Gurmukh Johal, Purdue University, A profound link between maize metabolism and immunity: how did we miss it?

A thorough understanding of how pathogens cause disease and how plants defend themselves is crucial for global food security. With this in mind, we have been studying the interaction of maize with the fungal pathogen Cochliobolus carbonum race 1 (CCR1) as a model pathosystem to explore the dynamics of host immunity and underlying components. CCR1 has the ability to decimate corn but is rendered harmless by the Hm1 disease resistance gene. The wild-type form of Hm1 confers absolute protection against CCR1 in every part of the host and at every stage of development. However, weak mutant forms of Hm1 exist whose ability to confer resistance improves with plant age. Analysis of this age-associated or adult plant resistance has revealed an unexpected but profound link between maize immunity and metabolism. Not surprisingly, any stress, treatment or condition that compromises corn’s ability to photosynthesize makes it more susceptible to diverse pathogens. Our goal is to understand how this happens and how the knowledge gained could be translated to breed disease resistant corn while also boosting its yield potential.