Saturation (SI) and compensation (CI) irradiances [µmol(photon) m⁻² s⁻¹] were 383.00±18.40 and 12.95±0.42 for wild C. nitidissima (in mid-July) and 691.00±47.39 and 21.91±1.28 for wild C. sinensis, respectively. C. nitidissima is a shade tolerant species, whereas C. sinensis has a wide ecological range of adaptability to irradiance. Both wild and cultivated C. nitidissima demonstrated low maximum net photosynthetic rate, maximum carboxylation rate, maximum electron transfer rate, and SI, which indicated low photosynthesis ability of leaves that were unable to adapt to strong irradiance environment. Both C. nitidissima and C. sinensis demonstrated strong photosynthetic adaptabilty in new environments. Hence proper shading may raise photosynthetic efficiency of cultivated C. nitidissima and promote its growth.

Not only are the plants of the golden camellia group examples of high-quality camellia germplasm, but they are also a plant group with rich medicinal and nutritional value, and these plants are used as food, cosmetics and traditional medicine in China. There are approximately 50 species in this group around the world, and more than 30 species of golden camellia plants have been listed in China. The leaves and flowers of these species have similar shapes, and as such, they are often confused as the same species. Our study used simplified genome sequencing technology to construct a phylogenetic tree of plants in the Chinese golden camellia group, and we also described the evolutionary relationships. At the same time, the secondary metabolic indexes of the total phenols, total flavonoids, total anthocyanins and ellagic acid in the leaves were determined, and principal component clustering analysis was also performed. The results showed that the phylogenetic relationship and genetic distance among the plant species of Chinese golden camellia group plants were fully revealed. The cluster analysis of chemical secondary metabolism and genetic phylogenetic trees showed some of the same trends, thereby indicating that secondary metabolism golden camellia can be used as biomarkers for golden camellia. The research results provide phylogenetic information for the genotype and performance diversity of the golden camellia that is regionally distributed in China, as well as provide a theoretical basis for the research and development of potential bioactive substances.

Karst tiankengs in China are globally significant locations for studying ecological environments and plant diversity. However, there are few reports on how the unique geographical environment of tiankengs affects plant genetic diversity and genetic structure. This study used Hyper-seq gene sequencing technology to develop large-scale genomic SNPs of Manglietia aromatica, both within and outside the tiankengs. Its aim was to investigate the impact of tiankengs on the genetic diversity and genetic structure of the M. aromatica population. The analysis results indicate that the genetic diversity of the populations within the tiankeng (π = 0.2044) is higher than that of the populations outside of it (π = 0.1671), indicating that the tiankengs have a positive impact on species diversity. The genetic differentiation coefficient (F_ST) between the populations inside and outside the tiankeng was 0.0534 and the F_ST values of populations within the tiankeng were 0.077, 0.082, and 0.141, meaning that the genetic variation in the tiankengs is very high. The genetic similarity outside the tiankengs is also very high, indicating that the tiankengs are effectively preserving the genetic diversity of M. aromatica. Furthermore, the gene introgression analysis results gave no proof of gene flow between the three tiankeng populations. This suggests that the tiankengs not only protect species diversity, but also hinder gene flow between populations to some extent. However, this hindrance may gradually subside with the evolution of the tiankengs. The genetic structure analysis revealed that the M. aromatica population in Guangxi, China, can be classified into three subpopulations. The first is the tiankeng subpopulation, including all the populations in tiankengs. The second subpopulation consists of populations surrounding the tiankengs. These two subpopulations are distributed in Leye County in northwestern Guangxi, China, and are very close to each other. The third is the Huanjiang subpopulation, which is located far away from the tiankengs. Considering the direction of gene flow and genetic structure, it is speculated that the populations in the tiankengs evolved from the populations near the pit mouth. This study confirms that the tiankengs are shelters and provide a suitable habitat for the endangered plant M. aromatica, because its genetic diversity is well conserved and the species is well adapted to the habitat within the tiankengs.

The genus Ottelia comprises approximately 21 submerged macrophyte species primarily found in tropical Africa and Southeast Asia. The classification of several Ottelia species as vulnerable under the criteria “A2c” in the China Species Red List emphasizes the urgency of establishing a credible taxonomy. The ambiguity in taxonomy and evolutionary history persists, primarily stemming from the absence of a robust phylogeny at the species level. The rapid progress in high-throughput sequencing technology has facilitated the retrieval of complete chloroplast (cp) genome sequences, offering a molecular foundation for conducting phylogenetic analyses. In this study, the entire cp genomes of five samples of four Ottelia species were sequenced. All five Ottelia samples exhibited a circular, quadripartite-structured molecule, with lengths ranging from 156,823 to 162,442 bp. A total of 75–88 simple sequence repeats (SSRs) in the cp genomes of the five Ottelia samples were observed, which could be used for species identification. A preliminary phylogenetic analysis revealed that O. fengshanensis, O. acuminata, and O. guanyangensis clustered with strong support (100 BS). O. acuminata var. jingxiensis was resolved as a sister to O. acuminata var. lunanensis (100 BS), and both were further found to be sisters to O. balansae. The widely distributed O. alismoides exhibited a close phylogenetic relationship as the sister taxon to all the Chinese endemic taxa, supported by robust values. Together, our thorough examination of the entire cp genomes of the five Ottelia samples provides eminent insights into reconstructing their phylogeny. Furthermore, it illuminates the evolutionary dynamics of the cp genome within the Ottelia genus.

Cycas is one of the most ancient extant seed plant lineages on Earth, with a fossil record and evolutionary history dating back to the Carboniferous period. In this study, six screened SSR primer pairs were used to analyze the genetic diversity and population structure of 640 samples from 41 populations representing eight Cycas species collected from Guangxi, with the aim of providing a theoretical basis for the conservation of wild cycad resources in this region. The results showed that the average number of alleles (Na) across the eight species ranged from 1.945 to 3.643, the average effective number of alleles (Ne) ranged from 1.548 to 2.245, Shannon’s information index (I) ranged from 0.446 to 0.824, observed heterozygosity (Ho) ranged from 0.222 to 0.453, and expected heterozygosity (He) ranged from 0.293 to 0.443, indicating a moderate overall level of genetic diversity. Among the species, C. sexseminifera exhibited the highest genetic diversity (I = 0.824, He = 0.443), whereas C. guizhouensis showed the lowest (I = 0.446, He = 0.293). In addition, the interspecific genetic differentiation coefficient (F_st) ranged from 0.047 to 0.354, and gene flow (N_m) ranged from 0.456 to 5.094. Except for C. guizhouensis, relatively high levels of gene flow were detected among species. Principal Coordinates Analysis (PCoA) revealed that the 640 samples could be divided into three genetic clusters, which were not strictly consistent with species boundaries. AMOVA further indicated that 78% of the total genetic variation was distributed within populations, including 60% within individuals and 18% among individuals within populations. These findings provide important insights into the genetic diversity and differentiation patterns of Cycas species distributed in Guangxi and offer a theoretical foundation for their introduction, ex situ conservation, and scientific management of genetic resources.

Malania oleifera is an endangered woody oil tree species endemic to China, where light conditions play a key role in seedling establishment. However, responses of seedling-associated bacterial communities to shading remain poorly characterized. This study investigated phyllosphere and rhizosphere bacterial communities under different shading regimes using 16S rRNA amplicon sequencing in two-year-old seedlings. Seedlings were subjected to 75%, 50%, and 25% shading, full-light conditions, and a field-grown reference group. The phyllosphere bacterial community showed lower alpha diversity and stronger compositional variation across shading treatments than the rhizosphere community, indicating higher sensitivity of leaf-associated bacteria to changes in the light environment. The rhizosphere maintained a larger shared bacterial pool and more stable community composition, with treatment-related differences mainly reflected in shifts in relative abundance. Functional prediction using PICRUSt2 indicated that phyllosphere bacterial functions were more responsive to shading than those in the rhizosphere, particularly pathways associated with genetic information processing and metabolism. PICRUSt2-based KEGG predictions suggested that both the phyllosphere and rhizosphere communities in the less-shaded and unshaded treatments were enriched for pathways related to aromatic compound degradation. Co-occurrence network analysis further revealed that phyllosphere association patterns were more sensitive to shading variation, whereas rhizosphere network complexity remained relatively stable. Shading exerted compartment-specific effects on the bacterial communities of M. oleifera seedlings, with the phyllosphere microbiota showing higher sensitivity to light variation than the rhizosphere communities.