Date: 14th March 2018
Title: MLO-based powdery mildew resistance: An apparently universal “weapon” to combat powdery mildew disease
Location: Biocentre 2, seminar room 1015, Viikinkaari 5
Host: Kirk Overmyer
Abstract: Loss-of-function mutant alleles of the barley Mlo locus are known to confer durable, broad-spectrum resistance against the powdery mildew disease caused by the ascomycete barley (Hordeum vulgare) pathogen Blumeria graminis f.sp. hordei. This type of antifungal immunity was discovered more than 70 years ago and has been widely used in European agriculture for more than 30 years. We previously showed that powdery mildew resistance conferred by mlo alleles is not restricted to barley, but also occurs in Arabidopsis, tomato and pea. The molecular basis of this unusual type of disease resistance remains, however, mysterious. We exploit the genetic and molecular tools available for the dicot reference species, Arabidopsis thaliana, and the monocot barley to get insights into the molecular mechanisms leading to mlo resistance. We further attempt to unravel the basic biochemical activity of Mlo proteins to understand their role in plant-powdery mildew interactions. In this context, we recently discovered that a myosin motor protein is required for mlo resistance in barley and that the Arabidopsis MLO2 protein seems to modulate prototypical plant responses upon exposure to microbe-associated molecular patterns (MAMPs). We also aim to transfer mlo-based resistance to species that are difficult to manipulate genetically, such as hexaploid bread wheat, by avoiding transgenic approaches.
Ralph Panstruga is a professor at RWTH Aachen University. There he is affiliated with the Institute for Biology I (Botany) and heads the research unit of Plant Molecular Cell Biology. His main research interest is to study the interaction between plants and pathogenic powdery mildew fungi at the cellular and molecular level. A particular focus in this context is to unravel the molecular basis of broad-spectrum powdery mildew resistance conferred by loss-of-function alleles of host Mlo genes (see Abstract). However, he is not only interested in the plant side of the interaction, but also in mechanisms of fungal pathogenicity and evolution. Thus, genomics approaches to analyse the architecture and co-evolutionary patterns of powdery mildew genomes are a second major research area of his lab. Particular emphasis in this context is given to genes encoding so-called effector proteins – small, secreted polypeptides supposed to be delivered to host cells for manipulation of immune responses and redirection of nutrients towards the fungal pathogen.