Positional Cloning of Fhb1 Gene in Wheat

Fusarium Head Blight (FHB) also known as scab caused by ascomycetous fungus Fusarium graminearum [teleomorph Gibberella zeae (Schweinitz) Petch] is a destructive disease of wheat, barley, and other small grain crops. It leads to billions of dollars in crop losses worldwide. A quantitative trait locus (QTL) Fhb1 located on chromosome 3B short arm of a few Chinese landraces is the most consistently reported and widely deployed source of resistance to scab. We report the positional cloning of Fhb1 from Sumai 3, a Chinese cultivar resistant to scab. The QTL was previously mendelized in a Near Isogenic Line (NIL) set. A Sumai 3 BAC library with ~3x genome coverage was constructed, and markers derived from wheat reference landrace Chinese Spring spanning the QTL were used to screen the library. Four BACs forming the minimum tiling path were sequenced, and genes were annotated. Putative candidate genes were shortlisted and reverse genetics tools of Targeting Induced Local Lesions in Genome (TILLING) and RNAi-induced gene silencing were used to validate the gene. The results from the research will be presented.