Description

[Synopsis]

Fusarium head blight (FHB, scab) caused by Fusarium graminearum is one of the most destructive diseases of wheat in areas where the weather is warm and humid after the heading of wheat. It reduces grain yield and quality due to grain shriveling. FHB also produces mycotoxins harmful to animals and human health, such as deoxynivalenol (DON), nivalenol (NIV), T-2 toxin, zearalenone (ZEA) and their derivatives. For controlling this disease, host resistance should be considered. Repeated screening of the genetic resources led to the identification of several resistant cultivars of spring wheat, such as Shinchunaga, Nobeokabouzu-komugi and Nyubai from the Japanese gene pool. Sumai 3, Ning 7840 and CItr 11028 were also identified as resistant cultivars to FHB from the Chinese gene pool. The genetic constitutions of sources of resistance to FHB originating from different gene pools, however, have not yet been elucidated. It is essential to study the genetics of the resistance to FHB, including the identification of the genes responsible for resistance to FHB in several gene pools, so that different genes can be combined to improve the overall resistance of wheat. The objectives of the present study were to examine the difference in genetic constitution of resistance to FHB between Nobeokabouzu-komugi and Sumai 3 using doubled haploid lines (DHLs) derived from F1 cross.
From the cross combination of both highly resistant cultivars, transgressive segregants with the reaction of moderately resistant to FHB were found. Both parents seem to have at least one common gene for the resistance, because no DHL with the susceptible class was segregated. Chi-square test indicated that the segregation for the reaction to FHB fitted a three-gene model (7 R : 1 MR) in the population (Table 1 and Fig. 1). It is suggested that Nobeokabouzu-komugi have three dominant genes for the resistance, of which two are unique and the another gene is identical to that of Sumai 3. This finding presents an important promise for pyramiding resistance genes from different genetic background. Furthermore, many lines with very high level of resistance combining genes from the both parents have been selected for possible use as parental lines.