The illusion of progress: why most introgressions from wild Triticeae fail to improve wheat agronomically

The progressive narrowing of the genetic base of bread wheat ( Triticum aestivum L.) threatens yield gains and stress resilience under climate change. Wild Triticeae species are widely viewed as a vital source of adaptive diversity, yet despite decades of research and the discovery of numerous genes and introgression lines, only a tiny fraction has delivered validated agronomic benefits. Because introgression from the secondary gene pool ( Aegilops spp.) follows distinct genetic rules, this review deliberately focuses on more distant genera within the tertiary gene pool. This review critically dissects that disconnect, revealing a systematic “illusion of progress.” We demonstrate how methodological biases—particularly reliance on surrogate traits under controlled conditions and insufficient multi-environment validation—interact with genetic constraints such as linkage drag, polygenic architecture, and segment instability to inflate early-stage promise while suppressing field-level reproducibility. By contrasting successful and unsuccessful introgressions, we identify the conditions essential for translational impact: major-effect loci, minimal linkage drag, stable expression across environments, and rigorous field testing. To bridge the lab-to-field gap, we advocate for agronomically relevant phenotyping, precision introgression including genome editing, integration with genomic selection, and a fundamental shift from reporting gene-level discoveries to demonstrating measurable yield performance. This work provides a conceptual framework for evaluating introgression outcomes and offers actionable strategies to improve the efficiency of exotic gene transfer in wheat breeding, thereby addressing a central challenge in plant breeding and food security.