ORIGINAL PAPER Hyaluronic acid of Streptococcus sp. as a potent elicitor for induction of systemic resistance against plant diseases Kyungseok Park Æ Diby Paul Æ Elchae Kim Æ Joseph W. Kloepper Received: 11 August 2007 / Accepted: 16 October 2007 / Published online: 27 October 2007 Ó Springer Science+Business Media B.V. 2007 Abstract The potential of hyaluronic acid (HA) in inducing systemic resistance to cucumber, tomato and pepper was tested in planta. In the study, HA was found to be a potent agent for suppressing disease caused by Cucumber Mosaic Virus (CMV) (in pepper), Pseudomonas syringae pv. tomato (tomato speck disease), Xanthomonas axonopodis pv. vesicatoria (tomato spot disease), Pseu- domonas syringae pv. lachrymans (cucumber angular leaf spot), and Colletotrichum orbiculare (cucumber anthrac- nose). Disease control was obtained with spraying, injection and drenching of plants with HA. HA did not exhibit direct antimicrobial action against the pathogens tested. Studies carried out in transgenic tobacco indicated that defense genes PR 1a and PDF 1.2 were activated upon treatment with HA, demonstrating salicylic acid (SA) and jasmonic acid (JA) pathways getting activated during defense. Further work is warranted to evaluate the use of HA-mediated disease suppression in crop plants. Keywords Hyaluronic acid Á Elicitor Á Induced systemic resistance Á Plant disease Introduction Induction of disease resistance following treatment with active microbial and chemical inducers has been reported to provide protection against invasion of pathogens in several plant species (van Loon et al. 1998). A number of chemicals have been demonstrated to induce systemic resistance to plants to combat diseases (Chen et al. 1993; Cohen et al. 1994; Metraux et al. 1991; Davis et al. 1989). The prominent ones are 2,6 dichloro isonicotinic acid (in cucumber) (Staub et al. 1992), benzothiadiazole (Lawton et al. 1996), methyl jasmonate (Epple et al. 1997) and probenazole (Yoshioka et al. 2001). Many of these have been commercialized under different trade names, includ- ing BION (BTH by Novartis/Syngnta) (Kunz et al. 1997), Oxycom (Salicylic acid by Redox Chemicals Inc., Burley, ID, USA), and Oryzemate (Probenazole by Meijiseika Co., Tokyo, Japan). The application of these products has been demonstrated to induce expression of defense transcripts in plants (Friedrich et al. 1996; Lawton et al. 1996). The objective of this study was to determine if bacte- rially produced hyaluronic acid (HA) could induce systemic disease protection in plants. HA is a naturally occurring biopolymer, which serves important biological functions in bacteria and higher animals including humans. In Gram-positive streptococci it appears as a mucoid cap- sule surrounding the bacterium. HA is comprised of linear, unbranching, polyanionic disaccharide units consisting of glucuronic acid (GlcUA) an N-acetyl glucosamine (Glc- NAc) joined alternately by beta 1–3 and beta 1–4 glycosidic bonds (Fig. 1). Bacterial fermentation methods for large-scale economic production of HA have been well standardized as HA is of used in medical and cosmetic industry extensively (Akasaka et al. 1998; Hasegawa et al. 1999). K. Park (&) Plant Pathology Department, National Institute of Agricultural Science and Technology, RDA, Suwon 441-707, Korea e-mail: kspark@rda.go.kr D. Paul Department of Environmental Engineering, Konkuk University, Seoul, Korea E. Kim Vacctech-Venture cooperation Co., Daejeon, Korea J. W. Kloepper Department of Entomology and Plant Pathology, Auburn University, Auburn, AL 36849, USA 123 World J Microbiol Biotechnol (2008) 24:1153–1158 DOI 10.1007/s11274-007-9587-0