"For fungal plant pathogens, the germinated spore provides the first interaction with the host. Spore germlings move across the plant surface and differ in penetration strategies for ingress into plant surfaces, including pressurized melanized appressoria, which physically punch through the plant cuticle, and non-melanized appressoria, which penetrate with the help of enzymes to breach the cuticle. We applied comparative transcriptomics to two well-studied plant pathogens, Fusarium graminearum and Magnaporthe oryzae, representing these two modes of penetration, to better characterize the genetic programing of the early host-pathogen interface. Four sequential stages of development following spore localization on the plant surface, from spore swelling to appressorium formation, were collected for each species on medium and on barley, and transcriptomic analyses were performed. In both species, gene expression in the first three stages under both conditions was largely similar, whereas the final stage was strongly influenced by the environment. Appressorium formation was characterized by the greatest number of differentially expressed genes, many of unknown function. Laser dissection microscopy was used to perform transcriptomics of initial infection points by F. graminearum. Analysis revealed new and important aspects of early fungal ingress in this species. Expression of the trichothecene genes involved in biosynthesis of deoxynivalenol by F. graminearum showed that toxisomes are not fully functional until after penetration. Expression of autophagy genes, distinct between species, gave evidence for differential use of autophagy in the infection process. The use of comparative gene expression of divergent fungi to study evolution of infection court establishment may lead to potentially highly effective targets for antifungal strategies.</p><p>"