Comparative phytohormone profiles, lipid kinase and lipid phosphatase activities in barley aleurone, coleoptile, and root tissues.
We analyzed lipid kinase and lipid phosphatase activities and determined endogenous phytohormone levels by liquid chromatography-tandem mass spectrometry in root and coleoptile tissues following germination of barley (Hordeum vulgare) seeds. The enzymes showing highest activity in aleurone cells were diacylglycerol kinase (DAG-k, EC 2.7.1.107) and phosphatidate kinase (PA-k). The ratio of gibberellins (GAs) to abscisic acid (ABA) was 2-fold higher in aleurone than in coleoptile or root tissues. In coleoptiles, phosphatidylinositol 4-kinase (PI4-k, EC 2.7.1.67) showed the highest enzyme activity, and jasmonic acid (JA) level was higher than in aleurone. In roots, activities of PI4-k, DAG-k, and PA-k were similar, and salicylic acid (SA) showed the highest concentration. In the assays to evaluate the hydrolysis of DGPP (diacylglycerol pyrophosphate) and PA (phosphatidic acid) we observed that PA hydrolysis by LPPs (lipid phosphate phosphatases) was not modified; however, the diacylglycerol pyrophosphate phosphatase (DGPPase) was strikingly higher in coleoptile and root tissues than to aleurone. Relevance of these findings in terms of signaling responses and seedling growth is discussed.
Dpto. Química Biológica, FCEFQN, Universidad Nacional de Río Cuarto, X5804BYA Río Cuarto, Córdoba, Argentina.
Maria V
MV
Meringer
Ana L
AL
Villasuso
Susana J
SJ
Pasquaré
Norma M
NM
Giusto
Estela E
EE
Machado
Graciela E
GE
Racagni
D019870:1-Phosphatidylinositol 4-Kinase / Q000378:metabolism; D018548:Cotyledon / Q000378:metabolism*; D019852:Diacylglycerol Kinase / Q000378:metabolism; D011756:Diphosphates / Q000378:metabolism; D018525:Germination / Q000502:physiology; D005990:Glycerol / Q000031:analogs & derivatives / Q000378:metabolism; D005994:Glycerophosphates / Q000378:metabolism; D001467:Hordeum / Q000201:enzymology* / Q000254:growth & development / Q000378:metabolism; D010711:Phosphatidate Phosphatase / Q000378:metabolism; D010712:Phosphatidic Acids / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000378:metabolism*; D010770:Phosphotransferases / Q000378:metabolism*; D017856:Phosphotransferases (Phosphate Group Acceptor) / Q000378:metabolism; D010937:Plant Growth Regulators / Q000378:metabolism*; D010940:Plant Proteins / Q000378:metabolism; D018517:Plant Roots / Q000378:metabolism*; D011755:Pyrophosphatases / Q000378:metabolism; D012639:Seeds / Q000378:metabolism*; D015398:Signal Transduction
D011756:Diphosphates; D005994:Glycerophosphates; D010712:Phosphatidic Acids; D010937:Plant Growth Regulators; D010940:Plant Proteins; C408642:diacylglycerol pyrophosphate; D010770:Phosphotransferases; D019852:Diacylglycerol Kinase; D019870:1-Phosphatidylinositol 4-Kinase; D017856:Phosphotransferases (Phosphate Group Acceptor); C099834:phosphatidic acid kinase; C112948:lipid phosphate phosphatase; D010744:Phosphoric Monoester Hydrolases; D010711:Phosphatidate Phosphatase; D011755:Pyrophosphatases; C097892:diacylglycerol pyrophosphate phosphatase; D005990:Glycerol