Genotype Dependent Systemic Resistance in Maize Caused by Foliar Infection and by Foliar Damage

Systemic resistance (SR) occurs when systemic signals derived from sites of previous pathogen attacks result in increased resistance levels to subsequent pathogenesis at distal sites. Although much research on this phenomenon has been conducted in dicotyledonous species, little is known about SR in monocotyledonous models. In this study we investigate SR in maize caused by foliar infection with Cochliobolus heterostrophus- the causal agent of southern leaf blight (SLB) disease - and by leaf damage. In juvenile maize, we observed that both prior infection with C. heterostrophus and cutting of the third and fourth leaves led to enhanced resistance to SLB in the fifth leaf. Levels of SR induction were variable between genotypes and between growth conditions. C. heterostrophus infection induced local and systemic expression of the defense-associated transcript ZmPR1. We discuss the implications of these findings that provide insights into the systemic disease resistance response in maize.