Isolation and molecular analysis of the pepper Bs4C resistance gene that mediates recognition of the cognate Xanthomonas TAL effector protein AvrBs4

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Microbial diseases are a continuous threat to cultivated crops that provide the basis of our global food supply. Wild relatives of cultivated crops represent a rich resource of antimicrobial immune systems that however need to be characterized genetically before their potential can be exploited in breeding programs. Due to technical limitations, plant immune systems were studied in the past primarily in model plants with small genomes. Yet, next-generation sequencing (NGS) technologies facilitate now direct isolation of valuable traits from complex plant genomes and transcriptomes. In the framework of this proposal we want to isolate and characterize the pepper resistance (R) gene Bs4C that confers resistance to Xanthomonas campestris pv. vesicatoria (Xcv), the causal agent of bacterial spot disease on pepper and tomato. NGS-based transcriptome profiling was used to identify Bs4C candidate genes (2.2.1.5). We will apply reverse transcription (RT)-PCR, genetic mapping and functional analysis to clarify which of the identified candidate genes represents Bs4C (3.2.1.1 - 3.2.1.8). If we fail to identify Bs4C within the identified transcripts we will apply NGS-based genome re-sequencing, genetic mapping and functional analysis to identify Bs4C (3.2.1.12). Upon isolation we will characterize the Bs4C gene at the molecular level to clarify how it mediates recognition of Xcv and execution of an immune response (3.2.1.9 - 3.2.1.11). At the technical level we aim to establish a novel R gene cloning strategy that is applicable to complex crop genomes and that implements NGS technology.