Interactive effects of ozone and drought stress on plants: A review

Ground-level ozone (O₃) and drought are two key factors limiting plant growth. O₃ can enter into the plant tissue through the stomata, then causing the formation of reactive oxygen species (ROS) which inspires programmed cell death. Drought usually induces the accumulation of ROS due to damage to antioxidant systems of plants. The effects of two kinds of stress on plants are similar due to the accumulation of ROS, resulting in reduced photosynthesis rate and physiological metabolism, eventually decreased plant growth and biomass. Nevertheless, O₃ and drought interacts synergistically to accumulate detrimental effects or antagonistically to reduce harmful effects. Actually, it is complex interactive process between O₃ and drought. On the one hand, O₃ triggers stomatal sluggishness or even dysfunction, which exacerbates water transpiration of leaves, water loss from plants and further O₃ phytotoxicity. On the other hand, drought induces stomatal closure, and thus protecting plants against the O₃ influx and evaporation of water. However, prolonged drought could limit the uptake of CO₂ and thus result in reduced plant growth. The response of plants to both O₃ and drought not only depends on the occurring sequence and duration of any factor but also rely on the difference in physiological metabolism of the plant itself. The interactive effects of O₃ and drought on stomatal characteristics, photosynthetic carbon mechanism, antioxidant response and growth development are reviewed in this paper and the aspects to be further studied are also suggested.