Plastidial retrograde modulation of light and hormonal signaling: an odyssey

What is it about?

The transition from an engulfed autonomous unicellular photosynthetic bacterium to a semi-autonomous endosymbiont plastid was accompanied by the transfer of genetic material from the endosymbiont to the nuclear genome of the host, ensued by the establishment of plastids-to-nucleus (retrograde) signaling. The retrograde coordinated activities of the two subcellular genomes ensures chloroplast biogenesis and function as the photosynthetic hub, sensing and signaling center tailoring growth-regulating and adaptive processes. This review specifically focuses on the current knowledge of selected stress-induced retrograde signals, Genomes Uncoupled 1 (GUN1), methylerythritol cyclodiphosphate (MEcPP), apocarotenoid and β-cyclocitral, and 3’-phosphoadenosine 5'-phosphate (PAP), evolved to establish the photoautotrophic lifestyle, and instrumental in integration of light and hormonal signaling networks to ultimately fashion adaptive-responses in an ever-changing environment.

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