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Plants of the lycophyte genus Phlegmariurus contain the chemical compound Huperzine A, the effective medicinal component treating Alzheimer's disease, thus with huge economic value. To protect the natural resources, plants of the whole genus are listed as the National Key Protected Wild plants in China. In this paper, we revised the taxonomy of Phlegmariurus distributed in China based on morphological, ecological, and geographical evidence. We recognized 21 species from China, and organized them into four sections. Sect. Fargesiani X. C. Zhang & R. H. Jiang is newly established, and the other three sections were revised based on previous studies, i.e., Sect. Hamiltoniani C. Y. Yang, emend. X. C. Zhang & R. H. Jiang; Sect. Phlegmariurus; and Sect. Squarrosurus (Herter) X. C. Zhang & R. H. Jiang, comb. & stat. nov. We reduced the following taxon names to synonymies of various species of Phlegmariurus: Huperzia medogensis, Phlegmariurus austrosinicus, P. changii, P. nylamensis, P. cancellatus var. minor, P. qiongzhongensis, and P. shangsiensis.

Nine species of angiosperms are reported as new records from Guangxi, China. They are Machilus cicatricosa S. Lee, Portulaca quadrifida L., Pisonia aculeata L., Helicia yangchunensis H. S. Kiu, Rhynchosia minima (L.) DC., Jasminum rehderianum Kobuski, Ehretia asperula Zoll. et Mor., Zeuxine ovalifolia L. Li & S. J. Li and Cyperus javanicus Houtt. Detailed morphological description and field photos are provided, and the citation and geographical distribution of each species are also listed in this paper.

IntroductionThe leaf-chewing pest Heortia vitessoides severely threatens the growth and development of Aquilaria sinensis. In our previous study, we found that mechanical damage (MD) to stem enhanced A. sinensis sapling resistance to H. vitessoides larvae.MethodsTo reveal the defense mechanisms underlying this observation, we analyzed the types and contents of volatile organic compounds (VOCs), phytohormone contents, and expression of phytohormone-related genes in response to MD and herbivory wounding(HW).ResultsHere, we identified several VOCs, such as the pesticides fenobucarb and 2,4-di-tert-butylphenol, in mature leaf (ML) of MD-treated plants. Compared with salicylic acid (SA) or the ethylene (ET) pathway, jasmonic acid (JA) content and JA-related genes were more strongly upregulated. Interestingly, we found a dramatic difference between JA-related upstream and downstream genes expression in YL and ML, which confirmed that JA-Ile accumulation in MD-ML and HW-ML could be derived from local damaged site.DiscussionTaken together, we provide evidence that the JA pathway plays a dominant role in the A. sinensis response to MD and HW.

Camphor tree [Cinnamomum camphora (L.) J. Presl], a species in the magnoliid family Lauraceae, is known for its rich volatile oils and is used as a medical cardiotonic and as a scent in many perfumed hygiene products. Here, we present a high-quality chromosome-scale genome of C. camphora with a scaffold N50 of 64.34 Mb and an assembled genome size of 755.41 Mb. Phylogenetic inference revealed that the magnoliids are a sister group to the clade of eudicots and monocots. Comparative genomic analyses identified two rounds of ancient whole-genome duplication (WGD). Tandem duplicated genes exhibited a higher evolutionary rate, a more recent evolutionary history and a more clustered distribution on chromosomes, contributing to the production of secondary metabolites, especially monoterpenes and sesquiterpenes, which are the principal essential oil components. Three-dimensional analyses of the volatile metabolites, gene expression and climate data of samples with the same genotype grown in different locations showed that low temperature and low precipitation during the cold season modulate the expression of genes in the terpenoid biosynthesis pathways, especially TPS genes, which facilitates the accumulation of volatile compounds. Our study lays a theoretical foundation for policy-making regarding the agroforestry applications of camphor tree.

In this study, we investigated suitable habitats for the endangered tree fern, Sphaeropteris lepifera (J. Sm. ex Hook.) R.M. Tryon, based on fieldwork, ecological niche modeling, and regression approaches. We combined these data with the characterization of spore germination and gametophytic development in the laboratory to assess the reasons why S. lepifera is endangered and to propose a conservation strategy that focuses on suitable sites for reintroduction and accounts for the ecology and biphasic life cycle of the species. Our methods represent an integration of process- and correlation-based approaches to understanding the distributional patterns of this species, and this combined approach, while uncommonly applied, is a more robust strategy than either approach used in isolation. Our ecological niche models indicated that cold temperature extremes, temperature stability over long- and short-terms, and the seasonality of precipitation were among the most important abiotic environmental factors affecting the distribution of S. lepifera among the variables that we measured. Moreover, distribution of this fern species is also strongly influenced by the timing of development of male and female gametes. Additionally, we observed that slope aspect, specifically south-facing slopes, facilitates more incoming sunlight for mature trees, and simultaneously, provides greater, much-needed shade for fiddleheads on account of the canopy being denser. We believe that our study can provide important guidance on the restoration of S. lepifera in the wild. Specifically, potential restoration areas can be screened for the specific environmental factors that we infer to have a critical impact on the survival of the species.