PJB-2022-216
Application of ITS2 in species identification and classification of Rehmannia
JIUCHANG SU
Abstract
Internal transcribed spacer 2 (ITS2) sequence has a high ability to discriminate plants and can be applied to the phylogeny and species classification. In this study, the length of ITS2 sequence in Rehmannia is 224-235bp with 65% GC or so, its mutation rate is about 16.0%, further analysis found that ITS2 has higher interspecific diversity and lower intraspecific divergence in Rehmannia, R. glutinosa and R. solanifolia, R. piasezkii and R. elata might be relatively close relatives based on NJ phylogenetic tree of ITS2 sequence. Homology modeling results show that ITS2 secondary structure in Rehmannia is typically composed of four helices, the length or shape of each helix is variable, its interspecific difference is significant, and ITS2 secondary structure also exhibits more differences in some varieties of R. glutinosa. In addition, the species in Rehmannia are obviously differentiated from its relative genus Triaenophora based on ITS2 sequences and its secondary structures. Therefore, the results indicated that the discrimination ability of ITS2 could be significantly improved by its structural information, and ITS2 would have great feasibility in the application of species classification and identification.
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