Yunsheng Jiang

Malania oleifera, the sole species of its genus, is an endangered tree endemic to the karst regions of China and a valuable woody oil crop. However, deep seed dormancy and slow germination severely limit its propagation and utilization. In this study, freshly harvested mature seeds of M. oleifera were soaked in gibberellic acid (GA₃) solutions at different concentrations. Germination traits and physiological and biochemical parameters were assessed, and transcriptome sequencing was performed to investigate the mechanisms underlying GA₃-promoted seed germination. Soaking seeds in GA₃ for 24 h significantly promoted germination in a concentration-dependent manner. The strongest response occurred at 600 mg·L⁻¹ GA₃, with germination potential and germination percentage reaching 34.2% and 60.0%, respectively. The beneficial effect declined at 800 mg·L⁻¹. Treatment with 600 mg·L⁻¹ GA₃ significantly increased superoxide dismutase (SOD) and peroxidase (POD) activities and reduced malondialdehyde (MDA) content, indicating that an appropriate GA₃ concentration helped maintain redox balance during germination. Transcriptome analysis identified 7548 and 3571 differentially expressed genes in UT_vs_W24 and W24_vs_GA24, respectively. These results indicated that water soaking initiated germination-related transcriptional changes that were further modified by GA₃ treatment. Functional enrichment analysis showed that transcriptional changes induced by water soaking mainly involved carbohydrate and lipid metabolism, secondary metabolism, and responses to stimuli, whereas GA₃ treatment further modulated redox processes, defense responses, plant hormone signal transduction, and the mitogen-activated protein kinase (MAPK) signaling pathway. Reconstruction of the plant hormone and MAPK signaling pathways showed that GA₃ markedly affected the expression of genes involved in gibberellin, abscisic acid, auxin, and brassinosteroid signaling. GA₃ also regulated the MKK–MPK cascade and downstream transcription factors, including WRKYs. Together, these findings characterize the physiological responses of M. oleifera seeds to GA₃ and reveal the molecular mechanisms underlying GA₃-promoted germination, providing a basis for improving the propagation efficiency of this valuable species.

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.

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.

To investigate the rationality of water-use efficiency in agroforestry systems within this region, this study utilised the medicinal and edible plant Sophora japonica cv.jinhuai as a foundation. Five mixed planting models were established, incorporating Ardisia gigantifolia, Melicope pteleifolia, Camellia limonia, Belamcanda chinensis, Isatidis radix, and Pilea basicordata. Water-use efficiency (WUE) was analysed by measuring the carbon-stable isotope composition (δ¹³C) of plant leaves. Compared to previous studies that primarily focused on δ¹³C in single species or simple composite systems, this research innovatively evaluates the water-use efficiency (WUE) performance of different composite patterns and their impact on system stability at both the species and system levels, integrating the theory of fitness differentiation. Results indicate that the ranges of δ¹³C and WUE for the five mixed cropping systems were −27.0633‰ to 31.2188‰ and 27.7191 to 50.0365 μmol/mol, respectively. WUE ranking was: Sophora japonica cv.jinhuai—Camellia limonia—Pilea basicordata (SCP) > Sophora japonica cv.jinhuai—Camellia limonia (SC) > Sophora japonica cv.jinhuai—Belamcanda chinensis + Isatidis radix (SBI) > Sophora japonica cv.jinhuai—Melicope pteleifolia (SM) > Sophora japonica cv.jinhuai—Ardisia gigantifolia (SA). At the species level, the Sophora japonica cv.jinhuai—Camellia limonia—Pilea basicordata (SCP) composite planting model is better suited to karst arid environments, while the Sophora japonica cv.jinhuai—Ardisia gigantifolia (SA) composite planting model exhibits lower overall plant water-use efficiency (WUE) and weaker drought resistance. At the system level, Sophora japonica cv. jinhuai exhibited significantly higher water-use efficiency (WUE) than understory medicinal plants in most composite patterns, with pronounced differences in species fitness and poor system stability. The Sophora japonica cv.jinhuai—Camellia limonia—Pilea basicordata (SCP) model exhibited the highest WUE. Furthermore, no significant difference in WUE was observed between Sophora japonica cv.jinhuai and Pilea basicordata, indicating relatively high fitness matching and good coordination in water use. These species can coexist stably, suggesting promising application potential in karst arid environments. Therefore, this study not only evaluated the water-use performance of each species within the composite model but also identified SCP as the most suitable agroforestry configuration for karst regions from a system stability perspective. This provides a scientifically grounded basis for optimising agroforestry practices in these areas, integrating both species-level and system-level perspectives. It should be clarified that the WUE calculated based on δ¹³C in this study is a relative indicator rather than an absolute physiological measurement. Its reliability depends on the core assumptions and parameter settings of the isotope model.

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.

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.

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.

Plants of the golden Camellia group are not only high-quality camellia germplasm , but also a plant group with rich medicinal and nutritional value, which 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 camelliaplants have been published in China. The leaves and flowers of these species have similar shapes, so they are often confused as species. Our study used simplified genome sequencing technology to construct a phylogenetic tree of plants in the Chinese golden Camellia group and describe the evolutionary relationships . At the same time, the secondary metabolic indexes of total phenols, total flavonoids, total anthocyanins and ellagic acid in the leaves were determined., and principal component clustering analysis was performed . The results showed that the chemical classification and genetic phylogenetic trees showed some of the same trends, indicating that Camellia chinensis can be used as Biomarkers for chemical type. The research results provide phylogenetic information for the genotype and performance diversity of golden camelliaregionally distributed in China. At the same time, molecular biology phylogenetic methods are used to understand or explain the characteristics of secondary metabolites of golden Camellia , and provide theoretical basis for the search and development of potential bioactive substances.

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.