1. Introduction When plants are eaten by insect herbivores or wounded mechanically, the fatty acid linolenic acid (18:3) is metabolized to produce the plant hormone, jasmonic acid (JA), which accumulates to high levels in wounded tissues. The JA pathway is initiated in the chloroplasts and completed in the peroxisomes. JA is exported to the cytoplasm where it is conjugated to isoleucine to form JA-Ile. The latter binds to its receptor to induce the signal that turns on an array of defense genes, including the plant defense gene, PDF1.2. Enzymes that function in the JA pathway are encoded by genes that are localized within the nucleus. Lipoxygenase-2 (LOX-2), allene oxide synthase (AOS), and allene oxide cyclase (AOC) are synthesized within the cytoplasm, and imported into the chloroplast, while OPR-3 is imported into the peroxisomes. The proteins that are produced within the cytoplasm are recognized by receptors which are located in the membranes of the chloroplasts and peroxisomes. Receptors on the outer membrane of the chloroplast include atToc159, atToc132, and atToc120. These receptors is found in the same complex with Toc33/34, and Toc75, which is a protein channel. Mutation in the atToc159 receptor yields plants with an albino phenotype, and are called ppi2. Objective The objective was to evaluate the ability of ppi2 to accumulate mRNA that encode for enzymes that function in the JA pathway. We also evaluated the ability of the mutant to accumulate a JA responsive gene called, PDF 1.2, and also the gene that codes for the repressor of the JA pathway, JAZ1. Hypothesis The atToc-159 receptor complex is a major route in the import of LOX-2, AOS and AOC, which are enzymes that function in the initial steps of the JA pathway. We expect the wounded mutant to accumulate reduced levels of mRNA that encode LOX-2, AOS, OPR-3, and the JA responsive gene, PDF1.2. Discussion In the wounded wild type, the expression of LOX-2, AOS, OPR-3, and the JA responsive gene PDF 1.2 was upregulated. The expression of JAZ1 was comparable between the unwounded and wounded tissue, which suggests that the synthesis and degradation of JAZ1 proteins was tightly regulated. In the wounded mutant, the expression of LOX-2, AOS, and OPR-3 was suppressed. Interestingly, the jasmonate responsive gene PDF1.2 did not accumulate above the control level in the wounded mutant. This observation suggests that in the wounded mutant, JA or JA-Ile did not accumulate to levels high enough to induce the expression of PDF1.2. The data indicates that the expression of enzymes that function within the JA pathway require the presence of atToc159 receptor, we therefore conclude that this receptor is critical for the import of enzymes that function in the JA pathway. Acknowledgments Dr. Sue Musser, for assistance in the analysis of the qPCR data (W.I.U.). Matt Smith for the gift of the ppi2 seeds (Canada). Figure 1. Expression of LOX-2, AOS and OPR3 genes in the unwounded and wounded leaves of atToc159 mutant and wild type plants. Data represents the mean ± SEM of 4 replicates. The atToc159 receptor complex represents a critical point in the biosynthesis of jasmonic acid Author and co-authors: Danielle Sprout, Kayla Duffield, Samantha Workman Faculty Advisor: Dr. Afitlhile Department of Biological Sciences Figure 2. Expression of PDF1.2 and JAZ1 genes in the unwounded and wounded leaves of atToc159 mutant and wild type plants. Data represent the mean ± SEM of 4 replicates. UCEJAZ1 LOX-2AOSOPR-3 1 2 3 4 Figure 3. Expression level of LOX-2, AOS, OPR-3 and JAZ1 genes, which UCE is referenced as the internal control. 1:unwounded,wild type. 2: wounded,wild type. 3: unwounded, ppi2. 4:wounded, ppi2