Nymphaea candida C. Presl, a rare water lily species in China, is on the brink of extinction due to its extremely low natural germination rate. Obtaining robust seedlings suitable for artificial propagation has become a key for the conservation of this species. [Objective] To isolate and identify endophytic plant growth-promoting fungi from the roots of N. candida and evaluate their growth-promoting effects on seedlings. [Methods] Pot experiments were carried out with Chaetomium globosum isolated from N. candida to assess its effects on the growth of N. candida, soil physicochemical properties, rhizosphere microbial community structure, and leaf gene expression. [Results] The application of C. globosum significantly increased the leaf length, leaf width, number of leaves, and root length of N. candida by 46.74%, 96.08%, 64.71%, and 130.13%, respectively. Moreover, the application of C. globosum significantly increased soil organic matter, alkali-hydrolyzable nitrogen content, and sucrase activity. Rhizosphere microbial community analysis indicated that the application of C. globosum specifically enriched beneficial microorganisms, including norank-p-Cryptomycota, norank-o-Monhysterida, Surirella, and norank-p-Aphelidea. Leaf transcriptome analysis further revealed that C. globosum significantly upregulated the expression of the genes related to the steroid biosynthesis pathway. [Conclusion] C. globosum effectively promotes the growth of N. candida seedlings by improving the rhizosphere microenvironment, recruiting beneficial microorganisms, and regulating steroid biosynthesis in the leaves. Thus, the endophytic plant growth-promoting fungus C. globosum might be a reliable tool for the conservation of the endangered plant species N. candida.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |