Changes in the content of pollen total lipid and TAG in Arabidopsis thaliana DGAT1 mutant as11 .

In mature pollen grains, lipids are primarily stored in the form of lipid droplets that provide energy and act as a carbon source for normal pollen development and germination. Triacylglycerol (TAG) is the major form of stored plant lipids. Diacylglycerol transferase, which is encoded by in , is an important enzyme regulating triacylglycerol synthesis. Within the seeds of the mutant , the content of TAG is significantly decreased and the fatty acid composition also differs from the wild type. Transcriptome data of mature anthers showed that the genes involved in the TAG synthesis pathway were downregulated in . Analysis of gene expression patterns via transcriptome data also revealed that the expression of , which functions in a manner complementary to the gene, was significantly decreased in , whereas the amylopectin synthase genes and were upregulated in mutant . We also detected lower total lipid, TAG and fatty acid contents in mature pollen, with palmitic acid (C16:0) and linolenic acid (C18:3) being the major fatty acids in mature pollen. The cytological results showed that the lipid droplet content was reduced in mature pollen. In the binuclear pollen grain II stage, WT pollen contained lipid droplets that were primarily accumulated around the generative nucleus, whereas the pollen in the mutant was rich in starch grains that were primarily distributed around the vegetative nucleus. Ultrastructural analysis indicated that during pollen development in , the amount of endoplasmic reticulum in tapetal cells and pollen grains decreased, whereas the Golgi body content increased, which directly or indirectly led to a decrease in the levels of lipidosomes and an increase in the starch content in . Changes in the lipid content and fatty acid composition of the mutant as11 differ from those in the wild type during pollen development.