Hormone deficient mutants have distinct flavonoid proportion fingerprints in response to abiotic stress

Distinct flavonoid profiles (a.k.a. ‘fingerprints’) are produced in the vegetative tissues of plants in response to different abiotic stresses, yet it remained unknown whether flavonoid levels or their relative their proportions are more tightly regulated in response to stress. Here we show that the relative proportions of 19 flavonoids were more stringently controlled compared to their levels in response to variety of abiotic stresses. We screened mutants that are deficient in the biosynthesis of the stress response hormones ABA, Eth, JA, and GA by growing them in an abiotic stress condition that induces the biosynthesis of a wide variety of flavonoids and found that mutants deficient in a particular hormone generally had a distinct flavonoid proportion fingerprint. Our results suggest that flavonoid proportion fingerprints of uncharacterized mutants could be used to predict gene involvement in particular hormone pathways that signal responses to abiotic stress.