Centennial Honors College
Western Illinois University
Undergraduate Research Day 2012
Poster Presentation
The Expression of JAR1 Genes in an Arabidopsis Mutant, atToc132/120 (+/-)
Michelle Golz
Faculty Mentor: Dr. Meshack Afitlhile
Biology
Jasmonic acid (JA) is a plant hormone that accumulates at high level in plants that are
wounded or eaten by herbivores. JA synthesis begins in the chloroplast and is
completed in the peroxisomes, after which JA is transported to the cytoplasm where
jasmonate resistant enzyme 1 (JAR1) conjugates isoleucine (Ile) and JA to form JA-Ile.
The initial steps in the JA pathway, which occur in the chloroplasts, require nuclearencoded and cytoplasm synthesized enzymes, which are imported into the chloroplasts
in a process that is facilitated by receptors. In Arabidopsis, several chloroplast receptors
have been identified and studied in details and these include the Toc159 family of
receptors such as atToc159, atToc132 and atToc120. The atToc132 and atToc120 are
found in the same complex and they recognize, bind and import housekeeping proteins.
In this study, we will evaluate the ability of the atToc132/120 (+/-) mutant to synthesize
12-oxo-phytodienoic acid (OPDA), an intermediate in the JA pathway that is transported
from the chloroplasts to the peroxisomes. If the mutant does not accumulate OPDA,
then JA will not be synthesized and JAR1 will have no substrate to conjugate to Ile. In
this study, we will measure the abundance of mRNA for JAR1 and JA responsive gene,
PDF1.2 in both the wounded and unwounded tissues of the mutant and wild type.