Reproduction of sugar beet mosaic and tobacco mosaic viruses in anthocyanized beet plants

During our studies on the interaction of anthocyanins and plant virus diseases, reproduction of sugar beet mosaic (SBMV) and tobacco mosaic viruses (TMV) was investigated. Experiments were carried out in leaves of sugar beet,Beta vulgaris cv. Dobrovicka N and its spontaneous anthocyanized mutant. SBMV induces a systemic infection while TMV is responsible for primary local symptoms in sugar beet leaves only. Our quantitative analyses onAmaranthus caudatus L. andChenopodium quinoa Wilid. showed a significant decrease in concentration of SBMV in juice extracted from anthocyanized beet plants as compared with extracts from normal green infected plants. Significant differences were also obtained when SBMV — containing juice was tested in mixtures with healthy extracts from anthocyanized and normal green plants. Also the intensity of TMV symptoms in beet leaves was considerably decreased in leaves of antho-eyanized plants.     

A chenopod extensin lacks repetitive tetrahydroxyproline blocks

An extensin isolated from sugar beet (Beta vulgaris) cell suspension cultures fulfills all criteria for membership of the extensin family save one, notably, lack of the `diagnostic' pentamer Ser-Hyp-Hyp-Hyp-Hyp. However, sequence analysis of the major tryptic peptides shows that sugar beet extensin shares a motif in common with tomato extensin P1 but differs by the position of an insertion sequence [X] or [Y] which, in sugar beet, splits the tetrahydroxyproline block: Ser-Hyp-Hyp-[X]-Hyp-Hyp-Thr-Hyp-Val-Tyr-Lys, where [X] is [Val-His-Glu/Lys-Tyr-Pro], while in tomato the insertion sequence [Y] = [Val-Lys-Pro-Tyr-His-Pro] and, when it occurs, immediately follows the tetrahydroxyproline block: Ser-Hyp-Hyp-Hyp-Hyp-[Y]-Thr-Hyp-Val-Tyr-Lys. Based on these data we reinterpret three highly repetitive cDNA sequences, including nodulin N75 from soybean and wound-induced P33 of carrot, as extensins with split tetra(hydroxy)proline blocks.     

Effect of sink region cooling on translocation of photosynthate

The effect of metabolic inhibition of the sink tissues on translocation of ¹⁴C-labeled photosynthate was studied by cooling part or all of the sink region in a translocating sugar beet plant (Beta vulgaris L. var Klein Wanzleben).     

Monosomic addition lines of Beta corolliflora Zoss in sugar beet: cytological and molecular-marker analysis

Beta corolliflora is a wild relative of sugar beet (Beta vulgaris) with 2n=4x=36 chromosomes. Monosomic addition lines (2n=19) of B. corolliflora in B. vulgaris were identified from backcross progenies between triploid hybrids (genome constitution VVC) and sugar beet. They were characterized by DNA-fingerprinting using nine different B. corolliflora-specific repetitive sequences as probes and by fluorescence in situ hybridization (FISH) using two B. corollifora specific sequences and two rDNA probes. Unique banding patterns obtained after genomic Southern hybridization enabled the classification of monosomic addition lines into 11 clusters, three of which proved to have a wild beet chromosome fragment in addition to the sugar beet chromosomes as revealed by FISH. Repetitive sequences pBC216 and pBC1416 were found to be present only on wild beet chromosomes IV and V. Chromosomes I and IV were found to carry genes for 18S and 5S rRNA, respectively. An idiogram of B. corolliflora was established in the triploid VVC hybrid on the basis of chromosome size and FISH. Eight B. corolliflora addition lines could be unequivocally identified by Southern hybridization and FISH, one addition line carrying the missing wild beet chromosome is probably not viable under greenhouse conditions. The monosomic addition lines will serve as a bridge for transferring genes from wild species to sugar beet and will help to uncover genetic relationships between species of the genus Beta.     

Sugar beet guard cell protoplasts demonstrate a remarkable capacity for cell division enabling applications in stomatal physiology and molecular breeding

A highly-efficient protocol for the large-scale isolation ofguard cell protoplasts from sugar beet (Beta vulgaris L.) hasbeen developed. Optimization of conditions for culturing theseprotoplasts resulted in extensive cell division and colony formation,at frequencies exceeding 50%. Plants can subsequently be regeneratedfrom these guard cell-derived colonies. This provides definitiveconfirmation that, in sugar beet leaf protoplast populations,only guard cells are the source of totipotent protoplasts. Thesefindings are the outcome of a directed, non-empirical approachto overcoming plant cell recalcitrance which was initiated byexploiting computer-assisted microscopy to couple in vitro responseto cell origin. The results reaffirm the conclusion that, inplants, extreme degrees of cytodifferentiation need not entailterminal specialization. The responsive nature of this systemcan be ascribed to the unique use of cultures essentially comprisinga single in vivo cell type. A uniform model system has thusbeen created with potential for widespread application. Theirdistinct morphological (and mechanical) features make guardcells a valuable choice for studying various fundamental aspects,not only of stomatal physiology, but also of plant cell (de)differentiation,differential gene expression etc. Furthermore, an applied valuefor such a system can also be envisaged. Results indicate thatthese cells are highly amenable to genetic manipulation techniques.The importance of these observations to our understanding ofplant cell function and behaviour is discussed. Key words: Beta, guard cells, stomatal physiology, totipotency, transformation     

Illumina-based analysis of endophytic bacterial diversity and space-time dynamics in sugar beet on the north slope of Tianshan mountain

Plants harbors complex and variable microbial communities. Endophytic bacteria play an important function and potential role more effectively in developing sustainable systems of crop production. To examine how endophytic bacteria in sugar beet (Beta vulgaris L.) vary across both host growth period and location, PCR-based Illumina was applied to revealed the diversity and stability of endophytic bacteria in sugar beet on the north slope of Tianshan mountain, China. A total of 60.84 M effective sequences of 16S rRNA gene V3 region were obtained from sugar beet samples. These sequences revealed huge amount of operational taxonomic units (OTUs) in sugar beet, that is, 19–121 OTUs in a beet sample, at 3 % cutoff level and sequencing depth of 30,000 sequences. We identified 13 classes from the resulting 449,585 sequences. Alphaproteobacteria were the dominant class in all sugar beets, followed by Acidobacteria, Gemmatimonadetes and Actinobacteria. A marked difference in the diversity of endophytic bacteria in sugar beet for different growth periods was evident. The greatest number of OTUs was detected during rossette formation (109 OTUs) and tuber growth (146 OTUs). Endophytic bacteria diversity was reduced during seedling growth (66 OTUs) and sucrose accumulation (95 OTUs). Forty-three OTUs were common to all four periods. There were more tags of Alphaproteobacteria and Gammaproteobacteria in Shihezi than in Changji. The dynamics of endophytic bacteria communities were influenced by plant genotype and plant growth stage. To the best of our knowledge, this study is the first application of PCR-based Illumina pyrosequencing to characterize and compare multiple sugar beet samples.     

Interaction of rubidium or sodium with potassium in absorption by intact sugar beet plants

This study concerns the selective absorption of K and Rb or of K and Na by intact sugar beet (Beta vulgaris) plants from modified conventional nutrient solutions over an extended period of plant growth. Long term results agreed with those of short term experiments by other investigators using excised root systems and simple salt solutions. Potassium and Rb were mutually competitive in their absorption. High selectivity of K relative to Na absorption was observed. Sodium was excluded during the early growth period of sugar beets.     

The decisive step in betaxanthin biosynthesis is a spontaneous reaction1

Experiments were performed to confirm that the aldimine bond formation is a spontaneous reaction, because attempts to find an enzyme catalyzing the last decisive step in betaxanthin biosynthesis, the aldimine formation, failed. Feeding different amino acids to betalain-forming hairy root cultures of yellow beet (Beta vulgaris L. subsp. vulgaris “Golden Beet”) showed that all amino acids (S- and R-forms) led to the corresponding betaxanthins. We observed neither an amino acid specificity nor a stereoselectivity in this process. In addition, increasing the endogenous phenylalanine (Phe) level by feeding the Phe ammonia-lyase inhibitor 2-aminoindan 2-phosphonic acid yielded the Phe-derived betaxanthin. Feeding amino acids or 2-aminoindan 2-phosphonic acid to hypocotyls of fodder beet (B. vulgaris L. subsp. vulgaris “Altamo”) plants led to the same results. Furthermore, feeding cyclo-3-(3,4-dihydroxyphenyl)-alanine (cyclo-Dopa) to these hypocotyls resulted in betanidin formation, indicating that the decisive step in betacyanin formation proceeds spontaneously. Finally, feeding betalamic acid to broad bean (Vicia faba L.) seedlings, which are known to accumulate high levels of Dopa but do not synthesize betaxanthins, resulted in the formation of dopaxanthin. These results indicate that the condensation of betalamic acid with amino acids (possibly including cyclo-Dopa or amines) in planta is a spontaneous, not an enzyme-catalyzed reaction.     

Phytohormone changes during storage root growth in Beta species

The physiological and morphological factors necessary for efficient accumulation of sucrose in sugar beet (Beta vulgaris L.) are considered in relation to potential uses of plant growth regulators to modify the anatomy of storage roots so as to increase sucrose content and yield. The percentage of sucrose in root fresh and dry matter is closely related to root structure. Sugar beet, mangold and chard are three sub-species of Beta vulgaris that differ considerably in their anatomy, assimilate partitioning, sucrose concentration and root dry matter yield. The concentrations of indole-3-acetic acid (IAA), abscisic acid (ABA) and cytokinins were measured during the growth of the storage root in each of these cultivars. Correlations were found between the phytohormone levels and the formation of secondary cambia and their subsequent cell division and expansion activity.     

Impact of Field Dodder (<Emphasis Type="Italic">Cuscuta campestris</Emphasis> Yunk.) on Chlorophyll Fluorescence and Chlorophyll Content of Alfalfa and Sugar Beet Plants

The impact that the parasitic plant field dodder (Cuscuta campestris Yunk.) has on chlorophyll fluorescence and chlorophyll content of infested alfalfa (Medicago sativa L.) and sugar beet (Beta vulgaris L.) was examined under controlled conditions. Several parameters of chlorophyll fluorescence were measured in infested and non-infested alfalfa and sugar beet plants over a period of twenty days, beginning with the day of infestation. Chlorophyll contents (total, relative and ratio of chlorophyll a to b) were determined 1, 7, 14 and 20 days after infestation (DAI). Field dodder was found to affect both the total and relative chlorophyll contents in infested alfalfa and sugar beet, causing significant reduction in chlorophyll content in both host plants. This parasitic plant also affects a number of parameters of chlorophyll fluorescence (F_o, F_v/F_m, Φ_PSII, F_v and IF), showing that these parameters may be considered sensitive indicators of the impact that field dodder has on its host plants.     

Stability of Emulsions Using a New Natural Emulsifier: Sugar Beet Extract <Emphasis Type="Italic">(Beta vulgaris L.)</Emphasis>

This study describes the influence of environmental stresses on the stability of emulsions prepared by a natural sugar beet extract (Beta vulgaris L.). The emulsion stabilizing performance was compared to that of Quillaja extract, which is widely used within the food and beverage industry as natural surfactant. We investigated the influence of pH, ionic strength, heating and freeze-thawing on the mean particle size, ζ-potential and microstructure of oil-in-water emulsions (10% w/w oil, 0.75% w/w emulsifier). The emulsions stabilized by the anionic sugar beet extract were stable at pH 5–8 and against thermal treatments up to 60 °C. However, the prepared emulsions were unstable at acidic (pH 2–4) and basic pH conditions (pH 9), at high temperature (>60 °C), and at salt additions (> 0.1 M NaCl / CaCl₂). Moreover, they also phase separated upon freeze-thawing. Our results show that sugar beet extract is capable of stabilizing emulsions and may therefore be suitable as natural emulsifier for selected applications in the food and beverage industry.     

Source and sink leaf metabolism in relation to Phloem translocation: carbon partitioning and enzymology

The import-export transition in sugar beet leaves (Beta vulgaris) occurred at 40 to 50% leaf expansion and was characterized by loss in assimilate import and increase in photosynthesis. The metabolism and partitioning of assimilated and translocated C were determined during leaf development and related to the translocation status of the leaf. The import stage was characterized by C derived from either ¹⁴C-translocate or ¹⁴C-photosynthate being incorporated into protein and structural carbohydrates. Marked changes in the C partitioning were temporally correlated with the import-export conversion. Exporting leaves did not hydrolyze accumulated sucrose and the C derived from CO₂ fixation was preferentially incorporated into sucrose. Both source and sink leaves contained similar levels of acid invertase and sucrose synthetase activities (sucrose hydrolysis) while sucrose phosphate synthetase (sucrose synthesis) was detected only in exporting leaves. The results are discussed in terms of intracellular compartmentation of sucrose and sucrose-metabolizing enzymes in source and sink leaves.     

Azetidine-2-carboxylic acid in the food chain

Azetidine-2-carboxylic acid (Aze) 1 is a non-protein amino acid present in sugar beets and in table beets (Beta vulgaris). It is readily misincorporated into proteins in place of proline 2 in many species, including humans, and causes numerous toxic effects as well as congenital malformations. Its role in the pathogenesis of disease in humans has remained unexplored. Sugar beet agriculture, especially in the Northern Hemisphere, has become widespread during the past 150 years, and now accounts for nearly 30% of the world’s supply of sucrose. Sugar beet byproducts are also used as a dietary supplement for livestock. Therefore, this study was undertaken as an initial survey to identify Aze-containing links in the food chain. Herein, we report the presence of Aze 1 in three sugar beet byproducts that are fed to farm animals: sugar beet molasses, shredded sugar beet pulp, and pelleted sugar beet pulp.     

Carboxylate metabolism in sugar beet plants grown with excess Zn

The effects of Zn excess on carboxylate metabolism were investigated in sugar beet (Beta vulgaris L.) plants grown hydroponically in a growth chamber. Root extracts of plants grown with 50 or 100 μM Zn in the nutrient solution showed increases in several enzymatic activities related to organic acid metabolism, including citrate synthase and phosphoenolpyruvate carboxylase, when compared to activities in control root extracts. Root citric and malic acid concentrations increased in plants grown with 100 μM Zn, but not in plants grown with 50 μM Zn. In the xylem sap, plants grown with 50 and 100 μM Zn showed increases in the concentrations of citrate and malate compared to the controls. Leaves of plants grown with 50 or 100 μM Zn showed increases in the concentrations of citric and malic acid and in the activities of citrate synthase and fumarase. Leaf isocitrate dehydrogenase increased only in plants grown with 50 μM Zn when compared to the controls. In plants grown with 300 μM Zn, the only enzyme showing activity increases in root extracts was citrate synthase, whereas the activities of other enzymes decreased compared to the controls, and root citrate concentrations increased. In the 300 μM Zn-grown plants, the xylem concentrations of citric and malic acids were higher than those of controls, whereas in leaf extracts the activity of fumarase increased markedly, and the leaf citric acid concentration was higher than in the controls. Based on our data, a metabolic model of the carboxylate metabolism in sugar beet plants grown under Zn excess is proposed.     

Ethylene is differentially regulated during sugar beet germination and affects early root growth in a dose-dependent manner

Main conclusion

By integrating molecular, biochemical, and physiological data, ethylene biosynthesis in sugar beet was shown to be differentially regulated, affecting root elongation in a concentration-dependent manner. There is a close relation between ethylene production and seedling growth of sugar beet (Beta vulgaris L.), yet the exact function of ethylene during this early developmental stage is still unclear. While ethylene is mostly considered to be a root growth inhibitor, we found that external 1-aminocyclopropane-1-carboxylic acid (ACC) regulates root growth in sugar beet in a concentration-dependent manner: low concentrations stimulate root growth while high concentrations inhibit root growth. These results reveal that ethylene action during root elongation is strongly concentration dependent. Furthermore our detailed study of ethylene biosynthesis kinetics revealed a very strict gene regulation pattern of ACC synthase (ACS) and ACC oxidase (ACO), in which ACS is the rate liming step during sugar beet seedling development.     

利用mRNA差异显示技术分离甜菜M14品系特异表达基因的cDNA片段

二倍体栽培甜菜与白花甜菜杂交、进一步回交而获得的单体附加系M₁₄,其染色体组成中除了含有18条栽培甜菜染色体外,还附加有一条野生白花甜菜第9号染色体,该附加染色体通过母本的传递率为96.5%;单体附加系传递率如此高的原因是因为M₁₄中有无融合生殖基因的存在。本实验采用mRNA差异展示技术对甜菜无融合生殖品系M₁₄和正常有性生殖的二倍体栽培甜菜A_2Y花蕾减数分裂时期的基因表达进行了差异分析。采用GT₁₅A,GT₁₅G,GT₁₅C 3种锚定引物,共筛选了20个随机引物,通过RT-PCR检测,获得了6个阳性差异表达的cDNA片段,应用NCBI的BLASTx软件对测序结果进行同源序列、相似序列检索,为进一步克隆无融合生殖基因提供侯选cDNA片段。     

Phenotypic polymorphism and allele differentiation of isozymes in fodder beet,multigerm sugar beet and monogerm sugar beet

Summary Thirteen enzymes (MDH, SDH, LAP, PGM, PX, IDH, GPI, 6PGD, APH, GOT, GDH, ME and SOD) of 3 cultivated beet (B. vulgaris L.) gene pools, comprising 12 accessions of fodder beet, 11 of old multigerm sugar beet and 10 of modern monogerm sugar beet, were investigated using horizontal starch gel electrophoresis. Eleven accessions of primitive or wild B. vulgaris were also included for the comparison of isozymes. Variation in isozyme phenotypes was investigated to detect diversity in the three cultivated forms of beet. Phenotypic variation was observed in all except ME and SOD, which were monomorphic. A high degree of phenotypic polymorphism (Pj) was found in GDH, PGM, IDH, APH and MDH. Differences in phenotypic polymorphism in MDH, GPI and PX were recognized between fodder beet and both sugar beet groups. Average polymorphism for 13 enzymes in both sugar beets was significantly higher than that in fodder beet. For 13 enzymes, the existence of high isozyme diversity in both sugar beet gene pools was revealed. Allele frequencies in 13 alleles of five enzyme-coding loci, Lap, Px-1, Aph-1, Got-2 and Gdh-2, were investigated. New alleles, Px-1 ¹ and Got-2 ¹, were found in fodder beet accessions. No significant differences of average allele frequencies of five loci between fodder beet and both sugar beets were recognized. Several unique alleles and different isozyme phenotypes were observed in the accessions of B. vulgaris ssp. macrocarpa and ssp. adanensis. Future utilization of cultivated beet gene pools for sugar beet breeding is discussed from the viewpoint of genetic resources.