Genetic study of a new color of the beet Beta vulgaris L

A new genetic character of the beet Beta vulgaris L., named stem color, was described and studied genetically. This character was shown to be dominant trait and monogenically inherited. The first-year beet plants with the genotype Stc/_have red leafstalks, weakly colored central rib, and colored storage root; however, the root itself is not colored. The second-year plants have a red-colored low third of the floral shoot. The plants with the genotype stc/stc are uncolored. The Stc gene was localized to the first linkage group at a distance of 17.5 +/- 2.1 crossing over units from the gene B (Bolting), which controls the annual-perennial habit of beet.     

dw2, a new mutation of beet Beta vulgaris L

Twelve dwarf plants were found in the second hybrid generation of beet. The average height of mutant plants was 21.8 cm, their leaf blades and flowers were significantly smaller than normal, and the plants exhibited male and female sterility. This dwarfism was shown to be caused by a mutation differing from that previously described in beet, which is named dwarf2 (dw2). The experimental evidence suggests that this mutation appeared in one of the first-generation plants. Based on plant phenotype in the first hybrid generation and the number of mutant plants in the second one, this mutation is suggested to be under recessive monogenic control of the dw2 gene. The genotypic class segregation in the second hybrid generation indicates that the dw2 gene is inherited independently of genes m, at, and ap that control choricarpousness, gene male sterility, and pollen grain aggregation into tetrads.     

Genetic control of morphological characters of the beet (Beta vulgaris L.)

A brief review of theoretical and practical results of investigation of genetical control of a number of traits of beet, including self-incompatibility, monogerm-multigerm, cytoplasmic male sterility and some others is presented. Data concerning linkage groups of individual genes, determining morphological and biochemical traits are demonstrated.     

A new cytoplasmic male sterile genotype in the sugar beet Beta vulgaris L.: a molecular analysis

Summary Mitochondrial DNA (mtDNA) from fertile (N) and possibly new cytoplasmic male sterile (CMS) genotypes was studied in the sugar beet Beta vulgaris L. It was found by restriction endonuclease analysis that BMC-CMS, a cytoplasm that was derived from the wild beet Beta maritima, contained a unique type of mtDNA which is distinguishable from both the N and S-CMS, the only other CMS genotype that is currently availabe in B. vulgaris L. The organization of three genes: coxI, coxII and cob, was analyzed by hybridization with heterologous probes from maize. These genes have a similar structure in N and BMC-CMS that is different from S-CMS. It is concluded that BMC-CMS is a novel CMS genotype in the sugar beet.     

Genetic analysis of bolting after winter in sugar beet (Beta vulgaris L.)

Key message

This study reveals for the first time a major QTL for post-winter bolting resistance in sugar beet ( Beta vulgaris L.). The knowledge of this QTL is a major contribution towards the development of a winter sugar beet with controlled bolting behavior.

Abstract

In cool temperate climates, sugar beets are currently grown as a spring crop. They are sown in spring and harvested in autumn. Growing sugar beet as a winter crop with an extended vegetation period fails due to bolting after winter. Bolting after winter might be controlled by accumulating genes for post-winter bolting resistance. Previously, we had observed in field experiments a low post-winter bolting rate of 0.5 for sugar beet accession BETA 1773. This accession was crossed with a biennial sugar beet with regular bolting behavior to develop a F₃ mapping population. The population was grown in the greenhouse, exposed to artificial cold treatment for 16 weeks and transplanted to the field. Bolting was recorded twice a week from May until October. Post-winter bolting behavior was assessed by two different factors, bolting delay (determined as days to bolt after cold treatment) and post-winter bolting resistance (bolting rate after winter). For days to bolt, means of F₃ families ranged from 25 to 164 days while for bolting rate F₃ families ranged from 0 to 1. For each factor one QTL explaining about 65 % of the phenotypic variation was mapped to the same region on linkage group 9 with a partially recessive allele increasing bolting delay and post-winter bolting resistance. The results are discussed in relation to the potential use of marker-assisted breeding of winter sugar beets with controlled bolting.     

Cytogenetics of autotetraploid sugar beet (Beta vulgaris L.)

Summary Autotetraploid and diploid varieties of sugar beet were investigated for morphology, plant development, root and seed yield. The results obtained from the tetraploid varieties were evaluated according to the number of euploid and aneuploid plants found in each variety. Aneuploid plants often are characterized by delayed growth and poor root or seed yield, which reflects in the average yield of the tetraploid variety. Eutetraploid plants will compete successfully with their diploid counterparts. Until chromosomal stability of euploid plants will be found, aneuploid plants can be eliminated by mechanical selection only, which has to be repeated in each generation. A mechanical selection for euploidy will not only lower the amount of aneuploids in the tetraploid varieties, but also among the triploid hybrid seeds.

---

Zusammenfassung Autotetraploide und diploide Zuckerrübensorten wurden auf Morphologie, Wachstum sowie Rüben-und Samenertrag untersucht. Die Ergebnisse der tetraploiden Sorten wurden gemäß den in ihnen gefundenen Anteilen von euploiden und aneuploiden Pflanzen ausgewertet. Aneuploide Pflanzen sind oft durch verlangsamtes Wachstum und schlechten Rüben- oder Samenertrag gekennzeichnet, was sich im Durchschnittsertrag der tetraploiden Sorten widerspiegelt. Eutetraploide Pflanzen können erfolgreich mit den entsprechenden diploiden konkurrieren. Ehe nicht chromosomal stabile eutetraploide Pflanzen gefunden werden, können Aneuploide nur durch mechanische Selektion ausgelesen werden. Diese muß in jeder Generation wiederholt werden. Eine mechanische Selektion auf Aneuploide wird die Anzahl der Aneuploiden nicht nur in den tetraploiden Sorten herabsetzen, sondern auch unter den triploiden Hybridsamen.

---

Resumen Se investigó variedades autotetraploides y diploides de remolacha azucarera en relación con la morfología, el desarrollo y el rendimiento en raíz y semilla. Los resultados obtenidos de la variedad tetraploide se evaluaron de acuerdo con el número de plantas euploides y aneuploides halladas. Las plantas aneuploides se caracterizan frecuentemente por un crecimiento retardado y una producción pobre en raíz o semilla, propiedades que se reflejan en el rendimiento medio de las variedades tetraploides. Las plantas eutetraploides pueden competir con éxito con sus correspondientes diploides. Mientras no se alcance la estabilidad cromosómica de las plantas euploides, las aneuploides pueden únicamente eliminarse por medio de una selección mecánica, selección que debe repetirse en cada generación. Una selección mecánica para euploidía no sólo rebajará la proporción de aneuploides en las variedades tetraploides sino tambien dentro de las semillas híbridas triploides.

     

Molecular genetic investigation of sugar beet (Beta vulgaris L.)

Molecular genetic studies of sugar beet (Beta vulgaris L.) are reviewed as a basis for the development of genomics of this species. The methods used to study structural and functional genomics are considered. The results and their application to increase the efficiency of sugar beet breeding are discussed.     

A linkage map of sugar beet (Beta vulgaris L.)

Summary We have established a first linkage map for beets based on RFLP, isozyme and morphological markers. The population studied consisted of 96 F₂ individuals derived from an intraspecific cross. As was expected for outbreeding species, a relatively high degree of polymorphism was found within sugar beet; 47% of the DNA markers were polymorphic for the chosen population. The map consists of 115 independent chromosomal loci designated by 108 genomic DNA probes, 6 isozyme and one morphological marker. The loci cover 789 cM with an average spacing of 6.9 cM. They are dispersed over nine linkage groups corresponding to the haploid chromosome number of Beta species. Eighteen markers (15.4%) showed distorted segregation which, in most instances, can be explained by gametic selection of linked lethal loci. The application of the linkage map in sugar beet breeding is discussed.     

Genetic and chromosomal localization of the 5S rDNA locus in sugar beet (Beta vulgaris L.).

A digoxigenin-labelled 5S rDNA probe containing the 5S rRNA gene and the adjacent intergenic spacer was used for in situ hybridization to metaphase and interphase chromosomes of a trisomic stock from sugar beet (Beta vulgaris L.). Three chromosomes of primary trisomic line IV (T. Butterfass. Z. Bot. 52: 46-77. 1964) revealed signals close to the centromeres. Polymorphisms of 5S rDNA repeats in a segregating population were used to map genetically the 5S rRNA genes within a cluster of markers in linkage group II of sugar beet. The concentration of genetic markers around the centromere presumably reflects the suppressed recombination frequency in centromeric regions. The correlation of physical and genetic data allowed the assignment of a linkage group to sugar beet chromosome IV according to line IV of the primary trisomics.     

Improvement of protoplast culture protocols for Beta vulgaris L. (sugar beet)

Summary The effects of NaCl, feeder cells and the embedding of protoplasts in calcium alginate have been investigated in an attempt to improve culture conditions of recalcitrant sugar beet (Beta vulgaris L.) mesophyll protoplasts. While the use of NaCl in all instances proved detrimental to protoplast development, the other two treatments had clear beneficial effects. Minimum plating densities, necessary to sustain cell division, could be reduced to <5% (<4000 protoplasts / ml) of the control levels and plating efficiencies could be significantly enhanced by approx. 10 fold. Plants could still be regenerated from soft calli derived from mesophyll protoplasts cultured under the modified conditions at a frequency of 20–30 %. In particular, the use of alginate is considered of potentially great importance for the further application of beet protoplasts for other aims e.g. asymmetric hybridization.     

Low level of gene flow from cultivated beets (Beta vulgaris L. ssp. vulgaris) into Danish populations of sea beet (Beta vulgaris L. ssp. maritima (L.) Arcangeli)

Gene flow from sugar beets to sea beets occurs in the seed propagation areas in southern Europe. Some seed propagation also takes place in Denmark, but here the crop-wild gene flow has not been investigated. Hence, we studied gene flow to sea beet populations from sugar beet lines used in Danish seed propagation areas. A set of 12 Danish, two Swedish, one French, one Italian, one Dutch, and one Irish populations of sea beets, and four lines of sugar beet were analysed. To evaluate the genetic variation and gene flow, eight microsatellite loci were screened. This analysis revealed hybridization with cultivated beet in one of the sea beet populations from the centre of the Danish seed propagation area. Triploid hybrids found in this population were verified with flow cytometry. Possible hybrids or introgressed plants were also found in the French and Italian populations. However, individual assignment test using a Bayesian method provided 100% assignment success of diploid individuals into their correct subspecies of origin, and a Bayesian Markov chain Monte Carlo (MC MC) approach revealed clear distinction of individuals into groups according to their subspecies of origin, with a zero level of genetic admixture among subspecies. This underlines that introgression beyond the first hybridization is not extensive. The overall pattern of genetic distance and structure showed that Danish and Swedish sea beet populations were closely related to each other, and they are both more closely related to the population from Ireland than to the populations from France, the Netherlands, and Italy.     

Genetic approaches to sustainable pest management in sugar beet (Beta vulgaris)

Sugar beet (Beta vulgaris) is an important arable crop, traditionally used for sugar extraction, but more recently, for biofuel production. A wide range of pests, including beet cyst nematode (Heterodera schachtii), root‐knot nematodes (Meloidogyne spp.), green peach aphids (Myzus persicae) and beet root maggot (Tetanops myopaeformis), infest the roots or leaves of sugar beet, which leads to yield loss directly or through transmission of beet pathogens such as viruses. Conventional pest control approaches based on chemical application have led to high economic costs. Development of pest‐resistant sugar beet varieties could play an important role towards sustainable crop production while minimising environmental impact. Intensive Beta germplasm screening has been fruitful, and genetic lines resistant to nematodes, aphids and root maggot have been identified and integrated into sugar beet breeding programmes. A small number of genes responding to pest attack have been cloned from sugar beet and wild Beta species. This trend will continue towards a detailed understanding of the molecular mechanism of insect–host plant interactions and host resistance. Molecular biotechnological techniques have shown promise in developing transgenic pest resistance varieties at an accelerated speed with high accuracy. The use of transgenic technology is discussed with regard to biodiversity and food safety.     

Biolistic transformation of highly regenerative sugar beet (Beta vulgaris L.) leaves

Leaves of greenhouse-grown sugar beet (Beta vulgaris L.) plants that were first screened for high regeneration potential were transformed via particle bombardment with the uidA gene fused to the osmotin or proteinase inhibitor II gene promoter. Stably transformed calli were recovered as early as 7 weeks after bombardment and GUS-positive shoots regenerated 3 months after bombardment. The efficiency of transformation ranged from 0.9% to 3.7%, and stable integration of the uidA gene into the genome was confirmed by Southern blot analysis. The main advantages of direct bombardment of leaves to regenerate transformed sugar beet include (1) a readily available source of highly regenerative target tissue, (2) minimal tissue culture manipulation before and after bombardment, and (3) the overall rapid regeneration of transgenic shoots.     

Variability of cathodic peroxidases in sugar beet (Beta vulgaris L.) cultivars

Eighteen varieties of sugar beet (Beta vulgaris L.), originating from various European countries, were compared in respect of peroxidase variability level. They were cultivated in the same experimental plot. The cultivars differed in ploidy level: one variety was tetraploid, three were diploid and 14 varieties were triploid. The cathodic peroxidase system is controlled by four independent genes, of which only one is polymorphic. Consequently, the varieties were characterised by frequencies of 3 allozymes belonging to one locus. Only one variety proved to be fully monomorphic. Genetic similarities between the cultivars were illustrated by a dendrogram (UPGMA) and show different groups of varieties not related to their ploidy level.     

The "crystals" in the sugar beet (Beta vulgaris L.) leaves

Crystal containing cells widely distributed in plant tissues, though the origin of the crystals and their functions are still opened to question. Membrane vesicles in beet leaves are visible in electronic microscope. They originate in cytoplasm and penetrate into vacuole by pinocytosis with participation of tonoplast. In light microscope, vesicles are luminous likewise crystals in crystal cells. Such vesicles-"crystals" fulfill crystal cells also. The content of vesicles-"crystals" are electronic transparent at every path of leaf development. It was proposed that distinct vesicles-"crystals" in cytoplasm and vacuole and mass of them in crystal cells, vein bundles, and epidermal cells--all of them are lytic compartments. Later, obviously, true crystals are formed.     

Flavin excretion from roots of iron-deficient sugar beet (Beta vulgaris L.)

The characteristics of flavin excretion from iron-deficient sugar-beet roots have been studied. Roots from iron-deficient sugar beet excreted flavins when plants were allowed to decrease the pH of the nutrient solution, but not when plants were grown in nutrient solutions buffered at high pH. As shown by reversed-phase high-performance liquid chromatography, the two major flavins whose excretion was induced by iron deficiency were different from riboflavin, FMN and FAD. These flavins have been identified as riboflavin 3′-sulfate and riboflavin 5′-sulfate by electrospray-mass spectrometry, inductively coupled plasma emission spectroscopy, infrared spectrometry and¹H-nuclear magnetic resonance. We have characterized the time courses of accumulation of the different flavins in the nutrient solution and considered several possible roles for flavin excretion in iron acquisition.     

Restriction fragment map of sugar beet (Beta vulgaris L.) chloroplast DNA

Summary A restriction endonuclease fragment map of sugar beet chloroplast DNA (ctDNA) has been constructed with the enzymes SmaI, PstI and PvuII. The ctDNA was found to be contained in a circular molecule of 148.5 kbp. In common with many other higher plant ctDNAs, sugar beet ctDNA consists of two inverted repeat sequences of about 20.5 kbp separated by two single-copy regions of different sizes (about 23.2 and 84.3 kbp). Southern hybridization analyses indicated that the genes for rRNAs (23S+16S) and the large subunit of ribulose 1,5-bisphosphate carboxylase were located in the inverted repeats and the large single-copy regions, respectively.