Assessing the current genetic structure of 21 remnant populations and predicting the impacts of climate change on the geographic distribution of Phoebe sheareri in southern China.

Phoebe sheareri is a valuable tree species known as "Golden Nanmu" and is one of the most important protected tree species in China. However, natural populations are decreasing because of climate change and anthropogenic factors. To evaluate the genetic diversity and structure of remnant populations and the impacts of climate change on the distribution of potential suitable habitats, we conducted a field investigation and sampled 21 P. sheareri natural populations to evaluate their genetic diversity and structure using simple sequence repeat (SSR) molecular markers. Then, we predicted the distribution of suitable P. sheareri habitats across China under future scenarios (RCP 2.6 and RCP 8.5) and periods (2050 and 2070) using multivariate modeling methods-the MaxEnt model. The results showed a medium level of genetic diversity and low inbreeding in the 21 P. sheareri natural populations, and genetic differentiation among populations was significant, with 21.2 % genetic variation among populations. The remnant populations of P. sheareri were grouped into four genetic clusters based on genetic structure; five environmental variables involving four temperature variables and precipitation seasonality (Bio12) might determine the distribution of P. sheareri populations. In the future, the suitable habitats of P. sheareri are manifested as northward migration, and the highly suitable habitats are expected to increase. Our results highlight the importance of conservation units in situ, giving priority to populations with higher genetic diversity (e.g., TMS, FJS, and THY populations); sampling strategies for ex situ conservation, breeding and reforestation should consider climate change, especially Bio1 (annual mean temperature) and Bio12 (annual precipitation). Overall, this study may provide useful genetic information for strategies for the protection, management, and utilization of P. sheareri.

The chromosome-scale genome of Phoebe bournei reveals contrasting fates of terpene synthase (TPS)-a and TPS-b subfamilies.

Terpenoids, including aromatic volatile monoterpenoids and sesquiterpenoids, function in defense against pathogens and herbivores. Phoebe trees are remarkable for their scented wood and decay resistance. Unlike other Lauraceae species investigated to date, Phoebe species predominantly accumulate sesquiterpenoids instead of monoterpenoids. Limited genomic data restrict the elucidation of terpenoid variation and functions. Here, we present a chromosome-scale genome assembly of a Lauraceae tree, Phoebe bournei, and identify 72 full-length terpene synthase (TPS) genes. Genome-level comparison shows pervasive lineage-specific duplication and contraction of TPS subfamilies, which have contributed to the extreme terpenoid variation within Lauraceae species. Although the TPS-a and TPS-b subfamilies were both expanded via tandem duplication in P. bournei, more TPS-a copies were retained and constitutively expressed, whereas more TPS-b copies were lost. The TPS-a genes on chromosome 8 functionally diverged to synthesize eight highly accumulated sesquiterpenes in P. bournei. The essential oil of P. bournei and its main component, ß-caryophyllene, exhibited antifungal activities against the three most widespread canker pathogens of trees. The TPS-a and TPS-b subfamilies have experienced contrasting fates over the evolution of P. bournei. The abundant sesquiterpenoids produced by TPS-a proteins contribute to the excellent pathogen resistance of P. bournei trees. Overall, this study sheds light on the evolution and adaptation of terpenoids in Lauraceae and provides valuable resources for boosting plant immunity against pathogens in various trees and crops.

Phylogenomic and morphological evidence reveal a new species of spider lily, Lycorislongifolia (Amaryllidaceae) from China.

Lycorislongifolia, a new species from China, was described and illustrated here. Our phylogenomic evidence based on whole plastomes strongly supported the separate phylogenetic position of this new species, and morphologically it could also be distinguished by its long leaves with a distinct purplish-red midrib on the abaxial surface.

[Simultaneous determination of four glycosylflavones from Lophatherum gracile by RP-HPLC].

OBJECTIVE: To develop a RP-HPLC method for simultaneous determination of orientin, isorientin, vitexin and isovitexin in Lophatherum gracile from different habitat and harvesting time. METHOD: The HPLC method was applied and the chromatographic column was a Waters XBridge C18 column (4.6 mm x 250 mm, 5 microm). The mobile phase consisted of methanol-0.05% acetic acid (35:65). The flow rate was 1.0 mL min(-1) and the detection wavelength was set at 340 nm. The column temperature was set at 25 degrees C. RESULT: Four components were isolated well, the linear relationships were excellent. The mean recoveries and RSD values of orientin, isorientin, vitexin and isovitexin were 103.2%, 2.1%; 101.6%, 2.7%; 98.4%, 2.3%; 99.2%, 1.8%, respectively. CONCLUSION: The HPLC method is simple, sensitive and reliable, and can be used for the quality control of the medicinal material.

[Analysis of the inter-species relationships on lycoris Amaryllidaceae) by use of RAPD].

The fingerprints of 13 species in genus Lycoris were generated by use of RAPD method. Forty-one primers were screened from 520 random primers, and a total of 350 DNA fragments were amplified ranging from 0.3-3.0 kb, 253 (72.3%) of which were polymorphic. The average number of DNA band produced by each primer was 6.2. Nei's similarity coefficients and genetic distances were calculated by use of the software of TFPGA version 1.3 and dendrogram of Lycoris was constructed using UPGMA. It is indicated that the 13 species of the genus Lycoris were divided into two groups, and five species of the genus including L. rosea, L. haywardii, L. straminea, L. sprengeri and L. radiata with monotype karyotypes (I-shaped) were clustered together respectively. The basic chromosome number was x = 11. The others which have two-types karyotypes (I-shaped and V-shaped) were clustered together respectively. They were L. houdyshelii, L. albiflora, L. chinensis, L. longituba, L. anhuiensis, L. squmigera, L. caldwellii and L. aurea. The closest relationship was between L. rosea and L. haywardii. L. radiata is highly divergent from L. aurea. The results were in consistence with that of the analysis of chromosome karyotype. The present paper discussed the problems whether L. rosea, L. haywardii and L. stramina originated as natural hybrids and taxonomy position of L. albiflora, L. straminea and L. houdyshelii based on the RAPD analysis.