Abstract
We previously showed that AtATG6, an Arabidopsis homologue of ATG6, restored autophagy and vacuolar sorting of CPY protein in yeast atg6 mutant. In Arabidopsis cells, AtAtg6 and phosphatidylinositol 3-kinase (AtVps34) colocalized with AtAtg8, a marker protein of the pre-autophagosomal structure (PAS). Here we further show that GFP-FYVE proteins, which interact with phosphatidylinositol 3-phosphate, colocalized with AtAtg6 and AtAtg8 on the punctate structure, which may represent the PAS of plant cells. We propose that synthesis of phosphatidlylinositol-3 phosphate by phosphatidylinositol 3-kinase at the PAS is an important process in autophagosome formation. We have also found that atg6 was male sterile because ATG6-deleted pollen failed to germinate. Transmission electron microscope and environmental scanning electron microscope showed that atg6 mutant pollen grains were normal in appearance. All these results suggested that AtAtg6 is essential for pollen germination but not for early pollen development.
