Abstract Orchidaceae is a highly valuable horticultural and medicinal plant family worldwide; however, large-scale propagation and conservation remain severely limited. Orchid seeds depend on symbiotic fungi for germination, and pre-symbiotic communication is essential for establishing a successful association, a process that remains poorly understood. In this study, exudates were collected from the germination-promoting fungus Ceratobasidium sp. GS2 and applied to seeds of the terrestrial orchid Gymnadenia conopsea to investigate downstream responses. Multi-omics approaches, including RNA-seq, metabolomics, and phylogenetic analysis, combined with biological validation, revealed that the exudates elicited transcriptional and physiological responses in G. conopsea seeds, potentially promoting dormancy release. Exposure to fungal exudates increased the levels of brassinosteroids, cytokinins, and fatty acids in seeds. Exogenous hormone application confirmed that brassinosteroids and cytokinins promote fungal colonization and facilitate symbiotic seed germination. Phylogenetic analysis revealed the conservation of symbiotic genes in partially mycoheterotrophic orchids, and functional characterization confirmed the role of GcRAM2 in G. conopsea. These findings provide new insights into the mechanisms underlying orchid mycorrhizal symbiosis.
Yaoyao Wang, Xin Qian, Jiaxing Li et al.· IMA Fungus· 0 citations
Objective Continuous cropping obstacles and heavy chemical fertilizer use constrain Radix serratulae chinensis cultivation. This study evaluates the optimal concentration of plant growth-promoting rhizobacterium Bacillus amyloliquefaciens ART9 and investigates its underlying mechanisms via rhizosphere microbiome and host transcriptome analyses. Methods Seedlings were treated with ART9 suspensions at OD600 of 0.4, 0.6, and 1.0. Growth parameters, soil nutrient contents, rhizosphere bacterial communities, and root transcriptomic profiles were assessed to compare treatment effects. Results The OD600 0.6 treatment yielded the best performance, increasing plant height, stem diameter, and SPAD value by 48.56%, 14.09%, and 12.42%, respectively, over the control, and raising soil available nitrogen, phosphorus, and potassium by 177%, 179%, and 168%. Rhizosphere microbiota were significantly enriched with beneficial genera, notably Bacillus, Pseudomonas, and Sphingomonas. Transcriptomics revealed prominent enrichment in phenylpropanoid biosynthesis (map00940), plant hormone signal transduction (map04075), and circadian rhythm–plant (map04712) pathways. Upregulated genes included JAZ, ABF, PYL, PP2C, SPA1_2, and HY5, indicating coordinated regulation of hormone and light signaling. Conclusion ART9 systematically promotes growth of Radix serratulae chinensis by reshaping the rhizosphere microbiome and modulating hormone/light signaling pathways, supporting its development as a sustainable biofertilizer for medicinal plant production.
Jiaxin Wang, Jinjie Xu, Pengzhong Fu et al.· Frontiers in Plant Science· 0 citations
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