title: Induction of systemic resistance in Panax ginseng against Phytophthora cactorum by native Bacillus amyloliquefaciens HK34.
abstract: BACKGROUND
  Korean ginseng (Panax ginseng Meyer) is a perennial herb prone to various root diseases, with Phytophthora cactorum being considered one of the most dreaded pathogens. P. cactorum causes foliar blight and root rot. Although chemical pesticides are available for disease control, attention has been shifted to viable, eco-friendly, and cost-effective biological means such as plant growth-promoting rhizobacteria (PGPR) for control of diseases.
  
  
  METHODS
  Native Bacillus amyloliquefaciens strain HK34 was isolated from wild ginseng and assessed as a biological control agent for ginseng. Leaves from plants treated with HK34 were analyzed for induced systemic resistance (ISR) against P. cactorum in square plate assay. Treated plants were verified for differential expression of defense-related marker genes using quantitative reverse transcription polymerase chain reaction.
  
  
  RESULTS
  A total of 78 native rhizosphere bacilli from wild P. ginseng were isolated. One of the root-associated bacteria identified as B. amyloliquefaciens strain HK34 effectively induced resistance against P. cactorum when applied as soil drench once (99.1% disease control) and as a priming treatment two times in the early stages (83.9% disease control). A similar result was observed in the leaf samples of plants under field conditions, where the percentage of disease control was 85.6%. Significant upregulation of the genes PgPR10, PgPR5, and PgCAT in the leaves of plants treated with HK34 was observed against P. cactorum compared with untreated controls and only pathogen-treated plants.
  
  
  CONCLUSIONS
  The results of this study indicate HK34 as a potential biocontrol agent eliciting ISR in ginseng against P. cactorum.
authors.affiliation: Department of Genetic Engineering, Sungkyunkwan University, Suwon, Korea.
authors.forename: Byung Dae
authors.initials: BD
authors.lastname: Lee
authors.affiliation: Division of Agricultural Microbiology, National Academy of Agricultural Sciences, Rural Development Administration, Wanju, Korea.
authors.forename: Swarnalee
authors.initials: S
authors.lastname: Dutta
authors.affiliation: Department of Biology, Chungbuk National University, Cheongju, Chungbuk, Korea.
authors.forename: Hojin
authors.initials: H
authors.lastname: Ryu
authors.affiliation: Division of Agricultural Microbiology, National Academy of Agricultural Sciences, Rural Development Administration, Wanju, Korea.
authors.forename: Sung-Je
authors.initials: SJ
authors.lastname: Yoo
authors.affiliation: Department of Genetic Engineering, Sungkyunkwan University, Suwon, Korea.
authors.forename: Dong-Sang
authors.initials: DS
authors.lastname: Suh
authors.affiliation: Division of Agricultural Microbiology, National Academy of Agricultural Sciences, Rural Development Administration, Wanju, Korea.
authors.forename: Kyungseok
authors.initials: K
authors.lastname: Park
keywords: Panax ginseng; defense-related genes; induction of systemic resistance; native Bacillus; priming