Poster: Protein turnover

Abs # 817: AtATG181 is required for normal autophagy function in Arabidopsis

Presenter:	Xiong, yan , yxiong@iastate.edu
Authors	Xiong, yan  (A)   Contento, Anthony  (A)   Bassham, Diane C (A)
Affiliations:	(A): Department of Genetics, Developmental and Cellular Biology, Iowa State University, Ames, IA, 50010

Autophagy is a non-selective protein degradation pathway in which cytosolic components, and sometimes even whole organelles are delivered to the vacuole or lysosome for degradation by vacuolar proteases to recycle the nutrients. This pathway is thought to be essential during nutrient deprivation, environmental stress, senescence and programmed cell death. The mechanism of autophagy has been well studied in yeast and mammals and was found to be highly conserved between species. The ATG18 protein is essential for autophagy in yeast. We have identified 8 ATG18 homologs in Arabidopsis, named AtATG181 to AtATG188. To examine the function of Arabidopsis ATG18 genes, RNAi transgenic plants were generated with reduced expression of AtATG181. These transgenic plants are more sensitive to both nitrogen and carbon starvation and exhibit early senescence phenotypes both in intact plants and detached leaves, compared with wild-type plants. Using a specific autophagosome-staining drug, MDC (monodansylcadaverine), we found that root tips of Arabidopsis seedlings accumulate autophagosomes in nutrient starvation conditions, but this accumulation does not occur in the RNAi transgenic plants. Our data suggest that AtATG181 may be required for autophagosome formation.