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Poster: Molecular & Cellular Plant-Microbe Interactions: Biotechnology


Bioluminescent imaging as a sensitive tool for evaluation of Ralstonia solanacearum infection dynamics in resistant and susceptible pepper lines
H. Du (1), B. Chen (1), X. Zhang (1), S. Miller (2), G. Rajashekara (3), X. Xu (1), S. Geng (1) (1) Beijing Vegetable Research Center (BVRC) of BAAFS, China; (2) Department of Plant Pathology, Ohio Agricultural Research Development Center, Ohio State Univ

Bacterial wilt, caused by Ralstonia solanacearum, is a major disease affecting pepper (Capsicum annuum) production worldwide. In this study, we evaluated the resistance of 100 pepper lines using R. solanacearum strain Rs-SY1 (phylotype I, isolated from sweet pepper in South China) and identified one resistant pepper line, BVRC 1. In order to study the bacterial spatial-temporal distribution in planta in real time, we generated a strongly bioluminescent R. solanacearum strain (BL-Rs7) using pXX3 carrying luxCDABE genes. BL-Rs7 was similar to its parent strain Rs-SY1 in morphology and pathogenicity. Furthermore, luminescence intensity of BL-Rs7 strongly correlated with bacterial population in planta (R2 = 0.88). The utility of bioluminescence assay was validated by real-time in vivo monitoring of R. solanacearum infection dynamics in resistant and susceptible pepper lines BVRC 1 and BVRC 25, respectively, following root inoculation. The luminescence signals were detected in susceptible pepper plants from 3 days post inoculation (dpi), while little signal was detected in roots or stem of the resistant pepper line over 10 dpi and only a very low titer of bacteria was detected in the root. The results suggested that pepper line BVRC 1 exhibits resistance by interfering with translocation and multiplication of R. solanacearum in the stem.