The mechanism of SO2-induced stomatal closure differs from O3 and CO2 responses and is mediated by non-apoptotic cell death in guard cells ($) (Plant Cell Environ)

Stomata opening and closing are regulated by guard cells. Airborne pollutants such as ozone, sulfur dioxide, and nitrogen dioxide cause stomatal closure. In this study, Lia Ooi et al. tried to understand the molecular mechanism of SO₂-induced stomatal closure. SO₂ is found in three forms in aqueous solution (H₂CO₃, HSO₃^–, SO₃^2-) and the authors showed that H₂SO₃ is responsible for the stomata closure. Interestingly, SO₂ induces stomata closure using a different molecular mechanism than that used by O₃ and CO₂. The authors demonstrated that SO₂-induced stomatal closure correlates with non-apoptotic cell death in guard cells. This study reveals a unique stress avoidance response of stomata against SO₂ gas. (Summary by Arif Ashraf) Plant Cell Environ. 10.1111/pce.13406