Host and Non-Host Disease Resistances of Kimchi Cabbage Against Different Xanthomonas campestris Pathovars

Abstract

Department of Horticultural Sciences, Gyeongnam National University of Science and Technology (GNTech), Jinju 660-758,Korea(Received on April 1, 2012; Revised on May 31, 2012; Accepted on May 31, 2012)This study was conducted to investigate host and non-host disease resistances of kimchi cabbage plants tobacterial infection. Kimchi cabbage leaves respondeddifferently to infections with a virulent strain of Xanth-omonas campestris pv. campestris (Xcc) 8004 and twostrains (85-10 and Bv5-4a.1) of non-host bacteria X.campestris pv. vesicatoria (Xcv). Non-host bacteriatriggered a rapid tissue collapse of the leaves showing asbrown coloration at the infected sites, highly increasedion leakage, lipid peroxidation and accumulation of UV-stimulated autofluorescence materials at the inoculatedsites. During the observed interactions, bacterial pro-liferations within the leaf tissues were significantlydifferent. Bacterial number of Xcc 8004 progressivelyincreased within the inoculated leaf tissues over time,while growths of two non-host bacteria Xcv strains weredistinctly limited. Expressions of pathogenesis-relatedgenes, such as GST1, PR1, BGL2, VSP2, PR4 and LOX2,were differentially induced by host and non-host bacterialinfections of X. campestris pathovars. These resultsindicated that rapid host cellular responses to the non-host bacterial infections may contribute to an array ofdefense reactions to the non-host bacterial invasion.Keywords : kimchi cabbage, non-host disease resistance,programmed cell death, Xanthomonas campestris pathovarsPlants protect themselves actively against non-host patho-gens via an array of defense reactions, which are sometimessimilar to those against host pathogen infections. So far,non-host disease resistance have been classified into twotypes in diverse plant species (Mysore and Ryu, 2004; Ohet al., 2006). Type I and type II non-host disease resistanceis differentiated by appearance of visible cell death inresponse to infections by non-host fungal and bacterialpathogens. Hypersensitive cell death was not found in typeI non-host resistance, while rapid cell death usually observedin incompatible interactions between hosts and avirulentstrains appear in type II non-host resistance. During celldeath-mediated non-host disease resistance, host plantslaunched sophisticated defense mechanisms i.e. oxidativeburst, kinase cascades and accumulation of antimicrobialproteins usually found during incompatible interactions ofhost plant-pathogen (Dixon et al., 1994).Non-host disease resistance of kimchi cabbage plantswere previously reported against infection by Pseudomonassyringae pv. tomato (Pst) (Park et al., 2005). Hypersensitivecell death and accumulation of H