Figure 3.

RNA blot analysis of the expression of the SAR response gene PR-1 in Arabidopsis plants expressing ISR, SAR, or both. ISR was induced by growing the plants in soil containing WCS417r (417r). SAR was induced in wild-type Col-0 plants either by preinfecting three leaves per plant with Pst(avrRpt2) (avrPst) or by dipping the plants in 1 mM SA 3 days before harvest, or was constitutively expressed in mutant cpr1. Of the Pst(avrRpt2)-induced plants, the systemic, noninoculated tissue was collected. A PR-1 gene-specific probe was used to detect PR-1 transcripts. To check for equal loading, the blots were stripped and hybridized with a gene-specific probe for β-tubulin (Tub).