Quantitative analysis of herbivore-induced cytosolic calcium by using a Cameleon (YC 3.6) calcium sensor in Arabidopsis thaliana

Ca2+ is a key player in plant cell responses to biotic and abiotic stress. Owing to the central role of cytosolic Ca2+ ([Ca2+]cyt) during early signaling and the need for precise determination of [Ca2+]cyt variations, we used a Cameleon YC 3.6 reporter protein expressed in Arabidopsis thaliana to quantify [Ca2+]cyt variations upon leaf mechanical damage (MD), herbivory by 3rd and 5th instar larvae of Spodoptera littoralis and S. littoralis oral secretions (OS) applied to MD. YC 3.6 allowed a clear distinction between MD and herbivory and discriminated between the two larvae instars. To our knowledge this is the first report of quantitative [Ca2+]cyt determination upon herbivory using a Cameleon calcium sensor.