title: Antimycin A sensitive pathway independent from PGR5 cyclic electron transfer triggers non-photochemical reduction of PQ pool and state transitions in Arabidopsis thaliana.
abstract: We investigated the mechanism involved in triggering state transitions at 40°C in Arabidopsis thaliana. Leaves (1-6 week old) exposed to 40°C exhibited state II transition indicating its role as one of the earliest stress responsive mechanism apart from regulation of light energy distribution between photosystem (PS)II and PSI. Post illumination transients (rise in Fo') revealed that non-photochemical reduction of PQ pool at 40°C in dark is responsible for activation of STN7 kinase, consequently light harvesting complex (LHC)II phosphorylation leading to state II condition. Later, in pgr5 mutant, non-photochemical reduction of PQ pool was observed indicating the involvement of alternative electron transfer routes. In chlororespiratory mutant crr2-2, state II transition occurred signifying that the reduction of PQ pool is independent from NDH mediated cyclic electron transfer. Further, antimycin A inhibitor studies in wt and mutants revealed its inhibitory action on non-photochemical reduction of PQ pool affecting both LHCII phosphorylation and migration to PSI which leads to state I. Thus, our study showed that antimycin A sensitive pathway independent from PGR5 dependent cyclic electron transfer, is responsible for inducing non-photochemical reduction of PQ pool and state transitions at 40°C.
authors: Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
authors: Sreedhar
authors: S
authors: Nellaepalli
authors: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
authors: Sireesha
authors: S
authors: Kodru
authors: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India.
authors: Agepati S
authors: AS
authors: Raghavendra
authors: Department of Plant Sciences, School of Life Sciences, University of Hyderabad, Hyderabad 500046, Telangana, India. Electronic address: srgsl@uohyd.ernet.in.
authors: Rajagopal
authors: R
authors: Subramanyam
mesh_terms: D000968:Antimycin A / Q000494:pharmacology*; D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D029681:Arabidopsis Proteins / Q000235:genetics / Q000378:metabolism*; D002734:Chlorophyll / Q000378:metabolism; D000077194:Chlorophyll A; D004579:Electron Transport; D006358:Hot Temperature; D045342:Light-Harvesting Protein Complexes / Q000378:metabolism; D009154:Mutation; D010766:Phosphorylation; D045322:Photosynthetic Reaction Center Complex Proteins / Q000235:genetics / Q000378:metabolism*; D045331:Photosystem I Protein Complex / Q000378:metabolism; D045332:Photosystem II Protein Complex / Q000378:metabolism; D010971:Plastoquinone / Q000378:metabolism*; D011494:Protein Kinases / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D015398:Signal Transduction; D013312:Stress, Physiological
chemical_list: D029681:Arabidopsis Proteins; D045342:Light-Harvesting Protein Complexes; C465062:PGR5 protein, Arabidopsis; D045322:Photosynthetic Reaction Center Complex Proteins; D045331:Photosystem I Protein Complex; D045332:Photosystem II Protein Complex; D002734:Chlorophyll; D000968:Antimycin A; D011494:Protein Kinases; C120337:light-harvesting complex II kinase; D017346:Protein Serine-Threonine Kinases; C497212:STN7 protein, Arabidopsis; D010971:Plastoquinone; D000077194:Chlorophyll A