Mapping of five resistance genes to sugar-beet powdery mildew using AFLP and anchored SNP markers

Abstract

Sugar-beet powdery mildew, caused by the fungus Erysiphe betae, now occurs in all sugar-beet growing areas and can reduce sugar yield by up to 30%. Powdery mildew resistant plants from three novel sources were crossed with sugar beet to generate segregating populations. Evaluation of resistance was carried out in artificially inoculated field and controlled environment tests. The resistance level in two of the sources was found to be significantly higher than that in currently available sugar-beet cultivars. AFLP analysis was used in combination with bulked segregant analysis to develop markers linked to the resistant phenotype in each population. Five dominant major resistance genes were identified and assigned the proposed symbols Pm2 to Pm6. Pm3 conferred complete resistance to powdery mildew; the other genes conferred high levels of partial resistance. From the use of anchoring SNP markers, two genes were located to chromosome II and three to chromosome IV. Two of the genes on chromosome IV mapped to the same location and one of the genes on chromosome II mapped to the same region as the previously identified Pm1 gene. With the availability of these genes there is now excellent potential for achieving durable resistance to sugar-beet powdery mildew, thus reducing or obviating the need for chemical control.

Crop wild relative populations of Beta vulgaris allow direct mapping of agronomically important genes

“…The mapping data also indicated that the Kalundborg population segregates for only one resistance locus. Therefore, we assumed Rz2 and Rz3 to be identical, referring to them as Rz2 (refs 6, 7, 28, 29). …”

Root and Tuber Crops

“…6.8 Synthesis of three-way hybrid variety including tests of combining ability for O-types and pollinators polymorphisms (AFLP); (iv) simple sequence repeats (SSR); (v) single nucleotide polymorphisms (SNP), as well as morphological and isozyme markers (Barzen et al, 1992;Pillen et al, 1992Pillen et al, , 1993Boudry et al, 1994;Barzen et al, 1995;Uphoff and Wricke, 1995;Halldén et al, 1996;Schondelmaier et al, 1996;Nilsson et al, 1997;Schumacher et al, 1997;Hansen et al, 1999;Weber et al, 1999;Rae et al, 2000;Schneider et al, 2001;Möhring et al, 2004;Grimmer et al, 2007a;Schneider et al, 2007). The specific numbering of individual chromosomes, defined in genetic linkage maps, has been standardized.…”

“…Interestingly, a complete class of disease resistance genes, the TIR-type, is completely lacking in B. vulgaris (Tian et al, 2004). QTL approaches have identified chromosome regions associated with resistance to powdery mildew (Grimmer et al, 2007b), rhizoctonia crown and root rot (Lein et al, 2008), rhizomania (Gidner et al, 2005;Lein et al, 2007), Aphanomyces (Taguchi et al, 2009), and cercospora leaf spot Schäfer-Pregl et al, 1999;Setiawan et al, 2000). Generally, the genetic component of these measured traits can be portioned into 2-10 chromosome regions, and many of these could be considered oligogenic in their inheritance patterns.…”

“…Commercial markers have been developed for the Rz1 gene, and likely Rz2, however, the specific primer sequences being used are proprietary and are likely different among the various breeding companies. Markers for rhizomania resistance are available in the public sector (Scholten and Lange, 2000;Amiri et al, 2009), but new ones are desired for other specific genes or alleles conferring resistance to rhizomania or other diseases (Friesen et al, 2006;Grimmer et al, 2007b).…”

The action of three Beet yellows virus resistance QTLs depends on alleles at a novel genetic locus that controls symptom development

“…DNA extraction: Genomic DNA was extracted from snap‐frozen leaf tissue and quantified as described by Grimmer et al. (2007a).…”