Abstract
Autophagy is an intracellular process for vacuolar degradation of cytoplasmic components. Thus far, plant autophagy has been mainly studied by morphological analyses, accordingly, the physiological roles and molecular mechanism of autophagy in plants had not been made clear. A recent genome-wide search revealed significant conservation among autophagy genes (ATGs) in yeasts and plants. It has not been proved, however, that Arabidopsis ATG genes are required for plant autophagy. To evaluate this requirement, we established autophagy-monitoring systems in Arabidopsis roots and leaves using concanamycin A, a V-ATPase inhibitor and clearly proved that T-DNA-insertion mutants of the ATGs (atgs) are defective in autophagy. The atg mutants exhibited a reduction in the growth rate of roots under nitrogen-starved conditions and early senescence phenotype even in nutrient-rich conditions. In addition, hypersensitive response cell death was accelerated in the mutants during the plant innate immune response. We will discuss the physiological roles of plant autophgy.
