Genetic diversity analysis of Pinellia ternata based on SRAP and TRAP markers

Transcriptome Profiling Reveals Differential Gene Expression during the Process of Microtuber Formation in Pinellia ternata

Using petiole material as explants and directly inducing the formation of microtubers without going through the callus stage is an essential way to rapidly expand scarce medical plants such as Pinellia ternata. However, the early molecular mechanism underlying the formation of the microtuber is largely elusive. Here, we conducted cytology and dynamic transcriptome analyses of inchoate microtubers in Pinellia explants and identified 1092 differentially expressed genes after their cultivation in vitro for 0, 5, and 15 days. Compared with 0 day, the number and size of the microtuber cells were larger at 5 and 15 days of culture. Detailed categorization revealed that the differentially expressed genes were mainly related to responses to stimulus, biological regulation, organelles, membranes, transcription factor activity, and protein binding. Further analysis revealed that the microtuber at different incubation days exhibited quite a difference in both hormone signaling pathway transduction and the regulation pattern of transcription factors. Therefore, this study contributes to a better understanding of the early molecular regulation during the formation of the microtuber and provides new insights for the study of the rapid expansion of P. ternata and other medical plants.

Rhizosphere microbial diversity in rhizosphere of Pinellia ternata intercropped with maize

Dry tubers of Pinellia ternata (Thunb.) Breit are used in traditional Chinese medicine. Commonly known as "banxia" in China, the tubers contain valuable compounds, including alkaloids and polysaccharides that are widely used in pharmaceuticals. The quantity and quality of these important compounds are affected by whether P. ternata is grown as a sole crop or as an intercrop, and P. ternata cultivation has become challenging in recent years. By intercropping P. ternata, its maximum yield, as well as large numbers of chemical components, can be realized. Here, a large data set derived from next-generation sequencing was used to compare changes in the bacterial communities in rhizosphere soils of P. ternata and maize grown as sole crops and as intercrops. The overall microbial population in the rhizosphere of intercropped P. ternata was significantly larger than that of sole-cropped P. ternata, whereas the numbers of distinct microbial genera, ranging from 552 to 559 among treatments, were not significantly different between the two rhizospheres. The relative abundances of the genera differed. Specifically, the numbers of Acidobacteria and Anaerolineaceae species were significantly greater, and those of Bacillus were significantly lower, in the intercropped P. ternata rhizosphere than in the sole-cropped rhizosphere.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-03011-3.

UHPLC-MS-based metabolomic approach for the quality evaluation of Pinellia ternata tubers grown in shaded environments

Pinellia ternata is a native herb in China, and its tuber is widely-used in traditional Chinese medicines. It has been identified that the shading treatment promotes tuber production during cultivation. However, the tuber quality in shaded environments is unknown, which limits the scientific cultivation of P. ternata. In this study, a metabolomics approach based on UHPLC-MS was applied to assess the metabolic components of P. ternata in response to shading. Diverse metabolites were profiled using the metabolomics approach. Then, datasets of P. ternata cultivated in natural light (control) and shaded environments were subjected to multivariate analyses. Two P. ternata tuber products were well separated by the PCA. In total, four P. ternata alkaloids with contents that were not altered by the shaded environment were detected. Metabolomic analyses further identified several organic acids [mevalonic acid, 12,13-dihydroxy-9Z-octadecenoic acid (12, 13-DiHOME), urocanic acid, and γ-aminobutyric acid] that were largely enriched in the shaded environment, which likely contributed to tuber quality and growth. This study determined that shading probably improves the quality of P. ternata tubers and laid a foundation for exploring the regulatory mechanism of the shade response in P. ternata.

Pinellia ternata (Thunb.) Breit: A review of its germplasm resources, genetic diversity and active components

ETHNOPHARMACOLOGICAL RELEVANCE

The medicinal plant Pinellia ternata has been widely used in China, Korea, and Japan and has been demonstrated to be highly effective for treating cough, vomiting, infection, and inflammatory diseases. Modern pharmacological investigations have demonstrated its multiple activities, such as antitussive, expectorant, antiemetic, antitumor, antibacterial, and sedative-hypnotic activities.

AIM OF THE REVIEW

This review aims to summarize the information about the biological traits, genetic diversity, active components, and continuous cropping obstacle of P. ternata in order to improve its use.

MATERIALS AND METHODS

In this review, the relevant literature was gathered by using Pinellia ternata, genetic diversity, active components, and continuous cropping obstacle as the keywords from Google Scholar, PubMed, Springer Link, the Wiley online library, SciFinder, SCOPUS, Baidu Scholar, China national knowledge infrastructure (CNKI), and WANFANF DATA (up to April 2020).

RESULTS

P. ternata is the most widely used herb in the Pinellia genus to treat several diseases. The genetic diversity of P. ternata has been extensively studied, and its high genetic diversity level in China has been demonstrated. Modern pharmacological research has indicated that amino acids, alkaloids, and polysaccharides are the main active components supporting P. ternata's medicinal effects. However, an efficient method for determining its active components is still unavailable. The method used to evaluate Pinelliae Rhizoma (PR) quality standards should be further optimized. The continuous cropping obstacle has a significant effect on the quantity and quality of P. ternata. The underlying mechanism of the continuous cropping obstacle needs to be further explored.

CONCLUSIONS

P. ternata has emerged as a valuable source of traditional medicine. Some uses of P. ternata in medicine have been validated by pharmacological investigations. However, a more efficient analytical method should be established to evaluate the quality of PR based on multiple quality markers. Furthermore, high-performance liquid chromatography (HPLC) and DNA barcoding should be introduced to identify the authenticity of PR. In addition, the genes involved in the metabolic synthesis pathways of the main active components, population genetic relationships, the quality control of processed PR, and the continuous cropping obstacle need to be further elucidated. We hope this review will allow for better utilization of this valuable herb.

Genetic divergence in Tunisian castor bean genotypes based on trap markers

In the present study, the representatives of the genus Ricinus communis collected from 12 different parts of Tunisia were differentiated by the DNA fingerprinting patterns using 30 TRAP primers. The efficacy of the TRAP technique in this study is further supported by the obtained PIC values of the primers used in the analysis. PCR amplification of DNA using 30 primers for TRAP analysis produced 490 DNA fragments that could be scored in all 56 genotypes of Tunisian castor. The number of amplified fragments varied from 3 (TRAP 04 x arb 1, TRAP 22 x arb 3 and TRAP 23 x arb 3) to 13 (TRAP 56 x arb 2), and the amplicon size ranged from 100 to 1600 bp. Of the 490 amplified bands, 377 were polymorphic, with an average of 5.71 polymorphic bands per primer. To determine the level of polymorphism in the analysed group of Tunisian castor genotypes polymorphic information content (PIC) was calculated. The lowest values of polymorphic information content were recorded for TRAP 10 x arb 1 (0.555) and the highest PIC values were detected for TRAP 44 x arb 2 (0.961) with an average of 0.770. A dendrogram was constructed from a genetic distance matrix based on profiles of the 30 TRAP primers using the unweighted pair-group method with the arithmetic average (UPGMA). According to analysis, the collection of 56 Tunisian castor genotypes were clustered into five main clusters. Moreover, functional TRAP markers would be efficiently useful in genetic studies for castor genetic improvement.

Breaking the Summer Dormancy of Pinellia ternata by Introducing a Heat Tolerance Receptor-Like Kinase ERECTA Gene

Pinellia ternata is a perennial traditional Chinese medicinal plant that undergoes different phenological patterns of dormancy depending on where it is growing. Plants grown in central and southern China typically display two growth cycles every year before and after hot summer days, exhibiting a summer dormancy. However, germplasms from these areas do not go into a dormancy phase in northern China where the summer monthly average temperatures range from 29-31°C. The northern China herbal growers prefer plant stocks from central China due to their longer growing quality and better tuber harvests. Here, we introduced a heat responsive receptor-like kinase ERECTA (ER) gene into P. ternata to explore changes in the growth cycle which were aimed at disrupting the summer dormancy. The 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGR) gene was also co-transformed with ER to improve the commercial trait. For the thermo-tolerance evaluation, all plants were treated with high temperatures (35°C/40°C) in a growth chamber or grown in natural field temperature in an isolated field before measurement of different agricultural, biochemical and physiological traits. The transgenics showed significantly (P < 0.05) higher heat tolerance, maintaining healthy vegetative growth unlike the empty vector (EV) harboring controls that became chlorotic and necrotic. Better performance in some of the monitored physiological traits was evident for overexpression lines exposed to the heat stress. In open isolated field trials, the transgenic genotypes did not show a summer dormancy but had a survival rate of 84-95%. The tuber biomasses were also significantly (P < 0.05) higher for the transgenic lines as compared to the EV controls, except for line ER118. Metabolites analysis indicated that the HMGR overexpressing lines (HMGR orHMGR + ER) exhibited significantly higher amounts of bioactive compounds including aromadendrene-4, 10-diol and 4, 8, 13-cyclotetradecatriene-1, 3-diol, 1, 5, 9-trimethyl-12-(1-methylethyl). Our findings show that the summer dormancy of P. ternata which is a naturally evolved trait, can be removed by a single heat responsive gene. The study contributes to generating heat tolerant new Pinellia varieties with enhanced commercially valuable chemicals.

Full-length transcriptome analysis of shade-induced promotion of tuber production in Pinellia ternata

BACKGROUND

Pinellia ternata is native to China and has been used as a traditional herb due to its antiemetic, antitussive, analgesic, and anxiolytic effects. When exposed to strong light intensity and high temperature during the reproductive growth process, P. ternata withers in a phenomenon known as "sprout tumble", which largely limits tuber production. Shade was previously found to delay sprout tumble formation (STF); however, no information exists regarding this process at the molecular level. Hence, we determined the genes involved in tuber development and STF in P. ternata.

RESULTS

Compared to that with natural sun-light (control), shade significantly induced chlorophyll accumulation, increased chlorophyll fluorescence parameters including initial fluorescence, maximal fluorescence, and qP, and dramatically repressed chlorophyll a:b and NPQ. Catalase (CAT) activity was largely induced by shade, and tuber products were largely increased in this environment. Transcriptome profiles of P. ternata grown in natural sun-light and shaded environments were analyzed by a combination of next generation sequencing (NGS) and third generation single-molecule real-time (SMRT) sequencing. Corrections of SMRT long reads based on NGS short reads yielded 136,163 non-redundant transcripts, with an average N50 length of 2578 bp. In total, 6738 deferentially-expressed genes (DEGs) were obtained from the comparisons, specifically D5S vs D5CK, D20S vs D20CK, D20S vs D5S, and D20CK vs D5CK, of which, 6384 DEGs (94.8%) were generated from the D20S vs D20CK comparison. Gene annotation and functional analyses revealed that these genes were related to auxin signal transduction, polysaccharide and sugar metabolism, phenylpropanoid biosynthesis, and photosynthesis. Moreover, the expression of genes enriched in photosynthesis appeared to be significantly altered by shade. The expression patterns of 16 candidate genes were consistent with changes in their transcript abundance as identified by RNA-Seq, and these might contribute to STF and tuber production.

CONCLUSION

The full-length transcripts identified in this study have provided a more accurate depiction of P. ternata gene transcription. Further, we identified potential genes involved in STF and tuber growth. Such data could serve as a genetic resource and a foundation for further research on this important traditional herb.

Genetic variation in Whitmania pigra, Hirudo nipponica and Poecilobdella manillensis, three endemic and endangered species in China using SSR and TRAP markers

Leeches are not only important medicinal animals worldwide but also are endangered. We aimed to (i) explore the level of genetic diversity within/among populations of three leeches, (ii) assess genetic differentiation among these three leeches, and (iii) discuss an appropriate strategy for conserving leech germplasm. A total of 315 individuals of Whitmania pigra, Hirudo nipponica and Poecilobdella manillensis from 21 populations were collected in China and Vietnam. The genetic structure and genetic diversity among and within the 21 populations were evaluated using target region amplified polymorphism (TRAP) and simple sequence repeat (SSR) markers. Sixteen pairs of TRAP primers generated a total of 398 fragments, of which 396 (99.50%) were polymorphic; fourteen pairs of SSR primers generated a total of 60 fragments, of which 59 (98.33%) were polymorphic. Shannon's index (I) and Nei's gene diversity index (H) for the three leeches were high at the species level (I=0.4980 and H=0.3323 for TRAPs, I=0.4487 and H=0.2969 for SSRs in W. pigra; I=0.4147/0.3769, H=0.2788/0.2566 for H. nipponica; and I=0.4616/0.4717, H=0.3099/0.3203 for P. manillensis). However, low genetic diversity was determined at the population level; the average genetic diversity measures within populations were H=0.1767/0.1376, I=0.2589/0.2043 for W. pigra, H=0.2149/0.2021, I=0.3184/0.3000 for H. nipponica and H=0.2850/0.2724, I=0.4152/0.3967 for P. manillensis. We conclude that there was limited gene exchange within/among populations and species, as the gene flow number (Nm) was 0.5493/0.5807. However, for all three species, the genetic diversity was different at the population level. Gene differentiation (Gst) and Nm were 0.4682 /0.5364 and 0.5678/0.4321 for W. pigra, 0.2294/0.2127 and 1.6797/1.8512 for H. nipponica and 0.1214/0.1496 and 3.6202/2.8412 for P. manillensis. STRUCTURE analysis, Unweighted Pair-Group Method with Arithmetic means (UPGMA) cluster analysis and Principal Coordinates Analysis (PCOA) all yielded similar results. The isolation-by-distance pattern was not significant for any of the three species by the Mantel test. These data emphasize the need for management, conservation, and rehabilitation of this animal species. Finally, an appropriate strategy for conserving leech is proposed.