The genus Ormosia comprises approximately 130 species, which are found in tropical regions all over the world. The taxonomy and evolutionary history are still ambiguous due to the lack of a solid phylogeny at the species level. Due to the fast advancement of high-throughput sequencing technology, it is now possible to retrieve the full chloroplast (cp) genome sequence, providing a molecular basis for phylogenetic analysis. Five species of Ormosia were used in this work, and their whole cp genomes were sequenced. One circular, quadripartite-structured molecule, ranging from 169,797 to 173,946 base pairs in length, was present in all five Ormosia species. The cp genomes of the five newly sequenced Ormosia species were further compared with the published cp genomes of O. pinnata. Ten hypervariable regions (Pi > 0.025) were uncovered in the Ormosia chloroplast genomes, among which petN-psbM showed the highest Pi value. Phylogenetic analysis revealed that O. microphylla and O. olivacea clustered with strong support. O. balansae was resolved as a sister to O. pinnata, and they were further found to be sisters to the remaining 13 Ormosia species. The cp genes of O. elliptica showed a close relationship to O. hosiei, and O. semicastrata clustered with O. emarginata. Taken together, the comprehensive analysis of the complete cp genomes of five Ormosia species offers valuable insight and information for reconstructing their phylogeny and sheds light on the evolutionary dynamics of the chloroplast genome in Ormosia.

Horsfieldia hainanensis is China’s second-class key protected wild plant with high scientific research, timber, and medicinal values. In this study, the SNP molecular marker technology was used to determine the genetic diversity, genetic structure, genetic differentiation, genetic relationship, and its influencing factors of H. hainanensis populations. It provided a scientific basis for the formulation of its protection strategy. The results showed that (1) the genetic diversity of H. hainanensis populations exhibited a very low level (π = 0.0011). (2) The overall genetic differentiation of H. hainanensis populations was relatively large. There was a significant genetic differentiation between Hainan populations and Guangxi and Yunnan populations on the mainland (FST = 0.556); the genetic differentiation between Guangxi and Yunnan populations was relatively smaller (FST = 0.242). There is a natural water barrier around Hainan Island that reduces the gene exchange between island populations and mainland populations. Therefore, geographical isolation is one of the main factors affecting the genetic differentiation of H. hainanensis populations (p = 0.0103 < 0.05). (3) The genetic relationship between Hainan populations and Yunnan and Guangxi populations was relatively distant, while the genetic relationship between Yunnan and Guangxi populations was relatively closer. In conclusion, it is recommended that during in situ protection, the Guangxi population with higher genetic diversity should be preferentially protected, especially the populations in NG and SL should be regarded as the key protected populations of wild populations. The gene exchange between Yunnan population (MLP) and Guangxi populations (NG, SL, DX1, and DX2) should be enhanced by means of artificial pollination in different localities. During ex situ protection, the germplasm resource collection work of the population (NG, SL) with higher genetic diversity should be carried out preferentially. The technical research on tissue culture and rapid propagation should be actively carried out. A germplasm resource nursery should be established. The individuals should be planted according to provenance and family, but the planting distance between individuals can be appropriately reduced to increase the gene exchange between individuals and make up for the defects during in situ protection.

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.

Habenaria dentata has medicinal and ornamental value, but the number of wild populations is decreasing dramatically. Thus, conducting research on its genetic diversity and structure is necessary to provide a basis for its conservation. This study aimed to explore the genetic diversity of the wild plant H. dentata and protect and optimize its wild resources. The genetic diversity of 133 samples from six wild populations of H. dentata was analyzed using Inter Simple Sequence Repeat molecular markers to provide a scientific basis for the screening of improved germplasm resources. The results showed that the average number of alleles was 1.765, the average number of effective alleles was 1.424, the average Nei’s gene diversity index was 0.252, the average Shannon diversity index was 0.381, and the average percentage of polymorphic loci was 76.499%. The variation within the populations was 77.34%, and the variation between the populations was 22.66%. The gene flow was 1.705, which was greater than 1. The results of the cluster analysis showed that the six populations were mainly divided into four clusters and were not classified according to their geographical location. There was no significant correlation between the geographical location and genetic distance between the populations (r = 0.557, p > 0.05). The genetic diversity of H. dentata is high. Among the six wild populations, the genetic diversity of the Mulun population was the highest and this population can be used as a key protection unit. The study on the genetic diversity of H. dentata can not only reveal the reasons for the decrease in the number of individuals in the population to a certain extent, and put forward the protection strategy, but also provide a scientific basis for the breeding of excellent seed resources.

The rare and endangered wild plant, Horsfieldia hainanensis, has been listed as a second-level key protected plant in China. Currently, its habitat is severely damaged, and the population has dramatically declined, necessitating urgent intervention for protection. In this study, the aim was to explore the correlations and differences from the perspectives of photosynthetic characteristics and leaf structure, providing scientific references for in-situ conservation and ex-situ cultivation. The results revealed the following: (1) The maximum net photosynthetic rate (P_max) and light saturation point (LSP) of mature trees were significantly higher than those of seedlings, while the light compensation point (LCP), CO₂ compensation point (CCP), and CO₂ saturation point (CSP) were significantly lower in seedlings. (2) The average daily net photosynthetic rate of mature trees was significantly higher than that of seedlings. When both mature trees and seedlings exhibited a “midday depression” phenomenon, accompanied by an increase in intercellular CO₂ concentration (C_i), it indicated that the “midday depression” was caused by non-stomatal limiting factors. (4) Both mature trees and seedlings showed peak values of water use efficiency (WUE) under low light conditions. Mature trees had smaller upper and lower epidermis thickness but larger leaf thickness, and their leaf structure, characterized by well-developed palisade and spongy tissues, conformed to the cellular structure adaptations for low light. Therefore, both were more adapted to low light conditions. (5) The stomatal density (SD) and individual stomatal area (SA) of seedlings were significantly higher than those of mature trees. (6) The total chlorophyll content of mature trees was significantly higher than that of seedlings, while the chlorophyll a/chlorophyll b ratio was significantly lower in mature trees and remained below three in both cases. In summary, the photosynthetic capacity and light adaptability of mature trees are stronger than those of seedlings, but both mature trees and seedlings exhibit shade-tolerant characteristics. For in-situ conservation, it is possible to promote the growth and development of seedlings by appropriately employing artificial “windowing” or shading methods based on the actual growth environment of the seedlings. In the case of ex-situ cultivation, seedlings should be provided with appropriate shading initially, while ensuring sufficient moisture and CO₂ concentration. As the plants grow, the shading intensity can be gradually reduced. Once the plants reach maturity, they have a broader range of light adaptability and can be transplanted to environments with less shading.

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.