Figure 5.

Influence of pretreatment with BTH on the subsequent induction of PAL and PR-1 gene activation and callose deposition in leaves of Arabidopsis wild-type and npr1/nim1 mutant plants. Wild-type and npr1/nim1 mutant plants were pretreated with 100 μm BTH (+) or with the wettable powder carrier only (−). After 3 d, leaves of the plants were left untreated (−), dipped into a solution of MgCl₂/Silwet in the absence (−) or presence (+) of Pst DC3000 (A), slightly squeezed with forceps (+; B and C), or infiltrated with water (+; B and C). A and B, Three hours (A) and 2 h (B) post-treatment, total RNA was extracted from an aliquot of leaves and was analyzed for the accumulation of PAL transcripts by RNA gel blotting. PR-1 gene activation was assayed at the 24-h time point. To check for equal sample loading, the membranes of the PAL blots were stripped and rehybridized with an Arabidopsis β-tubulin cDNA probe. C, Another aliquot of wounded or water-infiltrated leaves was analyzed for the accumulation of callose at the 7-h time point post-stimulation. At this time point, callose content in leaves treated with the wettable powder carrier only was 44.8 μg of PE (g fresh weight)⁻¹. This value was subtracted from all samples. Values given are averages of two replicates.