Effects of Elevated Ozone on Polka Dot Plant (Hypoestes phyllostachya) with Variegated Leaves.

In this study, impacts of O3 on four cultivars ('Rose', 'Pink', 'Blush' and 'White') of the polka dot plant with variegated leaves were investigated for the first time. Ozone fumigation [(120 ± 20 ppb) for 14 days (8 h day-1, from 8:30 to 16:30)] resulted in visible foliar injuries, decreased contents of pigments (chlorophyll a and b, and carotenoid), the inhibition of photosynthesis, the increase of quantum yield of non-regulated heat dissipation and fluorescence emission (Y(NO)), and the damage of cell membrane. Elevated O3 increased the content of anthocyanin (Ant). 'White' showed the highest, and 'Rose' the lowest amount of injured leaf area, indicating that the former was the most sensitive, and the latter the most tolerant to O3 stress. After O3 exposure, the highest Ant content was found in 'Rose', followed by 'Pink', 'Blush', and 'White'. Levels of Ant were likely responsible for the different sensitivities to O3 due to their roles in photoprotection.