Changes in root traits and rhizosphere microbiome are important ways to optimize plant phosphorus (P) efficiency and promote multifunctionality in intercropping. However, whether and how synthetic microbial communities isolated from polyculture systems can facilitate plant growth and P uptake are still largely unknown. A field experiment was first carried out to assess the rice yield and P uptake in the rice/soybean intercropping systems, and a synthetic microbial community (SynCom) isolated from intercropped rice was then constructed to elucidate the potential mechanisms of growth-promoting effects on rice growth and P uptake in a series of pot experiments. Our results showed that the yield and P uptake of intercropped rice were lower than those of rice grown in monoculture. However, bacterial networks in the rice rhizosphere were more stable in polyculture, exhibiting more hub nodes and greater modularity compared to the rice monoculture. A bacterial synthetic community (SynCom) composed of four bacterial strains (Variovorax paradoxus, Novosphingobium subterraneum, Hydrogenophaga pseudoflava, Acidovorax sp.) significantly enhanced the biomass and P uptake of potted rice plants. These growth-promoting effects are underpinned by multiple pathways, including the direct activation of soil available P, increased root surface area and root tip number, reduced root diameter, and promotion of root-to-shoot P translocation through up-regulation of Pi transporter genes (OsPht1;1, OsPht1;2, OsPht1;4, OsPht1;6). This study highlights the potential of harnessing synthetic microbial communities to enhance nutrient acquisition and improve crop production.

Soil salinity is one of the most limiting factors for global agriculture, threatening crop productivity and food security. This chapter synthesizes current knowledge on the physiological and ecological mechanisms underlying plant adaptation to salt stress and proposes integrative biological strategies to enhance crop salt tolerance. Particular emphasis is placed on root interactions and rhizosphere processes, beneficial microbial inoculants, and the use of biostimulants and exogenous signaling compounds. By evaluating these strategies collectively, the chapter highlights their synergistic potential to provide sustainable and ecosystem-based solutions for salinity management. The chapter begins with root-mediated mechanisms that regulate ion transport, water balance, and rhizosphere modifications. It then addresses the role of beneficial microorganisms in promoting plant salt resilience through nutrient mobilization, hormone regulation, and stress alleviation. The potential of biostimulants and small molecules as external modulators of stress responses is also explored. Finally, this chapter integrates these approaches into a holistic framework, emphasizing the importance of ecological synergy and cross-disciplinary collaboration in developing scalable solutions. By bridging insights from plant physiology, soil microbiology, and agricultural practices, and incorporating the application of big data and large-scale models for optimizing salt tolerance alongside precision management in smart agriculture, this chapter provides a roadmap for advancing green and integrative strategies to enhance crop adaptation and performance in saline environments.