Autophagy Mechanism on Plant Recovery after Starvation

Plants need internal mechanisms in order to cope with the changing environment. A common effect is energy deprivation, causing a set of physiological, metabolic and molecular events, including inhibition of growth, activation of catalytic pathways to provide nutrients, metabolites and energy, and decreased biosynthetic enzyme activity.

One of the major cellular catabolic processes is autophagy, a conserved eukaryotic that causes the degradation of cytoplasmic components in lytic organelles (vacuole in plants). The genes participating in the autophagic process are termed ATG genes. In plants, atg mutants showed decreased ability to cope under conditions of stress, and specifically, hyper-sensitivity to carbon starvation and reduced recovery from starvation. However, the underlying cause to their inability to recover is still unknown.

In the current study, we set up a carbon starvation recovery system and examined WT and atg mutant plants. Indeed, the WT were able to recover while the atg mutants did not. We also evaluated autophagic activity and ATG gene expression at several time points during recovery and discovered that the autophagy mechanism is still active after the stress is gone. Since atg mutants are continuously autophagy deficient, it is impossible to assess the contribution of autophagy to recovery from the stress by itself. We prepared inducible atg knock-down lines in Arabidopsis plants. We used two approaches: a micro-RNA construct under the control of an estradiol-inducible promotor and temperature-sensitive protein degradation constructs. This approach will allow us to examine the role of autophagy during recovery, while separating it from the starvation response.