Genetics of partial resistance of wheat to septoria tritici blotch

Septoria tritici blotch (STB), caused by the fungus Mycosphaerella graminicola, is the major foliar disease of wheat in many countries. Most resistance in wheat cultivars is partial resistance, which is polygenic, or oligogenic and non-specific to particular pathogen genotypes, and hence is durable. Selection for partial resistance to STB may be restricted if that trait has a significant cost, for example reduced yield, which is the most important target for many wheat breeders. The first aim of the research reported here was to investigate if partial resistance to STB in wheat reduces yield, and if so, which yield components are affected. The second aim was to identify quantitative trait loci which account for this correlation. The data were obtained from a F1-doubled-haploid population of Senat x Savannah (Eriksen et al. 2003, TAG 107:515-527). Quantitative trait loci (QTL) controlling STB were located on four chromosomes. Here, genes increasing STB scores were closely linked in coupling to genes increasing yield components, including thousand grain weight and grains m-2, and to genes that increase the qualitative trait grain protein content. Hence, there is a yield penalty of resistance to STB but it should be possible for breeders to select high-yielding resistant varieties by selecting genes which improve resistance but do not depress yield. The last part of this work refers to the location of a susceptible gene in the double haploid population Hobbit sib x Hobbit sib (Bezostaya 1 5BS-7BS). A QTL controlling susceptibility to STB was detected on a segment of chromosome 5B in this population. This QTL for susceptibility was closely linked with a QTL for heading date.

Name dc:type.qualificationname

mphil

Level dc:type.qualificationlevel

masters

Grantor dc:publisher.institution

University of East Anglia

Year dc:date.issued

2009

Author dc:creator

• Solares Diaz, Gloria

Language dc:language

en