Figure 4.

Accumulation of H₂O₂ in leaves from wild-type and PGβS-AS transgenic tomato plants. A, Terminal leaflet from a 6- to 8-week-old wild-type plant (left) and from a transgenic plant (right) were excised and vacuum infiltrated with a solution of DAB. After 1 h of stain development, the leaflets were photographed. B, Assays of H₂O₂ levels in leaf extracts from 6-week-old wild-type plants and from transgenic tomato plants of similar age expressing the PGβS-AS gene. Quantification of H₂O₂ from extracts was performed as described in “Materials and Methods.” Data are means ± sd; n = 6.