Avoiding trade-off when enhancing Fusarium head blight resistance of barley

Fusarium head blight (FHB) is an economically important disease of barley caused by mycotoxin-producing Fusarium species. Resistance to FHB is associated with several agronomic traits, particularly height. Taller cultivars are generally more resistant; however increased height is less favourable due to the prospect of lodging, creating a trade-off between disease resistance and agronomic qualities. Disease assays with pathogens of differing trophic lifestyles were conducted using barley BRI1 mutation lines, which display brassinosteroid (BR) insensitivity and a semi-dwarf phenotype. Interestingly, bri1 semi-dwarf lines did not display increased susceptibility to FHB. Additionally, bri1 mutation provided advantageous resistance to necrotrophs but did not increase susceptibility to biotrophs, demonstrating an absence of a resistance trade-off. The barley cultivars Chevallier and Armelle display significant FHB resistance, yet also possess a tall height phenotype. To determine whether the resistance of these cultivars was associated with height, bi-parental populations were created by crossing to the short, modern variety NFC Tipple. High density genetic maps of the populations were produced using Genotyping-by-Sequencing and 384-SNP BeadXpress assays to enable quantitative trait loci (QTL) mapping of both FHB and agronomic traits. Within the C×T population, a QTL for FHB resistance was identified on chromosome 6H which was not associated with either height or heading date, suggesting that resistance in this region is not due to linkage or pleiotropy with these traits. In contrast, FHB resistance within the A×T population was coincident with both height and heading date QTL on 3H. QTL analysis of malting traits of Chevallier, an English malting landrace, was also undertaken. Chevallier compared favourably to NFC Tipple, a modern malting cultivar, for several malting characteristics including free amino nitrogen, diastatic power and wort β-glucan content. This demonstrates that Chevallier may be a useful potential source of both FHB disease resistance and quality traits.

Name dc:type.qualificationname

phd

Level dc:type.qualificationlevel

doctoral

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2015

Author dc:creator

• Goddard, Rachel

Language dc:language

en