Heterologous expression of the barley-specific HvbZIP87 transcription factor in wheat enhances broad-spectrum disease resistance with balanced yield

NPR1, a protein that interacts with bZIP transcription factors known as TGAs, plays a pivotal role in coordinating systemic acquired resistance (SAR) in plants. Nevertheless, the molecular intricacies governing SAR in the Triticeae family, which includes crops like wheat and barley, are still largely enigmatic. We identified HvbZIP87, a barley-specific transcription factor, induced in SAR, more strongly in transgenic barley with HvNPR1 knocked down. The objective of this research is to explore the role of HvbZIP87 in SAR and the defense mechanisms of plants, focusing on transgenic wheat lines that have been engineered to overexpress HvbZIP87 (HvbZIP87-OE). Initially, the broad-spectrum disease resistance and SAR levels of HvbZIP87-OE lines were evaluated. Multiple techniques were employed to validate the direct protein interaction between HvbZIP87 and NPR1. RNA-seq and DAP-seq were performed to analyze the gene regulatory effects of HvbZIP87 in transgenic wheat lines. Transgenic wheat lines expressing HvbZIP87 exhibited significantly enhanced SAR levels and improved plant defense to stripe rust, leaf rust, spot blotch, and Fusarium crown rot. Despite some adverse effects on agronomic traits, the heterologous expression of HvbZIP87 in wheat resulted in a balanced yield due to larger harvested seeds. Intriguingly, HvbZIP87 physically interacted with TaNPR1 in the plant cell nucleus. Transcriptome sequencing and DAP-seq have revealed the regulatory networks and cis-elements governed by HvbZIP87 in the wheat genome. The genes TaPR1, TaPR2, TaPR4, and TaPR5, among several PR genes, were forecasted to undergo direct regulation by HvbZIP87. Additionally, we identified TaMYC2 transcription factor as another protein interactor of HvbZIP87. Silencing TaMYC2 further enhanced wheat's resistance to stripe rust, suggesting its negative regulatory role in plant defense. We have identified a unique protein that interacts with TaNPR1 in the SAR pathway of Triticeae species and have clarified its role in conferring resistance.