Genetic variation of Croton stellatopilosus Ohba based on non-coding DNA sequences of ITS, trnK and trnL-F regions

Croton stellatopilosus Ohba (Plau-noi), a well-known Thai medicinal plant, was investigated for its genetic variation by analyzing three DNA regions, one nuclear internal transcribed spacer (ITS) region and two chloroplast trnL-F intergenic spacer and trnK intron regions. The results of ITS sequencing from 30 leaf samples showed that there were two major genotypes of C. stellatopilosus which were designated as STEL Type A and B. In addition, various nucleotide additive sequences which had presumably arisen from these two groups were also found. These so-called putative hybrids, interestingly, displayed trnK intron sequences identical to the STEL Type B but different from the Type A. For the trnL-F region, all the 30 samples showed identical sequences. Thus, it was suggested that in the hybridization of C. stellatopilosus, the Type A genotype acts as paternal parent whereas the Type B genotype acts as maternal parent. In addition, all C. stellatopilosus samples were analyzed for their plaunotol content using TLC densitometry. We found that the Type A genotype, hybrid group and Type B genotype had plaunotol content in the ranges 0.209-0.492, 0.319-0.896 and 0.442-1.000% (w/w) dry weight, respectively. The results indicated that there is a correlation between the plaunotol contents and non-coding DNA sequences of ITS, trnK and trnL-F regions of C. stellatopilosus.