Harrison-Lowe, Nicola , Olsen, Laura .
Autophagy Protein 6 (ATG6) is required for post-microsporogenesis pollen development in Arabidopsis thaliana.
Autophagy is an inducible, intracellular recycling pathway that extends the life of an organism in hostile conditions. Autophagy allows for sequestration of cytoplasmic components into vesicles that traffic to the vacuole for degradation. AtATG6 is a homologue of mammalian Beclin 1 and yeast Atg6p/Vps30p. Screening of all available atg6 tDNA-insertional lines indicates that AtATG6 is an essential protein as the homozygous state is lethal. atg6(+/-) plants displayed variable phenotypes, including retarded growth in comparison to wild-type plants, increased anthocyanin production, and decreased silique production. Transformation of atg6(+/-) plants with a 35S:ATG6 overexpresson construct can complement heterozygote phenotypes. Progeny segregation of 50:50, wild-type to heterozygous plants, and the lack of aborted seeds in siliques, suggest a germ cell defect. Pollen from atg6(+/-) was crossed into glabra-2 plants and produced only wild-type progeny indicating a pollen defect was responsible for loss of homozygous segregants (progeny from the reciprocal cross segregated 50:50). PCR performed on pollen from atg6(+/-) plants revealed that the TDNA was present in the mature pollen population, suggesting the defect is post-microsporogenesis. Furthermore, qrt-1(-/-)/atg6(+/-) plants produced tetrads that were trinucleate and stained uniformly with Alexander stain. However, qrt-1(-/-)/atg6(+/-) pollen exhibited different germination efficiencies in vitro. Finally, a series of in vivo pollen tube guidance experiments revealed no defects in pollen tube growth or guidance. While it is not knwon whether ATG6 acts in an autophagy-dependant or independent manner during pollen development, this data suggests novel connections between autophagy and reproductive biology.
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1 - University of Michigan, Molecular, Cellular and Developmental biology, Ann Arbor, MI
2 - University of Michigan, Molecular, Cellular and Developmental biology
Presentation Type: Plant Biology Abstract
Location: Exhibit Hall (Northeast, Southwest & Southeast)/Hilton
Date: Sunday, July 8th, 2007
Time: 8:00 AM