A cell wall invertase modulates resistance to fusarium crown rot and sharp eyespot in common wheat

ABSTRACT Fusarium crown rot (FCR) and sharp eyespot (SE) are serious soil‐borne diseases in wheat and its relatives that have been reported to cause wheat yield losses in many areas. In this study, the expression of a cell wall invertase gene, TaCWI‐B1, was identified to be associated with FCR resistance through a combination of bulk segregant RNA sequencing and genome resequencing in a recombinant inbred line population. Two bi‐parental populations were developed to further verify TaCWI‐B1 association with FCR resistance. Overexpression lines and ethyl methanesulfonate (EMS) mutants revealed TaCWI‐B1 positively regulating FCR resistance. Determination of cell wall thickness and components showed that the TaCWI‐B1‐overexpression lines exhibited considerably increased thickness and pectin and cellulose contents. Furthermore, we found that TaCWI‐B1 directly interacted with an alpha‐galactosidase (TaGAL). EMS mutants showed that TaGAL negatively modulated FCR resistance. The expression of TaGAL is negatively correlated with TaCWI‐B1 levels, thus may reduce mannan degradation in the cell wall, consequently leading to thickening of the cell wall. Additionally, TaCWI‐B1‐overexpression lines and TaGAL mutants showed higher resistance to SE; however, TaCWI‐B1 mutants were more susceptible to SE than controls. This study provides insights into a FCR and SE resistance gene to combat soil‐borne diseases in common wheat. The cell wall invertase gene TaCWI was cloned and associated with resistance against wheat Fusarium crown rot and sharp eyespot. Thickening of the cell wall by TaCWI may counteract the effects of the alpha‐galactosidase TaGAL, which is associated with susceptibility to the two diseases.