Plant autophagy puts the brakes on cell death by controlling salicylic acid signaling

Abstract

It has long been recognized that autophagy in plants is important for nutrient recycling and plays a critical role in the ability of plants to adapt to environmental extremes such as nutrient deprivation. Recent reverse genetic studies, however, hint at other roles for autophagy, showing that autophagy defects in higher plants result in early senescence and excessive immunityrelated programmed cell death (PCD), irrespective of nutrient conditions. Until now, the mechanisms by which cells die in the absence of autophagy were unclear. In our study, using biochemical, pharmacological and genetic approaches, we reveal that excessive salicylic acid (SA) signaling is a major factor in autophagydefective plant-dependent cell death and that the SA signal can induce autophagy. These findings suggest a novel physiological function for plant autophagy that operates via a negative feedback loop to modulate proper SA signaling. © 2010 Landes Bioscience.