Characterization of COMT1-mediated low phosphorus resistance mechanism by metabolomics in tomato plants

Abstract

Caffeic acid O-methyltransferase (COMT) controls the biosynthesis of lignin and melatonin. Though melatonin-induced stress tolerance has been widely studied, little can be found about COMT1-mediated low phosphorus (LP) stress tolerance and metabolic characteristic. Transgenic plants overexpressing COMT1 (COMT1) exhibited a significant increase in tolerance to LP stress by promoting plant growth and P uptake compared with wild type (WT) plants. Then, a LCMS based approach was used to conduct a detailed broad-scale identification of metabolic responses of WT and COMT1 tomato roots to LP stress. Totally, 5918 metabolites were identified in the present study, which contained 480–551 significantly changed metabolites (SCMs) in four comparative groups. PCA analysis of these SCMs strongly showed a COMT1-mediated LP resistance process at metabolic level. These SCMs were enriched in 11 shared pathways in comparative groups of “LP effect” and “COMT1 effect”. We further condensed these pathways to five parts: citrate cycle, amino acids biosynthesis and metabolism, arginine-mediated nitric oxide and polyamine metabolism, linoleic acids metabolism, organic acids and derivatives metabolism. A detailed discussion around these five metabolic parts was conducted to unravel tomato LP response and COMT1-mediated resistance mechanism. Taken together, this metabolomics analysis provided more global insights into the physiological and molecular mechanisms of COMT1 against LP stress in tomato plants at metabolic levels.