Dopamine alleviates cadmium stress in apple trees by recruiting beneficial microorganisms to enhance the physiological resilience revealed by high-throughput sequencing and soil metabolomics

Abstract

Dopamine has demonstrated promise as a stress-relief substance. However, the function of dopamine in Cd tolerance and its mechanism remains largely unknown. The current study was performed to investigate the mechanism of dopamine on alleviating apple Cd stress through regular application of CdCl₂ and dopamine solution to potting soil. The results indicated that dopamine significantly reduced reactive oxygen species (ROS) and Cd accumulation and alleviated the inhibitory effect of Cd stress on the growth of apple plants through activation of the antioxidant system, enhancement of photosynthetic capacity, and regulation of gene expression related to Cd absorption and detoxification. The richness of the rhizosphere microbial community increased, and community composition and assembly were affected by dopamine treatment. Network analysis of microbial communities showed that the numbers of nodes and total links increased significantly after dopamine treatment, while the keystone species shifted. Linear discriminant analysis effect size indicated that some biomarkers were significantly enriched after dopamine treatment, suggesting that dopamine induced plants to recruit potentially beneficial microorganisms (Pseudoxanthomonas, Aeromicrobium, Bradyrhizobium, Frankia, Saccharimonadales, Novosphingobium, and Streptomyces) to resist Cd stress. The co-occurrence network showed several metabolites that were positively correlated with relative growth rate and negatively correlated with Cd accumulation, suggesting that potentially beneficial microorganisms may be attracted by several metabolites (L-threonic acid, profenamine, juniperic acid and (3 β,5 ξ,9 ξ)-3,6,19-trihydroxyurs-12-en-28-oic acid). Our results demonstrate that dopamine alleviates Cd stress in apple trees by recruiting beneficial microorganisms to enhance the physiological resilience revealed. This study provides an effective means to reduce the harm to agricultural production caused by heavy metals.

Acknowledgements

This work was supported by the National Natural Science Foundation of China (No. 31901964), the Science and Technology Project of Hebei Education Department (No. BJK2022012), and the Earmarked fund for the China Agricultural Research System (No. CARS-27).

Author contributions

B.L., Y.C., and P.D. conceived and designed the experiments. Y.C. and P.D. performed the experiments with assistance from J.Z. and J.J. Y.C. and P.D. analysed the data and drafted the manuscript. J.X. provided laboratory apparatus. B.L. provided financial support and revised the manuscript. All authors read and approved this manuscript.

Data availability

Data will be made available on request.

Conflict of interest statement

The authors declare that they have no competing interests.

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