Induction of Crassulacean Acid like Metabolism in the C4 plant Portulaca oleracea L. under drought conditions. Changes in PEPCarboxylase

LARA, MARÍA VALERIA; DISANTE, KAREN BEATRIZ; PODESTÁ, FLORENCIO ERNESTO; ANDREO, CARLOS SANTIAGO; DRINCOVICH, MARÍA FABIANA

PS2001 Proceedings: 12th International Congress of Photosynthesis (ISBN 0643 6711 6)

CSIRO Publishing

Lugar: Collinwood, Australia ; Año: 2001 p. 1 - 4

Although most land plants can be categorized as C3, C4 and CAM (Crassulacean AcidMetabolism) according to the photosynthetic pathway (Ehleringer and Monson 1993), a widevariety of species share characteristics of the different photosynthetic groups. For example,C3-C4 intermediate species are thought to represent a stage in the evolutionary transition fromC3 to C4 photosynthesis (Rawsthorne 1992), while other species shift from one type ofphotosynthesis to other depending on the age or environment as the shift from C3photosynthesis to CAM (Osmond 1978, Winter and Smith 1989). The transition from C4photosynthesis to CAM has been previously suggested in P. oleracea, P. grandiflora and P.mundula when subject to drought-stress conditions or short photoperiods by acid malicfluctuations and CO2 exchange measurements (Koch and Kennedy 1980, 1982; Ku et al.1981; Kraybill and Martin 1996; Mazen 1996). Nevertheless, characteristics of this transitionat molecular level have not been studied. Portulaca is an excellent system to studyphotosynthetic metabolism transitions because not only may involve expression/regulation ofphotosynthetic enzymes but also may increased our understanding of C4 plant responses toenvironmental stress.The aim of this study was to find out the conditions for the induction of a CAM-likemetabolism in P. oleracea L. and to compare physiological and biochemical parameters inboth conditions. Because PEPC is regulated in a different manner in C4 and CAM plants, thisenzyme was studied in detail.