Genetic analysis of Fusarium root and crown rot (FCR) resistance in wheat (Triticum aestivum)

Abstract

Fusarium graminearum is a predominant pathogen causing Fusarium head blight (FHB) of wheat in most wheat growing regions including Europe. It is also causing a severer soil-borne disease Fusarium root and crown rot (FCR) of wheat. In Germany F. graminearum has become the dominant species in the last decade along with climate change under higher temperatures. FCR has been much less studied comparing to FHB. In the present study 28 FCR resistance QTL were identified. QTL qSbSI-3B and qSLR-4B.2 were overlapping with the well-recognized FHB resistance QTL Fhb1 and Fhb4, other QTL were found to be specific for FCR resistance. A FCR resistance QTL was found to be linked to the semi-dwarfing gene Rht1 which has been documented in the literature before to be linked to FCR and FHB resistance. FCR resistance mediated by this QTL was linked to short plants whereas FHB resistance mediated QTL reported in the literature was linked to tall plants. This suggests that pleiotropic effects of the Rht1 gene exist which might be linked to the mode of Fusarium infection for FCR and FHB disease. Furthermore, within the underlying overlapping FCR and FHB resistance QTL putative F. graminearum defense related genes were identified and that involved in cell wall strengthening, pathogen-associated molecular pattern (PAMP) detection, immobilization of zoospores of soil-borne pathogens and DON detoxification. The nature of these genes suggests that broad-spectrum resistance to different Fusarium-induced diseases is an important part of the resistance reaction in the studied cultivars. Effective wheat breeding for FCR and FHB resistance should target on QTL/genes and alleles involved in resistance against both diseases, but with effects aligned to the same direction without yield penalty.