Saturday, 15 July 2006

Biocontrol of Late Blight (Phytophthora capsici) in Pepper by Chitin Broth Containing Multitude of Chitinolytic Bacteria.

Kim Sung Jae Sr., Jin Rong De, Ryu Ji Yeon, Yun Kyoung Mi, Kim Yong Woong, and Kim Kil Yong. Division of Applied BioScience and Biotechnology, College of Agriculture and Life Science, Chonnam National Univ, 300, Yong Bong Dong, Buk Ku, Gwangju, South Korea

To investigated protective effect of chitinolytic bacteria against late blight (Phytophthora capsici. L) in pepper plants, pathogenesis-related proteins and plant defense enzymes related to cell wall lignification, root mortality, and soil microbial activity were examined. Pepper plants were grown in pots containing non-sterile soil and received Chitin Broth (CB), Chitin Broth + P. capsici (CB+P), Mineral Nutrient (MN), and Mineral Nutrient + P. capsici (MN+P). Chitin Broth-treated Plants (CB+P) were protected from the P. capsici and had lower root mortality compared to Mineral Nutrient-treated plants (MN+P), where soil enzyme activities (chitinase and -1, 3-glucanase) and CFU of chitinolytic bacteria in rhizosphere soil at CB+P treatment were about 2 and 1,000 times higher than those at MN+P treatment, respectively. Activities of PR-proteins in leaves on MN+P-treated plants increased, while those decreased in roots after P. capsici infection. Activities of lignification-related enzymes in leaves on MN+P-treated plants were shown to have a similar pattern with PR-proteins; however, those in roots increased early stage and than decreased. Activities of PR-proteins and lignification-related enzymes were not different among CB, CB+P, and MN treatments throughout the experimental period. These results indicate that chitin broth containing multitude of chitinolytic bacteria could increase microbial activities in rhizosphere, which alleviate pathogenic attack from P. capsici.

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