Interaction between plastid and mitochondrial retrograde signalling pathways during changes to plastid redox status

BLANCO N.E.; GUINEA-DIAZ M,; WHELAN, J.; STRAND, Å

PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES

ROYAL SOC

Lugar: Londres; Año: 2014 vol. 369

0962-8436

Mitochondria and chloroplasts depend upon each other; photosynthesisprovides substrates formitochondrial respirationandmitochondrialmetabolismis essential for sustaining photosynthetic carbon assimilation. In addition,mitochondrialrespiration protects photosynthesis against photoinhibition bydissipating excess redox equivalents from the chloroplasts. Genetic defects inmitochondrial function result in an excessive reduction and energization of thechloroplast. Thus, it is clear that the activities of mitochondria and plastidsneed to be coordinated, but the manner by which the organelles communicateto coordinate their activities is unknown. The regulator of alternative oxidase(rao1) mutant was isolated as a mutant unable to induce AOX1a expression inresponse to the inhibitor of the mitochondrial cytochrome c reductase (complexIII), antimycin A. RAO1 encodes the nuclear localized cyclin-dependent kinaseE1 (CDKE1). Interestingly, the rao1 mutant demonstrates a genome uncoupledphenotype also inresponse to redox changes inthephotosynthetic electrontransportchain. Thus, CDKE1 was shown to regulate both LIGHT HARVESTINGCOMPLEX B (LHCB) and ALTERNATIVE OXIDASE 1 (AOX1a) expression inresponse to retrograde signals. Our results suggest that CDKE1 is a centralnuclear component integrating mitochondrial and plastid retrograde signalsand plays a role in regulating energy metabolism during the response to stress.