Minisymposium 2: Oxidative Stress

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Abs # M0201: Autophagy is required for plants to survive under abiotic stresses

Presenter:	Xiong, Yan       Contact Presenter
Authors	Xiong, Yan  (A) (B)  Bassham, Diane C (A) (B)
Affiliations:	(A): Iowa State University (B): Department of Genetics, Development and Cell Biology

Autophagy is a process in which cytoplasmic components are degraded in the vacuole to provide raw materials and energy for the maintenance of essential cellular functions. It occurs when organisms are subjected to environmental stress conditions or during certain stages of development. Upon induction of autophagy, a portion of cytoplasm is surrounded by a double membrane structure to form an autophagosome. The outer membrane of the autophagosome then fuses with the vacuole and the inner membrane and its contents are degraded by vacuolar hydrolases. Using two autophagy markers, monodansylcadaverine (MDC) and GFP-AtATG8e, we found that abiotic stresses such as nutrient deprivation, high salinity, osmotic stress and oxidative stress can induce autophagy in Arabidopsis plants. Autophagy-defective RNAi-AtATG18a transgenic plants are more sensitive to these abiotic stresses than wild type plants, implying an important role for autophagy in the response to these conditions. Under oxidative stress, RNAi-AtATG18a plants accumulate a higher level of oxidized proteins than wild type plants, due to a lower degradation rate. Furthermore, when treated with concanamycin A to inhibit vacuolar enzyme activity, oxidized proteins can be detected in the vacuole of wild type root cells but not RNAi-AtATG18a roots cells. Together, our data suggests that autophagy is involved in degrading oxidized proteins during oxidative stress in Arabidopsis. The physiological role of autophagy in other abiotic stresses is under investigation.