A map of the barley genome consisting of 295 loci was constructed. These loci include 152 cDNA restriction fragment length polymorphism (RFLP), 114 genomic DNA RFLP, 14 random amplified polymorphic DNA (RAPD), five isozyme, two morphological, one disease resistance and seven specific amplicon polymorphism (SAP) markers. The RFLP-identified loci include 63 that were detected using cloned known function genes as probes. The map covers 1,250 centiMorgans (cM) with a 4.2 cM average distance between markers. The genetic lengths of the chromosomes range from 124 to 223 cM and are in approximate agreement with their physical lengths. The centromeres were localized to within a few markers on all of the barley chromosomes except chromosome 5. Telomeric regions were mapped for the short (plus) arms of chromosomes 1, 2 and 3 and the long (minus) arm of chromosomes 7.

Fusarium yellows, caused by the soil-borne fungus Fusarium oxysporum f. sp. betae (Fob), can lead to significant yield losses in sugar beet. This fungus is variable in pathogenicity, morphology, host range and symptom production, and is not a well characterized pathogen on sugar beet. From 1998 to 2003, 86 isolates of F. oxysporum and 20 other Fusarium species from sugar beet, along with four F. oxysporum isolates from dry bean and five from spinach, were obtained from diseased plants and characterized for pathogenicity to sugar beet. A group of sugar beet Fusarium isolates from different geographic areas (including nonpathogenic and pathogenic F. oxysporum, F. solani, F. proliferatum and F. avenaceum), F. oxysporum from dry bean and spinach, and Fusarium DNA from Europe were chosen for phylogenetic analysis. Sequence data from b-tubulin, EF1a and ITS DNA were used to examine whether Fusarium diversity is related to geographic origin and pathogenicity. Parsimony and Bayesian MCMC analyses of individual and combined datasets revealed no clades based on geographic origin and a single clade consisting exclusively of pathogens. The presence of FOB and nonpathogenic isolates in clades predominately made up of Fusarium species from sugar beet and other hosts indicates that F. oxysporum f. sp. betae is not monophyletic.

This study tests the effect of glyphosate application on disease severity in glyphosate-resistant sugar beet, and examines whether the increase in disease is fungal or plant mediated. In greenhouse studies of glyphosate-resistant sugar beet, increased disease severity was observed following glyphosate application and inoculation with certain isolates of Rhizoctonia solani Kuhn and Fusarium oxysporum Schlecht. f. sp. betae Snyd. & Hans. Significant increases in disease severity were noted for R. solani AG-2-2 isolate R-9 and moderately virulent F. oxysporum isolate FOB13 on both cultivars tested, regardless of the duration between glyphosate application and pathogen challenge, but not with highly virulent F. oxysporum isolate F-19 or an isolate of R. solani AG-4. The increase in disease does not appear to be fungal mediated, since in vitro studies showed no positive impact of glyphosate on fungal growth or overwintering structure production or germination for either pathogen. Studies of glyphosate impact on sugar beet physiology showed that shikimic acid accumulation is tissue specific and the rate of accumulation is greatly reduced in resistant cultivars when compared with a susceptible cultivar. The results indicate that precautions need to be taken when certain soil-borne diseases are present if weed management for sugar beet is to include post-emergence glyphosate treatments.

In sugarbeet (Beta vulgaris subsp. vulgaris), many linkage maps have been constructed, but the availability of markers continues to limit utility of genetic maps in public domain programs. Here a framework genetic map is presented that is expandable and transferable to research programs interested in locating their markers on a consensus map. In its current framework, the primary markers used were amplified fragment length polymorphisms (AFLPs) that were anchored to Butterfass chromosome‐nomenclature linkage groups using linkage group specific markers validated in other populations. Thus, a common framework has been established that anchors 331 markers, including 23 newly mapped simple sequence repeat (SSR) markers, having a combined total of 526.3 cM among the nine beet linkage groups. The source of the mapping population was a sugarbeet × table beet population, and this is the first report of a map constructed with a relatively wide cross in B. vulgaris Segregation distortion was common (22% of loci), particularly extreme for Butterfass Chromosome 5, and predominantly favored the sugarbeet (seed parent) allele. Physical segments of the beet genome that carry mapped markers have been identified, demonstrating that physical and genetic mapping are facile and complementary applications for beet improvement.

The beet-cyst nematode (Heterodera schachtii\ud Schmidt) is one of the major pests of sugar beet. The identification\ud of molecular markers associated with nematode tolerance\ud would be helpful for developing tolerant varieties. The\ud aim of this study was to identify single nucleotide polymorphism\ud (SNP) markers linked to nematode tolerance from the\ud Beta vulgaris ssp. maritima source WB242. A WB242-\ud derived F2 population was phenotyped for host-plant nematode\ud reaction revealing a 3:1 segregation ratio of the tolerant and\ud susceptible phenotypes and suggesting the action of a gene\ud designated as HsBvm-1. Bulked segregant analysis (BSA)\ud was used. The most tolerant and susceptible individuals were\ud pooled and subjected to restriction site associated DNA sequencing\ud (RAD-Seq) analysis, which identified 7,241 SNPs.\ud A subset of 384 candidate SNPs segregating between bulks\ud were genotyped on the 20 most-tolerant and most-susceptible\ud individuals, identifying a single marker (SNP192) showing\ud complete association with nematode tolerance. Segregation of\ud SNP192 confirmed the inheritance of tolerance by a single\ud gene. This association was further validated on a set of 26\ud commercial tolerant and susceptible varieties, showing the\ud presence of the SNP192 WB242-type allele only in the tolerant\ud varieties. We identified and mapped on chromosome 5 the first\ud nematode tolerance gene (HsBvm-1) from Beta vulgaris ssp.\ud maritima and released information on SNP192, a linked marker\ud valuable for high-throughput, marker-assisted breeding of nematode\ud tolerance in sugar beet