甜菜胞囊线虫抗性基因及遗传工程改良策略

甜菜胞囊线虫(Heterodera schachtii)是甜菜的重要病害之一,给甜菜生产造成了极大的损失。随着分子生物学和遗传工程技术的发展,采用遗传工程改良策略进行甜菜抗性品种选育是甜菜胞囊线虫防治中最经济、有效的方法。介绍了甜菜胞囊线虫的生育史及抗性机制,综述了甜菜胞囊线虫抗性基因的克隆和鉴定研究进展及甜菜胞囊线虫抗性育种的遗传工程改良策略,并提出今后甜菜胞囊线虫抗性育种的展望。     

超表达AVP1基因提高甜菜的耐低磷和耐盐抗旱性

为探讨H⁺-焦磷酸酶编码基因对甜菜磷吸收和抗性的影响,实现优良基因在甜菜基因工程中的利用,研究在甜菜中超表达拟南芥液泡膜H⁺-焦磷酸酶编码基因AVP1,对转基因甜菜分析其耐低磷、耐盐性和抗旱性。结果显示,AVP1基因在甜菜植株的叶片和块根中表达,且在逆境胁迫下增强表达量响应胁迫;低磷处理条件下,转基因甜菜与野生型甜菜相比具有更高的含磷量,可提高甜菜对磷的吸收利用效率;干旱、盐胁迫处理条件下,AVP1基因在转基因甜菜中显著上升,在盐胁迫或干旱处理条件下,转基因植株的生长受抑程度相对较轻。随着盐和干旱胁迫的加剧,转基因植株体内MDA含量与野生型植株相比较低而脯氨酸含量显著增加,AVP1基因可通过减轻逆境对甜菜细胞膜的损伤及提高甜菜细胞的渗透调节能力,进而增强甜菜对高盐和干旱胁迫的抗性。     

Analysis of gene inheritance and expression in hybrids between transgenic sugar beet and wild beets

Reciprocal gene exchange between cultivated sugar beet and wild beets in seed production areas is probably the reason for the occurence of weed beets in sugar beet production fields. Therefore, when releasing transgenic sugar beet plants into the environment, gene transfer to wild beets ( Beta vulgaris ssp. maritima ) has to be considered. In this study the transfer of BNYVV- (beet necrotic yellow vein virus) resistance and herbicide-tolerance genes from two transgenic sugar beet lines that were released in field experiments in 1993 and 1994 in Germany to different wild beet accessions was investigated. In order to evaluate the consequences of outcrossing, manual pollinations of emasculated wild beet plants with homozygous transgenic sugar beet plants were performed. In the resulting hybrids the transgenes were stably inherited according to Mendelian law. Gene expression in leaves and roots of the hybrids was in the same range as in the original transgenic sugar beet plants. Moreover, it was found that in one of the wild beet accessions, transfer and expression of the BNYVV resistance gene did considerably increase the level of virus resistance.     

Mitochondrial minisatellite polymorphisms in fodder and sugar beets reveal genetic bottlenecks associated with domestication

Historically, sugar beets were selected from fodder beets. We used mitochondrial minisatellite loci to analyze cytoplasmic genetic diversity in fodder beet and sugar beet. Among the 8 sugar beet accessions examined we identified 3 multi-locus haplotypes. These 3 haplotypes were a subset of 5 haplotypes identified among the 29 fodder beet accessions examined. All but one haplotype in fodder beet comprised, in turn, a subset of 12 haplotypes identified previously in leaf beets. Such apparent decreases in cytoplasmic genetic diversity must result from genetic bottlenecks associated with domestication and the ensuing breeding processes. We also detected the haplotype associated with the male-sterile Owen cytoplasm of sugar beet in the fodder beet gene pool. Furthermore, the presence of a 39 kDa protein associated with the Owen cytoplasm was confirmed in two fodder beet plants by Western blot analysis. These results lead us to speculate that the Owen cytoplasm may have originated in fodder beet, from which sugar beet was derived.     

Influence of phloem transport, N-fertilization and ion accumulation on sucrose storage in the taproots of fodder beet and sugar beet

To investigate the factors governing the accumulation of sucroseand amino acids in the taproots of sugar beet, their contentswere measured in the leaves, phloem sap and the taproots ofsugar beet, fodder beet and a hybrid between both, grown oneither 3.0 or 0.5 mM nitrate. In the taproots the contents ofmalate, citrate and inorganic ions were also determined. Forthe high sucrose accumulation in sugar beet as compared to theother varieties three factors were found. (a) In sugar beet,less amino acids and more sucrose are taken up into the phloemthan in fodder beet. (b) In sugar beet, the sucrose and aminoacid syntheses are less sensitive to the nitrate concentrationsthat are required for optimal plant growth than in other varieties.In fodder beet, upon raising the nitrate concentration from0.5 mM to 3 mM, the synthesis and storage of sucrose is decreasedand that of amino acids increased. The corresponding valuesin sugar beet (0.5 mM) are similar to those in fodder beet andare not much affected by an increase of nitrate. (c) The sucroseaccumulation is limited by the accumulation of inorganic ionsin the taproots. The sucrose content in the taproots is negativelycorrelated to the total ion content. Whereas sucrose representstwo-third of all solutes in the taproots of sugar beet, it amountsto only one-third of the solutes in fodder beet taproots. Key words: Amino acids, Beta vulgans L, phloem sap, potassium, sucrose storage, sugar beet, taproots, transport     

黄土高原甜菜叶片生长特性及其对块根产量、含糖量的影响

通过对旱地甜菜叶片生长特性及摘除不同叶组对块根产量,含糖量,显微结构的影响研究,结果表明：甜菜第10-20片叶的叶龄最长,积温最高,是甜菜的主要功能叶;甜菜从第20片叶期起进入块根,糖份增长期,从第55叶期起进入糖份积累期;摘除不同叶组的叶片对甜菜块根产量,含糖量及显微结构均有不同程度降低作用,摘除前期叶组对甜菜块根产量,产糖量,根径减幅较大,摘除后期叶组对块根含糖量,维管束环数,维管束环密度减幅较大;摘除第1-30片叶对甜菜影响最大。     

Bodenbewohnende Schädlinge und Seitenwurzelfäule der Zuckerrübe in Abhängigkeit von der Rotation – Ergebnisse eines Fruchtfolgeversuches

Soil inhabiting pests and rot of feeding roots of sugar beet depending on rotation - Results of a long-term trial Over a period of 17 years a trial was carried out with sugar beet, cereals and oilseed rape in different crop rotations on a field near Göttingen (Lower Saxony). The frequency of sugar beet in the rotation was 17, 25, 33 and 67 %. In absence of beet nematodes, root and sugar yield of the beet decreased after repeated growing of sugar beet in short rotations compared to variants with long rotations. Sugar content and beet quality were only slightly influenced. By applying a bioassay (BW-Test) with young beet plants in the greenhouse it was shown that increasing infections on the tips of rootlets of the beet plants were the cause for decreasing beet yield in close rotations. Mortality of young beet plants and progress of infection in the test indicated roughly the quantity of pathogenic fungi in the soil. In the roots of the bait platits the parasitic fungus Aphanomyces cochlioides predominated. Rate of infection and yield reduction in the field were decisively influenced by weather conditions. Differences in yield between sugar beet grown in a three-year and a four-year rotation, however, were not significant. An occurrence of beet pests depending on crop rotation was stated only for Atomaria linearis and this only in a few years.     

SUGAR BEET YELLOWS: A PRELIMINARY STUDY OF THE DISTRIBUTION AND INTERRELATIONSHIPS OF VIRUSES AND VIRUS STRAINS FOUND IN EAST ANGLIA, 1955-57

Aphid transmissions to sugar beet seedlings from yellowed sugar beet leaves collected from commercial fields in East Anglia during the summers of 1955, 1956 and 1957, showed the occurrence of two yellowing viruses. One was sugar beet yellows virus (SBYV) and produced vein-etch and yellowing symptoms on beet seedlings in the glasshouse; the other produced yellowing but no etch. These two viruses were apparently unrelated, so that sugar beet tolerant to one of them would not necessarily be tolerant to the other. The second virus, called 'sugar beet mild yellowing virus' (SBMYV), decreased the root yield of sugar beet plants grown under glass, by as much as did the milder SBYV strains, but less than did the severe SBYV strains. The proportions of the two viruses in the samples differed from year to year and from place to place.     

Comparaison des teneurs en saccharose et en nucléotides riches en énergie des graines en germination d'une betterave sucrière et d'une betterave fourragère

Comparison of a sugar beet with a forage beet variety shows that, during germination, the seedlings have the same nucleoside triphosphate content, but those of sugar beet contain more sucrose and less UDPG than those of forage beet.     

CALCIUM CHLOROACETATE AS A SOIL DRESSING AGAINST BEET EELWORM: HETERODERA SCHACHTH SCHMIDT, WITH CERTAIN ADDITIONAL OBSERVATIONS

Calcium chloroacetate at 3 and 6 cwt./acre produced significant increases in the yields of sugar beet (both washed beet and total sugar) in a trial on fen soil of the 'skirt' type infested with beet eelworm, Heterodera schachtii Schmidt. However, the material had no effect on the eelworm content of the soil whether measured by cysts, viable cysts or eggs and larvae. An instance is recorded of a significant drop in the level of the beet eelworm infestation in the presence of sugar beet.     

Dietary sugar beet fiber ameliorates diarrhea as an acute gamma-radiation injury in rats

Gamma radiation induces diarrhea as an acute injury. We have studied whether ingestion of sugar beet fiber influences radiation-induced diarrhea. Abdominal irradiation with gamma rays induced diarrhea in male Wistar/ST rats from 2 to 7 days after a single sublethal dose. The body weight of the irradiated rats was decreased temporarily at 4 days after irradiation regardless of the ingestion of sugar beet fiber. At day 8, it returned to almost the same level as that of unirradiated rats. A change in daily food intake resulted in a pattern similar to that for body weight. Dietary sugar beet fiber had little significant effect on the changes in body weight and daily food intake, and its ingestion significantly decreased gamma-ray-induced diarrhea. Changes in biochemical and histological parameters in intestinal mucosa (small intestine, cecum and colon) were not greatly influenced by the ingestion of sugar beet fiber through the periods of diarrhea. It was concluded that dietary sugar beet fiber ameliorated the diarrhea induced by abdominal irradiation. We suggest that the inhibitory effect of the ingestion of sugar beet fiber is due to its effects on the luminal environment, such as support for bacterial function in the luminal contents in the colon of animals that ingest sugar beet fiber.     

Restricted host range of the weevil Aubeonymus mariaefranciscae, a new sugar-beet pest

The extent of feeding, fecundity and fertility of a new sugar beet pest, Aubeonymus mariaefranciscae Roudier (Coleoptera: Curculionidae), on a range of plants from different families was determined. We have found that the adult weevils were only able to feed and oviposit on two closely related cultivated plants, beet and sugar beet, both subspecies of Beta vulgaris L., suggesting a restricted host range for this curculionid. None of 16 secondary metabolites (widely distributed among plants, and representative of different chemical groups), nor any of 19 non-host extracts from 13 different families, deterred the adults of this curculionid from feeding on sugar beet. We found a phagostimulatory effect when beet and sugar beet homogenates from various plant tissues were supplied to adult weevils on weeds that they do not feed on. Conversely, no effect was observed when sucrose was provided. These findings suggest that host selection by A. mariaefranciscae adults is due to the presence of an undetermined phagostimulant compound(s) in beet and sugar beet, instead of the recognition of deterrent substances among the non-host plants.     

Adenylate patterns of autumn-sown sugar beet differ from spring-sown sugar beet. Implications for root quality

Sugar beet ( Beta vulgaris L) is generally cultivated using two different planting and harvest patterns. In northern zones, spring sugar beet is sown in spring and harvested in autumn, whereas in subtropical latitudes, autumn sugar beet is sown in autumn and harvested in summer. The industrial quality of the root is frequently higher in spring-sown sugar beet crops. In order to explore physiological changes associated with this fact, this study has been focused on the seasonal changes of adenosine 5'-triphosphate and adenosine 5'-diphosphate levels in the storage roots of sugar beet plants, as an index of its metabolic status. The results obtained correspond to a different metabolic status of spring and autumn sugar beet at the moment of harvest. The adenylate patterns of autumn beets suggested a functional and active respiratory system. On the contrary, the patterns shown by spring beets corresponded to those we would expect to see in plants becoming dormant. The proline and glucose contents, which decrease the industrial quality of the root, and the respiratory rate measured in autumn-sown sugar beets, were nearly twice those of spring-sown sugar beets. The combination of an active respiratory system, which allows the carbohydrate catabolism and the synthesis of stress molecules, with the environmental factors at the time of the harvest, could be the underlying physiological mechanism causing some of the differences between spring- and autumn-sown sugar beet crops.     

Genetic localization of four genes for nematode (Heterodera schachtii Schm.) resistance in sugar beet (Beta vulgaris L.)

Sugar beet (Beta vulgaris L.) is highly susceptible to the beet cyst nematode (Heterodera schachtii Schm.). Three resistance genes originating from the wild beets B. procumbens (Hs1 ^pro-1) and B. webbiana (Hs1 ^web-1, Hs2 ^web-7) have been transferred to sugar beet via species hybridization. We describe the genetic localization of the nematode resistance genes in four different sugar beet lines using segregating F₂ populations and RFLP markers from our current sugar beet linkage map. The mapping studies yielded a surprising result. Although the four parental lines carrying the wild beet translocations were not related to each other, the four genes mapped to the same locus in sugar beet independent of the original translocation event. Close linkage (0–4.6 cM) was found with marker loci at one end of linkage group IV. In two populations, RFLP loci showed segregation distortion due to gametic selection. For the first time, the non-randomness of the translocation process promoting gene transfer from the wild beet to the sugar beet is demonstrated. The data suggest that the resistance genes were incorporated into the sugar beet chromosomes by non-allelic homologous recombination. The finding that the different resistance genes are allelic will have major implications on future attempts to breed sugar beet combining the different resistance genes.     

Intraspecific variation of Myzus persicae on sugar beet (Beta vulgaris)

Differences in inherited resistance among seven sugar-beet stocks had similar effects on Myzus persicae clones representing the range of variation in aphid response to resistant and susceptible sugar beet observed in fifty-eight clones collected between 1969 and 1971. Three sugar-beet stocks were consistently resistant. Statistically significant interactions between beet stocks and aphid clones did not indicate the existence of biotypes with specific abilities to overcome resistance. M. persicae clones differed in their vigour of colonizing sugar beet, irrespective of the differences between beet stocks. The readiness of adult aphids to settle determined the size of aphid population produced and included a component related to the response of the aphid clone to sugar beet as a host, and a component related to the resistance ranking of the beet stock. Breeding sugar beet with resistance to aphids will be simplified, as the results indicate that, at present, differences between aphid biotypes need not be considered a problem.     

Beet luteovirus coat protein sequence variation

The sequences of cDNA clones covering the coat protein genes of 29 isolates of beet mild yellowing virus from sugar beet and beet western yellows virus mainly from oilseed rape were compared. The sequences could be partitioned into seven distinct clusters falling into three main groups. Group 1 isolates were found both in oilseed rape and sugar beet mainly from north Europe; group 2 isolates were from hosts other than sugar beet in England and France; group 3 isolates were beet-specific and found from northern Italy and Iran. The factors affecting this variation and its significance in relation to coat protein-mediated protection are discussed.     

Bruising of sugar beet roots and consequential sugar loss: current understanding and research needs

Bruising of sugar beet roots and the consequential sugar loss do not receive the attention they deserve within the sugar beet industry. Recent harvester tests have indicated that current levels of bruising damage could be decreased with existing technology. There is, however, little understanding of biological factors affecting susceptibility to bruising of sugar beet roots. This paper examines the available information on causes of bruising, the significance of some tissue characteristics, the processes of sugar loss following bruising and agronomic, physiological and biochemical considerations relevant to bruising and the sugar loss that follows. Some research needs are identified in conclusion.     

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.     

Widespread distribution of Beet necrotic yellow vein virus in Iranian sugar beet industry

Beet necrotic yellow vein virus (BNYVV) is the most devastating pathogen of sugar beet worldwide. This virus has been reported in the majority of sugar beet growing regions of Iran as well. For the present study, we collected samples from different sugar beet varieties with suspected symptoms of BNYVV from the main important sugar beet growing regions in eight provinces of Iran. Infection of collected samples to BNYVV was tested by ELISA and RT-PCR. Upon testing of 167 collected samples of BNYVV suspected through ELISA and RT-PCR, 115 (68.9%) were infected. Different incidences of BNYVV through surveyed provinces may represent the presence of diverse infective viral sources or resistance genes in tested sugar beet varieties which need further attempts to develop control strategies. Results also showed that BNYVV has been recently distributed throughout some surveyed regions. Otherwise, trace infection or resistance to BNYVV infection in some varieties of distinct regions may represent proper sources of resistance to BNYVV.     

Populations of Rhizoctonia solani in soil under crops in rotation with sugar beet

Using a soil debris isolation method, populations of Rhizoctonia solani were monitored over a 4 -yr period in four fields which were initially cropped to sugar beet and in which four areas of Rhizoctonia crown rot diseased beets (DA) and four areas of apparently healthy beets (AH) had been selected and precisely located. Soil from these areas was assayed during the subsequent crops, which included sugar beet, tomato, cucumber, maize and soybean. No significant differences in colony counts were found between the soils in DA and AH on any of 30 sampling dates. R. solani population counts were, in general, quite low, except under sugar beet and following tomato harvest. Areas of diseased beet and high R. solani soil populations that developed in subsequent sugar beet crops did not necessarily coincide with the previously selected diseased areas. High R. solani populations developed from parasitic activity on sugar beet or saprophytically on tomato crop residues. Of the other crops, both maize and soybean may have slightly increased the low R. solani residual populations in soil. The monitoring of R. solani populations in the season prior to, and during the early season of sugar beet cropping did not provide a basis for forecasting disease in fields or sites within fields. The initiation of disease patches in these sugar beet fields was therefore governed by factors other than inoculum density.