Yingyong Paisooksantivatana

Isozyme polymorphism in Curcuma alismatifolia Gagnep. (Zingiberaceae) populations from Thailand

Abstract Over-collection of Curcuma alismatifolia Gagnep. and habitat destruction had greatly reduced the number of individuals in their natural habitat resulting in genetic erosion. We conducted the isozyme analyses to reveal the genetic diversity among natural populations compared with the cultivated populations. Out of seven enzyme systems analyzed in this study, five enzymes (ADH, GDH-1, LAP-1, GPI-2, PGM) which gave reproducible and consistent bands were used; DIA and EST were excluded due to their complex and inconsistent bands. The GPI-2 loci showed the most variable with six allozymes and 10 zymogram patterns followed by GDH-1 with 5 and 5, ADH with 3 and 5, PGM with 4 and 4, and LAP-1 with three allozymes and four zymogram patterns. Cultivated populations from Japan (cJ) and Thailand (cT) had the lowest percentage of polymorphic loci ( P =40–60%), alleles per locus ( A l =1.8), alleles per polymorphic locus ( A p =2.33–3.00), and gene diversity ( H s =0.216–0.304) compared with two lowland populations (L1, L2) with P =100%, A l =3.0–3.2, A p =3.0–3.2, H s =0.465–0.496; and six highland populations (H1–H6) with P =80–100%, A l =2.4–3.8, A p =2.4–3.8, H s =0.342–0.659. Within population, H1 (the highest elevation sampled in this study) had the greatest genetic diversity ( H s =0.659). Mean genetic diversity over all loci across all populations was 0.444. Mean genetic identity between cultivated populations ( I C ), lowland populations ( I L ), among highland populations ( I H ), and across all populations ( I SP ) were 0.950, 0.947, 0.944, and 0.922, respectively. Using UPGMA cluster analysis, H1 and cJ were separated first from the rest into distinct groups. Two lowland populations were placed together with H6, while cT was grouped in the same cluster of H2–H5.

Molecular cloning and expression levels of the monoterpene synthase gene (ZMM1) in Cassumunar ginger (Zingiber montanum (Koenig) Link ex Dietr.)

Cassumunar ginger (Zingiber montanum (Koenig) Link ex Dietr.) is a native Thai herb with a high content and large variety of terpenoids in its essential oil. Improving the essential oil content and quality of cassumunar ginger is difficult for a breeder due to its clonally propagated nature. In this research, we describe the isolation and expression level of the monoterpene synthase gene that controls the key step of essential oil synthesis in this plant and evaluate the mechanical wounding that may influence the transcription level of the monoterpene synthase gene. To isolate the gene, the selected clones from DNA derived from young leaves were sequenced and analyzed and the monoterpene synthase gene from cassumunar ginger (ZMM1) was identified. The ZMM1 CDS containing 1 773 bp (KF500399) is predicted to encode a protein of 590 amino acids. The deduced amino acid sequence is 40-74% identical with known sequences of other angiosperm monoterpene synthases belonging to the isoprenoid biosynthesis C1 superfamily. A transcript of ZMM1 was detected almost exclusively in the leaves and was related to leaf wounding. The results of this research offer insight into the control of monoterpene synthesis in this plant. This finding can be applied to breeding programs or crop management of cassumunar ginger for better yield and quality of essential oil.