Deciphering the mechanisms involved in Portulaca oleracea (C4) response to drought: metabolic changes including crassulacean acid-like metabolism induction and reversal upon re-watering

D'ANDREA, RODRIGO MATIAS; ANDREO, CARLOS SANTIAGO; LARA, MARÍA VALERIA

PHYSIOLOGIA PLANTARUM

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2014 vol. 152 p. 414 - 430

0031-9317

Portulaca oleracea is a C4 plant; however, under drought it can change itscarbon fixation metabolism into a crassulacean acid metabolism (CAM)-likeone. While the C3-CAM shift is well known, the C4-CAM transition has onlybeen described in Portulaca. Here, a CAM-like metabolism was inducedin P. oleracea by drought and then reversed by re-watering. Physiologicaland biochemical approaches were undertaken to evaluate the drought andrecovery responses. In CAM-like plants, chlorophyll fluorescence parameterswere transitory affected and non-radiative energy dissipation mechanismswere induced. Induction of flavonoids, betalains and antioxidant machinerymay be involved in photosynthetic machinery protection. Metabolic analysishighlights a clear metabolic shift, when a CAM-like metabolism is inducedand then reversed. Increases in nitrogenous compounds like free amino acidsand urea, and of pinitol could contribute to withstand drought. Reciprocalvariations in arginase and urease in drought-stressed and in re-watered plantssuggest urea synthesis is strictly regulated. Recovery of C4 metabolism wasaccounted by CO2 assimilation pattern andmalate levels. Increases in glyceroland in polyamines would be of importance of re-watered plants. Collectively,in P. oleracea multiple strategies, from induction of several metabolites to thetransitory development of a CAM-like metabolism, participate to enhance itsadaptation to drought.