Evidence of isolate-specific resistance in wheat and barley challenged with four Fusarium pathogens causing head blight


Nachaat Sakr, Baraa Warda, Mohammad Taha Qasm, Jamal Fandi, Hadi Alkhatib


Volume 29, Issue 3;
Pages: 213-221; 2023
ISSN: 2069-0053 (print), Agroprint;
ISSN (online): 2068-9551


Quantitative resistance (QR) interacting with the aggressiveness of pathogens is found to be isolate-nonspecific and durable. However, minor isolate-specific reactions have been observed in various pathosystems rendering QR efficiency to be lost as pathogen isolates adapt to it. To test this hypothesis in Fusarium head blight (FHB) associated with devastating agronomic effects on cereals, we elucidated pathogenic interactions between eight cultivars with contrasting in QR resistance of durum wheat, bread wheat and barley and 16 fungal isolates with diverse aggressiveness to explore whether specific reactions exist between pathogen isolates and host that might be included in QR eroding. The reaction of cultivars to FHB species revealed as difference in the level of head blight damage caused by diverse isolates was evaluated by measuring nine aggressiveness components at the earliest and latest plant stages. Combined analysis of bio-experiments demonstrated that isolate × cultivar interactions were significant. QR stability in cultivars to FHB infection was fulfilled over several experimental conditions; however, FHB isolates showed a different ranking to all cultivars for the majority of the correlations testing the stability of aggressiveness. Our data suggest that QR of wheat and barley to Fusarium is possibly explained by minor isolate-specific (quantitative trait loci) QTLs and QTLs that confer resistance to a large number of fungal isolates as well. These findings confirm the minor-gene for minor-gene system which suggests specific reactions between Fusarium isolates and QTLs for resistance. To our best knowledge, this report has highlighted for the first time that among of the major risk components for the erosion of QR observed in Triticum and Hordeum to head blight is the specificity of the resistance.

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