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FC1740 (Reg No. GP-293, PI 681717) and FC1741 (Reg No. GP-294, PI 681718) sugar beet germplasm (Beta vulgaris L.) were developed by the USDA-ARS at Fort Collins, CO, Salinas, CA, and Kimberly, ID, in cooperation with the Beet Sugar Development Foundation, Denver, CO. These germplasm are diploid, multigerm sugar beet populations in normal cytoplasm, segregating for self-sterility (Sf:SsSs), genetic male sterility (A:aa), and hypocotyl color (R:rr). FC1740 and FC1741 have excellent resistance to rhizomania (Beet necrotic yellow vein virus). FC1740 was selected as homozygous resistant to markers linked to both Rz1 and Rz2 genes for rhizomania resistance. FC1741 was selected as homozygous to the marker linked to the Rz2 gene for resistance. Both germplasm also have resistance to beet curly top (Beet curly top virus) and Fusarium yellows (Fusarium oxysporum Schlechtend.:Fr. f. sp. betae (D. Stewart) W. C. Snyder & H. N. Hans. and other Fusarium spp.), as well as moderate resistance to Aphanomyces root rot (Aphanomyces cochlioides Drechs.). Neither line exhibited resistance to Cercospora leaf spot (Cercospora beticola Sacc.), Rhizoctonia crown and root rot (Rhizoctonia solani Kuhn.) or sugar beet root aphid (Pemphigus spp.). These germplasm provide sources from which to select disease-resistant, multigerm pollinator parents with either or both of the Rz1 and Rz2 sources of rhizomania resistance. Because they are from the same population, they also are useful as controls of known genetic background in comparing entries screened for rhizomania resistance conditioned by Rz1 or Rz2.

The soil-borne fungus Fusarium oxysporum can cause both Fusarium yellows and Fusarium root rot diseases with severe yield losses in cultivated sugar beet. These two diseases cause similar foliar symptoms but different root response and have been proposed to be caused by two distinct F. oxysporum formae speciales. Fusarium yellows, caused by F. oxysporum f. sp. betae, presents vascular discoloration, whereas Fusarium root rot, due to F. oxysporum f. sp. radicis-betae, appears as black rot visible on the root surface. The aim of this work was to study the host-pathogen interaction between sugar beet lines and isolates originally characterized as Fusarium oxysporum f. sp. betae. Eight susceptible sugar beet lines, selected by the USDA-ARS (US) and UNIPD (University of Padova, Italy) breeding programs, were inoculated with three different isolates of F. oxysporum f. sp. betae, the causal agent of Fusarium yellows, representing different genetic groups. All inoculated lines developed symptoms, but severity, expressed as area under the disease progress curve (AUDPC), differed significantly (P

Rhizomania is one of the most devastating biotic stresses affecting sugar beet (Beta vulgaris L.). It is caused by Beet necrotic yellow vein virus (BNYVV) vectored by the plasmodiophorid Polymyxa betae K. The only means available to control the disease is the use of genetically resistant varieties. “Rizor” or “Holly” (Rz1) and WB42 (Rz2) have been the most widely used resistance sources in the commercial varieties. Recently, naturally occurring resistance-breaking (RB) rhizomania strains have been identified causing major concerns. The aim of this study was to identify SNP mutations that show associations with resistance to rhizomania in sugar beet plants grown under resistance-breaking (RB)-BNYVV soils. Rhizomania virus content was evaluated by indirect triple-antibody sandwich-ELISA within two F 2 segregating populations respectively grown on an AYPR and IV-BNYVV strain infected soils. Bulked segregant analysis (BSA) was performed. The resistant and susceptible plants were genotyped with a 384-SNPs panel. Of the 384 SNPs, SNP249 was found to associate with the resistance both to the AYPR strain (R 2 = 0.37; P = 0.0004) and to the IV-BNYVV (R 2 = 0.09; P = 0.0074). Our results suggested that the SNP249 could be readily applicable for marker-assisted breeding of resistance to AYPR strain of rhizomania.

Sugarbeet (Beta vulgaris L.) germplasm SR98 (Reg. No. GP287; PI 655951) was developed and released by the USDA– ARS at East Lansing, MI, in cooperation with the Beet Sugar Development Foundation, Denver, CO, and Michigan State University AgBioResearch, East Lansing, MI, to provide improved resistance to seedling disease and crown and root rot caused by Rhizoctonia solani Kuhn in a smooth-root genetic background that contributes to low soil tare. Previous smooth-root releases have been highly susceptible to diseases caused by R. solani. SR98 was derived from Rhizoctoniaresistant germplasm released from the USDA–ARS sugarbeet germplasm enhancement programs at Ft. Collins, CO, and East Lansing, MI, and has shown good yield potential in agronomic trials and moderate resistance to Aphanomyces blackleg (caused by Aphanomyces cochliodes Drechs.) and Cercospora leaf spot (caused by Cercospora beticola, Sacc.). SR98 can be used as a pollinator for hybrid production or a population from which breeders can select pollinators for developing Rhizoctonia-resistant hybrids adapted to the Great Lakes growing region.

Resistance gene analogs (RGAs) were searched bioinformatically in the sugar beet (Beta vulgaris L.) genome as potential candidates for improving resistance against different diseases. In the present study, Ion Torrent sequencing technology was used to identify mutations in 21 RGAs. The DNA samples of ninety-six individuals from six sea beets (Beta vulgaris L. subsp. maritima) and six sugar beet pollinators (eight individuals each) were used for the discovery of single-nucleotide polymorphisms (SNPs). Target amplicons of about 200 bp in length were designed with the Ion AmpliSeq Designer system in order to cover the DNA sequences of the RGAs. The number of SNPs ranged from 0 in four individuals to 278 in the pollinator R740 (which is resistant to rhizomania infection). Among different groups of beets, cytoplasmic male sterile lines had the highest number of SNPs (132) whereas the lowest number of SNPs belonged to O-types (95). The principal coordinates analysis (PCoA) showed that the polymorphisms inside the gene Bv8_184910_pkon (including the CCCTCC sequence) can effectively differentiate wild from cultivated beets, pointing at a possible mutation associated to rhizomania resistance that originated directly from cultivated beets. This is unlike other resistance sources that are introgressed from wild beets. This gene belongs to the receptor-like kinase (RLK) class of RGAs, and is associated to a hypothetical protein. In conclusion, this first report of using Ion Torrent sequencing technology in beet germplasm suggests that the identified sequence CCCTCC can be used in marker-assisted programs to differentiate wild from domestic beets and to identify other unknown disease resistance genes in beet.

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

Locating and quantifying genetic variation within crop wild relatives is an ongoing activity of gene banks tasked with ex situ conservation. Without detailed information about the population genetics of a species, geography often serves as a reasonable proxy for differentiation. With this in mind, this paper examines the genetic diversity and differentiation of Beta vulgaris subsp. maritima accessions collected along a well-studied latitudinal gradient along the French Atlantic coast of France as well as Corsica, for use as representative genotypes from the Mediterranean basin. The aim of this work is to identify the scale and magnitude of differentiation and diversity in this set of accessions, using both molecular and quantitative traits. We assessed clinal variation and admixture in genetic and morphometric data along this latitudinal gradient. Results from this study revealed a complex pattern of recent gene flow and immigration on a historical biogeographic structure. Our data suggest that a presumed latitudinal cline is in reality an admixed mosaic of genotypes.

Fusarium spp. cause severe damage in many agricultural crops, including sugar beet, with Fusarium oxysporum historically being considered as the most damaging of all species. Sugar beet needs to be protected from this class of soil-borne pathogens in order to ensure an optimal sugar yield in the field. Genetic control of the disease is crucial in managing these pathogens. Identification of single nucleotide polymorphism (SNP) markers linked to resistance can be a powerful tool for the introgression of valuable genes needed to develop Fusarium-resistant varieties. A candidate gene approach was carried out to identify SNP markers linked to putative Fusarium resistance sources in sugar beet. Five resistant analogue genes (RGAs) were screened by means of high resolution melting (HRM) analysis in a set of sugar beet lines, considered as resistant and susceptible to Fusarium oxysporum. HRM polymorphisms were observed in 80% of amplicons. Two HRM polymorphisms were significantly associated with Fusarium resistance (P

The primary targets of allele mining efforts are loci of agronomic importance. Agronomic loci typically exhibit patterns of allelic diversity that are consistent with a history of natural or artificial selection. Natural or artificial selection causes the distribution of genetic diversity at such loci to deviate substantially from the pattern found at neutral loci. The germplasm utilized for allele mining should contain maximum allelic variation at loci of interest, in the smallest possible number of samples. We show that the popular core collection assembly procedure "M" (marker allele richness), which leverages variation at neutral loci, performs worse than random assembly for retaining variation at a locus of agronomic importance in sugar beet (Beta vulgaris L. subsp. vulgaris) that is under selection. We present a corrected procedure ("M+") that outperforms M. An extensive coalescent simulation was performed to demonstrate more generally the retention of neutral versus selected allelic variation in core subsets assembled with M+. A negative correlation in level of allelic diversity between neutral and selected loci was observed in 42% of simulated data sets. When core collection assembly is guided by neutral marker loci, as is the current common practice, enhanced allelic variation at agronomically important loci should not necessarily be expected.

FC1018 (Reg. No. GP-273, PI 658059), FC1019 (Reg. No. GP-274, PI 658060), FC1020 (Reg. No. GP-275, PI 658061), and FC1022 (Reg. No. GP-276, PI 658062) sugarbeet (Beta vulgaris L.) germplasms were released in 2009 from seed lots 05FC1018; 05-FC1019; 07-, 08-, or 09-FC1020; and 05-FC1022, respectively, and tested under those designations. They were developed by the USDA-ARS at Fort Collins, CO and Salinas, CA in cooperation with the Beet Sugar Development Foundation, Denver, CO. All four germplasms are populations in fertile cytoplasm and segregate for self-sterility, multigermity, hypocotyl color, and the Rz1 gene, which confers resistance to some strains of Beet necrotic yellow vein virus, the causal agent of rhizomania. FC1018, FC1019, and FC1020 have moderate tolerance to root-rotting strains (AG2–2) of Rhizoctonia solani Kuhn (the causal agent of Rhizoctonia root and crown rot), Cercospora beticola Sacc. (the causal agent of Cercospora leaf spot), Beet curly top virus (BCTV), and Aphanomyces cochlioides Drechsl., which causes Aphanomyces root rot (Aphanomyces black root). They are populations that can be used to select disease-resistant, multigerm pollinator parents. FC1022 has a moderate tolerance to BCTV and had a relatively high sucrose concentration at Salinas when tested in a fi eld infested with rhizomania. Because of a large percentage of monogerm seedballs (45%) and O-type parentage, it should be possible to select monogerm, O-type lines from FC1022.

F1024 (Reg. No. GP-272, PI 658654) sugarbeet (Beta vulgaris L.) germplasm with resistance to sugarbeet root maggot (Tetanops myopaeformis von Roder) was released by the USDA-ARS and the North Dakota Agricultural Experiment Station, North Dakota State University, Fargo, ND on 15 Dec. 2009. F1024 was selected from a population formed by crossing F1016, a germplasm line resistant to root maggot, with a breeding line resistant to Cercospora leaf spot (CLS; caused by Cercospora beticola Sacc.). The population was subjected to three cycles of mass selection for resistance to root maggot followed by three cycles of selection among half-sib families. Under natural root maggot infestations, F1024 had a damage rating of 2.1 (on a scale of 1 to 9, where 0 = no maggot feeding, and 9 = >75% of root surface with feeding scars), compared with an average of 6.1 for two susceptible commercial hybrids. In a 2009 CLS evaluation, F1024 had a significantly lower disease rating than the susceptible check, and the difference between F1024 and the resistant checks was not significant. The performance of testcross hybrids between the component half-sib families of F1024 and a susceptible cytoplasmic-male-sterile line provided additional validation of the potential of root maggot-resistant hybrids in areas where root maggot is a perpetual threat.

Rhizoctonia solani is an important plant pathogen for a number of crops and maintaining an extensive collection of reference isolates is important in understanding relationships of this pathogen with multiple hosts. Current long-term storage methods typically call for frequent transfer increasing the risk of changes in morphological, physiological or virulence characteristics. Cryopreservation using storage in liquid nitrogen (LN) was evaluated to examine the potential for storage of a R. solani culture collection containing 106 isolates (primarily from sugar beet). Cultures were stored on autoclaved barley grains in the vapour phase of LN. After 60 days, 5 years and 10 years in storage, all isolates were tested for viability by calculating the percentage of barley grains from which R. solani mycelia grew. Five years after initial storage, all isolates except one had no change in viability. After 10 years in storage, 67 of 106 isolates had no significant decrease in viability, 39 of 106 isolates had a significant decrease in viability but only 9 isolates had less than 10% growth, with 4 having no growth. A subset of isolates stored for 10 years were tested for pathogenicity on a susceptible (FC901) and resistant (FC703) sugar beet germplasm. All isolates tested maintained approximately the same level of virulence that they had prior to storage on both germplasms. This indicates that cryogenic methods are suitable for the preservation or storage of R. solani culture collections, although efficacy may vary with individual isolates.

The combination of volatility in the oil market and finite oil resources and the effect on global climate change from the addition of CO2 to the atmosphere as a result of burning fossil fuels has increased the interest in sustainable energy generation from renewable biofuels. Most 1st generation biofuels in current production are liquid with bioethanol the product of fermentation. Sugar beet provides an abundance of sucrose, which is easily fermented by many microbes and on a per hectare basis; sugar beet is one of the most efficient sources of ethanol, however storage of harvested roots is problematic. Most studies have indicated sustainable biofuels have reduced greenhouse gas emissions (GHG) when compared to petroleum based fuels. Bioethanol from sugar beet reduces GHG comparably or superiorly to maize or sugarcane. There also are other biofuels from fermentation, including biomethanol, biobutanol ETBE, biomethane, and biohydrogen, many of which are more energy dense than ethanol. Storage of sugar beet is a problem that could be solved by ensilage and anaerobic digestion producing a biogas, which could yield more energy per hectare than bioethanol. As the global economy moves away from fossil fuels, sugar beet will play an increasing role in the adoption of more sustainable energy generation.

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 whetherFusarium 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.

Hecker and coworkers demonstrated that sugarbeet (Beta vulgaris L.) pollen could be stored in liquid nitrogen vapor phase (-160°C) (LN) for 1 year and remain viable. We demonstrate that pollen, stored for 17 years in LN was able to pollinate sugarbeet and produce viable seed. two viability staining tests showed no significant differences between stored and fresh pollen, and differences in pollen tube germination were small. Long-term storage of pollen provides opportunities for uses in sugarbeet breeding and genetic resources preservation. In a heterozygous crop such as sugarbeet, collected pollen would be a way to pre serve superior, individual genotypes for use over long peri ods of time. In plant breeding, stored pollen could be used as a long term tester (individual genotype or population) or from an individual genotype as the parent in a recurrent backcrossing scheme for genetic analysis. Collection and storage of pollen could be a way to obtain a more represen tative sample of the genetic diversity in wild populations. With restrictions on the international transport of seed becoming increasingly stringent, pollen could be an alter nate way to distribute Beta germplasm. However routine use of Beta pollen collections requires a more complete understanding of physiological responses to LN storage.

The development of sugar beet as an economically important field crop coincided with our increased understanding of modern genetic principles. It was developed in the late 1700s from white fodder beet; therefore, the genetic base of sugar beet is thought to be narrower than many open-pollinated crops. The wild sea beet is the progenitor of all domesticated beet and cross compatible with cultivated beet (domestic and cultivated are given subspecies level in the same species). The breeding system of sugar beet is complex and the crop is biennial, which lengthens the generation time to almost 1 year. A genetic-cytoplasmic male sterility (CMS) system is utilized for commercial hybrid production. Early breeding objectives were to improve the concentration and extractability of sucrose and little emphasis was placed on host–plant resistance to insect, nematode, and disease pests. As production areas expanded, these pests limited production, sometimes severely. The first systematic attempts to screen exotic and wild beet germplasm for disease resistance were initiated early in the 20th century. Many undesirable traits from wild beet were reportedly introgressed with the selected disease resistance and it was only in the late 1900s that the use of wild beet genetic resources became common place in public breeding programs. In North America, a pivotal development in utilizing the genetic resources available for sugar beet breeding was the formation in 1983 of the Sugarbeet Crop Germplasm Committee (CGC). Since the Sugarbeet CGC identified enhancing the commercial sugar beet germplasm pool as a high priority, there has been an aggressive evaluation of the National Plant Germplasm System (NPGS) Beta collection. This collection now has more than 2500 accessions from within the genus Beta. In 2002, it was estimated that close to 25,000 evaluation data points (descriptors × accessions evaluated) describing the collection were available in the Genetic Resources Information Network (GRIN) database. Over 3000 evaluations described levels of resistance of sugar beet and wild beet accessions to 10 major disease and insect pests of sugar beet. As soon as the evaluation data are collected, they are used to select the sources for the pre-breeding programs. There is a lag time in sugar beet of␣8–15 years between starting a germplasm development program and releasing the first germplasm, but successes of this program are available in the germplasm released to the commercial breeders. Resistance genes from wild beet for rhizomania and beet cyst nematode resistance have been commercialized.

Cercospora leaf spot of sugar beet, caused by the fungus Cercospora beticola, is a major foliar pathogen on sugar beet. Fungicide sprays have been used extensively to manage Cercospora leaf spot, including the benzimidazole fungicides. Resistance to benzimidazoles has been observed in isolates of C. beticola. The precise genetics of this resistance is not known in this fungus. We tested benzimidazole-tolerant and -sensitive isolates and found a single mutation in the β-tubulin gene of benzimidazole-tolerant isolates that corresponds to a mutation known to confer benzimidazole tolerance in other ascomycetes. This mutation is predicted to cause a change from glutamic acid to alanine in the protein product. Isolates containing this mutation further show an increased sensitivity to an N-phenylcarbamate, as would be predicted based on the mutant phenotype found in other filamentous fungi. Only a single mutation was found in isolates from different regions of the United States, isolated in different growing seasons.

Fusarium wilt is an economically important fungal disease of common bean and sugar beet in the Central High Plains (CHP) region of the USA, with yield losses approaching 30% under appropriate environmental conditions. The objective of this study was to characterize genetic diversity and pathogenicity of isolates of Fusarium oxysporum obtained from common bean and sugar beet plants in the CHP that exhibited Fusarium wilt symptoms. A total of 166 isolates of F. oxysporum isolated from diseased common bean plants were screened for pathogenicity on the universal susceptible common bean cultivar ‘UI 114’. Only four of 166 isolates were pathogenic and were designated F. oxysporum f.sp. phaseoli (Fop). A set of 34 isolates, including pathogenic Fop, F. oxysporum f.sp. betae (Fob) isolates pathogenic on sugar beet, and non-pathogenic (Fo) isolates, were selected for random-amplified polymorphic DNA (RAPD) analysis. A total of 12 RAPD primers, which generated 105 polymorphic bands, were used to construct an unweighted paired group method with arithmetic averages dendrogram based on Jaccard's coefficient of similarity. All CHP Fop isolates had identical RAPD banding patterns, suggesting low genetic diversity for Fop in this region. CHP Fob isolates showed a greater degree of diversity, but in general clustered together in a grouping distinct from Fop isolates. As RAPD markers revealed such a high level of genetic diversity across all isolates examined, we conclude that RAPD markers had only limited usefulness in correlating pathogenicity among the isolates and races in this study.

Rhizoctonia solaniKuhn is a serious plant pathogenic fungus, causing various types of damage to sugar beet (Beta vulgaris L.). In Europe, the disease is spreading and becoming a threat for the growing of this crop. Plant resistance seems to be the most practical and economical way to control the disease. Experiments were carried out to optimise a greenhouse procedure to screen plants of sugar beet for resistance to R. solani. In the first experiment, two susceptible accessions were evaluated for root and leaf symptoms, after being grown in seven different soil mixtures and inoculated with R. solani. The fungus infected all plants. It was concluded that leaf symptoms were not reliable for the rating of disease severity. Statistically significant differences between the soil mixtures were observed, and there were no significant differences between the two accessions. The two soil mixtures, showing the most severe disease symptoms, were selected for a second experiment, including both resistant and susceptible accessions. As in the first experiment, root symptoms were recorded using a 1-7 scale, and a significant expression of resistance was observed. The average severity of the disease in the greenhouse experiment generally was comparable with the infection in field experiments, and the ranking of the accessions was the same in the two types of experiments. It was concluded that evaluation procedures in the greenhouse could be used as a rapid assay to screen sugar beet plants for resistance to R. solani.

Fusarium wilt in common bean (Phaseolus vulgaris L.) caused by Fusarium oxysporum Schlechtend. Fr. forma specialis phaseoli Kendrick and Snyder (Fop) occurs worldwide and can result in severe yield loss. Because cultural methods to control disease loss are not completely effective, cultivars with genetic resistance are needed. The objectives of this study were to determine whether genetic control of resistance to Fop race 4 differs between germplasm of races Durango and Mesoamerica of common bean and to estimate heritability of resistance found in race Mesoamerica. Resistant and susceptible lines of races Durango and Mesoamerica were crossed within races to produce F 2 and F 3 progeny. Reaction to Fop was evaluated using a root-dip inoculation method and scored using a CIAT disease severity scale from one to nine. F 2 populations derived from race Durango parents showed a 3:1 (resistant/susceptible) plant segregation ratio, and F 3 progeny tests confirmed that resistance was controlled by a single dominant gene. F 2 data from crosses between parents of race Mesoamerica had continuous distributions for reaction to Fop race 4, suggesting polygenic control of resistance. The narrow-sense heritability estimate derived from midparent-offspring regression of 10 F 2 populations derived from Mesoamerican parents was 0.85 ± 0.34, and realized heritability estimates ranged from 0.25 ± 0.19 to 0.60 ± 0.16 among five populations. The heritability estimates as well as the continuous variation in disease severity observed support the hypothesis that resistance to Fop race 4 among parents of race Mesoamerican is polygenic.

Foliar application of methanol has improved growth and productivity experimentally in a number of agricultural crops. To test the possibility that methanol application might improve sugarbeet yield, we conducted a replicated field study at Fort Collins, Colorado in 1994 with two commercial sugarbeet varieties (Monohikari, Beta 2398) and one public breeding line (FC709-2). Methanol was foliarly applied at about ten day intervals throughout the growing season starting at 40 dap. Plants were treated with 50% methanol plus 0.1% Triton-X surfactant, or 50% methanol plus 0.1% Triton-X plus 0.2% monosodium glutamate (MSG) as a nitrogen source. Control plants received no spray treatment. Two regimes of irrigation were included, one that provided water at a level typical of commercial growing practice and one in which about 50% as much water was applied on the same schedule, intentionally causing chronic water stress. Photosynthetic gas exchange was determined on August 26 and September 8 at mid-day on a subset of plots. Root yield and percentage root sucrose were determined at harvest, and sucrose yield was calculated from those values. The summer was warm and dry in 1994 and even plants in the higher irrigation regime were water-stressed (i.e., wilted at mid-day), and no significant differences in root yield, percent root sucrose, or sucrose yield occurred due to irrigation treatment. Significant differences for each of the three parameters occurred among varieties and for methanol treatments. Both methanol treatments resulted in significantly lower root weight and sucrose yield than the control, and methanol plus MSG application resulted in significantly lower root weight and sucrose yield than application of only methanol. Percentage sucrose was statistically similar in control and methanol treatments, but treatment with methanol plus MSG resulted in lower percentage sucrose. Photosynthesis was increased in methanol treated plots, but this result was not consistent. If methanol treatment resulted in higher photosynthesis in the short term, this may have resulted in greater above-ground growth at the expense of root growth and root sucrose storage, which could account for the observed lower root and sucrose yield in the treated plots. If early-season methanol application timing and concentration could be adjusted to stimulate early canopy formation, so that maximal light interception could be achieved earlier in the season, this might lead to increased sucrose yield at harvest.

High-throughput single-nucleotide polymorphism (SNP) genotyping provides a rapid way of developing resourceful sets of markers for delineating genetic structure and for understanding the basis of the taxonomic discrimination. In this paper, we present a panel of 192 SNPs for effective genotyping in sugar beet using a high-throughput marker array technology, QuantStudio 12K Flex system, coupled with Taqman OpenArray technology. The selected SNPs were evaluated for genetic diversity among a set of 150 individuals representing 15 genotypes (10 individuals each) from five cytoplasmic male steriles (CMSs), five pollinators, and five commercial varieties. We demonstrated that the proposed panel of 192 SNPs effectively differentiated the studied genotypes. A higher degree of polymorphism was observed among the CMSs as compared to pollinators and commercial varieties. PCoA and STRUCTURE analysis revealed that CMSs, pollinators, and varieties clustered into three distinct subpopulations. Our results demonstrate the utility of the identified panel of 192 SNPs coupled with TaqMan OpenArray technology as a wide set of markers for high-throughput SNP genotyping in sugar beet.

Eight microsatellite loci were characterized within two cultivated beet ( Beta vulgaris ssp. vulgaris ) accessions and one accession of the wild progenitor of domesticated sugar beet, Beta vulgaris ssp. maritima . Allele diversity was high, yielding two to 11 alleles per locus. Polymorphism information content (PIC) values obtained for these eight loci where also high and indicate the highly informative nature of the microsatellites presented here. These described markers add to a small set of publicly available microsatellite markers for beet and will be instrumental in identifying patterns of genetic diversity and origins of domestication.

Bolton, M. D., Panella, L., Campbell, L., and Khan, M. F. R. 2010. Temperature, moisture, and fungicide effects in managing Rhizoctonia root and crown rot of sugar beet. Phytopathology 100:689-697. Rhizoctonia solani AG-2-2 is the causal agent of Rhizoctonia root and crown rot in sugar beet; however, recent increases in disease incidence and severity were grounds to reevaluate this pathosystem. To assess the capacity at which other anastomosis groups (AGs) are able to infect sugar beet, 15 AGs and intraspecific groups (ISGs) were tested for pathogenicity on resistant (‘FC708 CMS’) and susceptible (‘Monohikari’) seedlings and 10-week-old plants. Several AGs and ISGs were pathogenic on seedlings regardless of host resistance but only AG-2-2 IIIB and AG-22 IV caused significant disease on 10-week-old plants. Because fungicides need to be applied prior to infection for effective disease control, temperature and moisture parameters were assessed to identify potential thresholds that limit infection. Root and leaf disease indices were used to evaluate disease progression of AG-2-2 IIIB- and AG-2-2 IV-inoculated plants in controlled climate conditions of 7 to 22 growing degree days (GDDs) per day. Root disease ratings were positively correlated with increasing temperature of both ISGs, with maximum disease symptoms occurring at 22 GDDs/day. No disease symptoms were evident from either ISG at 10 GDDs/day but disease symptoms did occur in plants grown in growth chambers set to 11 GDDs/day. Using growth chambers adjusted to 22 GDDs/day, disease was evaluated at 25, 50, 75, and 100% moisture-holding capacity (MHC). Disease symptoms for each ISG were highest in soils with 75 and 100% MHC but disease still occurred at 25% MHC. Isolates were tested for their ability to cause disease at 1, 4, and 8 cm from the plant hypocotyl. Only AG-2-2 IIIB was able to cause disease symptoms at 8 cm during the evaluation period. In all experiments, isolates of AG-2-2 IIIB were found to be more aggressive than AG-2-2 IV. Using environmental parameters that we identified as the most conducive to disease development, azoxystrobin, prothioconazole, pyraclostrobin, difenoconazole/propiconazole, flutolanil, polyoxin D, and a water control were evaluated for their ability to suppress disease development by AG-2-2 IIIB and AG-2-2 IV 17 days after planting. Flutolanil, polyoxin-D, and azoxystrobin provided the highest level of disease suppression. Because R. solani AG-2-2 IIIB and AG-2-2 IV are affected by temperature and moisture, growers may be able to evaluate environmental parameters for optimization of fungicide application.

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 x 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.

Thirty-five PIs (Garden Beet, Sugar Beet, Leaf Beet, Fodder Beet, and wild beet) were screened at three locations: 1) an artificially produced epiphytotic (Ruppel, E.G., and J.O. Gaskill. 1971. Techniques for evaluating sugarbeet for resistance to Cercospora beticola in the field. J. Am. Soc. Sugar Beet Technol. 16: 384-389) in Fort Collins, CO ; 2) an artificially produced epiphytotic in Osijek, Croatia ; and 3) a naturally occurring epiphytotic in Osijek, Croatia. Randomized complete-block designs, with two replications were used to evaluate germplasm. Internal controls included a highly susceptible synthetic check and a resistant hybrid check, FC (504x502/2) x SP6322-0. Two-row plots were 4 m long, with 56 cm between rows and 20- to 25-cm within-row spacing. The artificially inoculated nurseries were inoculated twice, on 13 and 23 June in Osijek, and on 27 June and 8 July in Fort Collins. Visual evaluations on a scale from 0 (no disease) to 10 (plant dead) of PIs in the natural and artificial Cercospora epiphytotics were made in Croatia on 8, 18, and 28 Aug. Evaluations in Fort Collins were made on 2, 9, and 16 Sept, with the peak of the epidemic occurring on or about the last date. This project was supported by the USDA-ARS NPGS and USDA/FAS/RSED grant HR02. In Fort Collins, the 1997 leaf spot epidemic progressed rather slowly at first, but rapidly became quite severe by late August to early September. At our third evaluation, means of the resistant and susceptible internal controls were 3.7 and 7.3, respectively, across all trials in the nursery. An analysis of variance (PROC ANOVA - SAS) on the disease indices (visual evaluation scores) determined that there were significant differences among entries (P=0.05) on all three dates at all three locations. An LSD was generated for mean separations. Although the variation was higher in Osijek, some entries performed very differently at the different locations.