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Fusarium head blight (FHB), also called head scab, is one of the most challenging wheat diseases globally, severely affecting wheat production in warm and humid regions in East Asia, Europe, North America, Latin America, and African countries. The disease not only reduces wheat grain yield but causes mycotoxins contamination in the grain that are harmful to human and animal consumers.

Breeding for wheat germplasm resistant to FHB and its associated mycotoxin deoxynivalenol (DON) is an important component of wheat improvement at CIMMYT. Since the 1980s, CIMMYT has integrated a broad spectrum of resistant sources into its breeding program, especially introductions from China and Brazil, as well as wild relatives of wheat. Newly developed advanced breeding lines are routinely screened for FHB resistance and the results are used as an important criterion for selection.

Promising lines identified from breeding materials, germplasm bank collections, and introductions, are included in special nurseries called FHB Screening Nursery (FHBSN). These selected lines must undergo at least three years of field and greenhouse evaluation before they are distributed globally for potential use by national breeders. CIMMYT lines generally do not have very high FHB resistance, with the best ones exhibiting moderate/good resistance.

Genetic studies and haplotyping work indicated very low frequencies of Fhb1 and other major QTL, except for one on 2DL chromosome that has shown frequencies of 10-20% in recent breeding nurseries. Efforts on further increasing the frequency of Fhb1 and its combination with the 2DL QTL are ongoing, and some of such lines exhibited good resistance in field experiments.

Introduction of additional sources of resistance including the Fhb7 resistance gene is in progress, and their utilization in breeding is expected to further improve the FHB resistance of CIMMYT germplasm, which may in turn contribute to FHB resistance in African countries, where CIMMYT germplasm has been extensively utilized.

Thematic area: Enhancing wheat resistance against biotic stresses.