Localisation of genes for resistance against Blumeria graminis f.sp. hordei and Puccinia graminis in a cross between a barley cultivar and a wild barley (Hordeum vulgare ssp. spontaneum) line

Abstract

The aims of this investigation have been to map new (quantitative) resistance genes against powdery mildew, caused by Blumeria graminis f.sp. hordei L., and leaf rust, caused by Puccinia hordei L., in a cross between the barley ( Hordeum vulgare ssp. vulgare) cultivar "Vada" and the wild barley ( Hordeum vulgare ssp. spontaneum) line "1B-87" originating from Israel. The population consisted of 121 recombinant inbred lines. Resistance against leaf rust and powdery mildew was tested on detached leaves. The leaf rust isolate "I-80" and the powdery mildew isolate "Va-4", respectively, were used for the infection in this experiment. Moreover, powdery mildew disease severity was observed in the field at two different epidemic stages. In addition to other DNA markers, the map included 13 RGA (resistance gene analog) loci. The structure of the data demanded a non-parametric QTL-analysis. For each of the four observations, two QTLs with very high significance were localised. QTLs for resistance against powdery mildew were detected on chromosome 1H, 2H, 3H, 4H and 7H. QTLs for resistance against leaf rust were localised on 2H and 6H. Only one QTL was common for two of the powdery mildew related traits. Three of the seven QTLs were localised at the positions of the RGA-loci. Three of the five powdery mildew related QTLs are sharing their chromosomal position with known qualitative resistance genes. All detected QTLs behaved additively. Possible sources of the distorted segregation observed, the differences between the results for the different powdery mildew related traits and the relation between qualitative and quantitative resistance are discussed.

Resistance gene analogues identified through the NBS-profiling method map close to major genes and QTL for disease resistance in apple

“…Therefore, RGAs are more useful as landing markers than as candidate genes. Colocalization among RGAs and QTL have previously been observed in a number of species, including bean (Geffroy et al 2000), soybean (Kanazin et al 1996), lettuce (Shen et al 1998), A. thaliana (Speulman et al 1998), maize (Collins et al 1998) and barley (Backes et al 2003). These co-localizations raise the possibility that some of the genes underlying quantitative resistance share structural and functional similarities with R genes.…”

AB-QTL analysis in spring barley: II. Detection of favourable exotic alleles for agronomic traits introgressed from wild barley (H. vulgare ssp. spontaneum)

“…They predicted that for crops with a rather narrow genetic basis, but rich biodiversity resources, the introgression of exotic germplasm could lead to dramatic improvements in yield and other quality traits. For barley, the beneficial effect of exotic genes on biotic (Backes et al 2003;Fischbeck and Jahoor 1991;Zeller 1998) and abiotic (Jefferies et al 1999) stresses and to some extent on quality traits (Erkkila¨1998) has already been demonstrated. The potential use of wild germplasm for the improvement of agronomic traits, however, is still a matter of controversy.…”

Identification of QTLs for powdery mildew and scald resistance in barley

“…Where minor genes for PR co-localise to loci for major-genic resistance (e.g. in Backes et al, 2003), the minor genes for PR may be allelic versions of major genes for hypersensitivity, or be defeated alleles of such major genes. Evidence for the latter has been found in rice resistance to rice bacterial blight (Xanthomonas oryzae pv.…”