Interleukin 2 (IL-2) and interleukin 12 (IL-12) belong to lympho-hematopoietic cytokines and play a critical role in the promotion and enhancement of cellular response. IL-2 as the second signal of antigenic stimulation facilitates the transition of the cell cycle from phase G1 to phase S and is responsible for the regulation of T lymphocytes proliferation and the activation of cytotoxic T cells, natural killers, macrophages and granulocytes. IL-12 is the dominant factor in T helper cells polarization leading to the secretion of IFN-. Receptors for both of the cytokines (IL-2R or IL-12R) represent class I cytokine receptors composed of multiple subunits. Generally, they contain a similar extracellular conserved motif of four cysteines, and amino acid sequence - WSXWS (interacting directly with ligand) but possess no catalytic domens in the intrinsic tail of the chains. For this reason, to transfer the impact, the association with number of signaling molecules, allowing the activation of the signaling pathways is required. The connections of IL-2R or IL-12R with their ligands recruit receptor-associated cytoplasmic proteins from the JAK family (JAK1/JAK3 or JAK2/TYK2, respectively), which catalyze the phosphorylation of themselves and intrinsic tyrosine residues on the receptor, creating STAT docking sites. This phosphorylated and subsequent dimerised proteins bind rapidly to DNA and activate it. This review, presents the differences and similarities between the signaling pathways triggered by IL-2R or IL-12R ligation.
Plants can develop local and systemic wide-spectrum resistance induced by pathogens or by some chemical products, a phenomenon known as systemic acquired resistance (SAR). Non-pathogenic microbes or some elicitors can also induce resistance called induced systemic resistance (ISR). Plant growth regulators (e.g., jasmonates, salicylates, ethylene) play an important role in induction of these systemic resistance types. Jasmonic acid (JA) and its methyl ester (MeJA) as well as ethylene are thought to be important components of the signaling pathway regulating ISR response in plants, while salicylic acid (SA) and its methyl ester (MeSA) are required for induction of SAR. This review will focus on the present knowledge about the role of jasmonates in the induction of plant resistance induction against pathogens and their relation to ethylene and salicylates in the process.
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