Advanced host‒pathogen interactions in wheat and Zymoseptoria tritici: invasion strategies and plant defense mechanisms

Abstract

Bread wheat (Triticum aestivum) is a cornerstone of global food security, yet its productivity is severely threatened by numerous abiotic and biotic stresses, including Zymoseptoria tritici, the causal agent of Septoria tritici blotch (STB). STB is among the most destructive wheat diseases, causing yield losses up to 50% in Europe and 82% in Ethiopia. While fungicides are the primary control strategy, their cost, environmental impact and the emergence of resistant pathogen populations necessitate sustainable, genetics-based solutions. This review synthesizes current knowledge on wheat–Z. tritici interactions, including invasion mechanisms, host defense responses, and genetic resistance. We compiled 331 STB-resistance QTLs from over 20 studies (2003–2025) and identified the B genome as a major reservoir of resistance, harboring 140 QTLs. Chromosome 2B contained the highest QTL count (31), followed by 7 A and 7B, with 25 and 24 QTLs, respectively. Chromosome-wise QTL density per 100 Mb was also highest on 2B (3.34), 7 A (3.08), and 7B (2.70), highlighting regions as priority targets for fine mapping and marker-assisted breeding. Furthermore, several QTLs co-localize with established Stb genes, most notably Stb6, Stb4, Stb11, Stb18, Stb2, Stb8 and Stb9, highlighting genomic hotspots and potential for novel gene discovery. Regarding resistance type, 51% of compiled QTLs confer adult-plant resistance, 29.6% provide seedling resistance, and 19.3% are effective at both stages. Overall, this review provides a comprehensive overview of the host-pathogen interaction. It underscores the necessity of integrating genetic, genomic, and evolutionary insights to develop durable, resilient, and environmentally sustainable wheat varieties to safeguard global food sources.