Isolation and characterization of Panax ginseng geranylgeranyl-diphosphate synthase genes responding to drought stress Shadi Rahimi & Yu-Jin Kim & Balusamy Sri Renuka Devi & Altanzul Khorolragchaa & Johan Sukweenadhi & Deok-Chun Yang Accepted: 24 March 2015 # Koninklijke Nederlandse Planteziektenkundige Vereniging 2015 Abstract Geranylgeranyl-diphosphate synthases (GGDPS) catalyze branch point enzymatic reactions producing isoprenoid-derived products which are nec- essary for plant growth and responses to a wide range of biotic and abiotic stresses. In our study, full length geranylgeranyl-diphosphate synthase 1 (PgGGDPS1) and 2 (PgGGDPS2) cDNA were isolated and character- ized from the flower of Panax ginseng and 4-year old P. ginseng cv. Gumpoong. The cDNA had open reading frame of 1032 and 1116 bp with a deduced amino acid sequence of 343 and 371 residues for GGDPS1 and GGDPS2, respectively. The calculat- ed molecular mass of GGDPS1 and GGDPS2 were approximately 37.66 and 40.21 kDa with a predi- cated isoelectric point of 5.32 and 6.23 and predict- ed localization of plastid. A GenBank Blast X search revealed that the deduced amino acid of PgGGDPS1 shared a high degree of homology with GGDPS from Panax notoginseng. The transcription pattern of GGDPS genes was different at various developmental stages. Both GGDPS genes were highly expressed in aerial parts of the plant, espe- cially in rapidly growing tissues such as 4-year old flower and stem tissues. Transcript level of PgGGDPS1 was differentially induced in ginseng not only during Pseudomonas syringae pv tomato infection but also after exposure to abiotic stresses. Our results suggested that the induction of GGDPS genes specifically PgGGDPS1 by drought stress may affect chlorophyll levels, intracellular GA con- tent and accumulation of carotenoids as the precur- sor for higher production of ABA and possibly stomatal closure as the barrier for water loss. Keywords Drought . Gene characterization . Geranylgeranyl diphosphate synthase . Organ Expression . Panax ginseng Abbreviations ABA abscisic acid CLD chain length determination EST expressed sequence tags GA3 gibberellin GGDP geranylgeranyl diphosphate GGDPS geranylgeranyl-diphosphate synthase GGR geranylgeranyl reductase MJ methyl jasmonates RT- PCR reverse transcriptase-polymerase chain reaction SA salicylic acid YE yeast extract Eur J Plant Pathol DOI 10.1007/s10658-015-0648-1 Y.<J. Kim : D.<C. Yang (*) Department of Oriental Medicinal Biotechnology, College of Life Sciences, Kyung Hee University, Yongin 446-701, Republic of Korea e-mail: dcyang@khu.ac.kr S. Rahimi : Y.<J. Kim : B. S. R. Devi : A. Khorolragchaa : J. Sukweenadhi : D.<C. Yang Graduate School of Biotechnology and Ginseng Bank, College of Life Sciences, Kyung Hee University, Yongin 446-701, Republic of Korea