Technique to assess gene function in hop (humulus lupulus l.)-Powdery mildew interactions

Improving resistance to powdery mildew (Podosphaera macularis ssp. humuli, Pm) is a major objective in hop breeding. To achieve this, classical breeding can be assisted by marker-assisted breeding or by transgenic approaches. For both these techniques, it would be of advantage to have DNA sequences available with confirmed function in the hop-powdery mildew interaction. Here, we report on the adaptation of a transient transformation assay for the functional assessment of defence-or susceptibility-related genes in hop as already available for barley and wheat. As a proof of concept, we performed transient-induced gene silencing (TIGS) of a putative hop powdery mildew susceptibility factor in hair cells, which resulted in a significantly reduced penetration success of the powdery mildew fungus.