Rhizosphere Cercozoa reflect the physiological response of wheat plants to salinity stress

Highlights

	● Plant salinity stress index correlates with rhizosphere Cercozoa.
	● Salinity stress alleviation promotes predation of rhizosphere Cercozoa.
	● Cercomonas strain inoculation assists alleviation of salinity stress.

Abstract

Protists are essential components of the rhizosphere microbiome, which is crucial for plant growth, but little is known about the relationship between plant growth and rhizosphere protists under salinity stress. Here we investigated wheat (Triticum aestivum L.) rhizosphere protistan communities under naturally occurring salinity (NOS) and irrigation-reduced salinity (IRS), and linked a plant salinity stress index (PSSI) to different protistan groups in a nontidal coastal saline soil. We found that the PSSI was significantly correlated with rhizosphere cercozoan communities (including bacterivores, eukaryvores, and omnivores) and that these communities were important predictors of the PSSI. Structural equation modeling suggested that root exudation-induced change in bacterial community composition affected the communities of bacterivorous and omnivorous Cercozoa, which were significantly associated with the PSSI across wheat cultivars. Network analysis indicated more complex connections between rhizosphere bacteria and their protistan predators under IRS than under NOS, implying that alleviation of salinity stress promotes the predation of specific cercozoans on bacteria in rhizospheres. Moreover, the Cercomonas directa inoculation was conducive to alleviation of salinity stress. Taken together, these results suggest that the physiological response of wheat plants to salinity stress is closely linked to rhizosphere Cercozoa through trophic regulation within the rhizosphere microbiome.

Graphical abstract

Keywords

plant growth / soil salinity / rhizosphere microbiome / trophic interactions / protists / Cercozoa.

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Acknowledgements

The authors are grateful to the staff from the Shandong Dongying Institute of Geographic Sciences of the Chinese Academy of Sciences for the assistance of sample collection. This study was financially supported by the Strategic Priority Research Program of Chinese Academy of Sciences (Grant Nos. XDA24020104, XDA28110100, XDA28020203), the National Key R&D Program of China (Grant Nos. 2022YFD1500203, 2022YFD1500401), the China Agriculture Research System (Grant Nos. CARS-03, CARS-52), the National Natural Science Foundation of China (Grant No. 42177332), and the Youth Innovation Promotion Association of Chinese Academy of Sciences (Grant No. 2023325).

Conflict of interest statement

The authors declare no conflicts of interest.

Data availability statement

All sequence data from the field and glasshouse experiments have been deposited in the National Center of Biotechnology Information (NCBI) Sequence Read Archive under accession number PRJNA961219.

Electronic supplementary material

Supplementary material is available in the online version of this article at https://doi.org/10.1007/s42832-024-0268-9 and is accessible for authorized users.

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