FUSARIUM HEAD BLIGHT RESISTANCE IN WHEAT – ITS GENETIC MAKEUP AND IMPLICATIONS FOR RESISTANCE BREEDING Abstract uri icon

abstract

  • Fusarium fungi are among the most feared pathogens of small grain cereals, particularly wheat. Resistance to Fusarium is therefore a top priority for resistance breeding, and receives high attention in research. The search string: ‘Fusarium AND resistance AND wheat’ in the ISI Web of Knowledge finds in period 2008 -2018 more peer reviewed publications than any other wheat disease .Fusarium fungi are opportunistic pathogens, which preferentially penetrate and colonize cereal florets during flowering. Environmental conditions which either favor or hamper the fungus and the status of the plant during flowering have therefore a huge impact on disease establishment and development. Novel developments and discoveries in this research field during the past decade will be presented: 1) the very pronounced functions of morphological plant characters in head blight resistance; 2) improving FHB resistance in durum wheat using native and exotic resistance sources; 3) from marker assisted selection (MAS) to Genomic Selection (GS). Typical passive resistance factors are plant height and the extent of anther extrusion during flowering. Based on comparative mapping studies we conclude that 1) anther extrusion is a clearly quantitative trait, 2) a high degree of anther extrusion is strongly associated with reduced FHB susceptibility and 3) plant height genes, Rht-B1b and even more pronounced Rht-D1b are associated with increased FHB susceptibility and reduced anther extrusion, which could partly explain their effect on lowering FHB resistance. The famous FHB resistance allele Fhb1, which was discovered in Chinese germplasm, residing on chromosome 3B, most likely has a physiological function. In our results we always find Fhb1 associated with increased resistance to Fusarium spreading, and simultaneously resistance to the toxin deoxynivalenol (DON). We could recently show that Fhb1 improves field resistance to FHB also in durum wheat. Further tests on the functional characterization of Fhb1 in relation to DON detoxification are currently underway. Apart from few large effect QTL for FHB resistance, which are targeted in marker assisted selection (MAS), a great proportion of resistance is due to an unknown number of small effect genes. Breeders can make use of these small effect genes as well, using classical phenotypic selection, and since recently, using genomic selection (GS). Resistance selection utilizes often a skillful combination of phenotypic testing in provocation nurseries and of genome wide selection using genomic prediction and or marker assisted selection approaches.

publication date

  • July 2019