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Endophytic Trichoderma Isolates from Tropical Environments Delay Disease Onset and Induce Resistance Against Phytophthora capsici in Hot Pepper Using Multiple Mechanisms

March 2011 , Volume 24 , Number  3
Pages  336 - 351

Hanhong Bae,1,2 Daniel P. Roberts,1 Hyoun-Sub Lim,1,3 Mary D. Strem,1 Soo-Chul Park,4 Choong-Min Ryu,5 Rachel L. Melnick,1 and Bryan A. Bailey1

1U.S. Department of Agriculture, Agricultural Research Service, Beltsville Agricultural Research Center, Beltsville, MD 20705, U.S.A.; 2School of Biotechnology, Yeungnam University, 214-1 Daedong, Gyeongsan-si, Gyeongbuk-do 712-749, Korea; 3Department of Applied Biology, Chungnam National University, Daejeon, 305-764, Korea; 4Molecular Genetics Division, National Institute of Agricultural Science and Technology, RDA, Suweon 441-707, Korea; 5Systems Microbiology Research Center, Korea Research Institute of Bioscience and Biotechnology, Daejeon 305-600, Korea

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Accepted 17 November 2010.

Endophytic Trichoderma isolates collected in tropical environments were evaluated for biocontrol activity against Phytophthora capsici in hot pepper (Capsicum annuum). Six isolates were tested for parasitic and antimicrobial activity against P. capsici and for endophytic and induced resistance capabilities in pepper. Isolates DIS 70a, DIS 219b, and DIS 376f were P. capsici parasites, while DIS 70a, DIS 259j, DIS 320c, and DIS 376f metabolites inhibited P. capsici. All six isolates colonized roots but were inefficient stem colonizers. DIS 259j, DIS 320c, and DIS 376f induced defense-related expressed sequence tags (EST) in 32-day-old peppers. DIS 70a, DIS 259j, and DIS 376f delayed disease development. Initial colonization of roots by DIS 259j or DIS 376f induced EST with potential to impact Trichoderma endophytic colonization and disease development, including multiple lipid transferase protein (LTP)-like family members. The timing and intensity of induction varied between isolates. Expression of CaLTP-N, encoding a LTP-like protein in pepper, in N. benthamiana leaves reduced disease development in response to P. nicotianae inoculation, suggesting LTP are functional components of resistance induced by Trichoderma species. Trichoderma isolates were endophytic on pepper roots in which, depending on the isolate, they delayed disease development by P. capsici and induced strong and divergent defense reactions.

This article is in the public domain and not copyrightable. It may be freely reprinted with customary crediting of the source. The American Phytopathological Society, 2011.