Investigating the role of suppressed hydrolases during Pseudomonas syringae infection

Plants are constantly subject to invasion by pathogens including bacteria, fungi and oomycetes, which put both industrial and smaller-scale farmers at risk of considerable yield loss. Critical to the plant's ability to prevent disease is the outcome of plant-pathogen interaction in the apoplast, the extracellular space in leaves. Pathogenic bacteria release effectors into this space to manipulate the plant; plants respond through the production of hydrolytic enzymes including serine hydrolases, papain-like cysteine proteases (PLCPs) and glycosyl hydrolases.
Previous work in the van der Hoorn group has identified 22 plant hydrolases that are suppressed in the apoplast of the Solanaceous tobacco relative Nicotiana benthamiana upon infection with the bacteria Pseudomonas syringae. We aim to determine if this suppression is an evolutionary response to a role in immunity for the candidates. Quantification of bacterial growth following silencing or overexpression of candidates will be used to determine their importance in the immune response. We will then nominate strong candidates for further study, including determining the substrate and pathogen-derived interaction partners of the hydrolase. Thus, the aim of the DPhil is to identify novel hydrolases critical for the plant immune response, thereby increasing understanding of plant immunity and contributing to the development of sustainable practices to reduce yield losses caused by plant pathogens.