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Characterization and Management of Ralstonia solanacearum Populations in South Asia

Subedi, Nagendra
http://orcid.org/0000-0002-3726-6238
http://rave.ohiolink.edu/etdc/view?acc_num=osu1429719749

Abstract Details

2015, Doctor of Philosophy, Ohio State University, Plant Pathology.
Bacterial wilt caused by Ralstonia solanacearum (Smith) Yabuuchi is a major problem for tomato, eggplant and pepper production in South Asia. This disease is difficult to manage due to viability, adaptability, and diversity of the pathogen. To develop information regarding local pathogen population structure to inform disease management strategies, we characterized a collection of 100 R. solanacearum strains from South Asia using classical and recent molecular tools. All of the strains in this collection were race 1, phylotype I, and biovar III or IV. Based on phylogenetic analysis of endoglucanase gene sequences, we identified three sequevars (14, 47, and 48), and two putatively new sequevars among the South Asian strains. Cluster analysis of genomic fingerprinting profiles created by Rep-PCR divided strains into eight groups. Strains were not grouped based on geographic origin, host or biovar in either analysis. To identify resistant tomato, eggplant and pepper genotypes that can potentially be used in South Asia to manage this disease, we screened a worldwide collection of 37 tomato, eggplant, and pepper accessions against six selected South Asian R. solanacearum strains. Six tomato, nine eggplant, and three pepper accessions were highly resistant (=10% wilt), and three tomato, two eggplant and one of the pepper accessions were moderately resistant (=30% wilt). Biological control is a potentially economically feasible and environmentally safe and sustainable disease management practice. In this study we investigated 54 previously characterized bacterial biocontrol agents for their activity against diverse R. solanacearum strains from South Asia and evaluated the value of integration of these biocontrol agents with partial host resistance of tomato in management of bacterial wilt. Based on in vitro antagonism against 15 selected South Asian R. solanacearum strains, six biocontrol agents were selected to evaluate their biocontrol efficacy in a susceptible (L390) and a partially resistant (IRAT L3) tomato accessions. Biocontrol agents were almost four times more effective in suppressing bacterial wilt in IRAT L3 than in L390. Pseudomonas brassicacearum strains 93D8 and Wood 1R, and P. protegens strain Clinto 1 were the most effective strains with biocontrol efficacy of 67, 50 and 58% respectively, in IRAT L3. Bacterial wilt incidence was suppressed in all four experiments by Pseudomonas brassicacearum strain 93D8, and in three out of four experiments by P. vranovensis strain 15D11, P. protegens strain Clinto 1, and P. brassicacearum strain Wood 1R, in IRAT L3. However, in L390, the disease incidence was suppressed in only one experiment by P. protegens strains 15G2 and Clinto 1, and a mixture of all biocontrol agents. These results highlight the value of integration of biocontrol agents with host resistance in management of bacterial wilt.
Sally Miller (Advisor)
Christopher Taylor (Committee Member)
Pierce Paul (Committee Member)
Anne Dorrance (Committee Member)
140 p.
Plant Pathology

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Citations

  • Subedi, N. (2015). Characterization and Management of Ralstonia solanacearum Populations in South Asia [Doctoral dissertation, Ohio State University]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429719749

    APA Style (7th edition)

  • Subedi, Nagendra. Characterization and Management of Ralstonia solanacearum Populations in South Asia. 2015. Ohio State University, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=osu1429719749.

    MLA Style (8th edition)

  • Subedi, Nagendra. "Characterization and Management of Ralstonia solanacearum Populations in South Asia." Doctoral dissertation, Ohio State University, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=osu1429719749

    Chicago Manual of Style (17th edition)

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