Proteomic analysis of rice response involved in reduction of grain yield under elevated ozone stress

Ozone threat to crop production is increasing, particularly in Asian countries. Although exposure to ozone significantly reduces grain yields in sensitive rice cultivars, it remains unclear what factors cause different sensitivities to ozone and consequent grain yield reduction. To clarify the ozone-induced metabolic changes affecting rice yields, proteomic analyses were conducted of flag leaves in three rice cultivars (Kirara 397, Koshihikari, Takanari) showing various levels of yield and injury response under elevated ozone conditions.

Ozone reduced grain yields in Kirara 397 and Takanari, but not in Koshihikari. In ozone treated Kirara 397, Koshihikari, and Takanari, respectively, 31, 18, and 11 proteins were differently expressed. Ozone exposure decreased proteins associated with photosynthesis and glycolysis in Kirara 397, but increased them in Koshihikari.

Especially, Kirara 397 showed a remarkable decrease in proteins related to photosynthetic electron transport, suggesting that the elevated ozone suppressed the photosynthetic apparatus in Kirara 397, thereby suppressing yields. However, proteins involved in photosynthesis and other energy metabolism showed no remarkable decrease in Takanari.

These results suggest that ozone-induced yield reduction in Takanari results from mechanisms other than those inhibiting the metabolic pathway in photosynthesis.