Terpene Synthase Gene OtLIS Confers Wheat Resistance to Sitobion avenae by Regulating Linalool Emission

Sitobion avenae (Fabricius) is a major insect pest of wheat worldwide that reduces crop yield and quality annually. Few germplasm resources with resistant genes to aphids have been identified and characterized. Here, octoploid Trititrigia, a species used in wheat distant hybridization breeding, was found to be repellent to S. avenae after 2 year field investigations and associated with physiological and behavioral assays. Linalool monoterpene was identified to accumulate dominantly in plants in response to S. avenae infestation. We cloned the resistance gene OtLIS by assembling the transcriptome of aphid-infested or healthy octoploid Trititrigia. Functional characterization analysis indicated that OtLIS encoded a terpene synthase and conferred resistance to S. avenae by linalool emission before and after aphid feeding. Our study suggests that the octoploid Trititrigia with the aphid-resistant gene OtLIS may have potential as a target resource for further breeding aphid-resistant wheat cultivars.