Background : Tropospheric ozone (O3) is a secondary air pollutant that negatively affects numerous agricultural crop and forest. The tropospheric ozone is constantly increasing due to fossil fuel air pollutants. Here, we study the response of tartary buckwheat to ozone gas includes physiological and biochemical changes such as change in gene expression and metabolism.
Methods and Results : Tartary buckwheat plants have green stems and leaves under normal conditions, while the plants exposed to the ozone have red stems and reddish green leaves. The expression of most flavonoid biosynthetic genes were significantly upregulated in ozone-treated buckwheat plants, exceting the expression of FtF3’H2. The contents of two anthocyanins, cyanidin 3-O-glucoside and cyanidin 3-O-rutinoside, were significantly increased by ozone treatment. From the metabolic profiling based on the GC-TOF-MS analysis, we identified the effect of ozone on thirty-five metabolites, including sugars, amino acids, and organic acids. Most of the metabolites result in significantly decreased or nearly remain unchanged in the ozone-treated plants compared with untreated plants, excepting alanine, proline, tryptophan, sucrose, and raffinose. To identify the effect of ozone on the leaf, we analyzed the epidermal cells on the leaf surface by scanning electron microscopy. Interestingly, amount of epidermal cells were partially destructed in ozone-treated plants.
Conclusion : By analyzing both primary and secondary metabolites of tartary buchwheat without or with ozone, we identified that ozone affects the modulation of the metabolites as well as gene expression in tartary buchwheat.