Leaf morphometry, genetic variation, and phylogeny of White Kwao Krua Pueraria mirifica in Thailand

Abstract

Pueraria mirifica (leaf pod, and flower) were collected from many localities (cultivars) throughout Thailand for morphometric and genetic analyses in order to evaluate the evolutionary relationship to the chemical (isoflavonoid) analysis. In morphometric analysis, the results showed that all cultivears were moderately classified. The leaf morphometry could separate the cultivars into 5 groups. The pod morphometry indicated that all cultivars belong into 2 groups. In addition, the flower morphometry could classify the cultivars into 3 groups. It could summarize that P. mirifica cultivars have low variation in morphometric approach. Due to correlation analysis, patterns of characterization of P. mirifica in Thailand were determined. The leaf, pod, and flower morphometry of P. mirifica presented that the morphological traits are correlated to angular distances on latitude and longitude. In genetic analysis, direct sequencing and RAPD were used. About direct sequencing, PCR products of ITS, trnL, and trnL-F could be amplified and sequenced. All obtained sequences indicated low level of genetic variation among the cultivars in Thailand. However, the sequence divergence of ITS (0-25.2%) was higher than that of other 2 regions. Due to RAPD, total of 93 polymorphic bands were generated. The average of genetic distance was varied from 0 to 0.4381. According to 4 NJ phylogenies (3 phylogenies by direct sequencing and 1 phylogeny by RAPD), the obtained topologies were different. Although the genetic polymorphism among cultivars was, the RAPD tree could moderately illustrate the cultivar classification depending on provinces and regions of Thailand. In chemical (isoflavonoid) content analysis, it showed 2 classified groups. Remarkably, variation of chemical contents among cultivars was also low. Furthermore, there was no significant correlation in isoflavonid contents against latitude and longitude. In summary, all 3 analyses indicated low variation among cultivars of P. mirifica in Thailand.