Ozone-induced ethylene and foliar injury responses are altered in 1-aminocyclopropane-1-carboxylate synthase antisense potato plants.

•  In potato (Solanum tuberosum), two 1-aminocyclopropane-1-carboxylate synthase (ACS) genes are induced by ozone (O ). Antisense inhibition of these ethylene (C H ) biosynthetic genes allowed us to examine the relationship between O -induced C H emission and foliar injury. •  Thirty-two lines (antisense for ST-ACS4 or ST-ACS5) were screened in the glasshouse for acute O -induced C H and lesions. Stomatal conductance and ACS transcripts were quantified for selected C H -altered lines. Six lines were field-tested for chronic O effects. •  Ten lines produced less, and four lines produced more, acute-O -induced C H than nontransformed (NT) plants. Ethylene levels did not appear to be correlated with stomatal conductance. ST-ACS4 and -5 transcript were reduced in transgenic plants, except in two C H over-producing lines. In the field, these C H over-producing lines displayed stunting and leaf rolling in charcoal-filtered (CF) air and chronic O , and they sustained the most severe O injury. •  When C H production was strongly suppressed or enhanced, corresponding reductions or increases in lesion severity were observed, suggesting a critical role for C H in the lesion formation process during O stress.