Arabidopsis AtGPAT1, a member of the membrane-bound glycerol-3-phosphate acyltransferase gene family, is essential for tapetum differentiation and male fertility.
Membrane-bound glycerol-3-phosphate acyltransferase (GPAT; EC 2.3.1.15) mediates the initial step of glycerolipid biosynthesis in the extraplastidic compartments of plant cells. Here, we report the molecular characterization of a novel GPAT gene family from Arabidopsis, designated AtGPAT. The corresponding polypeptides possess transmembrane domains and GPAT activity when expressed heterologously in a yeast lipid mutant. The functional significance of one isoform, AtGPAT1, is the focus of the present study. Disruption of the AtGPAT1 gene causes a massive pollen development arrest, and subsequent introduction of the gene into the mutant plant rescues the phenotype, illustrating a pivotal role for AtGPAT1 in pollen development. Microscopic examinations revealed that the gene lesion results in a perturbed degeneration of the tapetum, which is associated with altered endoplasmic reticulum profiles and reduced secretion. In addition to the sporophytic effect, AtGPAT1 also exerts a gametophytic effect on pollen performance, as the competitive ability of a pollen grain to pollinate is dependent on the presence of an AtGPAT1 gene. Deficiency in AtGPAT1 correlates with several fatty acid composition changes in flower tissues and seeds. Unexpectedly, however, a loss of AtGPAT1 causes no significant change in seed oil content.
Zheng
Zhifu
Z
Plant Biotechnology Institute, National Research Council of Canada, Saskatoon, Saskatchewan S7N OW9, Canada.
Xia
Qun
Q
Dauk
Melanie
M
Shen
Wenyun
W
Selvaraj
Gopalan
G
Zou
Jitao
J
D000595:Amino Acid Sequence; D017360:Arabidopsis / Q000201:enzymology* / Q000235:genetics* / Q000254:growth & development; D004269:DNA, Bacterial / Q000235:genetics; D017343:Genes, Plant; D005992:Glycerol-3-Phosphate O-Acyltransferase / Q000737:chemistry / Q000235:genetics* / Q000378:metabolism*; D008563:Membrane Lipids / Q000096:biosynthesis; D008566:Membranes / Q000201:enzymology; D008854:Microscopy, Electron; D008969:Molecular Sequence Data; D005810:Multigene Family; D016254:Mutagenesis, Insertional; D009154:Mutation; D011058:Pollen / Q000201:enzymology / Q000254:growth & development; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D004269:DNA, Bacterial; D008563:Membrane Lipids; D011994:Recombinant Proteins; C036483:T-DNA; D005992:Glycerol-3-Phosphate O-Acyltransferase