Mitogen-Activated Protein Kinase: A Potent Signaling Protein that Combats Biotic and Abiotic Stress in Plants

초록

Serine kinases, also identified as mitogen-activated protein kinases (MAPKs), are involved in the transmission of cellular signals that carry out different cellular processes, i.e., mitosis, gene expression, cell proliferation, survival, and death. Moreover, it also leads to various other physiological processes in plants including metabolism, differentiation, stress response, and apoptosis. The MAPK family of proteins is responsible for initiating four distinct pathways through their components: ERK1/2 (extracellular signal-regulated kinase), c-Jun N-terminal kinases, p38 MAPK, and the stress activated protein kinases including ERK5 as a member of this family. Arabidopsis is generally used as a standard plant for determining the nomenclature of plant MAPK, and MAPK kinases. MAPK cascades contain certain protein kinase tiers which are activated by phosphorylating each other upon exposure to extracellular stimuli including, ERK1/2, ERK5/BMK1, p38, and JNK/SAPK signals. MAPK cascades also regulate multiple physiological functions by triggering immune system responses in multiple activities of various species of plants including, anther development, embryogenesis, zygote elongation, organ abscission, stomata pattering, and root development. MAPK has been reported in plant physiology regulation in responses to various biotic and abiotic stresses like cold, salt, metal, mechanical stress, ozone, extreme temperature, UV radiation, and insect, and pathogen infections. This process is mediated by hormones and phytochemicals including, ethylene and jasmonic acids which help to protect the plant from these environmental effects. Numerous studies on MAPK cascades have been performed in the past few decades and several MAPK cascades in plants have been identified, but certain details of MAPK regulation by upstream signaling components remain unknown. In the near future, MAPK cascades activated by external signals and unidentified MAPKs will be important research topics for most researchers.

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