Integrated metabolomics and transcriptomics analysis reveals γ-aminobutyric acid enhances the ozone tolerance of wheat by accumulation of flavonoids

Wheat is susceptible to atmospheric ozone (O-3) pollution, thus the increasing O-3 is a serious threat to wheat production. gamma-aminobutyric acid (GABA) is found to play key roles in the tolerance of plants to stress. However, few studies elaborated the function of GABA in response of wheat to O-3. Here, we incorporated metabolome and transcriptome data to provide a more comprehensive insight on the role of GABA in enhancing the O-3-tolerance of wheat. In our study, there were 31, 23, and 32 differentially accumulated flavonoids in the carbon-filtered air with GABA, elevated O-3 with or without GABA treatments compared to the carbon-filtered air treatment, respectively. Elevated O-3 triggered the accumulation of dihydroflavone, flavonols, and flavanols. Exogenous GABA enhanced dihydroflavone and dihydroflavonol, and also altered the expression of genes encoding some key enzymes in the flavonoid synthesis pathway. Additionally, GABA stimulated proline accumulation and antioxidant enzyme activities under elevated O-3, resulting in the less accumulation of H2O2 and malondialdehyde. Consequently, GABA alleviated the grain yield loss from 19.6% to 9.6% induced by elevated O-3. Our study provided comprehensive insight into the role of GABA in the alleviating the detrimental effects of elevated O-3 on wheat, and a new avenue to mitigate O-3 damage to the productivity of crops.