Plant autophagy--more than a starvation response.

Autophagy is a conserved mechanism for the degradation of cellular contents in order to recycle nutrients or break down damaged or toxic material. This occurs by the uptake of cytoplasmic constituents into the vacuole, where they are degraded by vacuolar hydrolases. In plants, autophagy has been known for some time to be important for nutrient remobilization during sugar and nitrogen starvation and leaf senescence, but recent research has uncovered additional crucial roles for plant autophagy. These roles include the degradation of oxidized proteins during oxidative stress, disposal of protein aggregates, and possibly even removal of damaged proteins and organelles during normal growth conditions as a housekeeping function. A surprising regulatory function for autophagy in programmed cell death during the hypersensitive response to pathogen infection has also been identified.