Abstract
Owing to their significant medicinal and edible values, the natural Dendrobium species have underdone over-collection and habitat destruction, and cultivated species emerged for candidates. However, these Dendrobium plants are similar in shape to be easily confused, leading to extreme difficulties for identification based on their morphological and chemical features. In this study, the rDNA ITS region sequence analysis was developed for rapid and accurate identification of thirteen wild and cultivated Dendrobium species belonging to two sections Formosae and Chrysotoxae. By cloning and sequencing the rDNA ITS region genes from 13 Dendrobium species, the phylogenetic relationships among them were analyzed. Results showed that the variation of the ITS region, together with the lengths and Guanine and Cytosine contents of ITS, 5.8s rDNA, ITS1 and ITS2 sequences occurred in the tested Dendrobium species, and which from section Chrysotoxae was higher than that from section Formsae. Phylogenetic analysis based on neighbor-joining and maximum p-arsimony trees indicated that the Dendrobium species of sections Formosae and Chrysotoxae could be well divided into two groups. A majority of Dendrobium species exhibited distinctive ITS2 secondary structures, while for those with close genetic relationships were similar. Therefore, the ITS2 region sequence analysis is simple, quick, and highly reliable that can be used as an effective tool for molecular identification and classification, as well as the reconstruction of the phylogeny of wild and cultivated Dendrobium species belonging to different sections.
Highlights
The genus Dendrobium is one of the largest genera in the family Orchidaceae including approximately 1600 species (Chiang et al 2012; Wu et al 2009) that is mainly distributed in tropical and subtropical Asia, and northern and eastern Australia (World Checklist of Selected Plant Families 2015; Zhu et al 2009)
polymerase chain reaction (PCR) amplification and sequence characteristics The sequencing characteristics were aligned with BLAST in National Center for Biotechnology Information (NCBI)
As for the 7 Dendrobium plants of section Formsae: it could be found that the lengths of internal transcribed spacer (ITS) sequence among the 13 Dendrobium species varied from 630 to 646 bp for the ITS region, from 228 to 240 bp for the ITS1 region, and from 243 to 247 bp for the ITS2 region, while was 163 bp for the 5.8s ribosomal DNA (rDNA) gene
Summary
The genus Dendrobium is one of the largest genera in the family Orchidaceae including approximately 1600 species (Chiang et al 2012; Wu et al 2009) that is mainly distributed in tropical and subtropical Asia, and northern and eastern Australia (World Checklist of Selected Plant Families 2015; Zhu et al 2009). Dendrobiums species have been thought as one of the most valuable medicinal genus in folk medicine and industrial crop with excellent medicinal merits, such as clearing unhealthy heat, nourishing Yin, benefiting the stomach, enhancing the body’s immunity, resisting cancer, and prolonging life (Ge et al.2018; Zha et al 2017; Zhao et al 2017) They have long been extensively used as the popular tonic and traditional Chinese medicines (TCMs) in many Asian countries (Chinese Pharmacopoeia Committee 2015), as well as a high-quality health food in South and Southeast Asia for hundreds of years (Kanlayavattanakul et al 2018; Zhu et al 2009). Whereas, motivated by the medicinal values and economic benefits, a few of other species, such as D. officinale, D. longicorna, D. aphyllum, D. bellatulum, etc., are widely used in various herbal
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