A Study of Phospholipids and Galactolipids in Pollen of Two Lines of Brassica napus L. (Rapeseed) with Different Ratios of Linoleic to Linolenic Acid

Abstract

The phospholipids and galactolipids of the pollen-coat and internal domains of two lines of Brassica napus, Wesroona and IXLIN, with different linoleic/linolenic acid ratios (18:2/18:3) have been characterized by normal phase silica high performance liquid chromatography and gas liquid chromatography. The polar lipids of the pollen-coat are similar to leaf lipids in the high proportion of galactolipids (almost 50%) and the fatty acids; 18:3, palmitic (16:0) and hexadecatrienoic (16:3). In contrast, the pollen internal domain, although rich in 18:3, 18:2 and 16:0, is composed primarily of phosphatidyl-choline, -ethanolamine, and -inositol whose 18:2/18:3 ratio is correlated with that of the seed generation. The difference between the two divergent 18:2/18:3 ratio lines is most evident in the internal domain phospholipids. The 18:2/18:3 ratio of the galactolipids of both pollen domains is not significantly effected by the line genotype. The results are interpreted in terms of the previously described 'prokaryotic' and 'eukaryotic' plant desaturation pathways (PG Roughan, CR Slack [1982] Annu Rev Plant Physiol 33: 97-132). We propose that the eukaryotic pathway is the major desaturation pathway providing polyunsaturated fatty acids to the haploid-specified internal domain in which the IXLIN genotype modifies the activity of the sn-2 linoleoyl phosphatidylcholine desaturase/s of the endoplasmic reticulum. In the diploid-specified pollen-coat, our evidence suggests that a combination of the prokaryotic and eukaryotic pathways contribute polyunsaturated fatty acids.

Arabidopsis Type B Monogalactosyldiacylglycerol Synthase Genes Are Expressed during Pollen Tube Growth and Induced by Phosphate Starvation

“…This finding is in accord with the fact that large amounts of galactolipids are found in the pollen coat (Evans et al, 1990) and that these lipids are considered to localize in amyloplasts, which accumulate starches (Singh et al, 1991). In Arabidopsis, the plastids observed in early microspores released from tetrads have no inner membrane system.…”

High night temperature decreases leaf photosynthesis and pollen function in grain sorghum

“…This indicates that the decreased content of MGDG under HNT stress was due to decreased biosynthesis and not by conversion to DGDG. Galactolipids (MGDG and DGDG) were reported in the pollen coat (Evans et al 1990). Kobayashi et al (2004) observed that MGDG genes (atMGD1, atMGD2 and atMGD3) were expressed in pollen grains (membrane) of Arabidopsis thaliana a (L.) Heyhn.…”

Biogenesis and function of the lipidic structures of pollen grains

“…Compositional studies in Brassica napus have shown that intracellular pollen membranes are made up primarily of phospholipids, namely phosphatidylcholine, phosphatidylethanolamine and phosphatidylinositol (Evans et al 1990). Fatty acid analysis has demonstrated that the intracellular membrane lipids change their composition significantly during pollen development, with particular increases in palmitic and linolenic acids and corresponding declines in the amounts of oleic and linoleic acids .…”