The Soil-Plant Interaction Innovation Team at the Institute of Agricultural Resources and Regional Planning (IARRP), Chinese Academy of Agricultural Sciences, has made significant progress in the study of plant-microbe interactions and the green control of soil-borne diseases. The team has demonstrated that calcium (Ca) can function as an inorganic plant immunity booster by promoting the enrichment of beneficial root-associated microbiota, thereby effectively suppressing tomato bacterial wilt caused by Ralstonia solanacearum. The findings provide a simple and effective strategy for regulating the root microbiome through soil nutrient management to achieve sustainable control of soil-borne diseases.

The study, entitled "Calcium-containing inorganic immunity booster drives the enrichment of specific root endophytic microbiota against Ralstonia solanacearum", was published in the leading microbiology journal Microbiome.

Soil nutrient imbalance and outbreaks of soil-borne diseases are major constraints on global agricultural productivity, severely affecting crop yield and quality. The root microbiome plays a critical role in maintaining plant health and disease resistance, and harnessing its regulatory potential is widely regarded as an environmentally friendly and sustainable plant protection strategy. However, how to efficiently manipulate the root microbiome to control soil-borne diseases remains a key scientific challenge.

In this study, the researchers proposed a nutrient-based approach to activate plant immunity while optimizing the root microbiome. Through experiments involving seven levels of Ca application combined with pathogen inoculation, the team employed multi-omics analyses to systematically investigate tomato defense responses and root microbiome dynamics under Ca regulation. The results revealed a multi-level synergistic mechanism linking soil nutrient regulation, plant immune activation, changes in root exudates, and the targeted enrichment of beneficial microbes.

The main findings showed that Ca supplementation significantly activated systemic resistance in tomato plants by increasing root salicylic acid and trehalose contents as well as the activities of defense-related enzymes. High Ca levels markedly reshaped the root microbial community, enriching 16 bacterial taxa, including Dyella japonica, Rhodanobacter glycinis, Paenibacillus polymyxa, and Pseudomonas aeruginosa. As these beneficial microbes accumulated, the incidence of tomato bacterial wilt was reduced dramatically from 80% to zero. In vitro experiments further demonstrated that salicylic acid, trehalose, and Ca each promoted the growth of the enriched beneficial bacteria to varying degrees.

Based on these insights, the researchers constructed a synthetic microbial community (SynCom) with both antagonistic activity against R. solanacearum and tolerance to high Ca conditions. The combined application of Ca and the SynCom effectively suppressed tomato bacterial wilt, highlighting the strong synergistic potential of nutrient management and microbiome engineering.

Bi Jingjing and Wei Buqing, doctoral students at IARRP, are co-first authors of the paper. Researchers Song Alin, Yi Keke, and Fan Fenliang are co-corresponding authors. The study was supported by the State Key Laboratory of Efficient Utilization of Arid and Semi-arid Arable Land in Northern China, the National Key R&D Program of China, and the CAAS Science and Technology Innovation Program.

Original article link: https://doi.org/10.1186/s40168-025-02228-1