Figure 4

Quantification by qRT-PCR of the transcriptional activity of the plant defense response gene PR-1 in healthy and chlorotic tissue of leaves infected with B. lactucae in the resistant line RH08-0464 (RH) and the susceptible cultivar Triple Threat (TT). The data illustrate mean expression of PR-1 in three replicates relatively to its activity in the healthy tissue of RH08-0464, which was set to a value of 1. RH-Healthy and –Chlorotic, indicates PR-1 expression in healthy and chlorotic tissue of line RH08-0464, respectively; TT-Healthy and –Chlorotic, indicates PR-1 expression in healthy and chlorotic tissue of cultivar Triple Threat, respectively. PR-1 expression data was normalized to that of the ACT7 gene across samples. Error bars indicate standard error of the mean. Different letters indicate means that are significantly different at P < 0.05.