Cytoplasmic calcium influx mediated by Lr14a regulates stomatal immunity against leaf rust in wheat

The race-specific resistance gene Lr14a in wheat confers a unique type of heterogenous resistance reaction. It encodes an ankyrin-repeat transmembrane domain protein that confers immunity against the fungal pathogen Puccinia triticina. Here, we show that Lr14a functions as a calcium-permeable channel, mediating cytoplasmic Ca²⁺ influx that is crucial for leaf rust resistance in wheat. Infection with avirulent isolates induced Lr14a expression predominantly in mesophyll cells while triggering cell death in guard cells in wheat. This study revealed a mechanism by which the product of an R gene regulates stomatal immunity non-cell autonomously through the mediation of calcium signaling.