Basal defense is enhanced in a wheat cultivar resistant to Fusarium head blight

Fusarium head blight (FHB), mainly caused by the fungal pathogen Fusarium graminearum, is one of the most destructive wheat diseases. Besides directly affecting the yield, the mycotoxin residing in the kernel greatly threatens the health of humans and livestock. Xinong 979 (XN979) is a widely cultivated wheat elite with high yield and FHB resistance. However, its resistance mechanism remains unclear. In this study, we studied the expression of genes involved in plant defense in XN979 by comparative transcriptomics. We found that the FHB resistance in XN979 consists of two lines of defense. The first line of defense, which is constitutive, is knitted via the enhanced basal expression of lignin and jasmonic acid (JA) biosynthesis genes. The second line of defense, which is induced upon F. graminearum infection, is contributed by the limited suppression of photosynthesis and the struggle of biotic stress-responding genes. Meanwhile, the effective defense in XN979 leads to an inhibition of fungal gene expression, especially in the early infection stage. The formation of the FHB resistance in XN979 may coincide with the breeding strategies, such as selecting high grain yield and lodging resistance traits. This study will facilitate our understanding of wheat - F. graminearum interaction and is insightful for breeding FHB-resistant wheat.