Susceptibility Is New Resistance: Wheat Susceptibility Genes and Exploitation in Resistance Breeding

Adapted pathogens and pests seriously threaten global wheat production. During pathogen and pest infections, wheat susceptibility (S) genes are exploited to support the compatibility of wheat with pathogens and pests. A plethora of wheat S genes were recently identified and revealed to regulate multiple processes, including pathogen (pre)penetration, plant immunity, pathogen sustenance, and pest feeding. The inactivation of some S genes via newly developed genome editing and TILLING techniques could reduce compatibility and confer broad-spectrum and durable resistance, which provide a new avenue for wheat resistance improvement. In this review, we summarized recent advances in the characterization of wheat S genes and highlighted their multifaceted roles in facilitating compatible interactions of wheat with adapted pathogens and pests. Current strategies, limitations, and future directions in exploiting S genes in wheat resistance breeding are discussed.