CML8 and GAD4 function in (Z)–3–hexenol–mediated defense by
regulating GABA accumulation in Arabidopsis
(Z)–3–hexenol, a small gaseous molecule, is produced in plants under
biotic stress and induces defense responses in neighboring plants.
However, the research on little is known about how (Z)–3–hexenol
induces plant defense–related signaling. In this study, we uncovered
how (Z)–3–hexenol treatment enhances insect resistance by increasing
γ–aminobutyric acid (GABA) contents in Arabidopsis thaliana leaves.
First, (Z)–3–hexenol increases the intracellular content of the
signaling molecule calcium in Arabidopsis leaf mesophyll cells. Both
intracellular and extracellular calcium stores regulate these changes in
calcium content. Then, CML8 and GAD4 are involved in calcium signaling.
Yeast two–hybrid assays, firefly luciferase complementation imaging,
and GST pull–down assays demonstrated that CML8 interacts with GAD4.
Finally, (Z)–3–hexenol treatment increased the GABA contents in
Arabidopsis leaves, thus increasing plant resistance to the insect
Plutella xylostella. This study revealed the mechanism of activating
plant insect defense induced by (Z)–3–hexenol, which is of great
significance for the study of volatiles as biological control measures.