An Arabidopsis homolog of yeast ATG6/VPS30 is essential for pollen germination.
Yeast (Saccharomyces cerevisiae) Atg6/Vps30 is required for autophagy and the sorting of vacuolar hydrolases, such as carboxypeptidase Y. In higher eukaryotes, however, roles for ATG6/VPS30 homologs in vesicle sorting have remained obscure. Here, we show that AtATG6, an Arabidopsis (Arabidopsis thaliana) homolog of yeast ATG6/VPS30, restored both autophagy and vacuolar sorting of carboxypeptidase Y in a yeast atg6/vps30 mutant. In Arabidopsis cells, green fluorescent protein-AtAtg6 protein localized to punctate structures and colocalized with AtAtg8, a marker protein of the preautophagosomal structure. Disruption of AtATG6 by T-DNA insertion resulted in male sterility that was confirmed by reciprocal crossing experiments. Microscopic analyses of AtATG6 heterozygous plants (AtATG6/atatg6) crossed with the quartet mutant revealed that AtATG6-deficient pollen developed normally, but did not germinate. Because other atatg mutants are fertile, AtAtg6 likely mediates pollen germination in a manner independent of autophagy. We propose that Arabidopsis Atg6/Vps30 functions not only in autophagy, but also plays a pivotal role in pollen germination.
Fujiki
Yuki
Y
Department of Cell Biology, National Institute for Basic Biology, Okazaki 444-8585, Japan.
Yoshimoto
Kohki
K
Ohsumi
Yoshinori
Y
D033942:Adaptor Proteins, Vesicular Transport / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D017360:Arabidopsis / Q000254:growth & development* / Q000378:metabolism / Q000648:ultrastructure; D029681:Arabidopsis Proteins / Q000032:analysis / Q000235:genetics / Q000502:physiology*; D001343:Autophagy; D000071186:Beclin-1; D018525:Germination; D049452:Green Fluorescent Proteins / Q000032:analysis; D008969:Molecular Sequence Data; D009154:Mutation; D011058:Pollen / Q000254:growth & development / Q000378:metabolism / Q000648:ultrastructure; D021381:Protein Transport; D011993:Recombinant Fusion Proteins / Q000032:analysis; D012441:Saccharomyces cerevisiae / Q000235:genetics; D014617:Vacuoles / Q000378:metabolism
D033942:Adaptor Proteins, Vesicular Transport; D029681:Arabidopsis Proteins; D000071186:Beclin-1; D011993:Recombinant Fusion Proteins; C519561:beclin 1 protein, Arabidopsis; D049452:Green Fluorescent Proteins