185 Yinong Yang (ed.), Rice Protocols, Methods in Molecular Biology, vol. 956, DOI 10.1007/978-1-62703-194-3_13, © Springer Science+Business Media, LLC 2013 Chapter 13 Quantification of Jasmonic and Salicylic Acids in Rice Seedling Leaves Kyoungwon Cho, Oksoo Han, Shigeru Tamogami, Junko Shibato, Akihiro Kubo, Ganesh Kumar Agrawal, and Randeep Rakwal Abstract Jasmonic acid (JA) and salicylic acid (SA) are critical signaling components involved in various aspects of plant growth, development, and defense. Their constitutive levels vary from plant to plant and also from tissue to tissue within the same plant. Moreover, their quantitative levels change when plant is exposed to biotic and abiotic stresses. To better understand the JA- and SA-mediated signaling and metabolic path- ways, it is important to precisely quantify their levels in plants/tissues/organs. However, their extraction and quantification are not trivial and still technically challenging. An effort has been made in various labo- ratories to develop a simple and standard procedure that can be utilized for quantification of JA and SA. Here, we present the experimental procedure and our decade of experience on extracting and quantifying them in an absolute manner in leaves of rice seedlings. We must mention that this method has been applied to both monocotyledonous and dicotyledonous plants for absolute quantification of JA and SA. As col- laboration is the key towards rapid progress in science and technology, we are always open to sharing our experience in this field with any active research group with an aim to improve the procedure further and eventually to connect the importance of their (JA and SA) quantitative levels with networks of signaling and metabolic pathways in plants. Key words: Oryza sativa, Jasmonic acid, Salicylic acid, Extraction, Quantification Plants have evolved activated defense mechanisms to protect them- selves from various biotic and abiotic stresses. Jasmonic acid (JA) and salicylic acid (SA) are the known key mediators of signaling pathways, leading to activation of plant defense systems and responses (1–5). Jasmonic acid is biosynthesized from linolenic acid by subsequent enzyme reaction of 13-lipoxygenase, allene oxide synthase, allene oxide cyclase, 12-oxo-phytodienoic acid reductase, and three β-oxidation steps (6, 7). The SA is known to be synthesized 1. Introduction