High red/far-red ratio promotes root colonization ofSerratia plymuthicaA21-4 in tomato by root exudates-stimulated chemotaxis and biofilm formation

Abstract

Effective colonization on plant roots is a prerequisite for plant growth promoting rhizobacterias (PGPR) to exert beneficial activities. However, how light modulates root colonization of PGPR remains unclear. Here, we found that high red/far red(R/FR) light promoted and low R/FR light inhibited the colonization of Serratia plymuthica A21-4 on tomato. Non-targeted metabolomic analysis of root exudates collected from different R/FR ratio treated tomato seedlings with A21-4 inoculation showed that 64 primary metabolites in high R/FR light-grown plants significantly increased compared with those determined for low R/FR light-grown plants. Among them, 7 amino acids, 1 organic acid and 1 sugar obviously induced the chemotaxis and biofilm formation of A21-4 compared to the control. Furthermore, exogenous addition of five artificial root exudate compontents (leucine, methionine, glutamine, 6-aminocaproic acid and melezitose) regained and further increased the colonization ability of A21-4 in tomato under low R/FR light and high R/FR light, respectively, indicating their involvement in high R/FR light-regulated the interaction of tomato root and A21-4. Taken together, our results, for the first time, clearly demonstrate that high R/FR light-induced root exudates play a key role in chemotaxis, biofilm formation and root colonization of A21-4, which can help promote the combined application of light supplementation and PGPR to facilitate crop growth and health in agricultural production.

Light and substrate composition control root exudation rates at the initial stages of soilless lettuce cultivation

“…The lateral irradiation with far-IR light (wavelength > 10.000 nm) of seedlings of Avena fatua has been shown to increase the secretion of sesquiterpenes (Pomilio et al, 2000). The root exudation profile of Solanum lycopersicum changed with red/far-red ratio (Guo et al, 2024). Pure red and blue LED light combined stimulated a higher exudation compared to plants grown in broad-spectrum light (Zhou et al, 2022).…”