Lipid synthesis in germinating Tradescantia pollen

Biogenesis and function of the lipidic structures of pollen grains

“…2) and their common regulation by the gametophytic genome. Several enzymes and cofactors involved in fatty acid biosynthesis have been detected in intracellular fractions of mature dehydrated Brassica napus pollen grains (Evans et al 1992;Piffanelli et al 1997), suggesting that the rapid onset of membrane synthesis to ensure pollen tube growth after germination may be at least partially due to a set of lipid biosynthetic enzymes already present in the mature pollen grains (Whipple and Mascarenhas 1978).…”

Germination‐induced changes in acyl lipids and free sterols of olive pollen

“…Compositional changes associated with germination in haploid tissues are not well documented, and only fragmentary studies have been conducted with different pollen grains (Whipple & Mascarenhas, 1978;Helsper & Pierson, 1986). Mobilization of endogenous substances occurs during germination and tube growth of pollen (Bergamini-Mulcahy & Mulcahy, 1983), and son-ie authors have observed that the state of the vegetative cell men-ibranes is one of the principal factors determining germination capacity and that the viability of pollen from diverse species is determined by the stability of its membranes (Shivanna & Heslop-Harrison, 1981).…”

Microspore and Microgametophyte Development in Relation to Biological Activity of Environmental Pollutants

“…The total radioactivity incorporated into both neutral lipids and polar lipids showed no (lifferences whether or not pollen was grown wAith or without cycloheximide and actinomycin D. These results indicate that all the proteins, i.e., enzymes required for the synthesis of both neutral an(l polar lipids are already present in the mature ungerminated pollen grain and are functionally stable for the 2.5-hr period which was studied. None of these enzymes appear to be synthesized during pollen tube growth (4). The conclusions about the presence of enzymes in the pollen grain made from the study of enzymes of lipid synthesis are generally found to be true for all the enzymes that have been investigated.…”

“…Cell membrane synthesis is one of the major synthetic events in pollen tube growth and in Tradescantia a 50-fold increase in surface area of the pollen tube occur's within a short period of growth (3). We have accordingly studied the enzymes for lipid sviythesis to determine whether they were newly svnthesized during germination or were already present in the pollen grain at anthesis (4). In these experiments the incorporation of r14CI-acetate into in(livi(lual lipids was studied in the absence and presence of inhibitors of protein and RNA synthesis.…”

“…In these experiments the incorporation of r14CI-acetate into in(livi(lual lipids was studied in the absence and presence of inhibitors of protein and RNA synthesis. The incorporation of the precursor into a lipid was use(l as an indication of the presence of the enzymes necessary for the synthesis of that particular lipid (4). The total radioactivity incorporated into both neutral lipids and polar lipids showed no (lifferences whether or not pollen was grown wAith or without cycloheximide and actinomycin D. These results indicate that all the proteins, i.e., enzymes required for the synthesis of both neutral an(l polar lipids are already present in the mature ungerminated pollen grain and are functionally stable for the 2.5-hr period which was studied.…”