Engineering plant leucine rich repeat-receptors for enhanced pattern-triggered immunity (PTI) and effector-triggered immunity (ETI)

This chapter presents the cutting-edge knowledge on the immune mechanisms of plants in responding to microbial pathogens: bacteria, fungi, oomycetes and viruses. In the wide range of mechanisms of plant immunity, several approaches to enhance or alter the resistance conferred by PTI and ETI have been tested in various laboratories, such as transfer of Quantitative disease resistance genes, to gene pyramiding for avoidance of pathogen adaptation and evolution. The chapter describes the interfamily transfer of R genes, and the effectiveness of resistance gene chimeras to enhance the immune response in plants lacking an effective response to pathogen elicitors and effectors; the engineering of chimeras between various Receptor kinases, introduction of Transcription Activator Like (TAL) effector binding sites (EBE) in the promoters of executor R genes, and the modification of protease targeted sequences in R genes acting as bait for effector proteases, to activate guard R genes in the presence of other pathogens. Furthermore, it introduces the engineering of plant promoters to induce a timely activation of resistance genes only in the presence of the pathogens, for tissue specific and time window selective response. In the future, these technologies will be applicable to control the expression of resistance genes, either receptor kinases and NLR proteins, and to respond to pathogen virulence products with plant immunity or tolerance.