Twenty years of Chinese vascular plant novelties,2000 through 2019

From 2000 to 2019,11,895 new names or new additions to the Chinese vascular flora were proposed by 4226 individuals(4086 articles and 140 books),as documented in the Chinese Plant Names Index(CPNI).During those 20 years,4407 new taxa of vascular plants were described from China,including 7 new families,132 new genera,3543 new species,68 new subspecies,497 new varieties and 160 new forms.Additionally,3562 new combinations and names at new rank and 306 new replacement names were also proposed.Among these various new names were 150 invalid names and 108 illegitimate names,including some that have not been resolved.Six hundred and forty three vascular plants were reported as new to China,while 2349 names were reduced to synonyms of 1406 taxa.The data show that the Chinese flora increased in size at the rate of about 200 taxa annually during those years.Despite the increased attention given to biodiversity in recent years,the evidence indicates that a large number of species in China have yet to be discovered.Further basic investigation of the Chinese flora is needed.Additionally,in the past two decades only 8.5%of the newly published species have been based on molecular evidence,but in the past five years such data have increased significantly,reaching about 20%.Molecular data will undoubtedly become increasingly significant in the discovery of new species in the coming years.Yunnan,Guangxi,Sichuan,Xizang and Taiwan were important sources of new discoveries,with more than 3300 new taxa and records from these five provinces.By area,Taiwan and Hainan,two islands in southern China,have the highest density of newly discovered species.Regional plant surveys are still needed,especially in areas in the southwest and on the southern islands.

Effects of functional phylogeny of light-response-related orthologous genes on seedling survival in a subtropical forest

Background: Light is an important environmental factor affecting the growth and survival of plants in forest communities. The competition for light resources and divergent responses to light may affect plant species coexistence in natural forests through niche partitioning and environmental filtering, respectively.Methods: In the present study, sequences of light-response-related functional genes were extracted from transcriptomic data of 99 tree species in a subtropical forest and average and nearest taxon phylogenetic diversity of adult(A_Apd’, A_NTpd’) and seedling neighbors(S_Apd’, S_NTpd’) around each focal seedling were calculated to evaluate effects of differentiation in light-response-related genes on community assembly processes.Results: The results showed that seedling survival was related to S_NTpd’, S_Apd’and A_Apd’of two chlorophyll ab-binding proteins involved in the assembly of photosystem Ⅱ and two genes responsive to light intensity,indicating seedlings surrounded by neighbors with distinct light responses tended to have high survival rates.Conclusions: Our results indicated that niche partitioning due to competition for light resources between plants may act as the key mechanism in determining seedling dynamics in subtropical forests.

Gap-free genome assembly and CYP450 gene family analysis reveal the biosynthesis of anthocyanins in Scutellaria baicalensis

Scutellaria baicalensis Georgi,a member of the Lamiaceae family,is a widely utilized medicinal plant.The flavones extracted from S.baicalensis contribute to numerous health benefits,including anti-inflammatory,antiviral,and anti-tumor activities.However,the incomplete genome assembly hinders biological studies on S.baicalensis.This study presents the first telomere-to-telomere(T2T)gap-free genome assembly of S.baicalensis through the integration of Pacbio HiFi,Nanopore ultra-long and Hi-C technologies.A total of 384.59 Mb of genome size with a contig N50 of 42.44 Mb was obtained,and all sequences were anchored into nine pseudochromosomes without any gap or mismatch.In addition,we analysed the major cyanidin-and delphinidin-based anthocyanins involved in the determination of blue-purple flower using a widely-targeted metabolome approach.Based on the genome-wide identification of Cytochrome P450(CYP450)gene family,three genes(SbFBH1,2,and 5)encoding flavonoid 3′-hydroxylases(F3′Hs)and one gene(SbFBH7)encoding flavonoid 3′5′-hydroxylase(F3′5′H)were found to hydroxylate the B-ring of flavonoids.Our studies enrich the genomic information available for the Lamiaceae family and provide a toolkit for discovering CYP450 genes involved in the flavonoid decoration.

Diversity and conservation of Chinese wild begonias

Begonia, one of the most diverse plant taxa and the fifth or sixth largest angiosperm genus, consists of over1800 accepted species. The number of species recognized within this genus has greatly increased over the past 20 years, rising from 80 to 200 species in China alone. Based on recent field surveys, the number of begonia species in China is predicted to be between 250 and 300. Given the large number of begonia species that still remain to be described, further taxonomical work is urgently required. This is especially true for Chinese Begonia, in which there is a huge diversity of habitat, habit, plant size, leaf type, flower and fruit morphology, and most species are narrowly distributed in isolated habitats that are subject to negative disturbances from climate change, as well as agricultural and industrial activities. Although the conservation status for the majority of species has been evaluated using the standards of the International Union for Conservation of Nature, the results don't represent the truth in many species, and also about11.5% of which are data-absent. In addition, illegal collection and over-harvesting of wild begonias for ornamental or medicinal use has increased due to the rapid development of internet commerce. Far more often than predicted, these species should be categorized as rare and endangered and require immediate protection. Ex situ conservation of Chinese begonias started in 1995 and over 60% of the total species have been so far introduced into cultivation by several major botanical gardens in China. However, only few research institutions, limited funds and human resources have been involved in Begonia conservation;moreover, no project has conducted reintroduction. Therefore, more conservation-based work remains to be done. Improved conservation of Chinese begonias in the future depends on further field survey, an improved understanding of population diversity, and integrative approaches, including in situ and ex situ conservation, seed banking, and plant reintroduction. Species-targeted conservation zones should be established for endangered species excluded from the existing nature reserves. Additionally, laws pertaining to plant protection should be extended to prevent the illegal collection and transaction of wild plants, particularly for those species with unique habitats and small populations.

Effective genome editing and identification of a regiospecific gallic acid 4-O-glycosyltransferase in pomegranate(Punica granatum L.)

Pomegranate(Punica granatum L.)trees are woody perennials that bear colorful and nutritious fruits rich in phenolic metabolites,e.g.,hydrolyzable tannins(HTs)and flavonoids.We here report genome editing and gene discovery in pomegranate hairy roots using Clustered Regularly Interspaced Short Palindromic Repeats(CRISPR)/CRISPR-associated protein 9(Cas9)(CRISPR/Cas9),coupled with transcriptome and biochemical analyses.Single guide RNAs(sgRNAs)were designed to target two UDP-dependent glycosyltransferases(UGTs),PgUGT84A23 and PgUGT84A24,which possess overlapping activities inβ-glucogallin(a galloylglucose ester;biosynthetic precursor of HTs)biosynthesis.A unique accumulation of gallic acid 3-O-and 4-O-glucosides(galloylglucose ethers)was observed in the PgUGT84A23 and PgUGT84A24 dual CRISPR/Cas9-edited lines(i.e.,ugt84a23 ugt84a24)but not the control(empty vector)or PgUGT84A23/PgUGT84A24 single edited lines(ugt84a23 or ugt84a24).Transcriptome and real-time qPCR analyses identified 11 UGTs with increased expression in the ugt84a23 ugt84a24 hairy roots compared to the controls.Of the 11 candidate UGTs,only PgUGT72BD1 used gallic acid as substrate and produced a regiospecific product gallic acid 4-O-glucoside.This work demonstrates that the CRISPR/Cas9 method can facilitate functional genomics studies in pomegranate and shows promise for capitalizing on the metabolic potential of pomegranate for germplasm improvement.

Spatio-temporal Variation of Soil Respiration and Its Driving Factors in Semi-arid Regions of North China

Soil respiration(SR) is the second-largest flux in ecosystem carbon cycling. Due to the large spatio-temporal variability of environmental factors, SR varied among different vegetation types, thereby impeding accurate estimation of CO_2 emissions via SR. However, studies on spatio-temporal variation of SR are still scarce for semi-arid regions of North China. In this study, we conducted 12-month SR measurements in six land-use types, including two secondary forests(Populus tomentosa(PT) and Robinia pseudoacacia(RP)), three artificial plantations(Armeniaca sibirica(AS), Punica granatum(PG) and Ziziphus jujuba(ZJ)) and one natural grassland(GR), to quantify spatio-temporal variation of SR and distinguish its controlling factors. Results indicated that SR exhibited distinct seasonal patterns for the six sites. Soil respiration peaked in August 2012 and bottomed in April 2013. The temporal coefficient of variation(CV) of SR for the six sites ranged from 76.98% to 94.08%, while the spatial CV of SR ranged from 20.28% to 72.97% across the 12-month measurement. Soil temperature and soil moisture were the major controlling factors of temporal variation of SR in the six sites, while spatial variation in SR was mainly caused by the differences in soil total nitrogen(STN), soil organic carbon(SOC), net photosynthesis rate, and fine root biomass. Our results show that the annual average SR and Q_(10)(temperature sensitivity of soil respiration) values tended to decrease from secondary forests and grassland to plantations, indicating that the conversion of natural ecosystems to man-made ecosystems may reduce CO_2 emissions and SR temperature sensitivity. Due to the high spatio-temporal variation of SR in our study area, care should be taken when converting secondary forests and grassland to plantations from the point view of accurately quantifying CO_2 emissions via SR at regional scales.

Genetic diversity of the wild Asian lotus (Nelumbo nucifera) from Northern China

Asian lotus(Nelumbo nucifera Gaertn.)is an aquatic plant with ornamental,cultural,economic,and ecological values.China has abundant germplasm resources of Asian lotus.However,in many areas,the wild Asian lotuses have been destroyed and the germplasms is now facing extinction.In addition,the knowledge of the genetic diversity of the wild Asian lotus in China is poor.To identify and protect the germplasms of Chinese wild Asian lotus,eleven genomic-SSR primers,three EST-SSR primers,and three chloroplast DNA primers were used to investigate the genetic diversity among 69 samples of wild Asian lotus from 25 locations in northern China.The genetic diversity of 27 samples of wild Asian lotus from southern China and other countries,the ancient Asian lotus,Asian lotus cultivars from China,and Asian-American hybrids was also compared.The genetic diversity of the wild Asian lotus from northern China was characterized as medium,and themean values of observed heterozygosity(Ho)and expected heterozygosity(He)were 0.087 and 0.552,respectively.Based on a UPGMA dendrogram and STRUCTURE analysis,the wild Asian lotus samples in northern China were divided into three groups.The wild Asian lotus samples from northern China contained 16 haplotypes.The Nei’s genetic distance between the wild Asian lotus samples from the Songhua River basin and the Liao River basin in northeastern China was relatively small,and these germplasms might be relatively primitive compared to those from other regions.This study provides essential information regarding the genetic diversity of the wild Asian lotus resources in northern China,and provides a basis for further analysis of population-level genetic evolution through high-throughput sequencing.

Morphological study of floral nectaries in Euonymus and the probable origin of the echinate fruit surface

A conspicuous nectary disk is common but has a distinguishing morphology in the cosmopolitan genus Euonymus. Our study focuses on the morphology of floral nectaries in 21 representatives of Euonymus and Glyptopetalum. Two main types of nectaries were documented: a mix of inter-and extrastaminal nectaries existed between the corolla and the stigma, while the intrastaminal nectaries were distributed between the stigma and the stamen bases. The main route of nectar release in Euonymus is via modified stomata, and different nectarostomata locations were observed: in depressions, slightly raised above the epidermal surface or at the same level as the epidermis. Floral nectaries in E. sect. Echinococcus species developed into the protrusions on the fruit surface at the later stage. The development of nectaries not only explained the mystery of the origin of the echinate fruit surface, but also showed that differences in fruit surface might be inappropriate for use in infrageneric classification. These discoveries inform morphological observations of floral nectaries in Euonymus.

New Dimeric and seco-Abietane Diterpenoids from Salvia wardii

Two dimeric abietane diterpenoids,salviwardins A and B(1 and 2),and a seco-abietane diterpenoid salviwardin C(3),along with five known analogues(4–8),were isolated from the roots of Salvia wardii.The structures of these isolates were elucidated by extensive spectroscopic methods.The inhibitory activities of these isolates against five human cancer cell lines in vitro were also tested.

Lycophyte transcriptomes reveal two whole-genome duplications in Lycopodiaceae:Insights into the polyploidization of Phlegmariurus

Lycophytes are an ancient clade of the non-flowering vascular plants with chromosome numbers that vary from tens to hundreds.They are an excellent study system for examining whole-genome duplications(WGDs),or polyploidization,in spore-dispersed vascular plants.However,a lack of genome sequence data limits the reliable detection of very ancient WGDs,small-scale duplications(SSDs),and recent WGDs.Here,we integrated phylogenomic analysis and the distribution of synonymous substitutions per synonymous sites(Ks)of the transcriptomes of 13 species of lycophytes to identify,locate,and date multiple WGDs in the lycophyte family Lycopodiaceae.Additionally,we examined the genus Phlegmariurus for signs of genetic discordance,which can provide valuable insight into the underlying causes of such conflict(e.g.,hybridization,incomplete lineage sorting,or horizontal gene transfer).We found strong evidence that two WGD events occurred along the phylogenetic backbone of Lycopodiaceae,with one occurring in the common ancestor of extant Phlegmariurus(Lycopodiaceae)approximately 22-23 million years ago(Mya)and the other occurring in the common ancestor of Lycopodiaceae around 206-214 Mya.Interestingly,we found significant genetic discordance in the genus Phlegmariurus,indicating that the genus has a complex evolutionary history.This study provides molecular evidence for multiple WGDs in Lycopodiaceae and offers phylogenetic clues to the evolutionary history of Lycopodiaceae.

Agroinfection of sweet potato by vacuum infiltration of an infectious sweepovirus

Sweepovirus is an important monopartite begomovirus that infects plants of the genus Ipomoea worldwide. Development of artificial infection methods for sweepovirus using agroinoculation is a highly efficient means of studying infectivity in sweet potato. Unlike other begomoviruses, it has proven difficult to infect sweet potato plants with sweepoviruses using infectious clones. A novel sweepovirus, called Sweet potato leaf curl virus-Jiangsu(SPLCV-JS), was recently identified in China. In addition, the infectivity of the SPLCV-JS clone has been demonstrated in Nicotiana benthamiana. Here we describe the agroinfection of the sweet potato cultivar Xushu 22 with the SPLCV-JS infectious clone using vacuum infiltration. Yellowing symptoms were observed in newly emerged leaves. Molecular analysis confirmed successful inoculation by the detection of viral DNA. A synergistic effect of SPLCV-JS and the heterologous betasatellite DNA-β of Tomato yellow leaf curl China virus isolate Y10(TYLCCNV-Y10) on enhanced symptom severity and viral DNA accumulation was confirmed. The development of a routine agroinoculation system in sweet potato with SPLCV-JS using vacuum infiltration should facilitate the molecular study of sweepovirus in this host and permit the evaluation of virus resistance of sweet potato plants in breeding programs.

Study on the Genetic Transformation Conditions of Begonia wallichiana L.with Leaf Disc Method and Corresponding Identification Techniques

[Objectives]This study was conducted to improve the Agrobacterium-mediated genetic transformation system of Begonia wallichiana.[Methods]With sterilized tube seedling leaves as the recipient material and GFP as the reporter gene,optimization experiments were carried out in terms of infection time and method,co-cultivation time and method,and PCR detection technology.[Results]The transformation effect was better under the conditions of shaking Agrobacterium liquid,infection time of 1-2 h,and co-cultivation on sterilized filter paper for 2 d.After co-cultivation,the recipient material was first subjected to recovery culture,and then used for Hyg gradient screening,which was conducive to obtaining resistant transformants.The designed specific PCR detection technology could quickly identify false positives in resistant regenerated plants,and the proportion of transgenic plants was 16.7%.[Conclusions]The research results provide a new technical reference for the genetic transformation of ornamental plants.

Erratum to:New Dimeric and seco-Abietane Diterpenoids from Salvia wardii

Erratum to:Nat.Prod.Bioprospect.(2015)5:77–82 DOI 10.1007/s13659-015-0054-6 In the HTML version of the original publication,the graphical abstract was inadvertently omitted.The graphical abstract is given in this erratum.

The H^(+)-pyrophosphatase IbVP1 regulates carbon flux to influence the starch metabolism and yield of sweet potato

Storage roots of sweet potato are important sink organs for photoassimilates and energy,and carbohydrate metabolism in storage roots affects yield and starch production.Our previous study showed that sweet potato H+-pyrophosphatase(IbVP1)plays a vital role in mitigating iron deficiency and positively controls fibrous root growth.However,its roles in regulating starch production in storage roots have not been investigated.In this study,we found that IbVP1 overexpression in sweet potato improved the photosynthesis ability of and sucrose content in source leaves and increased both the starch content in and total yield of sink tissues.Using 13C-labeled sucrose feeding,we determined that IbVP1 overexpression promotes phloem loading and sucrose long-distance transport and enhances Pi-use efficiency.In sweet potato plants overexpressing IbVP1,the expression levels of starch biosynthesis pathway genes,especially AGPase and GBSSI,were upregulated,leading to changes in the structure,composition,and physicochemical properties of stored starch.Our study shows that the IbVP1 gene plays an important role in regulating starch metabolism in sweet potato.Application of the VP1 gene in genetic engineering of sweet potato cultivars may allow the improvement of starch production and yield under stress or nutrient-limited conditions.

Diterpenoids from Scutellaria barbata induce tumour-selective cytotoxicity by taking the brakes off apoptosis

Medicinal plants are an excellent source of structurally diverse,bio-active compounds with potential in the fight against cancer.One of the most promising is Scutellaria barbata,prescribed traditionally for the treatment of cancers.Scutebarbatine A is the major diterpenoid,produced in specialized large,peltate trichomes on leaves of S.barbata.It induces dose-dependent apoptosis,specifically in cancer cells.The major class of proteins down-regulated are pro-survival proteins,the Inhibitors of Apoptosis(IAPs),and IAP regulating proteins.We propose that scutebarbatine A works by releasing the molecular brakes(the IAPs)on apoptosis in cell death-evading cancer cells.Comparison between the cytotoxicity of methanolic extracts of S.barbata leaves and decoctions(Ban Zhi Lian)prepared traditionally,showed substantially different chemical compositions and differential induction of apoptosis.Analyses suggest polyvalency between the constituents in both extracts,and ways to produce enhanced chemopreventive preparations for the treatment of cancer.

Multiomics analyses of two Leonurus species illuminate leonurine biosynthesis and its evolution

The Lamiaceae family is renowned for its terpenoid-based medicinal components,but Leonurus,which has traditional medicinal uses,stands out for its alkaloid-rich composition.Leonurine,the principal active compound found in Leonurus,has demonstrated promising effects in reducing blood lipids and treating strokes.However,the biosynthetic pathway of leonurine remains largely unexplored.Here,we present the chromosome-level genome sequence assemblies of Leonurus japonicus,known for its high leonurine production,and Leonurus sibiricus,characterized by very limited leonurine production.By integrating genomics,RNA sequencing,metabolomics,and enzyme activity assay data,we constructed the leonurine biosynthesis pathway and identified the arginine decarboxylase(ADC),uridine diphosphate glucosyltransferase(UGT),and serine carboxypeptidase-like(SCPL)acyltransferase enzymes that catalyze key reactions in this pathway.Further analyses revealed that the UGT–SCPL gene cluster evolved by gene duplication in the ancestor of Leonurus and neofunctionalization of SCPL in L.japonicus,which contributed to the accumulation of leonurine specifically in L.japonicus.Collectively,our comprehensive study illuminates leonurine biosynthesis and its evolution in Leonurus.

Scutellaria baicalensis, the golden herb from the garden of Chinese medicinal plants

Scutellaria baicalensis Georgi, or Chinese skullcap, has been widely used as a medicinal plant in China for thousands of years, where the preparation from its roots is called Huang-Qin. It has been applied in the treatment of diarrhea, dysentery, hypertension, hemorrhaging, insomnia,inflammation and respiratory infections. Flavones such as baicalin, wogonoside and their aglycones baicalein wogonin are the major bioactive compounds extracted from the root of S. baicalensis. These flavones have been reported to have various pharmacological functions, including anti-cancer,hepatoprotection, antibacterial and antiviral, antioxidant,anticonvulsant and neuroprotective effects. In this review,we focus on clinical applications and the pharmacological properties of the medicinal plant and the flavones extracted from it. We also describe biotechnological and metabolic methods that have been used to elucidate the biosynthetic pathways of the bioactive compounds in Scutellaria.

Transcriptional Regulation of Plant Secondary Metabolism

Plant secondary metabolites play critical roles in plant-environment interactions. They are synthesized in different organs or tissues at particular developmental stages, and in response to various environmental stimuli, both biotic and abiotic. Accordingly, corresponding genes are regulated at the transcriptional level by multiple transcription factors. Several families of transcription factors have been identified to participate in controlling the biosynthesis and accumulation of secondary metabolites. These regulators integrate internal （often developmental） and external signals, bind to corresponding cis-elements -- which are often in the promoter regions -- to activate or repress the expression of enzyme-coding genes, and some of them interact with other transcription factors to form a complex. In this review, we summarize recent research in these areas, with an emphasis on newly-identified transcription factors and their functions in metabolism regulation.

Recent advances in biosynthesis of bioactive compounds in traditional Chinese medicinal plants

Plants synthesize and accumulate large amount of specialized(or secondary) metabolites also known as natural products, which provide a rich source for modern pharmacy. In China, plants have been used in traditional medicine for thousands of years. Recent development of molecular biology, genomics and functional genomics as well as high-throughput analytical chemical technologies has greatly promoted the research on medicinal plants. In this article, we review recent advances in the elucidation of biosynthesis of specialized metabolites in medicinal plants,including phenylpropanoids, terpenoids and alkaloids. These natural products may share a common upstream pathway to form a limited numbers of common precursors, but are characteristic in distinct modifications leading to highly variable structures. Although this review is focused on traditional Chinese medicine, other plants with a great medicinal interest or potential are also discussed. Understanding of their biosynthesis processes is critical for producing these highly value molecules at large scale and low cost in microbes and will benefit to not only human health but also plant resource conservation.

Arabidopsis Transcription Factors SPL1 and SPL12 Confer Plant Thermotolerance at Reproductive Stage

Plant reproductive organs are vulnerable to heat, but regulation of heat-shock responses in inflorescence is largely uncharacterized. Here, we report that two of the SQUAMOSA PROMOTER BINDING PROTEIN- LIKE （SPL） transcriptional factors in Arabidopsis, SPL1 and SPL12, act redundantly in thermotolerance at the reproductive stage. The spll-1 sp112-1 inflorescences displayed hypersensitivity to heat stress, whereas overexpression of SPL 1 or SPL 12 enhanced the thermotolerance in both Arabidopsis and tobacco. RNA sequencing revealed 1939 upregulated and 1479 downregulated genes in wild-type inflorescence upon heat stress, among which one-quarter （1,040） was misregulated in spll-1 sp112-1, indicating that SPL1 and SPL12 contribute greatly to the heat-triggered transcriptional reprogramming in inflorescence. Notably, heat stress induced a large number of abscisic acid （ABA） responsive genes, of which -39% were disturbed in heat induction in spll-1 sp112-1 inflorescence. Preapplication of ABA and overex- pression of SPL1 restored the inflorescence thermotolerance in spll-1 sp112-1 and in the ABA biosynthesis mutant aba2-1, but not in the pyl sextuple mutant defective in ABA receptors PYR 1/PYL 1/PYL2/PYL4/PYL5/ PYL8. Thus, inflorescence thermotolerance conferred by SPL1 and SPL2 involves PYL-mediated ABA signaling. The molecular network consisting of SPL1 and SPL12 illustrated here shed new light on the mechanisms of plant thermotolerance at the reproductive stage.