root-microbiome
The root microbiome is the complex community of microorganisms—bacteria, fungi, and archaea—that colonize plant roots and the surrounding rhizosphere environment. These microbial communities are essential to plant health, facilitating nutrient acquisition, enhancing disease resistance, and influencing plant development and physiology. Because roots create unique chemical and physical conditions that support diverse microbial life, the root microbiome represents a critical interface between plants and soil that fundamentally shapes plant growth and productivity.
open_in_new WikipediaPubMed · 2026-04-13
Scientists discovered a molecular switch in legume plants that links phosphorus sensing to the recruitment of nitrogen-fixing bacteria. When phosphorus is available, the SPX1/3-PHR2 network releases chemical signals (flavonoids) that attract beneficial microbes to plant roots, enabling the plant to also acquire nitrogen.
The SPX1/3-PHR2 regulatory network directly controls flavonoid biosynthesis genes, linking phosphate availability to nitrogen-fixing microbe recruitment.
Plants with disrupted SPX1/3 genes showed reduced flavonoid levels in root exudates and a measurably smaller population of nitrogen-fixing bacteria, including rhizobia, in the surrounding soil.
PHR2 binds directly to the promoter regions of flavonoid biosynthetic genes, providing a molecular mechanism by which phosphate status suppresses or promotes root nodule symbiosis.
