted of the most resistant genotypes from both gene pools. The distribution of genotypes generated by the phenetic analysis, placed the most resistant and susceptible genotypes of the anthracnose differential series at the extremities of the phenogram, providing support for the range in genotypic resistance exhibited by members of the differential series. Races of C. lindemuthianum isolated from Middle American genotypes showed broad virulence on germplasm from both gene pools, whereas races with Andean reaction showed high virulence only on Andean germplasm. The reduced virulence of Andean races on Middle American genotypes suggests selection of virulence factors congruent with diversity in P. vulgaris. In addition, races of C. lindemuthianum formed two clusters corresponding to the Middle American and Andean reaction groups based on the phenetic analysis. In the principal component analysis, most races with the Andean reaction were observed in the clusters C and D, except races 15 and 23 which clustered with Middle American races in cluster B. Only races 38, 39 and 47 from the Dominican Republic showed high similarity in both multivariate analyses and clustered based on geographic origin. Races from other countries showed no geographic effect. The overlapping of specific races, however, with races from different reaction groups might indicate that this group of isolates possesses factors of virulence to both host gene pools. Data based on virulence supports variability in C. lindemuthianum structured with diversity in P. vulgaris.

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Mark J. Bassett, Rian Lee, Tim Symanietz, and Phillip E. McClean

Two common bean (Phaseolus vulgaris L.) genes, J (modifies seedcoat color and pattern) and L (modifies partly colored seedcoat pattern), were tested for allelism using genetic tester stocks. Those stocks have a common genetic background by backcrossing to the recurrent parent, Florida dry bean breeding line 5-593, that has black self-colored seeds and purple flowers due to the genotype T P [C r] Z J G B V Rk. Specifically, the L gene from `Thuringia' and the lers gene from `Early Wax' were tested for allelism with the j gene from various genetic tester stocks. L was found to be identical with j, but l ers was a different allele at J. We propose the gene symbols J (formerly l), j (formerly L), and j ers (formerly l ers). The seedcoat genotype of `Thuringia' was found to be t P C z j g b v lae rk d. A new seedcoat pattern called reverse margo was found to be determined by the genotype T/t z/z j/j ers in a P C G B V genetic background. A randomly amplified polymorphic DNA marker was developed for the j gene (formerly L) from `Thuringia' using bulk segregant analysis in an F2 population segregating for j vs. J in a t z genetic background, i.e., from the cross t z j × t z J in BC1 to 5-593. The linkage distance between marker OL4525 and j was determined to be 1.2 cM. In a population segregating for J and j ers, the distance between the marker and j ers was determined to be 4.7 cM. The utility of marker OL4525 is limited primarily to the Middle American gene pool.

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Charles J. Wasonga, Marcial A. Pastor-Corrales, Timothy G. Porch, and Phillip D. Griffiths

-resistance genes); whereas the cultivars from the Middle American gene pool included ‘Great Northern 1140’ ( Ur-7 ), ‘Aurora’ ( Ur-3 ), ‘Mexico 309’ ( Ur-5 ), ‘Mexico 235’ ( Ur-3+ ), ‘Compuesto Negro Chimaltenango’ (CNC; unknown rust-resistance genes), and ‘PI

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Charles J. Wasonga, Marcial A. Pastor-Corrales, Timothy G. Porch, and Phillip D. Griffiths

grouped into Ur-4 , Ur-6 , Ur-9 , Ur-12 , and Ur-13 , which originate from beans of the Andean gene pool and Ur-3 , Ur-5 , Ur-7 , and Ur-11 from the Middle American gene pool ( Pastor-Corrales et al., 2007 ; Steadman et al., 2002 ). The Ur-3