First discovered in 1977, Abies ziyuanensis (Pinaceae) is listed as an endangered species by the International Union for Conservation of Nature (IUCN); its population continues to decline. Analyzing the rhizospheric fungal communities in the two largest populations of A. ziyuanensis within the Yinzhu Laoshan National Nature Reserve in Guangxi Zhuang Autonomous Region, China, and factors influencing the rhizosphere will establish a theoretical framework for the reintroduction of A. ziyuanensis. This study used ITS rRNA gene high-throughput sequencing and statistical data analysis to compare the functional diversity and structure of the molecular ecological network of rhizospheric fungal communities between A. ziyuanensis populations in Yinzhu Laoshan mountain in Guangxi at two sites, Shenbaotang and Sanjiaohutang. A total of 1755 OTUs were identified from the rhizospheric samples of 30 A. ziyuanensis; these were classified into seven trophic modes and 81 functional guilds. The most important functional types corresponded to the fungal phyla Ascomycota, Mortierellomycota, and Basidiomycota. Changes in the structure of the functional molecular ecological network of the rhizospheric fungal communities of A. ziyuanensis were mainly related to soil nutrient conditions and soil water content, with AK and TK being the most critical. The functional molecular ecological networks of the rhizosphere of A. ziyuanensis differed among populations; distinct functional-gene profiles were detected in the rhizosphere microbiomes of different A. ziyuanensis populations. These findings provide insight into the role of unique rhizospheric fungi in the growth and environmental adaptation of A. ziyuanensis, and for the discovery of superior rhizosphere-promoting fungi.

Background: Siraitia grosvenorii (monk fruit) is a dioecious medicinal crop native to southern China, yet its terpene synthase (TPS) gene family and the molecular basis of floral sexual dimorphism remain unexplored. Methods: Genome-wide identification of the TPS gene family was performed using HMMER and BLAST-based approaches. Phylogenetic classification, gene structure and conserved motif characterization, and comparative synteny analyses were conducted. Transcriptome data from leaves and fruits at different developmental stages were analyzed for tissue-specific expression profiling. Promoter cis-element analysis, protein–protein interaction network prediction, and molecular docking were performed to characterize the fruit-specific candidate SgTPS49. Results: A total of 58 SgTPS genes were identified and classified into six subfamilies, with TPS-a and TPS-b comprising 72.4% of the family. Approximately 88% of SgTPS genes arose from lineage-specific tandem duplication. Female flowers exhibited monoterpene-dominant scents and smaller corollas, whereas male flowers displayed a mid-morning sesquiterpene burst and greater morphological variation. SgTPS49 was specifically upregulated at 20 days post-pollination and possessed a unique promoter architecture devoid of classical hormone-responsive elements. Molecular docking supported its annotation as a putative monoterpene synthase with favorable GPP binding. Conclusions: This study provides the first comprehensive genomic resource for the SgTPS family in S. grosvenorii, reveals significant sexual dimorphism in floral traits, and identifies SgTPS49 as a key candidate for future functional validation.

Rhizosphere microbiota are key drivers of plant nutrition, immunity, and stress tolerance. Abies ziyuanensis L. K. Fu & S. L. Mo (Pinaceae) is an endangered conifer endemic to China, and its persistence may depend on its interactions with its belowground microbiome. However, how soil-borne bacterial functional groups respond to, and potentially support, A. ziyuanensis remains unclear. Based on amplicon high-throughput sequencing data of the 16S rRNA gene and soil physicochemical properties, the bacterial community structure in the rhizosphere soil of A. ziyuanensis in Yinzhu Laoshan National Nature Reserve in Guangxi Zhuang Autonomous Region, China, was analyzed, and the potential ecological functions and phenotypic characteristics of the bacterial community were predicted to determine the functional taxa characteristics (nitrogen cycle, phototrophy, and chemoheterotrophy) and dominant soil environmental factors. Proteobacteria, Acidobacteria, Actinobacteria, Planctomycetes, Verrucomicrobia, and Chloroflexi were the dominant bacterial taxa in the A. ziyuanensis rhizosphere soil, and all bacteria were significantly positively correlated with soil NO₃⁻-N (R = 0.47, p = 0.0079). Based on FAPROTAX, the A. ziyuanensis rhizosphere soil bacterial community had chemoheterotrophic-related functions, which were more prevalent than nitrogen cycle- and phototrophic-related functions, and the relative abundance of bacteria with nitrogen cycle-related functions was higher than that of those with phototrophic functions. The nitrogen nutrient- and phototrophic-related functional taxa in the rhizosphere soil bacterial community had significant correlations with soil physicochemical properties, whereas the chemoheterotrophic-related functional taxa did not show a significant correlation. Based on BugBase phenotype prediction, Acidobacteria, Proteobacteria, and Chloroflexi made the greatest contribution to the phenotype, with pathogenic and stress tolerance being the most important phenotypes. The pathogenic and stress-tolerant bacteria all belonged to Proteobacteria. The rhizosphere bacteria exhibited rich diversity and dominated several biogeochemical cycling processes. This study identifies beneficial rhizosphere bacteria of A. ziyuanensis, providing a theoretical basis for conserving soil bacterial diversity and guiding the targeted recruitment of functional bacteria by the endangered plant.