MULTIFACETED APPROACHES TO CONTROL FUSARIUM HEAD BLIGHT IN WHEAT: GENETIC MAPPING, MECHANISTIC STUDIES, AND FUNGICIDE EFFICACY ANALYSES

Abstract

Fusarium Head Blight (FHB), caused by the fungal pathogen Fusarium graminearum, is the second most important disease of wheat globally. This doctoral research contributes toward improving the two most widely used FHB management strategies: development of resistant cultivars and the use of fungicides. Given the quantitative nature of FHB resistance, pyramiding of multiple quantitative trait loci (QTLs) is required to develop resistant cultivars. Marker-assisted selection using diagnostic Kompetitive Allele-Specific PCR (KASP) assays is a cost and time-efficient approach. Toward this end, a previously identified resistance QTL from a moderately resistant soft red winter wheat cultivar Jamestown located on chromosome 1B was genetically mapped and diagnostic KASP assay was developed for it. Furthermore, a robust gene specific KASP marker was developed and validated for Fhb1, the most widely used QTL for resistance against FHB. Previously, a Pore-forming toxin-Like (PFT) gene was identified as the major underlying gene for Fhb1-mediated resistance in wheat. In the present research, functional characterization of PFT was done toward improving the understanding of the molecular mechanisms of FHB resistance. Ectopic expression of PFT in Arabidopsis conferred a broad-spectrum resistance against multiple fungal pathogens. PFT protein was purified from heterologous expression in Nicotiana benthamiana and used for various bioassays to elucidate the biological function of its individual domains. The experimental evidence supported our working hypothesis of PFT’s atypical mechanism of resistance. Working on the chemical control options for FHB, the efficacy and appropriate timing of application was investigated of a newly recommended fungicide for FHB-‘Miravis Ace.’ Overall, the knowledge and resources developed in this research would contribute towards improved integrated disease management of FHB in wheat.