Molecular markers for ozone stress isolated by suppression subtractive hybridization:: specificity of gene expression and identification of a novel stress-regulated gene

Suppression subtractive hybridization was used to identify genes regulated by ozone (100 nmol mol(-1)) in Pisum sativum. One novel gene (named PsUod1) was found. In addition, mRNA levels for four genes (encoding lipid transfer protein, pre-hevein-like protein, leucine-rich repeat protein, and disease-resistance response protein 230), which previously were shown to be regulated by biotic stress, increased. Finally, mRNA species for two genes (encoding extensin and pathogenesis-related protein 4A), previously shown to be regulated by ozone in other species, were found to increase in abundance. The ozone-specificity of the expression of these genes was studied by using UV-B radiation. PsUod1 and the genes encoding extensin, leucine-rich repeat protein, and disease-resistance response protein 230, were differentially regulated when comparing ozone and UV-B. Moreover, the mRNA levels for extensin, leucine-rich repeat protein and disease-resistance response protein 230 all increased under NaCl and aluminium stress and after wounding, whereas the message abundance for PsUod1 was unchanged under these stresses. Thus, in general, ozone caused changes similar to wounding, salt stress and aluminium stress, whereas UV-B radiation regulated gene expression differently.