Complex phenotypic profiles leading to ozone sensitivity in <i>Arabidopsis thaliana</i> mutants

<jats:title>ABSTRACT</jats:title><jats:p>Genetically tractable model plants offer the possibility of defining the plant O<jats:sub>3</jats:sub> response at the molecular level. To this end, we have isolated a collection of ozone (O<jats:sub>3</jats:sub>)‐sensitive mutants of <jats:italic>Arabidopsis thaliana</jats:italic>. Mutant phenotypes and genetics were characterized. Additionally, parameters associated with O<jats:sub>3</jats:sub> sensitivity were analysed, including stomatal conductance, sensitivity to and accumulation of reactive oxygen species, antioxidants, stress gene‐expression and the accumulation of stress hormones. Each mutant has a unique phenotypic profile, with O<jats:sub>3</jats:sub> sensitivity caused by a unique set of alterations in these systems. O<jats:sub>3</jats:sub> sensitivity in these mutants is not caused by gross deficiencies in the antioxidant pathways tested here. The <jats:italic>rcd3</jats:italic> mutant exhibits misregulated stomata. All mutants exhibited changes in stress hormones consistent with the known hormonal roles in defence and cell death regulation. One mutant, dubbed <jats:italic>re‐8</jats:italic>, is an allele of the classic leaf development mutant <jats:italic>reticulata</jats:italic> and exhibits phenotypes dependent on light conditions. This study shows that O<jats:sub>3</jats:sub> sensitivity can be determined by deficiencies in multiple interacting plant systems and provides genetic evidence linking these systems.</jats:p>