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The application of DNA barcoding has been significantly limited by the scarcity of reliable specimens and inadequate coverage and replication across all species. The deficiency of DNA barcode reference coverage is particularly striking for highly biodiverse subtropical and tropical regions. In this study, we present a comprehensive barcode library for woody plants in tropical and subtropical China. Our dataset includes a standard barcode library comprising the four most widely used barcodes (rbcL, matK, ITS, and ITS2) for 2,520 species from 4,654 samples across 49 orders, 144 families, and 693 genera, along with 79 samples identified at the genus level. This dataset also provides a super-barcode library consisting of 1,239 samples from 1,139 species, 411 genera, 113 families, and 40 orders. This newly developed library will serve as a valuable resource for DNA barcoding research in tropical and subtropical China and bordering countries, enable more accurate species identification, and contribute to the conservation and management of tropical and subtropical forests., (© 2023. The Author(s).)

Human disturbance and climate change have increased the risk of extinction for rare and endangered wild plant species. One effective way to conserve these rare and endangered species is through reintroduction. In this review, we summarize the advances in wild plant reintroduction from five perspectives: the establishment of reintroduction biology as an important tool for biodiversity conservation; the importance of genetic diversity in reintroduction; reintroduction under global climate change; recruitment limitation in reintroduction; and reintroduction and ecological restoration. In addition, we consider the future of plant reintroduction strategies.

Actin cytoskeleton is one of the major components of cytoskeleton in eukaryotic cells. In response to endogenous cues or external signals, actin filaments undergo quick polymerization and depolymerization with result in rapid reconstruction of actin cytoskeleton. The dynamic rearrangement of actin filaments in cells are regulated by actin-binding proteins. Profilin is a low-molecular-weight, actin-monomer-binding protein ubiquitously presents in organisms ranging from amoebae and fungi up to higher plants and mammals. Besides binding actin, profilin also binds to phosphatidylinositol 4,5-bisphosphate and poly-L-proline. Recent studies suggest that profilin is a multifunctional protein that has positive and negative regulatory effects on actin polymerization and, in certain case, may be involved in signal transduction. We have long been engaged in the studies on characteristic and function of profilin in plant cells, such as the function analysis of Arabidopsis PRF1 and PRF2, and the effects of profilin on the function of forming in modulating actin cytoskeleton. Here, with the combination of our results, we have reviewed the recent progress in profilin research, including its initial finding, biochemical properties, in vivo distribution and functions, as well as its role in signal transduction.

Endogenously formed coralloid roots in living cycads are known to be infected and maintained by a mutual partnership with photosynthetic cyanobacteria. In this study, two strains of filamentous, nitrogen-fixing endosymbiotic cyanobacteria from the green zone of the coralloid roots of Cycas fairylakea were isolated and grown in culture. The phylogenetic placement based on the 16S rRNA gene region and the secondary structures of the ITS between the 16S and 23S rRNA gene, in addition to traditional morphological characterization, were used to analyse the two strains. Results showed that the 16S rRNA gene sequences of the two strains, CF01 and CF06, displayed ≥97% similarity to the genus Desmonostoc. The phylogeny inferred by maximum likelihood, bayesian inference and neighbour-joining placed the two strains on a separate node away from other species of Desmonostoc. Hormogonial filaments were evident in the two symbiotic species. In addition, a few unique morphological structures in the CF01 and CF06 strains were observed. The D1-D1ʹ, Box-B and V3 helices generated from the ITS of 16S–23S sequences did not fit those of any described species of Desmonostoc, and this led to proposing the two strains as novel species. In compliance with the International Code of Nomenclature for algae, fungi, and plants, the two species are named Desmonostoc lechangense sp. nov. and Desmonostoc aggregatum sp. nov. [ABSTRACT FROM AUTHOR]

The protection and restoration of mangrove ecosystems depend on understanding the interaction between benthic organisms and mangrove succession. Although benthic protozoa are important in such ecosystems, protozoan community dynamics have seldom been studied during the mangrove succession. The benthic protozoa of a mangrove chronosequence that included a primary community (unvegetated shoal), an early community (Avicennia marina), a middle community (Aegiceras corniculatum), and a late community (Bruguiera gymnorrhiza + Rhizophora stylosa) were investigated to determine the changes in the benthic protozoan community during a mangrove succession at Zhanjiang, China. A total of 62 benthic protozoa taxa belonging to three classes, 26 orders, and 38 families were recorded. The abundance of benthic protozoa decreased significantly during mangrove succession, while species richness and diversity changed irregularly. Hierarchical clustering indicated that the distribution of the benthic protozoa closely corresponded with the mangrove successional stages. Further analyses indicated that the changes in the benthic protozoan community with mangrove succession were associated with the changes in total sediment nitrogen content and especially with vegetation characteristics, including plant height and crown breadth. The decline in the abundance of benthic protozoa during mangrove succession may be explained by the deterioration of benthic protozoan microhabitats. However, determining whether these or other factors are responsible for the change in the benthic protozoan community during mangrove succession will require additional research. [ABSTRACT FROM AUTHOR]

The quantitative role of the canopy size of nurse shrubs on microenvironment and native tree establishment in degraded tropical lands has been seldom studied. In a 21-month field experiment, we aimed to test the effect of a native shrub with different canopy sizes on the early establishment of native trees as part of the effort of forest restoration in tropical China. We examined the microenvironment, and the seedling establishment and growth of two native trees: Castanopsis fissa and Syzygium hancei in both open space (OS) microsite and microsite under the canopy of the native pioneer shrub Rhodomyrtus tomentosa. Shrub microsite was further divided into large canopy (LC), and medium canopy (MC) microsite, based on the shrub leaf area indices. Results showed that relative to OS, LC had higher soil nutrient concentration and water content, and lower photosynthetic active radiation (PAR), while MC had lower PAR and higher soil exchangeable Mg, K, and Ca. Survival and growth were mostly enhanced, while water stress and photoinhibition reduced for C. fissa seedlings in MC and S. hancei seedlings in LC. It is found that the beneficial effects of the native shrub on seedling establishment and growth result mostly from the improvement in nutrient and water availabilities, the reduction in plant stress caused by harsh summer light, and the specific ecological requirements of different tree species. We suggest that different canopy sizes of native shrub R. tomentosa may be explored to target different native trees and hence promote forest restoration in degraded tropical ecosystems. [ABSTRACT FROM AUTHOR]

Establishing seedlings in subtropical plantations is very important for forest health, succession and management. Information on seedling nutrient concentrations is essential for both the selection of suitable indigenous tree species to accelerate succession of the established plantation and sustainable forest management. In this study, we investigated the concentrations of nitrogen ([N]), phosphorus ([P]), and N∶P ratio in leaves, stems and roots of seedlings of three indigenous tree species (Castanopsis chinensis, Michelia chapensis and Psychotria rubra) transplanted with removing or retaining understory vegetation and litter at two typical subtropical forest plantations (Eucalyptus plantation and native species plantation). We also measured the relative growth rate (RGR) of seedling height, and developed the relationships between RGR and leaf [N], [P] and N∶P ratio. Results showed that treatments of understory vegetation and associated litter (i.e. removal or retained) generally had no significant effects on leaf [N], [P], N∶P ratio and RGR of the transplanted tree seedlings for the experimental period. But among different species, there were significant differences in nutrient concentrations. M. chapensis and P. rubra had higher [N] and [P] compared to C. chinensis. [N] and [P] also varied among different plant tissues with much higher values in leaves than in roots for all indigenous species. RGR of indigenous tree seedlings was mostly positively correlated with leaf [N] and [P], but negatively correlated with leaf N∶P ratio. Considering the low [P] and high N∶P ratio observed in the introduced indigenous tree seedlings, we propose that the current experimental plantations might be P limited for plant growth. [ABSTRACT FROM AUTHOR]

We investigated the effects of major environmental drivers associated with urbanization on species diversity and plant functional traits (PFTs) in the remnant subtropical evergreen broad-leaved forests in Metropolitan Guangzhou (Guangdong, China). Twenty environmental factors including topography, light, and soil properties were used to quantify the effects of urbanization. Vegetation data and soil properties were collected from 30 400-m plots at 6 study sites in urban and rural areas. The difference of plant species diversity and PFTs of remnant forests between urban and rural areas were analyzed. To discern the complex relationships, multivariate statistical analyses (e.g., canonical correspondence analysis and regression analysis) were employed. Pioneer species and stress-tolerant species can survive and vigorously establish their population dominance in the urban environment. The native herb diversity was lower in urban forests than in rural forests. Urban forests tend to prefer the species with Mesophanerophyte life form. In contrast, species in rural forests possessed Chamaephyte and Nanophanerophyte life forms and gravity/clonal growth dispersal mode. Soil pH and soil nutrients (K, Na, and TN) were positively related to herb diversity, while soil heavy metal concentrations (Cu) were negatively correlated with herb diversity. The herb plant species diversity declines and the species in the remnant forests usually have stress-tolerant functional traits in response to urbanization. The factors related to urbanization such as soil acidification, nutrient leaching, and heavy metal pollution were important in controlling the plant diversity in the forests along the urban-rural gradients. Urbanization affects the structure and functional traits of remnant subtropical evergreen broad-leaved forests. [ABSTRACT FROM AUTHOR]