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POSTERS: Host resistance screening

Resistance of solanaceous rootstocks to Ralstonia pseudosolanacearum strains
Hellen Kanyagha - The Ohio State University. David Francis- The Ohio State University, Department of Horticulture and Crop Science, Sally Miller- The Ohio State University, Department of Plant Pathology, Francesca Rotondo- The Ohio State University, Department of Plant Pathology

Grafting is a promising approach among the options available for the management of bacterial wilt of tomato. Bacterial wilt is caused predominantly in Africa by Ralstonia pseudosolanacearum phylotype III, while in Asia phylotype I predominates. However, due to genetic variability for virulence within R. pseudosolanacearum, rootstocks must be evaluated for resistance to multiple strains. Our study aimed to identify appropriate wilt-resistant solanaceous rootstock candidates for the management of bacterial wilt in multiple regions. We used a split plot completely randomized block design to evaluate responses of 11 Ohio tomato lines to three virulent R. pseudosolanacearum strains from East Africa and South Asia. We also evaluated the tomato line MT 56 (Makerere University Uganda) and the eggplant line EG 190 (World Vegetable Center) against fifteen additional strains, with tomato ‘Moneymaker’ as a susceptible control. Wilt incidence and severity were assessed, and latent infections identified by PCR (primers 759/760). Significant differences in wilting incidence were observed among cultivars (P < 0.001). EG 190 and OH-WG-120 exhibited no wilting symptoms to the strains tested, but latent infections were detected. Four Ohio lines (WG 220, 121, 211 and 215) were highly susceptible (up to 100% wilting in most of isolates), while the remaining lines had variable responses to the strains tested