Ophiostoma novo-ulmi, the causative agent of Dutch elm disease (DED), is able to colonize remote areas in infected plants of Ulmus such as the leaf midrib and secondary veins. Ďurkovič et al. compare leaf growth traits, primary xylem density components, gas exchange variables and chlorophyll a fluorescence yields between two Dutch elm hybrids that possess a contrasting tolerance to DED, and also employ atomic force microscopy mapping of nanomechanical properties of the cell walls of tracheary elements. They find that multivariate analysis clearly separates the two hybrids, and in the more disease-tolerant hybrid leaf growth, vascular, nanomechanical and gas exchange traits are not affected by the DED fungus, thus indicating it may provide valuable germplasm for future breeding.
