Implication of phospholipase D in response of Hordeum vulgare root to a short-term potassium deprivation

Hafsi, Chokri and Russo, Marco Antonio and Sgherri, Cristina and Izzo, Riccardo and Navari-Izzo, Flavia and Abdelly, Chedly (2009) Implication of phospholipase D in response of Hordeum vulgare root to a short-term potassium deprivation. Journal of Plant Physiology, 166/20 (5). pp. 499-506. ISSN 0306-4379

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Abstract

SUMMARY To verify a possible implication of lipids and some other compounds such as hydrogen peroxide (H2O2) and glyceraldehydes-3-phosphate dehydrogenase (G3PDH) in the response of Hordeum vulgare to an early potassium deprivation, plants were grown in hydroponics for 30 days with a modified Hewitt nutrient solution containing 3 mM K+ and then incubated for increasing time ranging from 2 h up to 36 h in the same medium deprived of K+. In contrast to leaves, root K+ concentration showed its greatest decrease after 6 h of treatment. The main lipids of the control barley roots were phospholipids (PL), representing more than 50% of the total lipids. PL did not change with treatment whereas free sterols (FS) amounts decreased following K+ deprivation, showing an about 17% reduction after 36 h. As regards the individual PL, 30 h K+ deprivation caused a reduction in phosphatidylcholine (PC), phosphatidylserine (PS) and phosphatidylinositol (PI) levels whereas phosphatidylglycerol (PG), phosphatidylethanolamine (PE) and phosphatidic acid (PA) increased. The maximum PA accumulation as well as the highest phospholipase D (PLD) activation, estimated by an accumulation of phosphatidylbutanol (PtBut), were observed after 24 h of K+ starvation. At the root level, after 6 h of incubation in –K solution, H2O2 level showed the maximum value. At the same time G3PDH activity reached the minimum. On the basis of a concomitant stimulation of PLD activity and, consequently, PA accumulation, enhancement of H2O2 production, and inhibition of G3PDH activity we can suggest a possible involvement of these three compounds in an early response to K+ deprivation.

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