White Kwao Krua variety classification by botanical characteristics and ISSR-Touchdown PCR technique

White Kwao Krua Pueraria candollei Grah. var. mirifica (Airy Shaw et Suvatabandhu) Niyomdham], is a herb used as an ingredient in supplementary and cosmetic. The tuberous roots of White Kwao Krua (WKK) contain estrogen-like substances. Seeds of WKK, collected from Prachuab Khiri Khan, were planted and propagated in the farm of Suranaree University of Technology, and their genetic backgrounds were ambiguous. Thirty six plants of WKK in the same age were sampled for classification using 7 botanical characteristics and DNA fingerprint by ISSR-Touchdown PCR technique. The relationship of the 7 botanical characteristics, using principle component analysis (PCA), showed the WKK plants fell into 3 groups. In the first group was plant number 34, which was distinguished from the other plants by its small leaf size. The second group consisted of 23 plants with elliptic leaf shape, acute leaf base, and acuminate leaf apex. The third group consisted of 12 plants with ovate leaf shape, obtuse leaf base, and cuspidate leaf apex. The ISSR-Touchdown PCR technique with 41 primers detected 355 loci of DNA with an average of 8.6 loci per primer. The sizes of DNA ranged between 280 bp to 1550 bp. Two hundred ninety three loci exhibited polymorphisms (82.54%) and the rest 62 loci were monomorphic (17.46%). The polymorphism information content (PIC) was between 0.0315–0.9779 (average 0.4779) and number of effective alleles per locus (N _e) ranged between 1.1250–1.8541 (average 1.5544). Unweighted pair group method with arithmetic mean (UPGMA), Jaccard similarity coefficient and PCA were used to find the construction of genetic relationship of WKK. The genetic similarity (GS) of WKK ranged between 0.50–0.86 (average 0.77). At the GS of 0.56 from cluster analysis, the WKK varieties could be divided in 2 major groups. The first group comprised of plant number 34 and 7, and the second group could be further divided into 2 subgroups at GS of 0.69. None of the WKK plants was identical in genetic, and they were expected to be derived from 5 genetic sources. These results showed that applying of the ISSR-Touchdown PCR technique could be used to classify WKK efficiently.