TAXONOMIC STATUS INVESTIGATING OF IMPATIENS SIRINDHORNIAE TRIBOUN & SUKSATHAN IN THAILAND

Abstract

This study aimed to investigate the taxonomic status of Impatiens sirindhorniae Triboun & Suksathan from two populations including: plants from limestone hills, Plai Phraya District, Krabi Province, which is type locality, and plants from Ratchaprapha Dam, Suratthani Province by morphological and biomolecular data. From the morphological study, it was found that plants from both populations had many different characteristics such as leaf shape, leaf tip, leaf base, leaf edge, flower color, and stem color. Plant specimens from Suratthani Province was higher variation in characteristics than plant specimens from Krabi Province. Whereas reproductive parts, such as the shape of pistil and stamen, ovary, pollen, pods, and seeds of those specimens from the two populations were very similar. The results of the molecular biology study using molecular markers found that the similarity of the nucleotide sequences using the ClustalX program of the matK gene and the rbcL gene of I. sirindhorniae of both populations was quite high. The matK gene region having the within-species nucleotide sequence variation is 0.00–0.40, which is lower than the inter-species variation of other Impatiens species in the range of 0.46–0.53. For the rbcL gene, the nucleotide sequence variation was 0.00 within species and 0.72–0.78 between species. Therefore, it can be concluded that although the plant from the two populations has different morphology in many characteristics, they are not enough to classify them into different taxonomic units (taxa). This is consistent with the results of the analysis of the nucleotide sequence variation of the matK and rbcL genes. The variation between the 2 populations was lower than other Impatiens species.