Strigolactones Targeting Plant–Microbe Dialogues From Roots to Soil: Unlocking Pathways for Sustainable Agriculture

Strigolactones (SLs) are phytohormones derived from carotenoids that influence various aspects of plant growth, development, and the ability of plants to respond to environmental changes and microbial interactions. Initially categorized as shoot branching inhibitors, SLs are now recognized as crucial rhizospheric signaling molecules that govern nutrient availability, hormonal control, and microbial interactions. Despite significant progress in SL biology, a cohesive synthesis connecting SL molecular signaling, rhizosphere communication, and stress tolerance remains fragmented, hindering their practical use in sustainable agriculture. A more comprehensive understanding of their synthesis process (D27-CCD7/8-MAX1-CLA cascade), their perception (D14-MAX2-SMXL module), and the impact of SMXL7 on chromatin has revealed significant implications on physiology. To enhance plant development under stress conditions, SLs drive auxin transport, regulate ABA-dependent stress signaling, influence the antagonistic effects of cytokinins, and coordinate gibberellin activity with the circadian rhythm. SLs augment arbuscular mycorrhizal colonization, stimulate nodulation, and attract plant growth-promoting rhizobacteria through chemotactic and metabolic interactions. Using GR24 and SL-conjugated nanomaterials enhances plant resistance to drought, salt, and metal stress. Modifying SL-transporters with CRISPR improves SL signaling and fosters beneficial symbiotic associations. The study is crucial because it underscores the importance of SLs in recruiting beneficial microorganisms and facilitating microbial-hormonal interactions. This review proposes a cohesive conceptual framework that integrates receptor specificity, rhizospheric sensing, and microbial response, beyond mere descriptive synthesis. It sets distinct research targets, such as receptor-specific SL-analogues, in situ sensing techniques, and tailored SL-responsive microbial consortia, to make biostimulation more precise and assist crops in withstanding climatic stress more effectively.