Breeding evaluation and precise mapping of Fhb8 for Fusarium head blight resistance in wheat (Triticum aestivum)

The percentage of Fusarium-damaged kernels (FDK) was proposed as a type of Fusarium head blight (FHB) resistance displayed in matured wheat kernels. In this study, Qfdk.nau-7D, a QTL identified in the Wangshuibai genome for its association with FDK, was introduced into FHB-susceptible common wheat line PH691 through marker-assisted selection and backcrossing. Evaluation of two resulted near-isogenic lines (NILs) showed that the contribution of Qfdk.nau-7D interval to lower FDK resulted from its effects on resistance to pathogen infection and to disease spread within the spike. Of a few major agronomic traits evaluated, head length was the only one that made difference between PH691 and the NILs. To reduce the QTL interval, a high-density marker map was constructed using a BC3F2 population of 97 plants. Through resistance evaluation of the homozygous recombinant lines in repeated field trials, Qfdk.nau-7D, designated as Fhb8, was placed in a 1.0-cM Xwgrb1500-Xwgrb1559 interval (from 93.9-96.5 Mb in CS) and showed co-segregation with Xwgrb1587. Moreover, it was found that the association of Fhb8 with head length was due to close linkage with spike length QTL HL2.