cDNAs induced by ozone from Atriplex canescens (saltbush) and their response to sulfur dioxide and water-deficit

Ozone effects on plant water relations have been reported to be similar to those of water-deficit. The objective was to identify ozone-inducible (OI) clones from Atriplex canescens (saltbush) and determine if they were also responsive to water-deficit as well as SO₂. cDNA clones derived from four different polyA RNAs which accumulate in 8-month-old shrub leaves exposed to ozone (0.2 μl I⁻¹, 6 h day⁻¹, 7 days) were isolated by differential screening, analyzed by northern blots, sequenced, and gene product homologies with other plant genes were determined. Clone OI12A-3 has homology with wound-inducible proteinase inhibitors, whereas clone OI8–3 protein is homologous to thiol proteases. Clones OI2–2 and OI14–3 putatively code for glycine-rich proteins with repeated motifs (Gly-Gly-Gly-Tyr-Gly-His)_n and putative cell-wall-targeting signal peptides. Clone OI2–2 and particularly clone OI14–3 were also induced by both SO₂ and water-deficit. These data indicate that woody plant genes associated with cell wall protein production and whose expression is induced by several stress factors may be responding to common oxidative stress pathways.