Candidate genes present on 7EL chromosome of Thinopyrum elongatum and responsible for FHB resistance

Thinopyrum elongatum, a close wild relative of wheat, carries genetic resistance to fusarium head blight (FHB) on the long arm of its chromosome 7E (7EL). By cross referencing genomic sequence databases for wheat chromosome 7 and Th. elongatum 7EL, a series of 7EL- and 7DL- specific markers have previously been designed. Using the current wheat 7D pseudomolecule information, a genetic order for the 7EL markers is proposed. In parallel to the primer design, a Chinese Spring (CS) ph1b line was crossed with a CS-7E(7D) substitution line to facilitate introgression of 7E fragments from Thinopyrum into the 7D chromosome of wheat. Progeny from BC1F5 and BC1F7 families have been genotyped and phenotyped to determine the 7EL region of introgression and the FHB response of the plant material. Genotyping was performed through PCR assays using the 7EL- and 7DL- specific markers. Phenotyping was performed by inoculating wheat heads with F. graminearum and measuring disease progression at 7 and 14 days post inoculation (dpi). In the progeny, FHB resistance is carried by the 7EL chromosome, in a small region of approximately 41-42 million base pairs, based on synteny with 7DL. Further work is being done to identify and test potential candidate genes present in this introgressed region.