Linking jasmonates with pigment accumulation and photoprotection in a high-mountain endemic plant, Saxifraga longifolia

Abstract

Jasmonates are widely found in the plant kingdom and play a key role in both plant biotic and abiotic defense and plant development. Jasmonates activity under abiotic stress conditions have been extensively investigated in model plants, but little is known about the bioactive forms and their functions in non-model species, particularly in plants growing in their natural environment. Here, we performed a jasmonate profiling approach to unravel changes in the specific jasmonate signature of leaves as a function of environmental conditions, including the measurement of both free and conjugated forms of jasmonates by UHPLC–MS/MS, during the summer and autumn in Saxifraga longifolia plants growing in their natural habitat in the Pyrenees. We evaluated the climatological factors governing specific jasmonate signatures and the correlation between jasmonate accumulation and leaf morphology, PSII efficiency and pigment accumulation, including anthocyanins, chlorophylls and carotenoids. The results showed a jasmonate profiling characterized by an accumulation of free jasmonic acid and its precursor, 12-oxo-phytodienoic acid, with the amino acid conjugated forms being much less abundant. Among amino acid conjugates, jasmonoyl-isoleucine, jasmonoyl-valine and jasmonoyl-phenylalanine were the most abundant forms. Contents of 12-oxo-phytodienoic acid decreased, while those of free jasmonic acid increased during summer drought stress events. The five amino acid conjugated forms did respond similarly to environmental changes with progressive decreases from summer to autumn, but irrespective of drought events. Endogenous contents of free jasmonic acid correlated positively with those of anthocyanins. Furthermore, exogenous jasmonate applications on leaves increased anthocyanin contents, thus confirming a link between jasmonates and anthocyanin accumulation in S. longifolia plants.