Yellow rust resistance in the winter wheat cultivar Claire is considered durable, as Claire has been grown extensively within the UK for over 10 years and the resistance has remained effective. To characterise this potentially durable source of resistance a doubled haploid (DH) population was produced between Claire and the yellow rust susceptible cultivar Lemhi. Construction of a genetic linkage map, together with phenotypic data allowed the estimation of the number, chromosomal position and degree of effect of yellow rust resistant QTL(s). Claire was found to exhibit a quantitative, adult plant resistance phenotype (APR) controlled by two major QTLs, both located on chromosome 2DL (QTLAPR.2Da and QTLAPR.2Db) and two minor QTLs, located on 2BL (QTLAPR.2B) and 7BL (QTLAPR.7B). These QTLs act additively to achieve a resistance response that has remained effective since Claire’s release in 1999. Marker loci associated with the two major QTLs and knowledge of Claire’s pedigree suggests QTLAPR.2Da could be a APR QTL, known to confer complete immunity to yellow rust, originating from the winter wheat cultivar Alcedo and that QTLAPR.2Db is the durable yellow rust resistance gene Yr16 derived from Cappelle-Desprez. However, DH lines containing QTLAPR.2Da exhibited either a complete or partial yellow rust resistance indicating a potential suppressor effect against the resistant phenotype conferred by this major QTL could be segregating within the population. Analysis of transcript levels of defence genes was used to examine the effect of the hypothesized suppressor on the expression of basal defence in DH lines containing QTLAPR.2Da. No correlation between the presence of the hypothesized suppressor and expression of basal defence genes was observed. The identification of four APR QTLs in Claire and a potential suppressor in Lemhi that affects QTLAPR.2Da will serve as a precursor to help elucidate the defence mechanisms of the yellow rust resistance in Claire.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:569326 |
| Date | January 2010 |
| Creators | Powell, Nicola Michelle |
| Publisher | University of East Anglia |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | https://ueaeprints.uea.ac.uk/10601/ |
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