Mutualism between Dark Septate Endophytes (DSEs) and their host plants under metal stress: a case study

Abstract

In the current study, a model of ‘fungus-root’ interaction was designed using host Zea mays inoculated with a metal-tolerant dark septate endophyte (DSE) strain of Exophiala pisciphila H93 both under nutritional- (Zn₀) and zinc-stressed (Zn₅₅₀) conditions. We found that the co-cultured maize benefited from the alleviated excessive Zn toxicity by its root-associated E. pisciphila, through significantly decreasing root Zn under Zn₅₅₀ conditions, or promoting the nutritional Zn in maize shoots and roots by 34.03% and 22.13% under Zn₀ conditions, respectively, compared with non-inoculated controls. Interestingly, H93 further enhanced the maize Zn tolerance by the bioaugmented Zn compartmentation in root cell walls to reduce the proportion of Zn in maize root soluble fractions and cell organelles under Zn₅₅₀ stress. In exchange for the maize carbon cost, the H93 extraradical hyphae tended to accumulate more toxic Zn, compared with H93 mycelia in the in vitro culture under Zn₅₅₀ conditions, and vice versa the co-cultured maize also promoted Zn tolerance of H93 via the repartitioning of subcellular Zn. Our results suggest the potentially mutual association of E. pisciphila and its host maize, by trading carbon for the increased abiotic tolerance.

GRAPHICAL ABSTRACT

KEYWORDS:

• Dark septate endophytes (DSEs)
• Exophiala pisciphila
• maize (Zea mays)
• heavy metal
• Zn
• mutualism

Acknowledgments

The authors gratefully acknowledge Fangdong Zhan (College of Resources and Environment, Yunnan Agricultural University, China) for his help in the metal analysis.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Authors’ contributions

Conceptualization, T.L. and Z.Z.; methodology, T.L. and Z.Z.; investigation, L.Z. and D.L.; writing (original draft preparation), D.L.; writing (review and editing), T.L. and Z.Z.; funding acquisition, T.L. and Z.Z.

Ethical approval

This article is original and has not been published elsewhere. All of the data generated or analyzed during this study are included in this published article, and all of the authors have read and agreed to the published version of the manuscript. The authors confirm that there are no ethical issues in the publication of the manuscript.

Data availability statement

Data for the manuscript have been deposited in the generalist repositories of Mendeley Data (https://data.mendeley.com/datasets/wg4wjhdjmv/1).

Additional information

Funding

This research was financially co-supported by the Major Science and Technology Project in Yunnan Province, PR China (No. 202001BB050001, No. 202001BB050065, and No. 2018FY001-010), the National Natural Science Foundation of China (No. 41761106), and ‘Double First-Class' University Project of Yunnan University (No. C176282105).