The identification of physiological traits in wheat confering passive resistance to Fusarium head blight

• Main Author: Jones, Stephen P. T.
• Published: University of Nottingham 2015
• Subjects: 633.1; SB Plant culture
• Online Access: http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664700

Fusarium head blight (FHB) is a devastating fungal disease of wheat and other small grain cereals worldwide caused by a complex of toxigenic Fusarium spp. and non-toxigenic Microdochium spp. Infection leads to a reduction of grain yield, loss of grain quality and the production of harmful mycotoxins. Control methods for FHB include both cultural and chemical strategies, however the development of cultivars with improved FHB resistance is considered as the most sustainable method for controlling the impact of this disease. Resistance to FHB is a polygenic trait and can be improved by stacking multiple resistance genes together, however there are currently no highly FHB resistant genotypes with acceptable agronomic characteristics available, therefore passive disease resistance can potentially make significant contributions to improved FHB resistance. The aim of this study was to identify novel physiological traits in wheat conferring passive resistance to FHB using ground inoculated field experiments to enable disease escape mechanisms to be expressed, and spray inoculated glasshouse experiments to test if the identified traits were associated with genetic resistance. The most consistent traits relating to FHB were flag leaf length, plant height and awn length. Since these relationships were present in both field and glasshouse experiments, they are likely caused by a genetic linkage or pleiotropy, with genes conferring FHB resistance or susceptibility. Remaining leaf area was less consistently related to FHB, however, since canopy leaf area showed a positive relationship with the development of FHB in ground inoculated field experiments, there is a basis to support the role of reduced canopy leaf area as conferring passive resistance to FHB. In general, relationships were poor between visual FHB symptoms and both pathogen DNA and grain mycotoxin contamination. This was theorised to be due to the use of a mixed species inoculation which introduced antagonism between FHB species and which included more than one producer of several mycotoxins quantified. Therefore the use of visual FHB assessments under mixed species inoculation is concluded to be a poor indicator of both pathogen infection and mycotoxin contamination.