Soil bacteria play a key role in the plant–soil system and can regulate the growth of Phoebe bournei seedlings under fertilization. However, there are few reports on how soil bacteria respond to fertilization and regulate seedling growth. This study adopted the “3414” field fertilization experiment, combined with soil microbial sequencing, nutrient contents, and biomass measurement, to explore the changes of soil chemical properties and bacterial structure under different NPK fertilization conditions and to establish the coupling relationship between soil bacteria, soil nutrients, and plant growth. The results showed that NPK fertilization decreased soil pH; increased soil N, P, and K content; reduced bacterial diversity and abundance; promoted the growth of dominant bacterial species; and enhanced Phoebe bournei seedlings’ soil N, P, and K elements. NPK fertilization promoted Proteobacteria growth, especially of three genera (Methylobacterium, Sphingobium, and Acinetobacter) and Actinobacteria, while it decreased Acidobacteria and Chloroflexi. By reducing the ratio of N to K and increasing P, NPK fertilization can slow soil acidification, promote bacterial reproduction, maintain P. bournei seedlings’ soil ecological stability, and balance the seedlings’ growth and sustainable soil utilization. AD3, Pseudomonas, and Rhodanobacter can be used as the marker species for N, P, and K fertilization, respectively, while Methylobacterium, Brevundimonas, Acinetobacter, and Sphingobium can be used as indicator species for soil pH and soil N, P, and K content changes, respectively. These results provided a theoretical basis and technical guidance for the effective fertilization and cultivation of robust P. bournei seedlings.

Advancement of the oil tea industry requires the development of high-yielding and superior-quality varieties of Camellia oleifera, a major oilseed crop. However, traditional breeding methods, hampered by lengthy cycles and low selection accuracy, significantly constrain the breeding process. Identifying single nucleotide polymorphisms (SNPs) associated with target traits, and applying molecular marker-assisted selection (MAS) for these traits, can thereby shorten the breeding cycles and amplify the breeding efficiency. In this study, we utilized the hexaploid C. oleifera as the reference genome to identify high-quality SNPs and constructed a high-density genetic linkage map of C. oleifera that spanned 1566.733 cM, included 3097 SNPs, and was anchored to 15 linkage groups. Using interval mapping, we localized quantitative trait loci (QTLs) for 11 juvenile traits in C. oleifera, identifying 15 QTLs for growth traits and 24 QTLs for leaf traits, including 4 stable QTLs. The logarithm of odds (LOD) scores for individual QTLs ranged from 3.48 to 14.62, explaining 9.86–48.61% of the phenotypic variance. We further identified 2 SNPs associated with growth traits (marker11-951 and marker12-68) and 10 SNPs associated with leaf traits (marker11-276, marker11-410, marker11-560, marker13-16, marker13-39, marker13-110, marker13-731, marker14-701, marker14-910, and marker14-1331). These results provide valuable insights into the genetic mapping of key traits in C. oleifera and will contribute to the development of new varieties with high yield and superior quality in the future.

Tea oil is an important high-quality edible oil derived from woody plants. Camellia oleifera is the largest and most widely planted oil-producing plant in the Camellia genus in China, and its seeds are the most important source for obtaining tea oil. In current research, improving the yield and quality of tea oil is the main goal of oil tea genetic breeding. The aim of this study was to investigate the degree of genetic variation in an early crossing population of C. oleifera and identify single nucleotide polymorphisms (SNPs) and genes significantly associated with fruit traits, which can provide a basis for marker-assisted selection and gene editing for achieving trait improvement in the future. In this study, we selected a crossing population of approximately 40-year-old C. oleifera with a total of 330 samples. Then, ddRAD sequencing was used for SNP calling and population genetic analysis, and association analysis was performed on fruit traits measured repeatedly for two consecutive years. The research results indicate that over 8 million high-quality SNPs have been identified, but the vast majority of SNPs occur in intergenic regions. The nucleotide polymorphism of this population is at a low level, and Tajima’s D values are mostly greater than 0, indicating that the change in this population was not suitable for the model of central evolution. The population structure analysis shows that the population has seven theoretical sources of genetic material and can be divided into seven groups, and the clustering analysis results support the population structure analysis results. Association analysis identified significant SNPs associated with genes related to the seed number of a single fruit and seed kernel oil content. Our findings provide a basis for molecular breeding and future genetic improvement of cultivated oil tea.

The Japanese fir, Cryptomeria japonica, is ecologically and commercially vital in China. However, infestations by Dendrolimus houi Lajonquière larvae cause widespread dieback, mimicking mechanical damage effects, with unclear differential impacts and mechanisms. To address this, 6th instar larvae of D. houi were introduced to three-year-old C. japonica seedlings to induce pest infestation, while mechanical damage and non-infested pests were controlled. Then, next-generation sequencing techniques were employed, and transcriptome sequencing was conducted to analyze the distinct damage mechanisms responding to C. japonica. This study revealed 10,412 DEGs between pest infestation and controls and 5535 DEGs comparing pest infestation to mechanical damage. Functional enrichment analysis highlighted the involvement of these DEGs in crucial processes such as photosynthesis, amino acid and nucleotide metabolism, flavonoid biosynthesis, and plant hormone signaling pathways. In particular, 786 unique DEGs were discerned in pest-infested samples. Key enriched pathways, such as pyruvate and propionate metabolism, were pinpointed, with flavonoid biosynthesis potentially closely linked to pest-feeding inductions. These findings provided valuable insights into the molecular responses of C. japonica to D. houi infestation, laying the foundation for future research aimed at developing pest-resistant varieties of Japanese fir.

In this study, we performed whole-genome resequencing (WGS) to investigate genomic variation and functional divergence among four wild Cymbidium species—C. ensifolium, C. sinense, C. kanran, and C. floribundum—collected from Fujian Province, China. A total of 350.58 Gbp of high-quality sequencing data was obtained from 13 samples, enabling comprehensive identification of SNPs and InDels. Genomic variants were unevenly distributed, with lower variation in gene-rich regions and higher levels in non-coding areas. Circos plots and variant density heatmaps revealed significant regional differences across chromosomes, with longer chromosomes exhibiting greater variant enrichment in 1 Mb windows. C. floribundum harbored the highest number of nonsynonymous SNPs and InDel-associated genes, whereas C. sinense and C. kanran had fewer mutations. KEGG pathway enrichment analysis revealed species-specific functional divergence, particularly in metabolism, stress response, and secondary metabolite biosynthesis. Population structure analysis and principal component analysis (PCA) indicated genetic differentiation among these species Notably, C. kanran exhibited high within-population genetic diversity. These findings provide essential genomic resources for the conservation and functional studies of wild Cymbidium species in subtropical China.

Camellia oleifera Abel, recognized as a woody oil-producing tree species, possesses considerable economic significance. To improve the breeding efficiency of C. oleifera, it is crucial to elucidate the genetic foundation underlying the mechanisms regulating fruit traits. In this study, a total of 6,252,197 high-quality single-nucleotide polymorphisms (SNPs) were identified from 109 germplasm accessions. Through genetic structure analysis, these accessions were categorized into two distinct populations. The average fixation index (Fst) was found to be 0.0153, indicating weak population differentiation. The genome-wide association analysis (GWAS) identified 157 significant loci. From these loci, 110 candidate genes were selected, which were associated with disease resistance, reproduction, development, and RNA biosynthesis. Twenty-three genes were involved in metabolic pathways, including genetic information-processing protein families, metabolic protein families, terpenoids, and polyketides. The identification of gene loci closely related to fruit traits not only provides genetic data for studying the molecular mechanisms of fruit traits but also offers new research avenues for molecular breeding of C. oleifera.