Figure 10.

Model depicting Arabidopsis resistance to aphids conferred by bik1 mutant. PAD4 is a positive regulator of aphid-induced plant antibiotic and antixenotic responses. PAD4-regulated defense, potentially resulting from ROS-mediated cell death, is suppressed by BIK1. Based on the intensity of DAB staining, the BIK1 suppression is presumably much stronger than the aphid induction, illustrated by thicker lines in the graph. BIK1 also suppresses SA and ET accumulation. SA has no direct influence on resistance to aphids. ET increased host repellence early on, possibly prior to significant ROS production.