Genetic diversity of Stemona parviflora : A threatened myrmecochorous medicinal plant in China

Search for Snail Repellents: Antimollusc Activities from Stemona parviflora and Six Other Chinese Stemona Species

Snails are important agricultural pests difficult to control, but data regarding molluscicidal assays are scant. Stemona alkaloids are typical secondary metabolites for the taxa and have been broadly investigated for their pharmacological and toxicological effects. This makes it possible for us to further develop the toxicities of these compounds to snails. In this work, we tested the antifeedant properties of leaves from seven Chinese Stemona species against the land snail species Bradybaena ravida in choice and non-choice feeding assays. The tested leaves Stemona parviflora exhibited the most deterrent effects, and a further phytochemical investigation of aerial parts led to the identification of 16 alkaloids. Among them, three novel alkaloids could be identified. The alkaloidal fraction and single alkaloids were further assayed against this snail species, and the results suggest a cocktail effect because the impact of the alkaloidal fraction was higher than the effects caused by single alkaloids. The study can promote the search process of natural antimollusc products from plants to control snails.

The Complete Chloroplast Genome of Endangered Species Stemona parviflora: Insight into the Phylogenetic Relationship and Conservation Implications

Stemona parviflora is an endangered species, narrowly endemic to Hainan and Southwest Guangdong. The taxonomic classification of S. parviflora remains controversial. Moreover, studying endangered species is helpful for current management and conservation. In this study, the first complete chloroplast genome of S. parviflora was assembled and compared with other Stemona species. The chloroplast genome size of S. parviflora was 154,552 bp, consisting of 87 protein-coding genes, 38 tRNA genes, 8 rRNA genes, and one pseudogene. The ψycf1 gene was lost in the cp genome of S. sessilifolia, but it was detected in four other species of Stemona. The inverted repeats (IR) regions have a relatively lower length variation compared with the large single copy (LSC) and small single copy (SSC) regions. Long repeat sequences and simple sequence repeat (SSR) were detected, and most SSR were distributed in the LSC region. Codon usage bias analyses revealed that the RSCU value of the genus Stemona has almost no difference. As with most angiosperm chloroplast genomes, protein-coding regions were more conservative than the inter-gene spacer. Seven genes (atpI, ccsA, cemA, matK, ndhA, petA, and rpoC1) were detected under positive selection in different Stemona species, which may result from adaptive evolution to different habitats. Phylogenetic analyses show the Stemona cluster in two main groups; S. parviflora were closest to S. tuberosa. A highly suitable region of S. parviflora was simulated by Maxent in this study; it is worth noting that the whole territory of Taiwan has changed to a low fitness area and below in the 2050 s, which may not be suitable for the introduction and cultivation of S. parviflora. In addition, limited by the dispersal capacity of S. parviflora, it is necessary to carry out artificial grafts to expand the survival areas of S. parviflora. Our results provide valuable information on characteristics of the chloroplast genome, phylogenetic relationships, and potential distribution range of the endangered species S. parviflora.

A simple PCR-RFLP method for identification and detection of medicinal toad and its crude drug even with serious degradation of DNA

The secretions of the venom glands, dry skin and whole body of several Bufo species have been used as traditional medicines in East Asia to treat heart failure and cancer. Due to the highly similar morphological features of Bufo species and their derived commercial crude drugs, along with the high similarity of chemical composition of the secretions of venom glands, it is very challenging to identify the medicinal toads and the related crude drugs. The cyt-b sequences provide useful information to authenticate medicinal Bufo species. Based on the cyt-b sequences, a simple PCR-RFLP method was established for the identification of the medicinally used Bufo species as well as their derived crude drugs. The 23 specimens from three medicinally used Bufo species, B. bufo gargarizans (Bbg), B. melanostictus (Bm) and B. raddei (Br), were clearly divided into 3 groups according to the sequences of amplified cyt-b regions, which could be digested by specific restriction enzymes NcoI, EcoRV and BstXI, respectively. Then the specific PCR-RFLP method was further used to identify 9 samples of commercial crude drugs even with serious degradation of DNA, and all nine samples were identified as B. bufo gargarizans. The method is suitable for identification of medicinally used Bufo species and the related crude drugs.

Development of 23 novel microsatellite markers of Amomum tsao-ko (Zingiberaceae) based on restriction-site-associated DNA sequencing

Amomum tsao-ko (Zingiberaceae) is a traditional Chinese medicine and condiment, and an important economic crop in the tropical forest of southwest China. However, few simple sequence repeat (SSR) markers are available in A. tsao-ko, which is hindering genetic research in this species. The aim of this study was to develop and characterize microsatellite markers for A. tsao-ko using restriction-site-associated DNA sequencing. A total of 115,482 microsatellites were identified using MISA software, and 13,411 SSR primer pairs were designed. 100 pairs of SSR primers were selected at random and used to evaluate polymorphisms among 4 A. tsao-ko samples. Finally, 23 pairs of SSR primers with clear bands and obvious polymorphism were selected for genetic diversity analysis of 72 A. tsao-ko accessions. The number of alleles and effective number of alleles per locus ranged from 2 to 6 and from 1.315 to 3.776, respectively. The observed heterozygosity ranged from 0.208 to 0.779, and the expected heterozygosity was from 0.239 to 0.735. The average values of the polymorphic information content were 0.454. Hardy–Weinberg equilibrium (HWE) analysis showed that 10 loci significantly deviated from HWE (P < 0.05). The pairwise F_ST and genetic distance values revealed low levels of genetic differentiation and high genetic similarity among six A. tsao-ko populations. These microsatellite markers developed will provide a valuable tool for further germplasm characterization, genetic diversity, and breeding studies in A. tsao-ko.