Jonathan Chevalier:
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Going through their life cycle plants, as all organisms, face
numerous developmental cues in addition to environmental challenges. All
those stimuli require rapid response to adapt and survive. Somatic cells
acclimate to changes in the environment by temporary reprogramming.
Much has been learned about transcription factors that induce these cellstate
switches in both plants and animals, but how cells rapidly modulate
their proteome remains elusive. In this study we show that autophagy, and
decay machinery, are necessary to efficiently adjust to new conditions.
In plants, autophagy is rapidly induced during temporary
reprogramming triggered by phytohormones, immune, and danger
signals. Quantitative proteomics following sequential reprogramming
revealed that autophagy is required for timely removal of the previous
cellular states allowing the new program to unfold and preventing
contradictory information being relay to the nucleus. Signatures of
previous cellular programs thus persist in autophagy-deficient cells,
affecting cellular decision-making. Autophagy appears to be needed to
keep the new program into physiological range and prevent accumulation
of newly synthesized protein. Concordantly, autophagy deficient cells fail
to acclimatize to dynamic climate changes. Similarly, they have defects in
dedifferentiating into pluripotent stem cells, and redifferentiation during
organogenesis. These observations indicate that autophagy mediates
cell-state switches that underlie somatic cell reprogramming in plants and
possibly other organisms, and thereby promotes phenotypic plasticity.