Implication of phospholipase D in response of Hordeum vulgare root to short-term potassium deprivation.
To verify the possible involvement of lipids and several other compounds including hydrogen peroxide (H(2)O(2)) and glyceraldehyde-3-phosphate dehydrogenase (G3PDH) in the response of Hordeum vulgare to early potassium deprivation, plants were grown in hydroponic conditions for 30d with a modified Hewitt nutrient solution containing 3mM K(+). They were then incubated for increasing periods of time ranging from 2 to 36h in the same medium deprived of K(+). In contrast to leaves, root K(+) concentration showed its greatest decrease after 6h 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) decreased following K(+) deprivation, showing a reduction of approximately 17% after 36h. With respect to the individual PL, 30h K(+) deprivation led to a reduction in phosphatidylcholine (PC), phosphatidylserine (PS), and phosphatidylinositol (PI) levels, whereas phosphatidylglycerol (PG), phosphatidylethanolamine (PE), and phosphatidic acid (PA) levels increased. The maximum PA accumulation and the highest phospholipase D (PLD) activation, estimated by an accumulation of phosphatidylbutanol (PtBut), were observed after 24h of K(+) starvation. At the root level, H(2)O(2) showed the maximum value after 6h of incubation in -K solution. In parallel, G3PDH activity reached its minimum. On the basis of a concomitant stimulation of PLD activity and, consequently, PA accumulation, enhancement of H(2)O(2) production, and inhibition of G3PDH activity, we suggest a possible involvement of these three compounds in an early response to K(+) deprivation.
Hafsi
Chokri
C
Laboratoire d'Adaptation des Plantes aux Stress Abiotiques, Centre de Biotechnologie, Hammam-Lif , Tunisie.
Russo
Marco A
MA
Sgherri
Cristina
C
Izzo
Riccardo
R
Navari-Izzo
Flavia
F
Abdelly
Chedly
C
D005987:Glyceraldehyde-3-Phosphate Dehydrogenases / Q000378:metabolism; D020404:Glycerophospholipids / Q000378:metabolism; D001467:Hordeum / Q000201:enzymology*; D006861:Hydrogen Peroxide / Q000378:metabolism; D010712:Phosphatidic Acids; D010739:Phospholipase D / Q000378:metabolism*; D010743:Phospholipids / Q000378:metabolism; D018515:Plant Leaves / Q000201:enzymology; D018517:Plant Roots / Q000201:enzymology; D011188:Potassium / Q000378:metabolism*; D036226:Seedlings / Q000201:enzymology; D013997:Time Factors
D020404:Glycerophospholipids; D010712:Phosphatidic Acids; D010743:Phospholipids; C068564:phosphatidylbutanol; D006861:Hydrogen Peroxide; D005987:Glyceraldehyde-3-Phosphate Dehydrogenases; D010739:Phospholipase D; D011188:Potassium