Endangered status and threatened population ecological factors in Salvia daiguii, an endemic species from Hunan, China.

Many species of Salvia have excellent ornamental, culinary, and medicinal values. Salvia daiguii, is an ornamental and highly medicinal perennial herb endemic to the prefecture-level city of Zhangjiajie in Hunan Province, China, with a narrow geographical distribution. However, currently, it has only been assessed as a Critically Endangered species according to the IUCN classification criteria, but its conservation has not yet been studied. This study investigated the distribution and niche characteristics of S. daiguii, and compared the differences in growth, flowering characteristics, and soil nutrients between the wild and ex situ populations. We also analyzed the effects of soil nutrients on plant growth and flowering characteristics. During the survey, we found 274 individuals on a rock approximately 200 m from ZEFR1. Nevertheless, S. daiguii were still restricted in three populations, TNFP, TGM, and ZEFR in Zhangjiajie City, with a total of about 500 plants and less than 250 mature individuals. Our results show that aspects such as adverse environmental conditions, low seedling renewal rate, a lack of soil nutrients, and competition for the characteristic niche of this and other dominant plants in the natural community are the main ecological factors affecting the growth, flowering, and geographic distribution of S. daiguii. Based on the results of field surveys, we recommend that (1) S. daiguii be classified as Critically Endangered C2b and China's List of Plant Species with Extremely Small Populations. (2) Comprehensive conservation strategies were developed, such as the establishment of nature reserves, reintroduction, public education, and institutional development to provide management recommendations related to the conservation of S. daiguii and other endangered plants.

Salvia guidongensis sp. nov.: unraveling a critical evolutionary link in East Asian Salvia from Central China integrating morphology, phylogeny, and plastid genomics.

Introduction: Salvia L., representing the largest genus within the mint family, is noted for its global distribution of approximately 1000 species, with East Asia, and particularly China, recognized as a critical center of diversity for the genus. Methods: Our research was conducted through extensive fieldwork in Guidong County, Hunan Province, China, where we identified a previously undescribed species of Salvia. The identification process involved detailed morphological observations, phylogenetic analyses, and plastid genomics. Results: The newly discovered species, Salvia guidongensis, exhibits unique characteristics not commonly observed in the East Asian lineage of Salvia, including dual floral colors within natural populations-either pale purple or pale yellow. Morphologically, while it shares similarities with members of sect. Glutinaria, S. guidongensis is distinct in its floral morphology, stature, and specific foliar traits. Phylogenetic analysis places S. guidongensis in a unique clade within the East Asian lineage of Salvia, suggesting it may serve as an important evolutionary link. Additionally, we explored the plastome features of S. guidongensis, comparing them with those of closely related species. Discussion: The discovery of S. guidongensis not only entriches the taxonomic tapestry of Salvia but also provides critical insights into the biogeography and evolutionary pathways of the genus in East Asia. By integrating morphological and molecular data, we validate the novel status of S. guidongensis and highlight its significance in bridging taxonomic and evolutionary gaps within Sect. Glutinaria of Salvia.

Preparation and Tribological Properties of a Multilayer Graphene-Reinforced TiO2 Composite Nanolubricant Additive.

The unique structure and physical properties of graphene and anatase TiO2 make them suitable for use as additives for engine lubricants. This study describes the use of dielectric barrier discharge plasma-assisted ball milling to synthesize a multilayer graphene-reinforced TiO2 composite nanolubricant additive (MGTC). A variety of physical and chemical tests were performed to characterize the resulting experimental materials, including X-ray diffraction (XRD), Fourier transform infrared (FT-IR), Raman, X-ray photoelectron spectroscopy (XPS), and scanning electron microscopy (SEM). Four-ball friction and wear testing machines were used to study the tribological properties and extreme pressure anti-wear properties of a base oil containing 0.1, 0.5, 1.0, and 1.5 wt % of the modified TiO2. Raman spectroscopy, XPS, SEM, and energy-dispersive spectrometry (EDS) analyses were used to examine and analyze the microstructure of the friction pairs. As a result of the plasma-assisted ball milling process, expanded graphite was successfully separated into multilayer graphene nanosheets, and spherical TiO2 was successfully bonded to the nanosheets of the multilayer graphene. The 1.0 wt % composite oil was found to provide good friction reduction and wear resistance. It had a film thickness of 27.5 nm, which was 167% thicker than base oil. Due to its excellent dispersion stability, the MGTC nanocomposite exhibited excellent lubrication performance, which was attributed to the formation of carbon protective films, titanium dioxide deposition films, transfer films, and the occurrence of nano ball effects on the surface of friction pairs.

Characterization of complete chloroplast genome of Salvia honania L. H. Bailey (Lamiaceae).

Salvia honania L. H. Bailey is an endemic species, mainly distributed in Henan and Hubei provinces in China. The first complete chloroplast genome of Salvia honania was sequenced and assembled in this study. The genome is 151,559 bp in length and contains 132 encoded genes in total, including 87 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. The phylogenomic analysis showed that Salvia honania was closely related to Salvia meiliensis according the current sampling extent.

The sage genome provides insight into the evolutionary dynamics of diterpene biosynthesis gene cluster in plants.

The widely cultivated medicinal and ornamental plant sage (Salvia officinalis L.) is an evergreen shrub of the Lamiaceae family, native to the Mediterranean. We assembled a high-quality sage genome of 480 Mb on seven chromosomes, and identified a biosynthetic gene cluster (BGC) encoding two pairs of diterpene synthases (diTPSs) that, together with the cytochromes P450 (CYPs) genes located inside and outside the cluster, form two expression cascades responsible for the shoot and root diterpenoids, respectively, thus extending BGC functionality from co-regulation to orchestrating metabolite production in different organs. Phylogenomic analysis indicates that the Salvia clades diverged in the early Miocene. In East Asia, most Salvia species are herbaceous and accumulate diterpenoids in storage roots. Notably, in Chinese sage S. miltiorrhiza, the diterpene BGC has contracted and the shoot cascade has been lost. Our data provide genomic insights of micro-evolution of growth type-associated patterning of specialized metabolite production in plants.

Two types of O-methyltransferase are involved in biosynthesis of anticancer methoxylated 4'-deoxyflavones in Scutellaria baicalensis Georgi.

The medicinal plant Scutellaria baicalensis Georgi is rich in specialized 4'-deoxyflavones, which are reported to have many health-promoting properties. We assayed Scutellaria flavones with different methoxyl groups on human cancer cell lines and found that polymethoxylated 4'-deoxyflavones, like skullcapflavone I and tenaxin I have stronger ability to induce apoptosis compared to unmethylated baicalein, showing that methoxylation enhances bioactivity as well as the physical properties of specialized flavones, while having no side-effects on healthy cells. We investigated the formation of methoxylated flavones and found that two O-methyltransferase (OMT) families are active in the roots of S. baicalensis. The Type II OMTs, SbPFOMT2 and SbPFOMT5, decorate one of two adjacent hydroxyl groups on flavones and are responsible for methylation on the C6, 8 and 3'-hydroxyl positions, to form oroxylin A, tenaxin II and chrysoeriol respectively. The Type I OMTs, SbFOMT3, SbFOMT5 and SbFOMT6 account mainly for C7-methoxylation of flavones, but SbFOMT5 can also methylate baicalein on its C5 and C6-hydroxyl positions. The dimethoxylated flavone, skullcapflavone I (found naturally in roots of S. baicalensis) can be produced in yeast by co-expressing SbPFOMT5 plus SbFOMT6 when the appropriately hydroxylated 4'-deoxyflavone substrates are supplied in the medium. Co-expression of SbPFOMT5 plus SbFOMT5 in yeast produced tenaxin I, also found in Scutellaria roots. This work showed that both type I and type II OMT enzymes are involved in biosynthesis of methoxylated flavones in S. baicalensis.

A 2-oxoglutarate-dependent dioxygenase converts dihydrofuran to furan in Salvia diterpenoids.

Tanshinone ⅡA (TⅡA), a diterpene quinone with a furan ring, is a bioactive compound found in the medicinal herb redroot sage (Salvia miltiorrhiza Bunge), in which both furan and dihydrofuran analogs are present in abundance. Progress has been made recently in elucidating the tanshinone biosynthetic pathway, including heterocyclization of the dihydrofuran D-ring by cytochrome P450s; however, dehydrogenation of dihydrofuran to furan, a key step of furan ring formation, remains uncharacterized. Here, by differential transcriptome mining, we identified six 2-oxoglutarate-dependent dioxygenase (2-ODD) genes whose expressions corresponded to tanshinone biosynthesis. We showed that Sm2-ODD14 acts as a dehydrogenase catalyzing the furan ring aromatization. In vitro Sm2-ODD14 converted cryptotanshinone to TⅡA and thus was designated TⅡA synthase (SmTⅡAS). Furthermore, SmTⅡAS showed a strict substrate specificity, and repression of SmTⅡAS expression in hairy root by RNAi led to increased accumulation of total dihydrofuran-tanshinones and decreased production of furan-tanshinones. We conclude that SmTⅡAS controls the metabolite flux from dihydrofuran- to furan-tanshinones, which influences medicinal properties of S. miltiorrhiza.

Elsholtziazhongyangii (Lamiaceae), a new species from Sichuan, China.

Elsholtziazhongyangii (Lamiaceae), a new species from Sichuan Province, China, is described and illustrated. The new species is morphologically similar to E.feddeif.feddei, but it can be easily distinguished from E.feddeif.feddei by smaller corolla (3.2-3.5 mm vs. 4.5-5.3 mm), bract indumentum (glabrous, except margin ciliate vs. villous, especially on veins abaxially, glabrous adaxially) and bract stalked (ca. 1.2 mm vs. sessile). Phylogenetic analyses, based on two nuclear ribosomal (ETS, ITS) and five plastid (rbcL, matK, trnL-F, ycf1, ycf1-rps15) regions, confirmed that the new species formed a monophyletic clade with robust support. The new species is currently known from western Sichuan.

Occurrence and Prevention of Delayed Autonomous Selfing in Salvia umbratica (Lamiaceae).

Delayed autonomous selfing (DAS) provides reproductive assurance under conditions of pollinator and/or pollen-limitation. Few plant species have been investigated to determine if DAS is terminated when a flower is sufficiently pollinated by a pollen vector, thereby saving plant resources for other purposes. We examined this possibility in bumblebee-pollinated Salvia umbratica. We first showed that DAS resulting in high fruit set (100%) and seed set (>80%) per flower occurred in the absence of insect pollinators by means of style recurvature and was completed in 94% of flowers 72 h after they opened. In contrast, in flowers pollinated immediately after opening, DAS was prevented by corollas dropping away before styles recurve toward the upper thecae. We next showed that hand-pollination of flowers immediately after they opened resulted in high fruit set (100%) and seed set (>80%) when 5-10 pollen grains or more were deposited on their stigmas, whereas fruit set and seed set were reduced to 45.00 and 22.50%, respectively, when pollen loads were reduced to 1-3 pollen grains. Finally, we showed that on average single pollinator visits deposited 26 pollen grains on stigmas of flowers that had just opened, which is more than enough to ensure high fruit and seed set. Our results indicate that flower longevity is highly correlated with the pollinator environment and female fitness of S. umbratica, with extended flower longevity allowing DAS to occur being advantageous when pollinators are absent, while reduced floral longevity and prevention of DAS being favored when flowers are pollinated by pollinators. Thus, flower longevity in S. umbratica varies so as to optimize reproductive output and resource efforts, and is dependent on the availability and effectiveness of pollinators to pollinate flowers.

Conservation Genomics of Wild Red Sage (Salvia miltiorrhiza) and Its Endangered Relatives in China: Population Structure and Interspecific Relationships Revealed From 2b-RAD Data.

Red sage (Salvia miltiorrhiza) is a widely used medicinal plant for treatment of cardiovascular and cerebrovascular diseases. Because of excessive excavation by huge market demand and habitat loss by human activities, the wild population resources of S. miltiorrhiza have reduced drastically in recent years. Meanwhile, population status of two closely related species S. bowleyana and S. paramiltiorrhiza were in a trend of decreasing due to their potential replacement of S. miltiorrhiza. Particularly, S. paramiltiorrhiza was threatened and endemic to a small region in eastern China. However, to date there has been no conservation genetic research reported for wild S. miltiorrhiza population and its endangered relatives. Assess the wild germplasm diversity for S. miltiorrhiza and its related species would provide fundamental genetic background for cultivation and molecular breeding of this medicinally important species. In the present study, we investigated the genetic diversity, population structure, and intra/inter-specific differentiation of S. miltiorrhiza and above two relatives using 2b-RAD genome-wide genotyping method. By investigating 81 individuals of S. miltiorrhiza, 55 individuals of S. bowleyana and 15 individuals of S. paramiltiorrhiza from 23 locations in China, we obtained 23,928 SNPs in total. A comparatively high genetic diversity was observed in S. miltiorrhiza (π = 0.0788, H e = 0.0783 ± 0.0007). The observed and expected heterozygosity in populations of these three species ranged from 0.0297 to 0.1481 and 0.0251 to 0.831, respectively. Two major lineage groups were detected in the examined S. miltiorrhiza populations. The results indicated that Dabie Mountain as a genetic diversity center of S. miltiorrhiza and possible complex inter-specific genetic exchange/hybridization occurred between S. miltiorrhiza and the two relatives. We suggest that strategic conservation and germplasm preservation should be considered not only for wild populations of S. miltiorrhiza, but also for its related S. bowleyana and S. paramiltiorrhiza.

[Effects of different carbon sources on growth and active component contents in Salvia miltiorrhiza and S. castanea f. tomentosa hairy roots].

Salvia miltiorrhiza(Sm) and Salvia castanea f. tomentosa(Sc) hairy roots were used as experimental materials to study the effects of six different carbon sources, galactose, fructose, lactose, glucose, arabinose and sucrose(control), on fresh weight, dry weight, contents and yields of salvianolic acids and tanshinones. The results showed that galactose was most beneficial to the growth of two kinds of hairy roots, while lactose and arabinose were not conducive to their growth. As for Sm hairy roots, fructose significantly promoted the accumulation of salvianolic acid B, and the content increased by 5.801 times and 10.151 times compared with the control group, respectively. Glucose significantly promoted the accumulation of salvianolic acids. The content and yield of rosmarinic acid were 7.674 times and 9.260 times of that of the control group, and the content and yield of salvianolic acid B were 5.532 times and 6.675 times of the control group. For the hairy roots of Sc, galactose significantly increased the content and yield of rosmarinic acid, reaching 7.820 times and 9.944 times of the control group, respectively. Fructose promoted the increase of the content and yield of cryptotanshinone, reaching 9.242 times and 6.609 times of the control group, respectively. The study confirmed the optimal carbon source for the hairy root culture of Sm and Sc, and provided theoretical guidance for large-scale production of Sm drug-derived components and the utilization of Sc.

Development of 19 novel microsatellite markers of lily-of-the-valley (Convallaria, Asparagaceae) from transcriptome sequencing.

The lily-of-the-valley Convallaria (Asparagaceae) consists of three herbaceous perennial species. The plants are commonly found in northern hemisphere, and are best-known for their ornamental and pharmaceutical value. In order to assess the genetic structure, diversity and demographic history of Convallaria species, 19 novel microsatellite markers were developed based on transcriptome data of C. keiskei. Polymorphism and cross-amplification of the markers were tested in three populations of C. keiskei and one population each of C. majalis and C. montana. The transferability rate in two species was both 89.5%. The average number of alleles detected per locus was 7.7, 3.3 and 2.7 in C. keiskei, C. majalis and C. montana, respectively, and the polymorphism information content correspondingly varied from 0.067 to 0.730, from 0.071 to 0.637 and from 0.195 to 0.680 at the population level. The observed and expected heterozygosity ranged from 0.000 to 1.000 and from 0.000 to 0.833, respectively. Seven of the 19 loci showed significant deviation from Hardy-Weinberg equilibrium. The availability of these markers will provide a useful molecular tool for further population genetics, phylogeographic and breeding studies of Convallaria species.

The complete chloroplast genome of endangered Zhangjiajie sage Salvia daiguii Y. K. Wei & Y. B. Huang (Lamiaceae).

The complete chloroplast genome of Zhangjiajie sage, Salvia daiguii, was assembled in this study. The genome is 151,434 bp in length and contained 134 encoded genes in total, including 88 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. The result of phylogenetic analysis based on 17 chloroplast genomes revealed that S. daiguii is clustered with Salvia miltiorrhiza in Lamiaceae.

The complete chloroplast genome of Russian sage Salvia yangii B. T. Drew (Lamiaceae).

The complete chloroplast genome of Russian sage Salvia yangii B. T. Drew was assembled in this study. The genome is 151,473 bp in length and contained 129 encoded genes in total, including 84 protein-coding genes, eight ribosomal RNA genes, and 37 transfer RNA genes. The result of phylogenetic analysis based on 15 chloroplast genomes revealed that S. yangii is closely related to common sage (Salvia officinalis) in Lamiaceae.

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.

[Effects of root-knot nematodes on cucumber leaf N and P contents, soil pH, and soil enzyme activities].

A pot experiment was conducted to study the effects of inoculation with root-knot nematodes on the cucumber leaf N and P contents, and the rhizospheric and non-rhizospheric soil pH and enzyme activities. The rhizospheric soil pH didn't have a significant decrease until the inoculation rate reached 6000 eggs per plant. With the increase of inoculation rate, the leaf N and P contents, rhizospheric soil peroxidase activity, and rhizospheric and non-rhizospheric soil polyphenol oxidase activity all decreased gradually, rhizospheric soil catalase activity was in adverse, non-rhizospheric soil pH decreased after an initial increase, and non-rhizospheric soil catalase activity had no regular change. After inoculation, rhizospheric soil urease activity decreased significantly, but rhizospheric and non-rhizospheric soil phosphatase activity and non-rhizospheric soil peroxidase activity only had a significant decrease under high inoculation rate. In most cases, there existed significant correlations between rhizospheric soil pH, enzyme activities, and leaf N and P contents; and in some cases, there existed significant correlations between non-rhizospheric soil pH, enzyme activities, and leaf N and P contents.

Taxonomy, diversity and origins of symbiotic endophytes of Achnatherum sibiricum in the Inner Mongolia Steppe of China.

We sampled five Achnatherum sibiricum populations and documented the distribution and abundance of endophytes. In total, 438 fungal isolates were obtained. They were classified into 11 morphotypes based on growth rate and morphological characters including colonial morphology, the production of conidiogenous cells, conidial size and dimension on potato dextrose agar medium. Both tub2 and actG sequences identified only a single product in all representative isolates from three dominant morphotypes. All sequences fell in the same main clade, including Neotyphodium gansuense and Neotyphodium gansuense var. inebrians from another Achnatherum species in North China, Achnatherum inebrians, and Neotyphodium guerinii from European grasses Melica ciliate and Melica transsilvanica. Based on both morphological and phylogenetic analyses, isolates in morphotype I were described as representing a novel Neotyphodium species, Neotyphodium sibiricum sp. nov. Isolates in both morphotype II and III were identified as representing N. gansuense. Both tub2 and actG sequences suggested that N. sibiricum and N. guerinii were probably derived from a common Epichloë ancestor.