The CRP4 gene is not induced in seedlings following flg22 treatment or heat stress. Semi-quantitative RT-PCR was used to test possible induction of CRP4 gene expression in seedlings under different conditions. (A) Treatment of seedlings with the bacterial elicitor flg22 for the indicated time periods results in induction of expression of the MAP kinase MPRK3 but not the CRP4 gene. Similar results were seen in wild-type non-transgenic seedlings (WT), a wild-type transgenic line [WT(T)], and an nrpe1 mutant, which is defective in the largest subunit of Pol V. (B) Heat treatment of seedlings for the indicated time periods does not result in induction of CRP4 gene expression whereas the Onsen retrotransposon is induced under the same conditions . In both panels, actin expression is shown as a constitutively expressed control.