Transcriptomic analysis unveils gene networks associated with the Fusarium head blight resistance transferred from Triticum turgidum ssp. carthlicum into durum wheat

Fusarium head blight (FHB) resistance in durum wheat gene pool is rarely reported. Tritichum turgidum ssp. carthlicum cv. Blackbird is a tetraploid species relative of durum wheat that offers partial FHB resistance. The objective of this study was to identify the defense mechanism underlying the resistance of Blackbird and report candidate regulatory resistance genes and single nucleotide polymorphism (SNP) markers within these genes for high-resolution mapping of resistance QTL reported for the durum cv. Strongfield × cv. Blackbird population. Gene network analysis identified seven gene networks associated with the resistance to FHB spread (Type II FHB resistance) with some showing moderate to high correlation with the plant height and relative maturity traits. Two gene networks showed subtle difference between inoculated and mock inoculated plants, supporting their involvement in basal defense. The candidate regulatory genes were involved in various layers of plant defense including pathogen recognition (mainly NBS-LRR proteins), signaling pathways including the abscisic acid and mitogen activated protein (MAP) kinase signaling, and downstream defense genes activation including transcription factors (mostly with dual role in defense and development), and cell death regulatory and cell wall reinforcement genes. The expression of five candidate genes measured by quantitative real-time PCR was correlated with that of RNA-seq, corroborating the technical and analytical accuracy of RNA-seq analysis. The results allowed identification of candidate hub genes within the interval of seven reported resistance QTL and SNP markers associated with them for future high resolution mapping studies.