关键词: 扩增子ITS测序, 毛棉杜鹃, 内生真菌, 组织分离培养, 生长势, 根, 真菌群落

Abstract:

Objective: This study aimed to analyze the endophytic fungal communities and diversity in the roots of Rhododendron moulmainense with varying growth potential in Wutong Mountain, Shenzhen, China. The goal was to identify representative endophytic fungi with potential benefits for plant growth and lay a foundation for utilizing these fungal resources. Method: Root samples from R. moulmainense with different growth potential were analyzed using amplicon ITS high-throughput sequencing and tissue isolation cultivation to characterize fungal taxa and diversity. Result: 1) Amplicon ITS high throughput sequencing of root associated fungi in R. moulmainense revealed distinct community profiles between good and poor growth potential samples. For good growth potential roots, 183 942 sequences were annotated into 11 phyla, 231 fungal species, and 778 operational taxonomic units (OTUs). In contrast, poor growth potential roots yielded 190 918 sequences, annotated into 10 phyla, 202 fungal species, and 1 009 OTUs. Despite differences in taxonomic richness, Basidiomycota and Ascomycota emerged as the dominant phyla across both growth potential groups. 2) Alpha diversity analysis revealed that the fungal communities in the roots of R. moulmainense with good growth potential exhibited greater diversity compared to those with poor growth potential. Principal Coordinate Analysis (PCoA) further demonstrated that communities sharing the same growth potential clustered closely, indicating high similarity, whereas communities from differing growth potential levels showed divergence. 3) Functional prediction analysis demonstrated that in the fungal communities associated with the roots of good growth potential R. moulmainense, symbiotrophic fungi accounted for nearly 60% of the total community. In contrast, fungal communities from poor growth potential roots exhibited a balanced distribution, with both saprotrophic fungi and symbiotrophic fungi each comprising approximately 40%. 4) Through tissue isolation and cultivation methods, a total of 172 endophytic fungal species were identified in the roots of R. moulmainense. Ascomycota dominated the fungal communities in both good and poor growth potential plants. Specifically, 98 fungal species were identified in good growth potential roots, while 109 species were found in poor growth potential roots. Among these, 12 representative fungal strains were isolated from good growth potential plants, compared to 6 strains from poor growth potential plants. Notably, typical Ericoid mycorrhizal fungi, including Oidiodendron and Pezicula ericae, were exclusively isolated from good growth potential roots. Conclusion: Amplicon ITS high-throughput sequencing and tissue isolation techniques revealed significant differences in the diversity of endophytic fungal communities within the roots of R. moulmainense exhibiting different growth potential. Compared to plants with poor growth potential, those with robust growth demonstrated a higher abundance of endophytic fungi, particularly dominated by taxa such as Oidiodendron and P. ericae, which were both more diverse and numerically prevalent. This discovery underscores a potential link between the root-associated mycobiome ecology of R. moulmainense and its growth performance, providing novel perspectives for further exploration of plant-microbe interactions and their role in enhancing plant resilience and vitality.

Key words: ITS sequencing of amplicons, Rhododendron moulmainense, endophytic fungi, tissue isolation and culture, growth potential, root, fungal community