Identification and transferring of a new Fusarium head blight resistance gene FhbRc2 from Roegneria ciliaris 3S^cL chromosome arm into common wheat

Fusarium head blight (FHB) threatens wheat production worldwide. Utilization of FHB resistant varieties is the most effective solution for disease control. Owing to the limited sources of FHB resistance, mining of novel resistance genes is crucial. Here, we report an FHB resistance gene from a wild wheat relative species, Roegneria ciliaris and developed FHB resistant germplasm containing this gene. Wheat-R. ciliaris disomic addition line DA3S^c showed enhanced type Ⅱ FHB resistance compared to its sister line 3S^c-Null without chromosome 3S^c, indicating that the resistance was contributed by the addition of 3S^c. The resistance gene on 3S^c was validated using F₂ and F_2:3 populations derived from the cross between DA3S^c and susceptible Aikang 58 (a susceptible cultivar), demonstrating that the lines with 3S^c had significantly enhanced FHB resistance compared to the individuals without 3S^c. This was the second resistance gene identified in R. ciliaris, designated FhbRc2. To transfer FhbRc2 to common wheat, we produced a double-monosomic chromosome population by crossing DA3S^c with the Chinese Spring nulli-tetrasomic line N3DT3B. Eight alien chromosome lines containing 3S^c were identified using genomic/fluorescence in situ hybridization and 3S^c-specific marker analysis. Only the lines carrying the long arm of 3S^c conferred FHB resistance, further locating FhbRc2 on 3S^cL. A compensating wheat-R. ciliaris Robertsonian translocation line T3DS·3S^cL harboring FhbRc2 is developed and provides a potential genetic resource in wheat breeding for enhanced FHB resistance.