Monitoring Host Nuclear Migration and Degradation with Green Fluorescent Protein during Compatible and Incompatible Interactions of Nicotiana tabacum with Colletotrichum Species

Recent evidence has emerged suggesting that nuclei sense and migrate towards infection sites in plants, and a novel approach to examine the dynamics of nuclei is described utilizing transgenic plants expressing a version of green fluorescent protein (GFP) that specifically labels plant nuclei. Nicotiana tabacum with GFPlabelled nuclei were inoculated with GFP-labelled strains of the hemibiotrophic fungi, Colletotrichum destructivum and C. graminicola. The nucleus in an epidermal host cell migrated to just underneath the appressorium of the compatible fungus, C. destructivum, but then migrated away from the developing fungus once it had penetrated and started to grow biotrophically. As the necrotrophic phase developed, the nuclei appeared to shrink and eventually their green fluorescence was no longer visible. The interaction of C. graminicola with N. tabacum was considered to show non-host incompatibility. The host nuclei in the epidermal cells also migrated underneath the appressoria. Once fungal penetration had failed, the nuclei then migrated back towards locations typically observed in epidermal cells of uninoculated plants. The use of both plant structures and a fungus that are labelled with a readily detectable fluorescent marker provides significant advantages as it permits direct observation of changes in living host and pathogen cells during a plant–fungal interaction