Inheritance of loose smut (Ustilago tritici) resistance in two hexaploid wheat (Triticum aestivum) lines

The genetics of resistance in wheat (Triticum aestivum L.) to loose smut caused by Ustilago tritici (Pers.) Rostr, is not well understood. In this study the inheritance of loose smut resistance was studied in two androgenetically derived doubled haploid populations and two inbred random head-to-row populations. The loose smut resistant experimental wheat line HY377 was crossed with the loose smut susceptible line L8474-D1 and the resistant line SC8021V2. Androgenetically derived doubled haploid populations and F-4-derived random inbred line populations were produced from each of the crosses HY377/L8474-D1 and HY377/SC8021V2. Lines derived from each cross were grown in the growth room and inoculated with individual and a mixture of races of loose smut. The segregation of resistance between HY377 and L8474-D1 to races T2, T10, T19, and T39 in both doubled haploid and random inbred line populations fit the expected ratio for a single major gene. The same populations inoculated to race T15 showed a different disease incidence phenotype. These results indicated at least one major gene and one minor gene segregating for resistance to race T15. Transgressive segregation for resistance to race T19 occurred in the progeny of the cross of HY377 and SC8021V2, indicating that these parents differed in genes for resistance to the race. Both the doubled haploid and random inbred line populations from the HY377/SC8021V2 cross showed the same pattern of segregation. The interpretations of inheritance drawn from random inbred line populations and doubled haploid populations were the same.