Sugar Beet Rhizomania Research Articles

Selection of natural isolates of Trichoderma spp. for biocontrol of Polymyxa betae as a vector of virus causing rhizomania in sugar beet

The soil fungus Polymyxa betae, Keskin, besides being a root parasite, plays a role of a vector in dissemination of Beet necrotic yellow vein virus (BNYVV) causing rhizomania in sugar beet. An alternative to its chemical control is the application of antagonistic microorganisms suppressing proliferation of the fungal vector. In the present work, 66 Trichoderma isolates have been obtained from sugar beet plantations from diverse locations in Slovakia. The ability of the selected isolates to grow at low temperature (10 °C) and to suppress the colonization of roots with P. betae and the multiplication of BNYVV in roots under glasshouse conditions were tested. The roots of sugar beet seedlings growing in the BNYVV-infested soil were analyzed by serological ELISA test using monoclonal and polyclonal antibodies for the presence of BNYVV and checked microscopically for the occurrence of cystosori of P. betae. The efficacy of the selected strains to suppress the proliferation of BNYVV varied on the average between 21 and 68%. On the basis of these tests, candidate strains for practical application in biocontrol of sugar beet rhizomania were selected.

The Continuing Saga of Rhizomania of Sugar Beets in the United States.

Historically, Beet necrotic yellow vein virus (BNYVV), which causes the disease rhizomania of sugar beet, has caused major reductions in root yield and quality wherever it occurred. In the United States, the disease was first identified in California in 1984 (12), but it now occurs in every major sugar beet production region in the country. Fortunately, strong genetic tolerance to BNYVV, conferred by the Rz1 gene, was identified soon after rhizomania was discovered in the United States, and it has been incorporated into regionally adapted cultivars that allow profitable sugar beet production in areas infested with the pathogen. Plants possessing Rz1 are susceptible to infection by P. betae and BNYVV, but virus titers remain low, and typically, infected plants exhibit normal, asymptomatic growth. However, in the Imperial Valley of California in 2002, plants in a field planted to a rhizomaniatolerant cultivar began to express symptoms of rhizomania (47). Large strips of diseased plants occurred across the field, and it was soon verified that certain isolates of BNYVV from the California Imperial Valley (CIV-BNYVV) had overcome genetic resistance. In other regions of the United States, individual plants, or clusters of plants, in fields planted to rhizomaniatolerant cultivars have also become infected by BNYVV and developed diagnostic symptoms of severe rhizomania. Although patterns of disease development have varied between California fields and those in other production regions in the United States, the breakdown of genetic resistance has caused considerable concern among those involved in sugar beet production. The purpose of this article is to provide an update on rhizomania and the activities that are currently underway to manage this continuing threat to the U.S. sugar beet industry. A review on the detection and distribution of rhizomania and soilborne viruses associated with sugar beet production in the United States (61), and a second more in-depth review on BNYVV and its vector, Polymyxa betae (Keskin) (60), have been published.

Root rot of sugarbeet in the Vojvodina Province

Large changes introduced in the sugar beet production technology in the Vojvodina Province over last 40 years resulted in changes in the etiology and harmfulness of different agents of sugar beet root diseases. Improvements in cultivation practices reduced the harmfulness of some diseases while increased the harmfulness of others. Some disease agents became obsolete, but others gained importance. New agents of root diseases were found. The most frequent damages, persisting over long periods of time were caused by seedling damping-off, Fusarium root rot, charcoal root rot, parasitic (Rhizomania) and non-parasitic root bearding. The parasitic damping-off caused by several fungal species but most frequently by Phoma betae occurred at the time when multigerm seeds were used in combination with extensive cultural practices. The agents of seedling diseases completely lost their significance as the consequence of switching to fungicide - treated monogerm seeds, earlier planting and improved soil tillage. In the period of intensive use of agricultural chemicals, seedling damping-off occurred frequently due to the phytotoxic action of chemicals (insecticides, herbicides and mineral fertilizers). In some years, frosts caused damping- off of sugar beet seedlings on a large scale in the Vojvodina Province. Poor sugar beet germination and emergence were frequently due to spring droughts. Sometimes they were due to strong winds. The occurrence of Fusarium root rot and charcoal root rot intensified on poor soils. Fusariosis symptoms were exhibited as plant wilting and different forms of root rot. In recent years root tip rot has occurred frequently in the first part of the growing season causing necrosis and dying of plants. Lateral roots tended to proliferate from the healthy tissue, giving the root a bearded appearance similar to Rhizomania. Fusarium oxysporum was the most frequent agent of this fusariosis. F. graminearum, F. equiseti, F. solani have also been identified in recent years as the agent of root rot, but its importance was much lower. Charcoal root rot and plant wilting (Macrophomina phaseolina) have caused extensive damages in sugar beets, especially under the conditions of severe drought and high temperatures in summer. In some years, it was the dominant agent of root rot. Mixed infections caused by fungi from the genera Fusarium and M. phaseolina were encountered frequently. The extent of damage caused by these diseases was reduced by improved pro- duction technology. Rhizomania of sugar beet (caused by beet necrotic yellow vein virus) was identified in Serbia in the 1970s. Results of recent investigations have shown that BNYVV is widespread in Vojvodina, since the virus was found on 36,7% (24,674 ha) of acreages from 67,213 ha of total sugar beet acreages inspected on incidence of BNYVV in the period from 1997 to 2004 year. In the last few years, the occurrence of Rhizoctonia root rot (Rhizoctonia solani) was registered in some localities in Vojvodina.

Occurrence And Spread Of Sugar Beet Rhizomania Caused By Beet Necrotic Yellow Vein Benyvirus In Some Governorates Of Egypt

Occurrence And Spread Of Sugar Beet Rhizomania Caused By Beet Necrotic Yellow Vein Benyvirus In Some Governorates Of Egypt

Spatial Association and Distribution of Beet necrotic yellow vein virus and Beet soilborne mosaic virus in Sugar Beet Fields.

Beet necrotic yellow vein virus (BNYVV) causes rhizomania of sugar beet (Beta vulgaris), which is characterized by stunting, leaf necrosis, constriction of the taproot, and extensive lateral- and feeder-root proliferation. Beet soilborne mosaic virus (BSBMV) causes similar but typically less severe symptoms than those of BNYVV. Both viruses are widely distributed in sugar beet-growing regions of the United States. Both viruses are vectored by the soilborne plasmodiophorid Polymyxa betae Keskin and are very similar in morphology and biology, sharing many characteristics in common. In 1999, soil samples were collected from sugar beet fields in Colorado, Minnesota, North Dakota, and Texas to determine the spatial association and covariation of the viruses in sugar beet fields. In 2000, additional samples were collected from fields in Minnesota and North Dakota. Over the 2-year period, soil samples were collected from 11 fields in various quadrat sizes. The viruses were assayed by growing sugar beet (cv. Beta 1395) in the soil samples and their incidence was determined using the double-antibody sandwich enzyme-linked immunosorbent assay. Both viruses were detected in samples from all fields but were in greater frequencies singly than in association. Association of the two viruses (where both viruses were detected in the same sample or bait plant) varied among fields, ranging from 1 to 42%. Geostatistical analysis revealed that both viruses, in large part, exhibited similar spatial patterns. In all but two fields, there was no spatial dependence among the sampling locations at sampled grid sizes. Their semivariances were constant at all separation distances in all directions indicating random spatial patterns. Overall, the spatial pattern of BNYVV appeared to be a little more structured than that of BSBMV. Even though both viruses are transmitted by the same vector and also exhibited similar distribution patterns, the incidence of one virus may not be estimated from that of the other due to lack of strong association and spatial dependence. However, similarity in spatial patterns of the two suggests that a similar sampling method can be employed for both viruses.

First Report of Rhizomania Disease of Sugar Beet Caused by Beet necrotic yellow vein virus in the Great Lakes Production Region.

Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV) and vectored by the soilborne fungus Polymyxa betae Keskin, is one of the most economically damaging diseases affecting sugar beet (Beta vulgaris L.). The virus likely originated in Europe and was first identified in California in 1983 (1). It has since spread among American sugar beet production regions in spite of vigorous sanitation efforts, quarantine, and disease monitoring (3). In the fall of 2002, mature sugar beet plants exhibiting typical rhizomania root symptoms, including proliferation of hairy roots, vascular discoloration, and some root constriction (2) were found in several fields scattered throughout central and eastern Michigan. Symptomatic beets were from numerous cultivars, all susceptible to rhizomania. Two to five sugar beet root samples were collected from each field and sent to the USDA-ARS in Salinas, CA for analysis. Hairy root tissue from symptomatic plants was used for mechanical inoculation of indicator plants. Mechanical inoculation produced necrotic lesions on Chenopodium quinoa and systemic infection of Beta vulgaris ssp. macrocarpa, both typical of BNYVV and identical to control inoculations with BNYVV. Symptomatic sugar beet roots were washed and tested using double antibody sandwich-enzyme linked immunosorbent assay (DAS-ELISA) for the presence of BNYVV using standard procedures and antiserum specific for BNYVV (3). Sugar beet roots were tested individually, and samples were considered positive when absorbance values were at least three times those of greenhouse-grown healthy sugar beet controls. Samples were tested from 16 fields, with 10 confirmed positive for BNYVV. Positive samples had mean absorbance values ranging from 0.341 to 1.631 (A405nm) after 30 min. The mean healthy control value was 0.097. Fields were considered positive if one beet tested positive for BNYVV, but in most cases, all beets tested from a field were uniformly positive or uniformly negative. In addition, soil-baiting experiments were conducted on seven of the fields. Sugar beet seedlings were grown in soil mixed with equal parts of sand for 6 weeks and were subsequently tested using DAS-ELISA for BNYVV. Results matched those of the root sampling. Fields testing positive for BNYVV were widely dispersed within a 100 square mile (160 km2) area including portions of Gratiot, Saginaw, Tuscola, and Sanilac counties in the central and eastern portions of the Lower Peninsula of Michigan. The confirmation of rhizomania in sugar beet from the Great Lakes Region marks the last major American sugar beet production region to be diagnosed with rhizomania disease, nearly 20 years after its discovery in California (1). In 2002, there were approximately 185,000 acres (approximately 75,00 ha) of sugar beet grown in the Great Lakes Region, (Michigan, Ohio, and southern Ontario, Canada). The wide geographic distribution of infested fields within the Michigan growing area suggests the entire region should monitor for symptoms, increase rotation to nonhost crops, and consider planting rhizomania resistant sugar beet cultivars to infested fields.

First Report of Beet soil-borne virus on Sugar Beet in Iran.

Sugar beet is a main field crop in Iran and is cultivated in 186,000 ha. During the summer of 2001, sugar beet (Beta vulgaris) plants with pale, often upright, narrow, and rolled leaves were collected from the six main beet cultivation provinces of Iran (Fars, Ghazvin, Kermanshah, Khorasan, Semnan, and Isfahan). Roots of symptomatic plants were small, often with constriction, and exhibited warty outgrowth, proliferation of fibrous roots, and vascular necrosis. Beet soil-borne virus (BSBV) and Beet necrotic yellow vein (BNYVV, genus Benyvirus) were detected in sugar beet root samples by tissue-blot immunoassay (TBIA) using BSBV- and BNYVV-specific monoclonal antibodies (As-0576.1 and As-0799.1/CG6-F4, respectively; DSMZ Plant Virus Collection, Germany). Root extracts of sugar beet plants infected with BSBV, were infective by mechanical inoculation to Chenopodium quinoa causing necrotic ring spots. BSBV was detected in inoculated plants by TBIA. Laboratory tests using TBIA on 2,387 randomly collected samples showed that BSBV was present in 406 plants (17%) and BNYVV was present in 1,347 plants (56.43%). BSBV resembles BNYVV, the causal agent of sugar beet rhizomania, morphologically and in its transmission by Polymyxa betae (1). BNYVV has been reported previously from Iran (2). To our knowledge, this is the first report of BSBV occurring on sugar beet in Iran.

First Report of Rhizomania of Sugar Beet in the Columbia River Basin of Washington and Oregon.

Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV) and vectored by the soilborne fungus, Polymyxa betae Keskin, is one of the most economically damaging diseases affecting sugar beet (Beta vulgaris L.) worldwide and has been found in most sugar beet-growing areas of the United States (2). During harvest in October 2000, sugar beet plants exhibiting typical symptoms of rhizomania (1) were found in a field near Paterson, WA. Sugar beet had been planted in the field in 1999 and 2000, but prior to this, the field had not been planted with sugar beet for approximately 20 years. Symptomatic roots from the field exhibited stunting, vascular discoloration, and proliferation of lateral rootlets. Leaves of affected plants were chlorotic. Four soil samples were taken from symptomatic areas of the field and diluted with an equal amount of sterile sand. Seeds of rhizomania-susceptible sugar beet cv. Beta 8422 were planted in the soil and sand mix and maintained in a controlled environment at 24°C and 12 h of daylight at one location and in the greenhouse at another. After 8 weeks, enzyme-linked immunosorbent assay (ELISA) was performed on roots of plants grown at each location. Triple-antibody sandwich (TAS) ELISA (Agdia, Inc., Elkhart, IN) was conducted at the University of Idaho, Twin Falls, ID and double-antibody sandwich (DAS) ELISA was performed at USDA-ARS, Salinas, CA, with antiserum specific for BNYVV (2). Two of four samples were positive for BNYVV in the ELISA tests at both locations based on absorbance values at least three times those of healthy controls. TAS-ELISA tests were conducted on roots collected in July 2001 from a field in Washington, 12.9 km from the first field, as well as from a field across the Columbia River near Boardman, OR. Samples from both fields tested positive for BNYVV. All three fields are within 24 km of one another. Four additional fields have subsequently been confirmed to be infected with BNYVV in this region, based on symptomology and ELISA. There are approximately 3,240 ha of sugar beet grown in the region, and growers have been advised as a result of this confirmation to plant resistant cultivars and increase the sugar beet rotation interval with nonhost crops to a minimum of 4 years.

Breeding for resistance to rhizomania in sugar beet: a review.

Currently rhizomania is the most important disease insugar beet worldwide, and attack can lead to seriousyield losses. The disease is caused by beet necroticyellow vein virus (BNYVV) that is transmitted by thesoil-borne fungus Polymyxa betae. Breeding sugarbeet cultivars with resistance to rhizomania isregarded as the most appropriate way to enablecontinued production of this crop in BNYVV-infestedfields and also to slow the spread of the disease.Breeding for resistance started with selection byscoring disease symptoms in field experiments. Thedevelopment of non-destructive greenhouse tests, withdetermination of the virus concentration in rootletsusing ELISA, has greatly improved the efficiency ofselection. In this paper the impact of scientificresearch on the progress in breeding cultivars withresistance to rhizomania is reviewed. This includesthe distribution, composition, and pathogenicity ofthe virus, the sources of resistance to virus andvector, the genetics of virus resistance, progresswith breeding methods, and the use of molecularmarkers and pathogen-derived resistance. The yieldsand quality characteristics of recently introducedresistant cultivars now equal those of the commercialsusceptible cultivars.

Single-Chain Fv Fusion Proteins Suitable as Coating and Detecting Reagents in a Double Antibody Sandwich Enzyme-Linked Immunosorbent Assay

A recombinant enzyme-linked immunosorbent assay (ELISA) system, entirely based on antibody fragments, is described here as an attractive alternative to assays using polyclonal antisera or monoclonal antibodies. Two expression vectors have been developed for cloning and production of single-chain Fv (scFv) fusion proteins suitable as coating and detecting reagents, respectively, in a highly sensitive double antibody sandwich ELISA. The coating reagent is produced from the vector pZIP1, as a bivalent miniantibody with a leucine zipper for dimerization. The detection reagent is a fusion protein, in which a modifiedEscherichia colialkaline phosphatase with increased specific activity is attached to the carboxy-terminus of the scFv. This conjugate is produced using pDAP2/S as cloning and expression vector. Optimized bacteria expression and simple one-step purification by hexahistidine tag-mediated metal chelate affinity chromatography yielded milligrams of ELISA reagent per liter of bacterial culture in both cases. A double antibody sandwich ELISA for the detection of beet necrotic yellow vein virus, the causal agent of sugarbeet rhizomania, was developed using fusion proteins obtained by means of pZIP1 and pDAP2/S. The plant pathogen was detected with a sensitivity higher than that reached in a conventional ELISA employing polyclonal antisera. Both plasmid vectors are compatible to phage display vectors such as pHEN1, pCOCK, and the pCANTAB series, allowing simple subcloning after isolation of scFv from phage display libraries. It is therefore easy to develop and produce an ELISA entirely by using bacterial recombination and expression techniques.

Resistance to Polymyxa betae in Beta Species of the Section Procumbentes, in Hybrids with B. vulgaris and in Monosomic Chromosome Additions of B. procumbens in B. vulgaris

AbstractResistance to Polymyxa betae was studied in Beta species of the section Procumbentes, in hybrids of B. vulgaris with B. procumbens or B. patellaris, and in monosomic additions of chromosomes of B. procumbens in B. vulgaris. In all experiments P. betae infested with beet necrotic yellow vein virus (BNYVV) was used. This virus causes rhizomania in sugar beet, and the effect of vector resistance was studied by measuring virus concentrations. Cystosori of P. betae were not found in the wild species and the hybrids. Virus concentrations in these plants were low, and in half the number of plants the virus could not be detected. Results of experiments with the monosomic additions indicate, that resistance to P. betae in B. procumbens is located on chromosomes 4 and 8. Some cystosori were present in these addition types, while cystosori were abundantly present in other addition types and all sib‐plants. Virus concentrations in the addition types 4 and 8 were lower than in their sib‐plants, but in almost all plants the virus could be detected. A significant correlation (r = 0.91; P < 0.05) between average numbers of cystosori and average virus concentrations was found when addition families of type 8 were tested together with B. procumbens and B. vulgaris cv. ‘Regina’.

Evaluation of Polymyxa betae Keskin Contaminated by Beet Necrotic Yellow Vein Virus in Soil

The fungus Polymyxa betae Keskin belongs to the family Plasmodiophoraceae and lives in the soil as an obligatory parasite of the roots of the Chenopodiaceae. When contaminated by beet necrotic yellow vein virus, this viruliferous fungus causes a serious disease of sugar beet known as rhizomania, whereas the infection by the fungus alone (aviruliferous fungus) causes only slight damage to the plant with little economic consequence. The manifestation of rhizomania in sugar beet is directly related to the concentration of infecting units of viruliferous P. betae present in the soil. (One infecting unit is a group of one or more sporosori that liberate zoospores capable of visibly infecting a plant.) By using current methods of analysis, it is possible to estimate the total quantity of P. betae present in the soil, but one cannot distinguish quantitatively the infecting units of aviruliferous from viruliferous P. betae. A new method has been developed based on the technique of the most probable number and enzyme-linked immunosorbent assay to estimate the concentration of infecting units of viruliferous P. betae in soil. The method is suitable for the routine analysis of numerous soil samples and allows one to estimate the concentration of viable forms of the fungus P. betae, whether or not contaminated by beet necrotic yellow vein virus, present in a soil affected by rhizomania or presumed healthy. The analyses performed with this method are economical and use a reagent kit and equipment in wide use.

In-Bed Fumigation for Control of Rhizomania of Sugar Beet

Preplant application of fumigants by single chisel in plant bed centers significantly increased beet and sugar yields of sugar beets 5-6 months old. Products containing dichloropropene were the most effective in controlling rhizomania. In separate studies, application of Telone II at 29.3, 43.9, and 58.6 L/ha raised sugar yields 83-182, 252, and 78-258%, respectively, compared to the control treatments. Vorlex, Vorlex 201, and Pichlor 60 also reduced disease incidence and significantly increased yield when applied at 132.7, 146.1, and 32.7 L/ha, respectively. Sealing the soil with water, although not essential for effective control, significantly increased yield over unsealed treatments with Telone II at 29.3 L/ha and all rates of Vorlex. Although metham-sodium and the low rate of chloropicrin (21.3 L/ha) did not control rhizomania, sugar yields were 42 and 44% greater, respectively, than in control treatments, possibly because other root pathogens were controlled. (...)

Sugarbeet rhizomania in England1

Concern about the introduction of rhizomania to UK heightened when the disease was confirmed in The Netherlands in 1983. A series of precautionary measures supported by legislation was quickly enacted to reduce this risk. Extensive surveys of harvested beet and of growing crops failed to reveal any infection until 1987 when a single isolated outbreak was found near Bury St Edmunds in Suffolk. Plants in the affected field showed typical rhizomania symptoms and laboratory tests confirmed the presence of beet necrotic yellow vein furovirus (BNYVV). Further investigation of isolates from the outbreak field revealed the presence of beet soil‐borne furovirus in addition to BNYVV and sometimes both were present in mixed infections. Intensive surveys in the immediate area of the outbreak, both by field inspections of growing crops and by soil bait testing, confirmed infection only in the one field and the margin of the adjacent field. Immediate containment measures were followed by soil sterilization with methyl bromide to minimize the movement of infection from the area. Surveys of beet will continue, but results to date suggest that the distribution of the disease is limited in extent.

First Report of Rhizomania of Sugar Beet from Texas

First Report of Rhizomania of Sugar Beet from Texas

Beet necrotic yellow vein virus: different isolates are serologically similar but differ in RNA composition

SUMMARYTwelve isolates of beet necrotic yellow vein virus, agent of rhizomania in sugar beet, have been obtained from five European countries and the USA. The isolates were cloned and multiplied in the local lesion host Chenopodium quinoa. By ELISA, a close serological relationship was observed among all the isolates. The isolates differed, however, in the number of viral RNA species present (2, 3 or 4) and in the lengths of RNAs 3 and 4, the two smallest RNAs. A comparison of the symptoms induced by the different isolates in C. quinoa revealed a correlation between the presence of a full‐length RNA 3 (about 1850 nucleotides) and the appearance of severe chlorotic local lesions.

Host range of Polymyxa betae Keskin strains in rhizomania-infested soils of sugar beet fields in Japan.

Host range of Polymyxa sp. isolated from various plants grown in rhizomania-infested soils of three different localities in Hokkaido was compared. Among 108 species of plants belonging to 23 families tested, 12 plants belonging to Chenopodiaceae, Amaranthaceae and Portulacaceae were infected with the fungus. The other 20 families including Gramineae were not infected. All isolates of Polymyxa sp. were identified as Polymyxa betae Keskin on the basis of their host range and morphological characteristics. The host range of the isolates was found to be limited to the family of the original host. Among the Chenopodiaceous isolates, that from sugar beet did not infect Chenopodium album, and those from C. album did not infect sugar beet. These P. betae isolates could be divided into several formae speciales; Amaranthus retroflexus isolates were identified as P. betae Keskin f. sp. amaranthi Barr, for the Portulaca oleracea isolates a new forma specialis P. betae Keskin f. sp. portulacae was proposed. Although sugar beet isolates and C. album isolates should be divided into different formae speciales, respectively, the classification of these isolates should await comparison with the Canadian isolate from C. album. From these results it is suggested that sugar beet isolates of P. betae which have a high infectivity to Beta vulgaris are associated with the incidence of rhizomania of sugar beet whereas the other two formae speciales and C. album isolates may not be involved.