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Poster: Biology & Disease Mgmt: Biological Control


Differential Colonization of Tomato Cultivars by the Biocontrol Agent Beauveria bassiana
S. YERUKALA (1), M. Dee (1), B. Ownley (1) (1) University of Tennessee, U.S.A.

Entomopathogenic Beauveria bassiana (Bb1198) is endophytic in tomato. Biocontrol of disease with Bb1198 is correlated with endophytic colonization. The aim of this study was to determine if colonization by Bb1198 is affected by tomato cultivar. Colonization of ‘Rutgers’ and ‘Mountain Spring’ by Bb1198 was tested in a gnotobiotic assay. Seed were treated with Bb1198 in 1% methylcellulose at 1.6×106 viable CFU/seed. Control seeds received methylcellulose. Replicated tests were factorials, in a CRD. Seed germination, BB1198 colonization, and plant growth were determined 17-21 days after treatment. Bb1198 was recovered from sections of root, stem, and leaf plated on semi-selective medium. Data were analyzed with mixed models ANOVA, and F-LSD (P<0.05). Germination was higher for ‘Mountain Spring’ seed treated with Bb1198 than control seed (94 vs 65%), germination of ‘Rutgers’ treated and control seed did not differ. Bb11-98 was not recovered from plants from control seed. For treated seed, colonization of ‘Rutgers’ was greater than ‘Mountain Spring’ (64 vs 29%). For both cultivars from treated seed, colonization of leaf (50%) and stem sections (67%) was greater than roots (23%). Leaf number was greatest in ‘Rutgers’ from seed treated with Bb1198, followed by control plants for both cultivars, and least in ‘Mountain Spring’ treated with Bb1198. Understanding factors that affect colonization, i.e., cultivar, could increase consistency of biocontrol by B. bassiana.