Gb3 encodes a unique kinase fusion protein conferring greenbug resistance in wheat

Understanding plant resistance to insects has lagged owing to a scarcity of cloned resistance genes. Here we report cloning of the greenbug resistance gene Gb3 in wheat (Triticum aestivum L.), initially introgressed into cultivars such as 'TAM112' from Aegilops tauschii. Gb3 encodes an intracellular kinase-pseudokinase protein, featuring a unique MAP3K-like domain. This gene probably originated through fusion, duplication and indel events in the Triticeae tribe, retaining its functionality in several Aegilops species. Transgenic Gb3 expression in the susceptible Fielder wheat enhanced resistance to multiple biotypes, while the Gb3 knockout in TAM112 resulted in susceptibility. Comprehensive analyses indicate that greenbugs preferentially feed on susceptible plants, inducing a prolonged oxidative stress response. Conversely, resistant plants expressing Gb3 mediate greenbug resistance by producing oxylipins and other defensive compounds. Our findings lay the groundwork for investigating plant-insect interactions and provide a crucial genetic resource for developing sustainable aphid resistance in cereal crops.