Genetic variation of chloroplast DNA in Zingiberaceae taxa from Myanmar assessed by PCR-restriction fragment length polymorphism analysis

We examined genetic variation in 22 accessions belonging to 11 species in four genera of the Zingiberaceae, mainly from Myanmar, by PCR-restriction fragment length polymorphism analysis to investigate their relationships within this family. Two of 10 chloroplast gene regions (trnS-trnfM and trnK2-trnQr) showed differential PCR amplification across the taxa. Restriction enzyme digestion of the PCR products revealed interspecific variability. The restriction patterns were used to classify the regions as either highly conserved or variable across the taxa. None of the regions was highly conserved across the four genera, and the level of conservation varied. The gene region trnS-trnfM appeared to display interspecific variability among most of the species. However, the relative efficiency of different restriction enzymes depended on the gene regions and genera investigated. Cluster analysis revealed interspecific discrimination among the taxa. The two Curcuma species (Curcuma zedoaria and Curcuma xanthorrhiza) appeared to be identical, thus supporting their recent classification as synonyms. The results provide the basis for selecting specific combinations of restriction enzymes and gene regions of chloroplast DNA (cpDNA) to identify interspecific variation in the Zingiberaceae and to identify both highly conserved and variable regions. Overall, cpDNA depicted comparatively diverse genetic profile of the studied germplasm. The genetic information revealed here can be applied to the conservation and future breeding of Zingiber and Curcuma species.