Production of reactive oxygen species, callose deposition and defense gene expression. Microbial pathogens evolved effectors to suppress PTI. In return, plant evolved resistance proteins that recognize effectors direct or indirect and activate effector-triggered immunity. Frequently, ETI responses are dependent on the defense hormone salicylic acid. Root-knot nematodes are sedentary Danshensu endoparasites of great agricultural importance. RKN are obligate biotrophs, penetrate the host roots behind the root cap and move towards the vascular cylinder where they initiate feeding on the cytoplasm of live cells and develop an elaborate feeding site known as giant cells. Cells around the feeding site undergo hyperplasia and hypertrophy resulting in the formation of galls, root symptoms associated with this group of nematodes. Nematode salivary secretions have been implicated in development and maintenance of the feeding site. Once feeding is initiated, RKN become sedentary and mature females lay eggs in gelatinous sacs protruding on the root surface. Although no information exists about how nematodes induce PTI, host defense responses against RKN are similar to biotrophic microbial pathogens and resistance to this pest is mediated by classical R gene responses frequently associated with cell death. Receptor like kinases are among the well characterized PRRs. Common features of the RLKs are the presence of an Nterminal signal sequence, an extracellular domain that varies in structure, a single membrane-spanning region, and a cytoplasmic protein kinase catalytic domain. RLKs with leucine-rich repeat -containing extracellular domains comprise the largest subfamily of transmembrane RLKs in plants with over 200 members in Arabidopsis thaliana. The LRR-RLK FLS2, belonging to LRR-RLK subfamily XII, was first identified in Arabidopsis by its ability to perceive the bacterial flagellin including the minimal epitope flg22. Responsiveness to flg22 is shared by members of all major clades of higher plants indicating that the PRR for this bacterial epitope is evolutionarily ancient and critical for antibacterial immunity. Interestingly, Arabidopsis fls2 mutant plants, compromised in flg22 perception, are more susceptible to the bacterial pathogen Pseudomonas syringae pv. tomato DC3000 only when spray inoculated and not when syringe infiltrated. In contrast, Fls2-silenced Nicotiana benthamiana plants were more susceptible to both virulent and nonpathogenic Pst strains when syringe infiltrated. However, it is not clear how many SERKs members Nicotiana species have. Only for tomato, all members of this family have been identified and unlike Arabidopsis, that has five members, tomato was found to have only three members. In both tomato and N. benthamiana, two members have particularly high levels of sequence similarity to AtSERK3/BAK1 suggesting recent duplication events in the lineage of these solanaceous species. Although a role for NbSERK3 has been identified in microbial pathogen defense, it is not clear which of the two NbSERK3 paralogs contribute to the resistance and whether the two members have redundant roles in defense. Similarly, Butenafine hydrochloride SlSERK3 is required for the resistance to the vascular fungal pathogen Verticillum mediated by the receptor like protein Ve1 and for defense responses induced by the fungal Ethylene-induced xylanase mediated by RLP LeEix. In these tomato and N. benthamiana studies, VIGS was used to evaluate the defense related roles of SERK3 and because of the high level of sequence identity.