Plant–Aphid Interactions in Cereal Crops: Wheat Plant Defense and Aphid Saliva-Mediated Coevolutionary Arms Race

Wheat aphids are among the most destructive pests of wheat, posing a serious threat to wheat production and global food security. The development of aphid-resistant wheat varieties is widely regarded as one of the most economical and sustainable strategies for aphid management. A comprehensive understanding of the plant defense mechanisms is fundamental to the breeding of resistant wheat germplasm. Recent studies have revealed that aphid salivary proteins play critical roles in manipulating host defenses, whereas wheat has evolved multiple layers of defense to perceive and respond to aphid attack. In this review, we summarize current advances in wheat–aphid interactions, focusing on the roles of aphid salivary effectors, aphid-induced immune signaling, physical and chemical defense barriers, herbivore-induced plant volatiles (HIPVs), resistance genes, and non-host resistance mechanisms. By integrating aphid effector biology with host immunity and resistance mechanisms, this review provides a conceptual framework for understanding wheat–aphid interactions and for developing durable and environmentally sustainable resistance strategies.