Long- and short-term phosphate deprivation in bean roots: Plasma membrane lipid alterations and transient stimulation of phospholipases

• Published in: Phytochemistry (Oxford) 2007-06, Vol.68 (11), p.1564-1571
• Main Authors: Russo, Marco Antonio, Quartacci, Mike F., Izzo, Riccardo, Belligno, Adalgisa, Navari-Izzo, Flavia
• Format: Article
• Language: English
• Subjects: Bean; beans; Biological and medical sciences; Cell Fractionation; Digalactosyldiacylglycerol; Fundamental and applied biological sciences. Psychology; Galactolipids - metabolism; Leguminosae; Membrane Lipids - metabolism; Metabolism; Metabolism. Physicochemical requirements; Phaseolus - enzymology; Phaseolus - metabolism; Phaseolus - ultrastructure; Phaseolus vulgaris; Phosphate deprivation; phosphates; Phosphates - metabolism; Phospholipase C; Phospholipase D; Phospholipases - metabolism; Phospholipids; plant biochemistry; Plant physiology and development; Plant Roots - enzymology; Plant Roots - metabolism; Plant Roots - ultrastructure; Plasma membrane; Roots; Time Factors
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/j.phytochem.2007.03.017

In bean roots subjected to phosphate deprivation the decrease in plasma membrane phospholipids is compensated for by an increase in the non-phosphorous digalactosyldiacylglycerol. Phosphate starvation also induces an activation of the phospholipid-hydrolysing phospholipases C and D. In a long-term experiment bean ( Phaseolus vulgaris L.) seedlings were grown for 18 days in hydroponics in either phosphate-sufficient (+P) or phosphate-deficient (−P) nutrient solutions. Phosphate deprivation halved the phosphorous content of roots. In plasma membrane (PM) fractions isolated from −P roots the phospholipid (PL) level was reduced from 35 to 21 mol%, while PL composition and degree of unsaturation were hardly altered. Digalactosyldiacylglycerol (DGDG) accumulated up to 26% of total PM lipids, replacing PL to a large extent. Molecular species and fatty acid compositions of DGDG in root PM were different compared to DGDG present in the −P plastids. In a short-term study, bean seedlings were grown for 18 days in hydroponics with a complete nutrient solution containing phosphate and then incubated in a −P medium for increasing time ranging from 1 up to 96 h. At the end of the starvation period phosphorous content of −P roots was reduced by 30% compared to +P ones. An activation of phospholipase D and phospholipase C was observed after 1 and 2 h of phosphate deprivation, respectively. Maximal phosphatidic acid accumulation was detected after 4 h of phosphate deprivation, when also DGDG started to accumulate in PM of bean roots. The fatty acid composition of PLD-derived phosphatidylbutanol resembled that of phosphatidylcholine.