Phytate metabolism in Petunia pollen

• Published in: Phytochemistry (Oxford) Vol. 23; no. 9; pp. 1841 - 1845
• Main Authors: Helsper, Johannes P.F.G., Linskens, Hans F., Jackson, John F.
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Ltd 01.01.1984; Elsevier
• Subjects: Analytical, structural and metabolic biochemistry; anther; Biological and medical sciences; Fundamental and applied biological sciences. Psychology; Lipids; metabolism; myo-inositol; Other biological molecules; pectic polysaccharide; Petunia hybrida; phosphatidylinositol; phospholipids; phytic acid; pollen; Solanaceae; Petunia hybrida; phytic acid; anther; phosphatidylinositol; pollen; metabolism; Solanaceae; phospholipids; pectic polysaccharide; myo-inositol; Vegetals; Dicotyledones; Angiospermae; Spermatophyta; Pollen; Metabolism
• ISSN: 0031-9422; 1873-3700
• DOI: 10.1016/S0031-9422(00)84928-6

Phytic acid has been detected in the anthers of young flower buds of Petunia hybrida, the amount increasing slowly as the flower develops until anther dehydration, when there was a more rapid increase in phytic acid content. In mature pollen, the phytic acid content was found to be 2.0 % by weight, of which 90 % was water soluble, while free myo-inositol was a relatively low 0.06 % by weight. Breakdown of phytic acid was initiated soon after pollen germination began, and its degradation products, myo-inositol and inorganic phosphate, were rapidly mobilized for phospholipid and pectin biosynthesis. Both are in high demand during pollen tube elongation. Utilization of myo-[2- 3H]inositol for phospholipid biosynthesis was about five times that for pectin synthesis during the first few hours of pollen germination. The label in the phospholipid was identified as the myo-inositol moiety of phosphaltidylinositol, while the pectin material contained predominantly labelled arabinose, with smaller amounts of label in galacturonic acid, glucose and xylose. A chase experiment showed that the myo-inositol moiety of phosphatidylinositol was subject to a relatively rapid turnover, while the label in pectin was not. Labelling germinating pollen with [ 32P]orthophosphate gave label in phosphatidic acid, phosphatidylinositol, phosphatidylethanolamine and phosphatidylcholine of the phospholipids. Phosphatidylinositol contained 30 % of this label initially, a proportion which declined to 10 % over longer periods of germination.