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.