Major genes for resistance to beet necrotic yellow vein virus (BNYVV) in Beta vulgaris

Summary Inheritance of resistance to beet necrotic yellow vein virus (BNYVV) was studied in segregating F2 and backcross families obtained from crosses between resistant plants of the sugar beet selection Holly-1-4 or the wild beet accession Beta vulgaris subsp. maritima WB42 and susceptible parents. Greenhouse tests were carried out, in which seedlings were grown in a mixture of sand and infested soil. Virus concentrations of BNYVV in the rootlets were estimated by ELISA. To discriminate resistant and susceptible plants, mixtures of normal distributions were fitted to log₁₀ virus concentrations, estimated for segregating F1, F2 and BC populations of both accessions. The hypothesis that Holly-1-4 contained one single dominant major gene was accepted. For WB42, results fitted with the hypotheses that resistance was based on either one (or more) dominant major gene(s) showing distorted segregation, or two complementary dominant genes, which are both required for resistance. Resistance from WB42 appeared to be more effective against BNYVV than resistance from Holly-1-4.This research was carried out as part of a PhD study at the Graduate School Experimental Plant Sciences (EPS), Department of Virology, Wageningen, The Netherlands     

Breeding for resistance to rhizomania in sugar-beet (Beta vulgaris L.)

In breeding for resistance to rhizomania, breeding material was routinely examined for resistance to the rhizomania virus over several years. This study was performed in order to investigate the value of virological examination of sugarbeet breeding material in breeding for resistance to the rhizomania virus. Tests were conducted with varieties susceptible or partially resistant to rhizomania, as well as with several new and more-resistant hybrids. A test on young plants showed that all genotypes contained beet necrotic yellow-vein virus (BNYVV), but that the virus content differed widely. Plants of two commercially used partially resistant varieties had, on average, only half the virus content of susceptible varieties in their roots, and plants of eight new hybrids still in the process of registration contained less than one third of that amount. There was a significant negative correlation between the quantity of BNYVV in young plant roots and final yield under disease conditions in the field. Opportunities for further improvement in the level of the resistance to BNYVV in sugarbeet by means of conventional breeding programmes are discussed.     

Identification and mapping of random amplified polymorphic DNA markers linked to a rhizomania resistance gene in sugar beet (Beta vulgaris L.) by bulked segregant analysis

Bulked segregant analysis was employed to identify random amplified polymorphic DNA (RAPD) markers linked to a gene that confers rhizomania resistance to a sugar beet line created from a Holly Sugar Company breeding population (USA). Polymorphism revealed with 160 arbitrary 10-mer oligonucleotide primers was screened in two bulks produced by separately pooling the individual DNAs from the six most resistant and the six most susceptible plants of an F₂ population segregating for rhizomania resistance. A study of the F₂ individuals showed that 19 primers generated 44 polymorphic markers which were then grouped into nine linkage groups. By analysis of variance, 12 were shown to have a significant effect upon the level of resistance and were mapped on a segment 22.3 cM long. A quantitative trait locus (QTL) of resistance was identified and located in a 4.6cM interval between two markers. It accounted for 67.4% of the observed variation and almost all the genetic variation. These results suggest that the identified QTL corresponds to a unique major gene conditioning the Holly resistance studied, which we have named Rz-l.     

The origin of rhizomania resistance in sugar beet

In the last 35 years, breeding has greatly reduced the damages caused by rhizomania in sugar beet crops. After the first encouraging results using the Alba genotypes, the cultivar Rizor represented a substantial step forward and has given good yield improvement in diseased fields in many parts of the world. The original variety and subsequent improved versions continued to offer good performances for about a decade, after which it was surpassed by other hybrids derived in part from the Rizor itself. Further progress in terms of sugar production became possible in 1986, when the Holly monogerm lines were released in USA and Europe. In spite of the incomplete information about the genealogy of the first resistant materials,many evidences and the molecular analyses on the different genotypes suggest a possible common progenitor and lineage. The resistant cultivars have kept the yield at an adequate level, allowing cultivation to continue in countries where the disease has reached epidemic proportions. The case of rhizomania resistance in sugar beet can therefore be considered as one of the most important achievements in plant breeding. This revised version was published online in August 2006 with corrections to the Cover Date.     

The inheritance of resistance to beet necrotic yellow vein virus (BNYVV) in B. vulgaris subsp. maritima, accession WB42: Statistical comparisons with Holly-1-4

In this study, the inheritance of resistance to Beet necrotic yellow vein virus (BNYVV) in accessions Holly-1-4and WB42 was investigated. Crosses between both resistant sources and susceptible parents were carried out and F₁F₂ and BC₁ populations were obtained. Virus concentrations in WB42and its F₁ populations were lower than in Holly-1-4. Observed ratios of susceptible and resistant plants in segregating populations of Holly-1-4 as well as WB42 were in agreement with hypothesis of one dominant major gene. Segregation of plants in F₂ populations obtained from crosses betweenHolly-1-4 and WB42 revealed that the resistance genes in Holly-1-4 and WB42 were nonallelic and linked loci. This revised version was published online in July 2006 with corrections to the Cover Date.     

甜菜抗丛根病育种研究进展

为了研究甜菜抗丛根病育种的抗性基因来源以及作用特点,笔者归纳了甜菜丛根病抗性的来源,包括Alba抗性源、Rizor和Holly抗性源、WB42抗性源、WB41和WB258抗性源以及R36抗性源,并介绍了5种甜菜丛根病的抗性基因特点.另外,对甜菜抗丛根病资源的育成方法进行了总结,包括回交、杂交和轮回选择.通过这些方法将携...     

Multiplicative models for cultivar by location interaction in testing sugar beets for resistance to beet necrotic yellow vein virus

Summary Sugar beet cultivars were evaluated for resistance to beet necrotic yellow vein virus (BNYVV) on various locations in two consecutive years. Resistance levels of cultivars were measured by virus assays of plants from the field and the greenhouse. Infection levels in the fields were characterised by sampling plants of a susceptible indicator cultivar. For each year, statistical analyses were performed on two-way tables of cultivar by location for yield and quality parameters. In analysis of variance (ANOVA) significant main effects and significant cultivar by location interaction were found for all parameters (P<0.05). Interactions were further investigated by multiplicative models. In the Additive Main effects and Multiplicative Interaction effects (AMMI) model, interaction was written as the product of a cultivar score and a location score. Cultivar interaction scores were highly correlated to virus concentrations of the cultivars, and location interaction scores to virus concentrations of the susceptible indicator cultivar. Main effects of cultivars and locations were less clearly related to virus concentrations than interaction effects. In general, virus concentrations of plants from a greenhouse test gave higher correlations than virus concentrations of plants from the field. In the factorial regression model, virus concentrations were incorporated in the model. The model can be understood as a two-way ANOVA, with greenhouse virus concentrations and virus concentration of the indicator cultivar as concomitant variables on the cultivar and location factor. Results of analyses with both multiplicative interaction models showed that interactions of all yield and quality parameters can be described in terms of virus concentrations. Therefore, the relative performance of susceptible and partially resistant cultivars in infested fields can be estimated by means of three independent parameters, (i) the level of resistance determined in a greenhouse experiment, (ii) the yield and quality in non-infested fields, and (iii) the level of infection in the field.Abbreviations AMMI model Additive Main effects and Multiplicative Interaction effects model - ANOVA analysis of variance - BNYVV beet necrotic yellow vein virus - ELISA enzyme-linked immunosorbent assay - -amino N -amino nitrogen - K Kalium (potassium) - Na Natrium (sodium)     

Sources of resistance to diseases of sugar beet in related Beta germplasm: II. Soil-borne diseases

Between 580 and 700 accessions of related cultivated and wild species of the genus Beta were assessed for resistance to four soil-borne diseases of sugar beet: two seedling damping-off diseases caused by the fungi Aphanomyces cochlioides and Pythium ultimum and two diseases of more mature plants, Rhizoctonia root and crown rot, caused by the fungus R. solani, and Rhizomania, caused by Beet necrotic yellow vein virus (BNYVV), a furovirus transmitted by the plasmodiophorid Polymyxa betae. Analysis of resistance data (assessed on an international standardised 1–9 scale of Resistance Scores) indicated that the highest levels of resistance ({RS} 2) to A. cochlioides and P. ultimum were to be found amongst accessions of the more distantly related sections Corollinae (93% of accessions tested) and Procumbentes (10%), respectively; although useful levels could also be found in the more closely related, and sexually compatible, section Beta (1–6%). Resistance to Rhizoctonia was also found in section Beta (5–7%), depending on whether field or glasshouse tests were used, but there was little evidence of generally high levels of resistance to Rhizomania among accessions of this section. None of the accessions of sections Corollinae and Procumbentes exhibited any notable resistance to Rhizoctonia. However, all sections Procumbentes and some sections Corollinae (4%) accessions were highly resistant to Rhizomania. Individuals with high levels of resistance to Rhizomania were identified from within some section Beta and Corollinae accessions, in which there was evidence of segregation.     

Natural variation within the genus Beta and its possible use for breeding sugar beet: A review

Summary Sugar beet is a relatively young crop, which supposedly has a narrow genetic base. Natural variation occurring in primitive beet varieties and in wild Beta species has been used for breeding sugar beet. This paper reviews information on desirable characteristics in Beta germplasm and the attempts made for the introgression of such characters into commercial breeding material. After an introduction on the availability of germplasm and the possibilities of hybridisation, attention is focussed on the mating system (especially male sterility), on morphological and physiological characteristics, including yield and sugar content, and on resistances to diseases and pests.     

Acetocarmine squash method for observing sugar beet chromosomes

Summary Based on successful results of an acetocarmine squash method for staining chromosomes of many plant species, the method was applied to chromosomes of sugar beet (Beta vulgaris L.). This simple method proved to be applicable to the relatively small chromosomes of sugar beet. Several known disadvantages of acetocarmine staining techniques are overcome by applying acid hydrolysis and maceration. Squashing the stained specimens in 45% acetic acid increases the contrast between stained chromosomes and destained cytoplasm. The advantages of this method are its simple procedure and applicability to both somatic and meiotic chromosomes. Uniform and high quality preparations make detailed analysis possible even with the relatively small chromosomes of sugar beet.Contribution from the Department of Agronomy and published with the approval of the Colorado State University Experiment Station as Scientific Series Paper No. 2334.Supported in part by a Research Grant from the Great Western Sugar Company, Longmont, Colorado.     

Reduced titer of BNYVV in transgenic sugar beets expressing the BNYVV coat protein

Summary Rhizomania is a disease of sugar beet caused by the furovirus beet necrotic yellow vein virus (BNYVV). Coat protein mediated resistance has been reported for a number of viral diseases. This approach to virus resistance was therefore attempted for control of rhizomania. Two constructs of the coat protein gene of BNYVV were introduced into sugar beet by Agrobacterium-mediated transformation. The mRNA level was estimated to be 0.01% of the poly A⁺ RNA. Expression of the coat protein gene was under the detection limit of our western blotting protocol i.e. below 0.01 g/50 g (0.02% of the total soluble protein). One transformation event per construct was tested in a greenhouse assay and in rhizomania infested soil in a field trial. In the greenhouse assay, transgenic plants showed a strong reduction of virus multiplication when compared to non-transgenic plants. This result was confirmed in the field trial, where a significant difference in virus multiplication was shown between plants with and without the coat protein gene.     

Sugar beets homozygous for resistance to beet cyst nematode (Heterodera schachtii Schm.), developed from monosomic additions of Beta procumbens to B. vulgaris

Summary Monosomic additions of Beta vulgaris x B. procumbens with resistance to beet cyst nematode (Heterodera schachtii Schm.) were used for the production of resistant diploids through incorporation of the B. procumbens chromosome fragment bearing the resistance gene(s) into one of the sugar beet chromosomes. The heterozygotes obtained accordingly were selfed for producing homozygotes. These homozygotes differed morphologically from commercial sugar beet varieties, but produced reasonable amounts of pollen. Female transmission of resistance was 100%, whereas male transmission, apart from some exceptions, was more than 90%. The number of hypersensitivity reactions to penetrated larvae was related to the degree of susceptibility. Larval development was severely retarded in the resistant plants, preventing most of them to produce cysts. If cysts were formed, their content was considerably less as compared to those in the susceptible plants.     

Ecological aspects of transgenic sugar beet: transfer and expression of herbicide resistance in hybrids with wild beets

Summary An increasing number of genetically engineered cultivars of several crops is being experimentally released into the environment. In future, crops with new transgenic traits will probably play an important role in agricultural practice. The long-term effect of transgenes on community ecology will depend on the distribution and establishment of transgenic plants in the wild, on the sexual transfer of their new genes to the environment and on the potential ecological impact of the transgenic trait. The starting point was the use of transgenic sugar beet lines, Beta vulgaris subspec. vulgaris var. altissima DÖLL (Helm 1957), with transgenes coding for rhizomania and herbicide (BASTA^®) resistance. The first two questions to answer were: Can the transgenes be transferred via pollen to wild beets, Beta vulgaris subspec. maritima (L.) ARCANG. or cultivated relatives such as red beet or spinach beet and are they expressed in the hybrids? Can transgenes be monitored in young Beta vulgaris-hybrids? The experimental transfer of transgenes was conducted in 1993 at a field location in northern Germany. The beets were hand-pollinated with transgenic pollen. In a non destructive biotest, the hybrid seedlings were tested for herbicide resistance. Transgenic plants showed no noxious phenotypic effects whereas control plants developed leaf necroses. All herbicide resistant hybrids within the biotest were assumed to be transgenic.     

Sources of resistance to diseases of sugar beet in related <Emphasis Type="Italic">Beta</Emphasis> germplasm: I. Foliar diseases

Resistance to four foliar diseases of sugar beet (Beta vulgaris ssp. vulgaris), virus yellows caused by Beet mild yellowing virus (BMYV) and Beet yellows virus (BYV), powdery mildew (Erysiphe betae) and Cercospora leaf spot (Cercospora beticola), was assessed in up to 600 accessions of closely related wild and cultivated Beta species. Most accessions were from the Section Beta, a taxon containing types most closely related to, and sexually compatible with, sugar beet and therefore most valuable for use in crop improvement. Between 1–12% of accessions were highly resistant (resistance scores of 2 on an international standardised resistance scale of 1–9) to these diseases. These levels, however, underestimate the potential number of resistant sources available from this section as some accessions with intermediate mean resistance scores contained a significant proportion of highly resistant plants within segregating populations. Variation in resistance to all diseases except BYV was observed within the Section Beta. Much higher levels of resistance were observed, and more frequently, in more distantly related sections of the genus Beta. Accessions of the Section Corollinae were highly resistant to both viruses (>62% of accessions tested), but less so to Cercospora (15%) and they were very susceptible to powdery mildew. Section Procumbentes accessions were highly resistant to BMYV and Cercospora (100%) but less so to powdery mildew (50%) and BYV (20%). However, sexual incompatibility between these sections and sugar beet make utilisation of these sources impractical using conventional breeding methods.     

Chromosome localisation of genes for resistance to Heterodera schachtii, Cercospora beticola and Polymyxa betae using sets of Beta procumbens and B. patellaris derived monosomic additions in B. vulgaris

Beet cyst nematodes (BCN, Heterodera schachtii), Cercospora beticola, and rhizomania, caused by the beet necrotic yellow vein virus (BNYVV) and vectored by the soil-borne fungus Polymyxa betae, are the most serious diseases of sugar beet ( Beta vulgaris subsp. vulgaris). The wild Beta species of section Procumbentes are known to be completely resistant to H. schachtii, C. beticola and P. betae. Alien monosomic additions (2n=19), plants of cultivated beet (2n=18) carrying different individual chromosomes of B. procumbens (2n=18) or B. patellaris (2n=36), were tested in greenhouse experiments for resistance to these pathogens. Gene(s) conferring full resistance to the beet cyst nematode in B. patellaris are located on chromosome 1.1, and the other tested chromosomes of B. patellaris are not involved in the expression of resistance. Artificial inoculation under greenhouse conditions, with in vitro produced inoculum of C. beticola and spot-percentage rating of the disease intensity, showed that the high level of resistance that was observed in the wild species B. procumbens and B. patellaris was not found in any of the monosomic additions tested. It was suggested that genes on various chromosomes of the wild species are needed to express full resistance, and that the chromosomes of group 7 of B. patellaris and chromosome 7 of B. procumbens have the largest effect. The greenhouse tests for resistance to P. betae in B. patellaris derived monosomic additions showed that the addition families of group 4.1 have a strong partial resistance, while the addition families of group 8.1 appeared to be completely resistant to the pathogen. Resistance to P. betae in the two wild species as well as in the two resistant addition types did not exclude infection with BNYVV, but resulted in a considerable reduction of the virus concentration. It was concluded that resistance to the vector would complement virus resistance, and may provide a more effective and durable control of rhizomania. This revised version was published online in July 2006 with corrections to the Cover Date.     

Peroxidase activity as a possible test for distinguishing s-plasm from n-plasm in sugar beet (Beta vulgaris L.)

Summary The O-type lines (N-plasm) of sugar beet (Beta vulgaris L.) proved to have a consistently lower peroxidase activity (49.2–62.7%) than their male sterile (MS) equivalents (S-plasm).Similar differences in peroxidase activity (45.4–56.3%) were found when O-type lines were compared with unrelated MS lines. They were also observed in different parts of the plant (cotyledons, hypocotyl + radicle, true leaves) and were reproducible.The fertile lines could be grouped by their level of peroxidase activity in categories of either S-plasm or N-plasm.The peroxidase activity test could be used for selection of N-plasm lines from fertile sugar beet populations and for selection of MS and O-type lines of higher stability.     

Breeding sugar beets with globe-shaped roots: selection and agronomical performance

Losses and costs during and after harvesting of sugar beets can be reduced by modifying the traditional shape of the roots. Crosses have been made between sugar beets and globe-shaped red table beets, and selection for root shape and sugar content was carried out in the progenies. The root yield of the selected material is equal to that of commercial varieties. The sugar content is still too low and the contents of juice impurities too high, but further selection can improve the material in these respects. The amount of dirt tare can be 40–60% less than that of the control variety.     

Induction of cytoplasmic male sterility and fertility reversion by mutagenesis; negative evidence from a study on sugar beet

Summary Attempts have been made to induce cytoplasmic male sterility (cms) and cytoplasmically inherited fertility reversion in sugar beet using various mutagenic agents by repeating techniques previously described. Despite the previous report of successful induction of cms and reversion at very high frequency it was not possible to repeat this success. Analysis of M₂ plants at the DNA level demonstrated no major rearrangements in chloroplast or mitochondrial DNA.     

Partial resistance of sugarbeet to beet cyst eelworm (Heterodera schachtii Schm.)

Summary Within Beta vulgaris and B. maritima origins some partial resistance to beet cyst eelworm was found which could be raised to a very limited extent by selection. However after the second backcross to commercial sugar beet varieties and successive selection of the inbreds this resistance was lost. It was demonstrated that in the rootsystem of resistant plants as much nematodes penetrate and develop as in susceptible ones but the ratio between males and females is different. It was therefore quite probable that this resistance is polyfactorial and merely recessive.     

An evaluation of single plant randomised field trials of sugar beet (Beta vulgaris L.)

Summary Diploid, monogerm families of sugar beet were grown in transplanted field trials randomised on a single-plant basis. Individual roots were weighed and a range of chemical characters were assessed. There was no significant difference in performance between plants that had members of their own family as nearest neighbours within the row and plants that had randomly assigned neighbours. Good correlations were found between the performance of families in single-plant trials and their performance in conventional plot trials. We conclude that single-plant randomisation could prove useful for genetical studies and for breeding trials particularly when seed or facilities are limited.