Molecular dissection of Xinong 511 spike rachis response to Fusarium head blight infection.

Fusarium head blight (FHB, also known as wheat scab or ear blight), caused primarily by the Fusarium graminearum, is a worldwide disease of wheat (Triticum aestivum L.). Studying the pathogen expansion patterns and molecular mechanisms of disease resistance in resistant wheat varieties is crucial for advancing wheat disease management strategies. Here, we found a significant difference between two wheat cultivars with different resistances, and it was revealed that they exhibited divergent pathogen infestation process. The susceptible cultivar showed extensive pathogen in the spike rachis, while resistant varieties only had limited pathogen spread and colonization. Meanwhile, wheat resistance to FHB was positively correlated with transcriptional reprogramming in the early stages, with higher expression of genes responding to plant defense related genes and phenylpropanoid pathway genes in the early stages of disease resistant variety. Weighted gene co-expression network analysis (WGCNA) of differential expression genes (DEGs) analysis led to the construction of a network modules associated with resistance genes, and an important role of heavy metal-associated (HMA) domain protein in plant defense was identified in the tan module. RNA-induced gene silencing preliminarily identified two key genes that resistance to FHB in wheat: a cytochrome P450 (CYP) gene involved in the flavonoid biosynthesis within the phenylpropanoid pathway and HMA gene. This study provides an in-depth analysis of the infection mechanisms of wheat by F. graminearum and elucidates the key molecular mechanisms involved, while being useful for advancing the breeding of wheat varieties resistant to FHB.