oryzaeinfection in rice. Plants posses several integrated signaling networks which predominantly involve protein kinases that perceive and respond to the different stimuli. was identified as downstream target of OsMPK7 through protein-protein interaction techniques and was found to be a positive regulator of defence response againstX. oryzaepathogen. The overexpression of OsMKK3-OsMPK7 upregulated genes involved in pathogenesis, cell wall structure maintenance and cell metabolism indicating possible mechanism of disease resistance. These leaves also showed restricted movement of the pathogen from the point of infection to uninfected area. Taken together, this work suggests a positive involvement of OsMKK3-OsMPK7-OsWRKY30 module in imparting disease resistance againstX. oryzaeinfection in rice. Plants posses several integrated signaling networks which predominantly involve protein kinases that perceive and respond to the different stimuli. One of the most important protein kinase cascades that transfer extracellular signals into intracellular responses is the highly distinct and conserved mitogen activated protein kinase (MAPK) cascade. The MAPK cascade comprises a linear cascade of three consecutively acting protein kinases, namely MAPKK Kinases, MAPK Kinases and PHTPP MAPKs, connected to each other by an event of phosphorylation. The sequential activation of the MAPK cascade ultimately results in activation of myriad of proteins leading to expression of specific sets of genes in response to environmental stimuli1, 2 . MAPKs are activated by dual phosphorylation of conserved threonine (T) and tyrosine (Y) residues in the motif TXY located in their activation loop by MAPKKs, which are themselves activated by MAPKKKs through phosphorylation of conserved serine (S) and/or threonine (T) residues in S/T-X3-5-S/T motif1, 3. The completion of rice genome project revealed 15 MAPKs and 8 MAPKKs, whereasin silicoanalysis of rice genome database revealed 75 MAPKKKs4, 5, 6. The MAPKs are divided into 4 groups based on protein structure and sequence motif TXY. The MAPKs having sequence motif of TEY are grouped into A, B and C whereas those having TDY sequence are organised into D group. In rice, the most studied members, OsMPK3 and OsMPK6 belongs to Group A and OsMPK4 belongs to Group B7, 8. However , the information is quite scant regarding the group C members comprising of OsMPK7 and OsMPK14. The other ten members fall in group D, the function of all these also remains elusive5. Upon microbial attack plants are equipped to sense and mount a defence response against pathogens due to the presence of specific receptors and signaling cascades1, 9, 10. Detection of Pathogen Associated Microbial Patterns (PAMPs) by membrane Pattern Recognition Receptors (PRRs) triggers early defence responses like activation of MAPKs, calcium flux and production of reactive oxygen species (ROS). These early events then causes activation of intermediate and late defence responses like activation of defence genes, strengthening of cell wall, phytoalexin biosynthesis, hypersensitive response and induced resistance9, 10, 11. ROS burst associated with PTI is known to activate MAPKs which in turn regulate ROS production12, 13. It has been examined that moderate concentration of ROS is essential in the regulation of biological processes, whereas its high concentrations result in oxidative stress and causes irreversible damage seen as typical sign of infection14. Arabidopsis MAPKs are known for prominent role in pathogen signaling10. MEKK1-MKK4/5-MPK3/6 in Arabidopsis is activated in response to PAMPs like bacterial flg22 elicitor, EF-Tu, Rat monoclonal to CD8.The 4AM43 monoclonal reacts with the mouse CD8 molecule which expressed on most thymocytes and mature T lymphocytes Ts / c sub-group cells.CD8 is an antigen co-recepter on T cells that interacts with MHC class I on antigen-presenting cells or epithelial cells.CD8 promotes T cells activation through its association with the TRC complex and protei tyrosine kinase lck Chitin, PGNs, which PHTPP ultimately leads to the transcriptional activation of several downstream targets like flg22-INDUCED RECEPTOR- LIKE KINASE 1 (FRK1), WRKY22, WRKY29, ACS2/6, NIA2, ERF104 and VIP1 leading to defence responses10, 15. Another MAPK module MEKK1-MKK1/2-MPK4 is considered to negatively regulate defence responses where MPK4 acts on its downstream substrates, MAP Kinase substrate 1 (MKS1) and WRKY3316, 17. Studies in Arabidopsis reports that MKK3 interact and activate MPK6 and MPK7 in response to Jasmonic acid andPseudomonas syringae, respectively which PHTPP further activates pathogenesis related genes18, 19. In comparison to Arabidopsis, rice MAPKs have been partially characterized. A couple of studies performed to find interaction between rice MAPKs and MAPKKs have put forward some of the major MAPK modules of which only a few are functionally characterized8, 20. A cascade consisting of OsMKK4-OsMPK3/6 has shown its negative role in MAMP-triggered immunity and positive regulator of drought, salt and cold stress20. OsMKK6 has been reported to be involved in regulating genes for biosynthesis of phytoalexin, a secondary metabolite known to get accumulated inMagnoporthe oryzaeinfected plants21. Interestingly, a unique interaction was.
