The genetic relationship among cassumunar gingers (Zingiber cassumunar) in Thailand was assessed by amplified fragment length polymorphism (AFLP). Twelve AFLP primer combinations generated a total of 309 fragments, of which, 242 bands were polymorphic with an average of 20.2 bands per primer pair. Genetic similarities were obtained using Jaccard similarity coefficients, and a phylogenetic tree was constructed using the UPGMA clustering method. Pairwise similarity estimated between cassumunar gingers ranged from 0.7644 to 1.00 with an average of 0.879. Cluster analysis divided the samples into five groups with a high co-phenetic correlation value (r = 0.99). Genetic variability within and among collection regions was estimated by analysis of molecular variance (AMOVA). High molecular variance (84%) was found within samples from the same region. The results implied dispersal of plant materials between collection regions. The genetic similarity assessed by AFLP showed that there are duplicate accessions in the germplasm collection. This genetic information is very useful for germplasm maintenance and a crop improvement program.

Genetic diversity among 126 rice accessions, including 110 Thai landraces and 16 varieties used as subspecies reference, were evaluated by three types of DNA markers, InDel (Insertion/Deletion), intersimple sequence repeat (ISSR) and simple sequence repeat (SSR) markers. Twelve InDel primer pairs, based on DNA sequence polymorphism between '93-11' (indica) and 'Nipponbare' (japonica), were used to identify subspecies of landraces. Most of the local rice samples had either '93-11' alleles or 'Nipponbare' alleles. The scatter plotting of the principal component analysis (PCA) and dendrogram results based on InDel data could clearly classify landraces into two groups, indica and japonica. InDel and SSR markers showed the average polymorphic information content (PIC) values of 0.3707 and 0.6367, respectively. The dendrogram, based on combining InDel, ISSR and SSR data, could classify rice samples into five clusters at a cutoff genetic similarity value of about 0.70. The genetic similarity within landraces was low, indicating that Thai local rice samples have a great genetic diversity. The results of this experiment provide helpful data for rice germplasm management in breeding program.

'Waan chak modlook' (Curcuma comosa Roxb.) is an important medicinal plant of Thailand, but the high similarity in morphological characteristics observed among Curcuma spp. may cause confusion in its utilization. The amplified fragment length polymorphism (AFLP) marker was used to identify and elucidate the phylogenetic relationships among 97 accessions of 'Waan chak modlook' collected throughout Thailand. Nine AFLP primer combinations generated a total of 202 bands, of which, 158 bands were polymorphic, with an average of 17.56 bands per primer pair. Pairwise similarity estimated between all samples ranged from 0.39 to 1.00 with an average of 0.67. The phylogenetic tree derived from AFLP data showed that the 'Waan chak modlook' accessions were divided into five clusters. Based on morphological characterizations, all samples could be assigned to four species: Curcuma sp.; Curcuma latifolia Rosc.; Curcuma elata Roxb.; and C. comosa. The results indicated that there were other Curcuma species that were misused as C. comosa. The DNA fingerprint data along with the morphological data provided the keys for the accurate identification of C. comosa from the other three related species.

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