1Division of Crop Biotechnics, KU Leuven, B-3001 Leuven, Belgium
2Botany Department, Faculty of Science, Tanta University, Tanta, Egypt
Received date: 08 May, 2016; Accepted date: 15 May, 2016; Published date: 22 May, 2016
Citation: El-Esawi (2016) Jasmonic Acid: Genetic Pathway, Signal Transduction and Action in Plant Development and Defence. Biochem Physiol 5:e149. doi:10.4172/2168-9652.1000e149
Copyright: © 2016 El-Esawi MA. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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(JA) is one of the most signaling phytohormones which play an essential role in plant development and response to biotic and abiotic stresses. It plays a key regulatory role in root elongation, pollen production, germination, fruit ripening, plant senescence [1]. Additionally, it activates plant defenses against pests, pathogens and abiotic stress. Jasmonic acid and its derivative methyl jasmonate are abundant in plant cells and have a physiological signaling mechanism. Recently, jasmonates have been reported to be the active forms precursors comprising certain amino acid conjugates [1]. Jasmonates are generally synthesized and accumulated upon environmental or developmental stimuli. Jasmonate signal transduction process is regulated by a signaling mechanism embracing certain repressor proteins which control different transcription factors regulating the expression of jasmonate responsive genes [1].
The first step of JA synthesis takes place in chloroplasts membranes, where a phospholipase generates both of α-linolenic acid and hexadecatrienoic acid from membrane phospholipids [1,2]. JAs synthesis occurs generally from the α-linolenic acid precursor through the octadecanoid pathway [1,3]. Chloroplastic 13-lipoxygenase oxidizes αLA forming the 13-hydroperoxy derivative of linolenic acid [4]. The Arabidopsis genome comprises six genes encoding lipoxygenases. Three of such genes (LOX2, LOX3 and LOX4) regulate JA production [1,5]. The next steps of JA synthesis occur in the peroxisome.
Following Jasmonic acid perception, the signal transduction process assembles on basic-helix-loophelix related transcription factors including the multifunctional MYC2 [1]. A cluster of proteins, JASMONATE-ZIM-DOMAIN (JAZ) repressors, controls JA response under stress conditions. JAZ repressors interact with CORONATINE INSENSITIVE1 which represents a part of the Skp-Cullin-F-box complex included in the co-reception of biologically active JA [1,6]. Pauwels et al. proposed a model to repress the activity of downstream transcription factors regulating JA signaling. In this model, JAZ proteins deactivate MYC2 in the absence of bioactive JAs [1,7]. JA-Ile– induced and SCFCOI1-mediated degradation of the JAZ proteins can remove this MYC2 blockage [1,8].
Jasmonic acid plays a key role in plant growth and reproduction [9]. Jasmonates have an important role in numerous physiological processes of plants, including senescence induction, floral development, growth inhibition, tendril coiling, fruit ripening, potato tuberization, fungi arbuscular mycorrhizal association and trichome formation [1,10]. In addition, Xue and Zhang have reported that jasmonic acid plays a regulatory role in the morphogenesis of leaf and root of soybean [11]. It has been reported that jasmonic acid controls male fertility, mediating stamen elongation and anther development by MYB24 and MYB21 [1,12]. In addition to the important role of cytological and molecular genetic markers in crop improvement, crop responses to biotic and abiotic stresses are also regulated by different plant hormones including, but not limited to, salicylic acid, jasmonic acid and ethylene, which have a signaling mechanism in plant defense regulation processes [1,13-27].
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