The research described in this týesis was focused on achieving a better understanding of the genetics of resistance of wheat to septoria tritici blotch (Mycosphaerella graminicola). Firstly, a detached leaf technique that could be a useful complement to field trials and an alternative to whole seedling assays in assessing cultivar resistance and investigating the genetics of the host-pathogen interaction was developed. Sets of inter-varietal substitution lines, developed at the John Innes Centre, involving known and possible sources of resistance to septoria tritici blotch, were tested with several single-pycnidium isolates in both the seedling and the adult plant stage. Two specific resistance genes were identified on chromosomes of `Synthetic 6x' and `Bezostaya 1'. A resistance gene, named Stb5, was identified using the M. graminicola isolate IP094269 and mapped on the short arm of chromosome 7D of `Synthetic 6x'. `Bezostaya I's specific resistance gene to IP0323 seems to be located in the same region as Stb6, and is indeed likely to be the same gene. `Bezostaya 1' and `Cappelle Desprez' also seemed to carry components for partial resistance. Triticum macha resistance to septoria tritici blotch on the other hand was both of a specific and isolatenon- specific nature. The specific components carried by T. macha seemed to be the Stb6 gene and an additional resistance gene, but it was not possible to identify their chromosomal location. To evaluate the relationship of heading date and plant height components to severity of septoria tritici blotch, an F6 single seed population of `Apollo' x `Thesee' was studied in natural conditions. Septoria tritici blotch levels were substantially lower in later-heading than in earlier-heading lines. Total plant height had comparatively little effect on disease severity, but increased distance between the two upper leaves increased disease levels. `Apollo' seems to carry partial resistance involving more than one QTL.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:390648 |
| Date | January 2001 |
| Creators | Arraiano, Lia Susana |
| Publisher | University of East Anglia |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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