Botanical Biometrics: Exploring Morphological, Palynological, and DNA Barcoding Variations in White Kwao Krua (Pueraria candollei Grah. ex Benth. and P. mirifica Airy Shaw & Suvat.)

Abstract

White Kwao Krua, a crucial Thai medicinal plant, contains various phytoestrogen substances used to alleviate menopausal symptoms in estrogen-deficient women. It originates from two species, namely Pueraria candollei Wall. ex Benth. and P. mirifica Airy Shaw & Suvat. However, there exists morphological variation, and the taxonomic status between both species is ambiguous, making discrimination challenging. In this study, we aim to clarify and differentiate the morphological characteristics, palynology, and DNA barcoding of both species. The morphological results showed the stipule size is a phenotypic marker for the differentiation of both species during the vegetative stage. The palynological results, however, exhibited similarity. Through an examination of nucleotide sequences and neighbor-joining tree analysis, it was determined that the DNA barcoding of the matK region has the capability to distinguish between P. candollei and P. mirifica at nucleotide position 702. Specifically, P. candollei manifested a G base, contrasting with the C base observed in P. mirifica. This study concludes that stipule size and the matK gene in DNA barcoding serve as a distinctive characteristic for distinguishing between P. candollei and P. mirifica. These methodologies prove valuable for ensuring the accurate identification of white Kwao Krua for horticulturists.