LAUSR

Ozone can cause damage to plant tissues. However, little information is available about this global and systematic damage mechanism of grape leaf photosynthetic apparatus. In this study, tandem mass tags (TMT) analysis and physiological responses indicated severe damage to the chloroplasts, with differentially expressed proteins mainly distributed in the chloroplasts. Under ozone stress, the expression of the PSI and PSII structural proteins PsbR, PsaK, PsaA and PSII reactive center protein D1 levels were down-regulated, and the inhibition of D1 protein turnover further aggravated the photodamage of photosystem II (PSII), resulting in a significant decrease in the actual photochemical efficiency of PSII (Y(II)) and actual photochemical efficiency of PSI (Y(I)). The xanthophyll cycle-related protein VDE and ZEP and the NDH subunit of the cyclic electron transport-related protein PGR5-like protein 1A and subcomplex B1 protein were upregulated in response to ozone stress, which was accompanied by a high level of ETRI-ETRII ratio. However, these defense mechanisms are not strong enough. Several dysfunctional antioxidant-related proteins have shown limited ability to scavenge reactive oxygen species, leading to reactive oxygen species burst and eventual photodamage. The system analysis provides new insights into the damage and molecular defense mechanisms of photosynthetic apparatus by ozone.