Silencing NappHS reduces TD transcript abundance in corolla, pistil, and stamens from wild-type (black bars), IRsys line 1 (white bars), and IRsys line 2 (gray bars) flowers of AZ (middle section) and UT (right section) accessions. TD expression is required for the production of JA-Ile. TD catalyzes the formation of α-keto butyrate from Thr, the first step in biosynthesis of Ile, which is conjugated to JA (left section).