Endophytic Fungal Community of Stellera chamaejasme L. and Its Possible Role in Improving Host Plants' Ecological Flexibility in Degraded Grasslands

Stellera chamaejasme L. is a widely distributed poisonous plant in Chinese degraded grasslands. To investigate the role of endophytic fungi (EF) in S. chamaejasme's quick spread in grasslands, the endophytic fungal community of S. chamaejasme was studied through culture-dependent and culture-independent methods, and the plant-growth-promoting (PGP) traits of some culturable isolates were tested. Further, the growth-promoting effects of 8 isolates which showed better PGP traits were evaluated by pot experiments. The results showed that a total of 546 culturable EF were isolated from 1114 plant tissue segments, and the colonization rate (CR) of EF in roots (33.27%) was significantly higher than that in shoots (22.39%). Consistent with this, the number of specific types of EF was greater in roots (8 genera) than in shoots (1 genus). The same phenomenon was found in culture-independent study. There were 95 specific genera found in roots, while only 18 specific genera were found in shoots. In addition, the dominant EF were different between the two study methods. Cladosporium (18.13%) and Penicillium (15.93%) were the dominant EF in culture-dependent study, while Apiotrichum (13.21%) and Athelopsis (5.62%) were the dominant EF in culture-independent study. PGP trait tests indicated that 91.30% of the tested isolates (69) showed phosphorus solubilization, IAA production, or siderophores production activity. The benefit of 8 isolates on host plants' growth was further studied by pot experiments, and the results indicated that all of the isolates can improve host plants' growth. Among them, STL3G74 (Aspergillus niger) showed the best growth-promotion effect; it can increase the plant's shoot and root dry biomass by 68.44% and 74.50%, respectively, when compared with the controls. Our findings revealed that S. chamaejasme has a wide range of fungal endophytic assemblages, and most of them possess PGP activities, which may play a key role in its quick spread in degraded grasslands.

Automated summary

The endophytic fungal community of Stellera chamaejasme was studied and it was found that the roots had a greater number of specific types of endophytic fungi compared to the shoots. The tested isolates showed plant-growth-promoting activities, and the Aspergillus niger isolate exhibited the best growth-promotion effect on the host plants.