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Titolo:
EFFECT OF SEVERE WATER-STRESS ON ASPECTS OF CRASSULACEAN ACID METABOLISM IN XEROSICYOS
Autore:
BASTIDE B; SIPES D; HANN J; TING IP;
Indirizzi:
UNIV CALIF RIVERSIDE,DEPT BOT & PLANT SCI RIVERSIDE CA 92521 UNIV CALIF RIVERSIDE,DEPT BOT & PLANT SCI RIVERSIDE CA 92521
Titolo Testata:
Plant physiology
fascicolo: 4, volume: 103, anno: 1993,
pagine: 1089 - 1096
SICI:
0032-0889(1993)103:4<1089:EOSWOA>2.0.ZU;2-B
Fonte:
ISI
Lingua:
ENG
Soggetto:
PHOSPHOENOLPYRUVATE CARBOXYLASE; MESEMBRYANTHEMUM-CRYSTALLINUM; PEPEROMIA-CAMPTOTRICHA; EXPRESSION; INDUCTION; ACTIVATION; DROUGHT; CARBON; RNA;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
40
Recensione:
Indirizzi per estratti:
Citazione:
B. Bastide et al., "EFFECT OF SEVERE WATER-STRESS ON ASPECTS OF CRASSULACEAN ACID METABOLISM IN XEROSICYOS", Plant physiology, 103(4), 1993, pp. 1089-1096

Abstract

Xerosicyos danguyi H. Humb. (Cucurbitaceae) is a Crassulacean acid metabolism (CAM) species native to Madagascar. Previously, it was shown that when grown under good water conditions, it is a typical CAM plant, but when water stressed, it shifts to a dampened form of CAM, termedCAM-idling, in which stomata are closed day and night but with a continued, low diurnal organic acid fluctuation. We have now studied the kinetics of some metabolic features of the shift from CAM to CAM-idlingunder severe water stress and the recovery upon rewatering. When water is withheld, there is a steady decrease in relative water content (RWC), reaching about 50%, at which point the water potential decreases precipitously from about -2 or -3 bars to -12 bars. Abscisic acid (ABA) increases sharply at about 75% RWC. Stomata close, which limits CO2 uptake, and there is a dampened diurnal organic acid fluctuation typical of CAM-idling. Throughout an extended stress period to 50% RWC, there is no change in chlorophyll, protein, and ribulose bisphosphate carboxylase activity compared with the well-watered plants. Despite the fact that the tissue was already in CAM, the stress is accompanied by an increase in phosphoenolpyruvate carboxylase (PEPc) mRNA, extractablePEPc activity, and PEPc protein (such that the specific activity remained approximately constant) and a decrease in the apparent K(m)(PEP). It is not known if the changes in K(m)(PEP) in response to drought are related to or are separate from the increases in PEPc protein and mRNA. The changes in K(m)(PEP) could be in response to the decreased endogenous levels of organic acids, but evidently are not an assay artifact. The increases in PEPc protein and mRNA appear to be related to thewater-stress treatment and may result from the increased concentration of ABA or the decreased levels of endogenous organic acids. When rewatered, the metabolism quickly returns to the well-watered control typical of CAM.

ASDD Area Sistemi Dipartimentali e Documentali, Università di Bologna, Catalogo delle riviste ed altri periodici
Documento generato il 15/07/20 alle ore 20:25:05