Microphenomics for interactions of barley with fungal pathogens

Current high-throughput plant phenotyping pipelines are mainly focused on quantitative assessment of macroscopic parameters. Such morphological or physiological parameters measured on entire plants or major plant parts are not well adapted to the accurate description of plant-pathogen interactions because plant pathogens are microorganisms causing only microscale changes in their hosts or non-hosts during the initial stages on infection, which often decide about susceptibility or resistance. This makes the use of microscopic phenomics techniques unavoidable. However, the high-throughput requirements of modern phenomics screens represent a considerable challenge to the available microscopic approaches and underlying instruments used to characterize plant-pathogen interactions. To meet this challenge we have developed a platform that combines high-throughput DNA cloning, single cell transformation protocols, and automated microscopy and phenotyping that we called ""microphenomics"". It was used to address the function of genes in nonhost- and race-nonspecific host resistance of barley interacting with the powdery mildew fungus Blumeria graminis. More than 1,300 genes derived from plant or fungal genomes were tested by silencing and approximately 100 of them had a significant effect on the resistance or susceptibility to the pathogen. The chapter gives an overview on the current status of this microphenomics platform for very early and early stages of plant-pathogen interactions.