Polygalacturonase inhibiting protein: isolation, developmental regulation and pathogen related expression in Panax ginseng C.A. Meyer Gayathri Sathiyaraj • Sathiyaraj Srinivasan • Sathiyamoorty Subramanium • Yu-Jin Kim • Yeon-Ju Kim • Woo-Saeng Kwon • Deok-Chun Yang Received: 9 September 2009 / Accepted: 18 November 2009 / Published online: 28 November 2009 Ó Springer Science+Business Media B.V. 2009 Abstract Polygalacturonase inhibiting proteins (PGIPs) are the major defense proteins which play an important role in resistance to infection of pathogens. A putative novel gene encoding PGIP was isolated from Panax ginseng C.A. Meyer, which shows 70.3 and 68.4% homology with chick pea and Arabidopsis PGIPs. The RACE PCR was pre- formed to isolate the full-length PGIP cDNA from Panax ginseng. Sequence analysis revealed that the cDNA of PgPGIP is of 1,275 bp in length and that it’s containing ORF encodes for a polypeptide of 366 amino acids. Domain analysis revealed that the deduced amino acid sequences of PgPGIP have a typical PGIP topology. The transcription level of PgPGIP was up-regulated in ginseng in response to wounding and infection with phytopatho- genic fungi i.e., Rhizoctonia solani, Fusarium oxysporum, Phythium ultimum, Botrytis cinerea, Colletotrichum glo- eosporioides and Cylindrocarpon destructans, which cau- ses drastic damage in ginseng plants. The constitutive PgPGIP expression of 4 years old plant, showed elevated transcript level, especially roots, showed maximum then buds, stems and leaves, indicating that the gene is devel- opmentally regulated. The crude PGIP extracts derived from the fungal infected plants directly reduces the aggressive potential of PGs from diverse group of fungi. Like other PGIPs, PgPGIP also possess board spectrum of inhibitory activity. Thus, the presence of PgPGIP gene and their active role in defense mechanism was proved. The structural model of PgPGIP was predicted based on the alignment generated by EBI-Align, the program ‘‘MOO- DELLER’’ and the predicted structure showed 10 b-strands and 10 a-helixes region. Keywords Polygalacturonase Á Polygalacturonase inhibiting protein Á Biotic stress Á Abiotic stress Á Relative expression Abbreviations PGs Polygalacturonase PGIPs Polygalacturonase inhibiting protein RT-PCR Reverse transcriptase polymerase chain reaction RACE Random amplification of cDNA ends PRP Pathogenesis related protein LRR Leucine rich repeats Introduction Plant-pathogenic bacteria and fungi must penetrate the plant cell wall in order to initiate and expand necrotic infections or to establish colonization sites for biotrophic infections within the plant. Many hydrolytic enzymes produced by fungal pathogens attack the nutrient-rich polymers that constitute the plant cell wall [1]. The cell- wall degrading enzymes produced by phytopathogens are endo and exo-polygalacturonases (PGs), pectate lyases, and glucanases. Polygalacturonase (PG: EC 3.2.1.15) is an important pathogenicity factor of fungi [2, 3]. Pathogenesis Electronic supplementary material The online version of this article (doi:10.1007/s11033-009-9936-1) contains supplementary material, which is available to authorized users. G. Sathiyaraj Á S. Srinivasan Á S. Subramanium Á Y.-J. Kim Á Y.-J. Kim Á W.-S. Kwon Á D.-C. Yang (&) Korean Ginseng Center for Most Valuable Products and Ginseng Genetic Resource Bank, Kyung Hee University, Suwon 449-701, South Korea e-mail: dcyang@khu.ac.kr 123 Mol Biol Rep (2010) 37:3445–3454 DOI 10.1007/s11033-009-9936-1