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Rhiana F. Jones, Paul W. Bosland, Robert L. Steiner, Richard W. Jones, and Mary A. O’Connell

-specific responses. This study reports for the first time, a direct comparison of the gene expression changes during the foliar blight syndrome using two different races of P. capsici on C. annuum host plants with resistant and susceptible phenotypes to those

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Narinder P.S. Dhillon, Supannika Sanguansil, Supornpun Srimat, Roland Schafleitner, B. Manjunath, Parag Agarwal, Qu Xiang, Mohammed Abu Taher Masud, Thaingi Myint, Ngo Thi Hanh, Tran Kim Cuong, Conrado H. Balatero, Venus Salutan-Bautista, Michel Pitrat, Aleš Lebeda, and James D. McCreight

pathotypes ( Lebeda et al., 2011 ) and races ( Lebeda et al., 2016 ). The use of disease-resistant varieties is an economical and safe approach for disease management. Accessions resistant to CPM have been identified in melon ( Cucumis melo ; Dhillon et al

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Beiquan Mou, Steven J. Klosterman, Amy Anchieta, Elisabeth Wood, and Krishna V. Subbarao

pathogenic races of V. dahliae have been identified in lettuce and tomato ( Baergen et al., 1993 ; Hayes et al., 2011b ; Vallad et al., 2006 ), and both of these races can be recovered from infested spinach ( Spinacia oleracea L.) seeds ( Short et al

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Ana María Prados-Ligero, María José Basallote-Ureba, Carlos José López-Herrera, and José María Melero-Vara

conditions; in contrast, cultivars with resistance to several Fod races show unstable and variable reactions to the disease ( Ben-Yephet et al., 1997 ). Garibaldi (1975 , 1977 ) first reported Fod races 1 and 2 in Italy and France. Subsequently, six

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Ariadna Monroy-Barbosa and Paul W. Bosland

pathogen presents different physiological races for the syndromes root rot and foliar blight, breeding P. capsici -resistant cultivars has been an arduous task ( Glosier et al., 2007 ; Oelke et al., 2003 ; Sy et al., 2008 ). P. capsici requires two

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David C. Zlesak, Darcy Ballantyne, Matthew Holen, Andrea Clark, Stan C. Hokanson, Kristen Smith, Jason D. Zurn, Nahla V. Bassil, and James M. Bradeen

genotype. Over the years, multiple research groups have collected isolates within their geographic region and classified them into physiological races based on virulence on a set of independently chosen host cultivars ( Bolton and Svejda, 1979 ; Debener et

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Phillip D. Griffiths, Laura Fredrick Marek, and Larry D. Robertson

characterized into at least six distinct races, the most important of these being races 1 and 4, which account for over 90% of black rot disease worldwide ( Vicente et al., 2001 ). B. oleracea accessions have not been identified that exhibit complete

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E. Zamora, P.W. Bosland, and S. Thomas

The resistance of `Carolina Cayenne' (Capsicum annuum L.) to root-knot nematode Meloidogyne incognita (Kofoid & White) Chitwood races 1, 2, 3, and 4 was measured. Egg counts from roots were used to determine the plant's resistance to M. incognita. Few eggs were observed on `Carolina Cayenne' roots, whereas all races of M. incognita produced numerous eggs on the susceptible `NuMex R Naky' roots. The results indicated `Carolina Cayenne' is a source of resistance to all known races of M. incognita.

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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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James D. McCreight

Powdery mildew is a serious disease of melon (Cucumis melo L.) worldwide. Twenty-two melon cultigens have been used to define 22 reported races of the pathogen Podosphaera xanthii (sect. Sphaerotheca) xanthii (Castag.) U. Braun & N. Shish. Comb. nov. [syn. Sphaerotheca fuliginea (Schlecht. ex Fr.) Poll.]. Discrepancies in the reactions of eight cultigens to populations of P. xanthii races 1 and 2 in California, Japan, and Spain revealed genetic differences among them that can be used to differentiate P. xanthii race 1 and 2 populations in these countries. Implicit in these results is the existence of previously unknown virulence factors in these populations of P. xanthii races 1 and 2 that permit designation of new races of P. xanthii on melon. Synthesis of these results with previous reports resulted in the identification of 28 putative races of P. xanthii on melon that include eight variants of race 1 and six variants of race 2. Six of the cultigens exhibited resistant blisters in response to heavy infection by P. xanthii in field and greenhouse tests.