Exogenous strigolactones impact metabolic profiles and phosphate starvation signalling in roots

Abstract

Strigolactones (SLs) are importantex-plantasignalling molecules in the rhizosphere,promoting the association with beneficial microorganisms, but also affecting plantinteractions with harmful organisms. They are also plant hormonesin-planta, actingas modulators of plant responses under nutrient-deficient conditions, mainly phos-phate (Pi) starvation. In the present work, we investigate the potential role of SLs asregulators of early Pi starvation signalling in plants. A short-term pulse of the syn-thetic SL analogue 20-epi-GR24 promoted SL accumulation and the expression of Pistarvation markers in tomato and wheat under Pi deprivation. 20-epi-GR24 applica-tion also increased SL production and the expression of Pi starvation markers undernormal Pi conditions, being its effect dependent on the endogenous SL levels.Remarkably, 20-epi-GR24 also impacted the root metabolic profile under these condi-tions, promoting the levels of metabolites associated to plant responses to Pi limita-tion, thus partially mimicking the pattern observed under Pi deprivation. The resultssuggest an endogenous role for SLs as Pi starvation signals. In agreement with thisidea, SL-deficient plants were less sensitive to this stress. Based on the results, wepropose that SLs may act as early modulators of plant responses to P starvation.