HYPERSENSITIVE TO HIGH LIGHT1 Interacts with LOW QUANTUM YIELD OFPHOTOSYSTEM II1 and Functions in Protection of Photosystem II from Photodamage inArabidopsis

摘要

Under high-irradiance conditions, plants must efficiently protect photosystem II () from damage. In this study, we demonstrate that the chloroplast protein HYPERSENSITIVE TO HIGH LIGHT1 (HHL1) is expressed in response to high light and functions in protecting against photodamage. Arabidopsis thaliana hhl1 mutants show hypersensitivity to high light, drastically decreased photosynthetic activity, higher nonphotochemical quenching activity, a faster xanthophyll cycle, and increased accumulation of reactive oxygen species following high-light exposure. Moreover, HHL1 deficiency accelerated the degradation of core subunits under high light, decreasing the accumulation of core subunits and –light-harvesting complex II supercomplex. HHL1 primarily localizes in the stroma-exposed thylakoid membranes and associates with the core monomer complex through direct interaction with core proteins CP43 and CP47. Interestingly, HHL1 also directly interacts, in vivo and in vitro, with LOW QUANTUM YIELD OF PHOTOSYSTEM II1 (LQY1), which functions in the repair and reassembly of . Furthermore, the hhl1 lqy1 double mutants show increased photosensitivity compared with single mutants. Taken together, these results suggest that HHL1 forms a complex with LQY1and participates in photodamage repair of under high light.