A gene complex for annual habit in sugar beet (Beta vulgaris L.)

Annual habit in sugar beet has been shown to be controlled by a dominant gene, B, which induces bolting under long days without the cold requirement usually essential for biennial cultivars. The induction of bolting by B, however, is often influenced by both environmental and genetic factors. We studied the genetic basis for bolting suppression, caused by delayed planting, in lines derived from a cross between annual and biennial lines. The F₂ progeny of a late-bolting F₁ plant yielded an unexpected segregation ratio of annuality from monogenic inheritance when planted in late May, there being an excess of non-bolting biennials, although the expected segregation was observed in the late April sowing. Bolting suppression was caused by restricted daylengths due to delayed planting because the segregation was normal under artificially induced long days. The analysis with Idh1, an isozyme marker proximal to B, demonstrated that heterozygous B plants were more susceptible to bolting suppression due to delayed planting than homozygous B plants. The results suggest that bolting suppression was controlled by a number of genes responsible for long daylength requirement, one of which was closely linked to B and formed a gene complex for annuality. The annual habit was controlled singly by B under long days but modified by the genes for long daylength requirement under restricted daylengths. This revised version was published online in July 2006 with corrections to the Cover Date.     

Graft-transmissio of male sterility in sugar beet (Beta vulgaris L.)

Cytoplasmic male sterility in sugar beet was successfully transmitted across the union where male sterile and equivalent O-type plants were reciprocally grafted. Two experiments are described. In the first, 30 pairs of developing flowering stems were exchange-grafted between male-sterile and O-type plants. Fifteen O-type scions exhibited full or partial male sterility when grafted to male-sterile stocks and sterility was observed in progeny from these in eleven cases. In flowers from side shoots of O-types grafted with male-sterile scions eight cases exhibited some male sterility and progeny from four of these retained the sterility. In the second experiment O-type seedlings were grafted to male-sterile seedlings and out of the 22 success-fully raised to flowering, male sterility was exhibited in 12 of them. Male sterility occurred among progeny of all 22, even where the sterility could not be detected in the scions. In six cases where the scion appeared fully male-sterile no pollen was produced in any of the progeny.     

A marker-assisted analysis of bolting tendency in sugar beet (Beta vulgaris L.)

Bolting tendency in sugar beet varies among breeding lines and cultivars. Four crosses were made between breeding lines susceptible and resistant to bolting in order to study the genetic basis of bolting tendency. Bolting percentage in F₂, after 8 weeks of low temperature treatment, varied among the crosses, suggesting a complicated genetic control of bolting tendency. Different segregation ratios were observed, in particular, between families derived from the bolting F₁ plants and those from their non-bolting siblings, the former families showing a significantly higher bolting percentage than the latter. A marker-assisted analysis with seven isozyme loci, Ak1, Gdh2, Idh1, Lap, Mdh1, Pgi2 and Pgm1, revealed that a locus with marked effect on bolting tendency was located near Idh1. Because of a close linkage of Idh1 with B for annuality, the gene tagged by Idh1 appeared to be equivalent or similar to B′ for easy bolting allelic to B as reported by Owen et al. (1940). The results obtained suggest that the B locus may not only have an important role in determining growth habits but also control various degrees of bolting tendency in individual sugar beet plants. A linked pair, Ak1-Lap, and Pgi2 also were found to affect bolting tendency, although their effects varied depending on the crosses and families tested. This revised version was published online in July 2006 with corrections to the Cover Date.     

Effects of weather variables on sugar beet yield development (Beta vulgaris L.)

There is much data on the impact of weather variables on the growth of sugar beet from studies conducted under controlled conditions or single field experiments, but these data are of only limited validity for other sites or larger areas. The aim of the present study was to quantify the influence of weather conditions on the growth of sugar beet for the further development of simulation models, based on data representative of sugar beet cultivation in Germany. For this purpose, 27 field trials were conducted in 2000–2001 in commercial fields with variable climatic and soil conditions. From the end of May until the end of the season, beets were harvested manually every 4 weeks, the dry matter yield of leaves and taproot was determined and their growth rates were calculated. Temperature, solar radiation, rainfall and humidity were recorded daily for each site and the potential evapotranspiration and climatic water balance were estimated. The soil water content to a depth of 0.9 m was determined at every harvest date.Several functions were developed to describe the growth of sugar beet as affected by the given meteorological variables. From sowing to the end of June, the dry matter accumulation of both leaves and taproot was strongly enhanced by increasing temperature and during this period leaf dry matter increased linearly with thermal time. After reaching 700 °C d, the taproot dry matter accumulated exponentially with thermal time. The optimum mean daily air temperature for taproot growth was approximately 18 °C. Higher temperature occurring in July and August decreased final taproot yield, but by the end of the season, growth was independent of temperature. High solar radiation advanced growth during the first 65 days after sowing and again in October.Neither the water input by rainfall and irrigation nor the climatic water balance adequately described the growth of the leaves or taproot, but it was shown that the increase in taproot dry matter during July and August depended on the amount of available water in the soil. The maximum sugar yield that can theoretically be achieved in Germany and comparable agroclimatic regions was calculated as 24 t ha⁻¹. The present data reliable for a large agroclimatic region in Europe are of significant value as input for simulation models.     

Combining different linkage maps in sugar beet (Beta vulgaris L.) to make one map

Several genetic maps for sugar beet (Beta vulgaris L.), from different German research groups, have been published and it is now possible to consider combining them with the aid of the common markers. The computer program JOINMAP (versions 1.3 and 2.0) was used for pair-wise combination of three populations. Several problems arose: the genetic background of the populations, different population structures (F₂ versus F₁× F₁), different number of polymorphic loci for common probes in the populations to be combined, different estimates of the recombination rates between the same markers and differences between the Join Map versions. The maps from two F₂ populations could be integrated into a single map, but it was more appropriate to construct separate maps for the F₂ populations and the F₁× F₁ population using common markers as reference points only.     

Combined linkage maps and QTLs in sugar beet (Beta vulgaris L.) from different populations

The construction of genetic maps is an expensive and time-consuming process. The breeder is therefore interested in using maps developed from other mapping populations but this is only possible if the genetic structure is similar for the chromosomal regions of interest. In this paper, maps of three populations of sugar beet (Beta vulgaris L.) with common polymorphic marker loci are compared. Maps were constructed with MAPMAKER 3.0 and JOINMAP 2.0. Both mapping programs gave, in general, the same order for common markers. However, the number of common markers was too low to construct a combined map for all chromosomes. For one population, in contrast to the other two, the map constructed with MAPMAKER 3.0 was much longer than that constructed with JOINMAP 2.0. For two of these populations yield traits were also available from different environments. For quantitative trait loci (QTL) analysis of the yield data, the packages MAPMAKER/QTL 1.1 and PLABQTL were used. No QTL common for the two populations could be detected. The program and the version used strongly influenced the estimated positions of QTLs. There was also a strong interaction with environments.     

Selection for sugar yield in sugar beet, Beta vulgaris, using different selection indices

In sugar beet breeding, sugar yield is mainly influenced by root yield and sugar content. In this short communication several indices to select for both traits simultaneously are compared in order to find the best one. The indices are correlated with the base index of Williams (1962) from independent experiments. The indices differ in the amount of information necessary for the calculation of their weights. Three different series of each eight sites gave similar results. The optimum index using all information from phenotypic and genotypic variances and covariances, did not perform best. Sugar content with its higher herit ability must have a larger weight than root yield. Heritabilities as index weights performed best, but two other indices using heritabilities and phenotypic but no genetic covariances also performed well.     

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.     

Integration of AFLP markers into a linkage map of sugar beet (Beta vulgaris L.)

The AFLP (amplified fragment length polymorphism) technique has been applied in establishing an extended linkage map of sugar beet. A total of 120 AFLPs were integrated into an existing linkage map based on RFLP markers. Four primer combinations yielded between 19 and 40 polymorphic bands in an F₂ population consisting of 94 plants. The AFLP loci were evenly distributed over the nine linkage groups, with the exception of linkage group V where the number of AFLPs was significantly low. The AFLPs were found to be reproducible even against the background of different combinations of Taq DNA polymerases and buffers. However, the quantity of higher molecular weight fragments (>400 bp) was reduced when using plant DNA of poor quality as a template. The results of these experiments are discussed, together with possible applications of AFLPs in sugar beet breeding.     

Overwintering of genetically modified sugar beet, Beta vulgaris L. subsp. vulgaris, as a source for dispersal of transgenic pollen

The potential impact of transgenic crops on community ecology will depend on the distribution and establishment of the new transgenic traits, on the sexual transfer of their new genes to the environment (Bartsch &; Pohl-Orf, 1996) and on the potential ecological impact of the transgenic trait. Flowering and pollen dispersal is important for outcrossing of the genetically engineered trait. For a biennial plant, like the cultivars of Beta vulgaris L., overwintering is normally necessary to become generative and to produce pollen and seeds (Abe et al., 1997), which usually does not happen with sugar beet as a field crop harvested in autumn (Longden 1989). The starting point for the project was a transgenic sugar beet, Beta vulgaris L. subsp. vulgaris (Lange et al., 1998), with rhizomania and herbicide ( Basta®, Liberty®) resistance. Cold tolerance is one of the most important factors for survival of sugar beet in Central- and North-Europe. Among other ways, spreading of transgenic traits into weed beet (Boudry et al., 1993) or wild beet can occur if genetically engineered – biennial – plants survive the winter, flower in spring and spread their pollen. Field experiments were performed with transgenic breeding lines and their hybrids, transgenic and non-transgenic hybrids with Swiss chard and three conventional beet cultivars to evaluate winter survival rates at seven different field sites. We could show that survival of sugar beet – transgenic as well as conventional ones – in Germany and at the Dutch border is possible. Survival rates were well correlated with temperature data and were unexpectedly high. Differences between sugar beet hybrids and breeding lines could be detected but not within different breeding lines or hybrids. There were no differences detectable between transgenic and non-transgenic plants. The data are crucial for the risk assessment of the release of transgenic sugar beet and are the basis for further experiments towards outcrossing and establishment.     

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.     

A genetic map of sugar beet (Beta vulgaris) based on RAPD markers

Linkage analysis of sugar beet (Beta vulgaris L.) was performed with random amplified polymorphic DNA (RAPD)-markers. From three segregating populations, a combined genetic map was constructed which comprises 85 RAPD, five isozyme, one RFLP marker and the genes for resistance against the nematode Heterodera schachtii Schm., one restorer locus for male sterility and the genes for annuality and hypocotyl colour. For mapping of the two unlinked restorer genes a statistical model was developed based on the maximum-likelihood function.     

甜菜种质资源品质性状鉴定与评价

旨在更加科学真实地评价甜菜种质资源的品质性状,有针对性地对种质资源优异品质性状进一步挖掘利用。引用甜菜块根蔗糖可回收率、杂质指数、可回收蔗糖量3 个综合指标,排除甜菜块根中有害性非糖分钾、钠、α-氮的影响,对参试的162 份甜菜种质资源2 年试验鉴定结果的有关品质性状进行分析。结果表明：甜菜块根中影响蔗糖提取的有害性非糖分钾、钠、α-氮在不同的种质资源材料间差异较大,其中钠含量在参试种质资源材料中极差达到4.763 mmol/100 g,为平均数的1.84 倍,变异系数34.43%;α-氮含量和钾含量在不同参试种质资源材料间也表现出较大差异,变异系数分别为16.90%和19.03%。通过对参试种质资源材料的评价,筛选出蔗糖含量高、有害性非糖分含量低的高糖组种质资源材料10份、中高糖组48份材料,2组平均蔗糖可回收率分别为15.88%和14.95%;筛选出杂质指数低于4.0、块根产量在45.00 t/hm2以上的丰产型种质资源材料7份,杂质指数4.0~4.5、块根产量在45.00 t/hm2以上丰产性较好的种质资源材料14 份。甜菜块根中可回收蔗糖量指标综合了蔗糖可回收率和块根产量2个性状指标,利用该项指标评价种质资源材料,可以挖掘出丰产优质的种质资源。用可回收蔗糖量指标评价甜菜品种,筛选丰产、高工艺品质的品种,兼顾甜菜种植者和制糖企业双方利益,有利于甜菜制糖产业可持续发展。     

Genetic study of bolting and stem length in sugar beet (Beta vulgaris L.) using a factorial cross design

Summary The objective was to study the genetic basis of bolting and stem length in sugar beet full-sibs, developed by a factorial mating design (N.C. design II). The extent to which the inheritance of these characters can be attributed to the additive and non-dominance variation was investigated. The genetic analysis consisted of three sets (4×10, 4×8, and 3×8) of progenies. Estimates of additive genetic variance (² _A) and variance due to dominance deviations with some fractions of epistatic variance (² _D) were obtained for both characters. Bolting had a relatively large proportion of total genetic variance accounted for by ² _A. In most cases, non-additive effects were also important in determining the type of gene action in bolting. Stem length showed similar genetic variation to bolting susceptibility. Bolting resistance seemed to be dominant to the bolting susceptibility in most cases. Narrow sense heritability estimated for bolting was generally very large (0.93 to 0.96), which suggests that early generation selection for bolting resistance in a sugar beet population would be successful.     

The effect of in planta TIBA and proline treatment on somatic embryogenesis of sugar beet (Beta vulgaris L.)

The effect of in planta TIBA and L-proline onin vitro seedlings and cell culture of sugar beet was investigated. Sterilized seeds were grownin vitro on 1/2 MS medium supplemented with 0 or3 mg/l TIBA. Calli obtained on young leaves cultured on MS medium containing 1 mg/l BAP, were used for the initiation of cell suspension cultures using MS basal composition supplemented with 0 or 50 mM proline. Aliquots of 1 ml from cell suspension culture were inoculated onto the first somatic embryo induction MS medium containing TIBA 0.5 mg/l, BAP 1.0 mg/l, and proline at 0 or 50 mM. After three weeks of culture, embryogenic calli were transferred to the second embryo induction medium supplemented with NAA and BAP at 0.2 and 0.5 mg/l, respectively. The frequency of somatic embryos of calli obtained from in plantaTIBA together with proline treatments on average was20 which was higher than that of the other treatments. This revised version was published online in July 2006 with corrections to the Cover Date.     

Correlation between polyovules and number of pistil lobes (stigmatic rays) in sugar beet (Beta vulgaris L.)

The polyovules phenomenon in sugar beet has the same importance for breeding as multigermity, because only mono-ovulic monogerm plants can be used for mechanized cultivation. The polyovules trait was investigated in two Japanese lines, mono-ovulic line NK-219-O and polyovulic line NK-183-cms. Plants of the former had three pistil lobes (stigmatic rays) in each flower, a single ovule per ovary, a single seed in the mature fruit and a single seedling germinated in subsequent tests. Plants of the latter had 5–6 pistil lobes in each flower, 2–3 ovules per ovary, double-seeds and double-seedlings. The correlations between a Pistil Lobes Index (PLI) and thenumber of ovules per ovary, percentage of double-seeds inan X-ray test, and percentage of double-seedlings in germination tests were 0.885, 0.838, and 0.749, respectivelyindicating close associations. These results are important both in sugar beet breeding for indirect selection to eliminate the undesirable polyovules trait and for botanicalinvestigations of the relationship among different parts of the gynoecium.     

The efficiency of between and within full-sib family selection in a recurrent selection programme in sugar beet (Beta vulgaris L.)

The efficiency of between and within family selection in a full-sib family recurrent selection programme was investigated using data from three cycles of recurrent selection. Correlations between mid-parent values and offspring were high for sugar content and juice purity characters, but low for root weight and sugar yield. This suggests that single root selection within full-sib families is effective in the improvement of sugar content and juice purity, but ineffective for root weight and sugar yield. Root weight and sugar yield will respond better to between full-sib family selection. This revised version was published online in July 2006 with corrections to the Cover Date.     

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.