bluuebunny/crossref_metadata_2025_split huggingface dataset:
Properties of cocksfoot streak and cocksfoot cryptic, two viruses infecting cocksfoot (Dactylis glomerata) in Scotland
Authors: TORRANCE LESLEY , JONES A T , DUNCAN G H 
Published: February 2008

SummaryA Scottish isolate of cocksfoot streak virus (CSV‐S) was found to have flexuous filamentous particles which, in sap of infected cocksfoot plants, had a modal length of 712 nm. It was transmitted from infected to healthy cocksfoot plants in a non‐persistent manner by Myzus persicae and by mechanical inoculation of infective sap extracts containing an anti‐oxidant. Apart from cocksfoot, mechanical inoculation of infective sap succeeded in infecting only four of 22 plant species tested. The infectivity of sap extracts containing 0.2% thioglycerol was lost after heating for 10 min at 55oC but not 50oC, storage at room temperature for 48 but not 24 hours, and after diluting 10‐2to 10‐3. Highly purified preparations of CSV‐S particles sedimented as a single component with a sedimentation coefficient of 139S and had a buoyant density in rubidium bromide of 1.31 g/cm3. Virus particles were composed of one protein and one ssRNA species with estimated Mr of 31 000 and 3.2 times 106respectively. In ELISA, an antiserum prepared to CSV‐S detected the virus in all aerial parts of infected cocksfoot plants and, when present in the ratio of 1 infected leaf: 1000 healthy leaves. Both CSV‐S‐infected and ‐uninfected cocksfoot also contained a previously undescribed virus with isometric particles c. 30 nm in diameter. This virus, named cocksfoot cryptic virus (CCV), was seed‐borne in two cvs of cocksfoot tested and its particles contained two dsRNA species of estimated Mr of 1.14 times 106and 1.27 times 106. Despite the fact that particles of CSV‐S were largely free from CCV particles following exclusion chromatography on agarose beads prior to immunisation, immunoelectron microscopy (IEM) showed that the antiserum prepared to CSV‐S also contained some antibodies to CCV. Evidence from IEM suggested a possible distant serological relationship of CCV to ryegrass and beet (BCV 1 or BCV 2, or both) cryptoviruses, all members of sub‐group A of crypto viruses.
The effects of osmotic pre‐sowing treatment on laboratory germination in a range of wild flower species
Authors: TALLOWIN J R B , ROOK A J , BROOKMAN S K E 
Published: February 2008

SummarySown seed of many wild flower species have slow or delayed germination which can allow unsown and undesirable species to colonise a prepared site. Ideally all seed sown should germinate immediately. Priming seed in an inert osmoticum can improve synchronisation and speed of germination. The objective of this study was to assess the efficacy of priming on a selection of 60 wild flower species from a total of 21 different families. The majority of the species selected were common constituents of commercial seed mixtures. Seeds were primed in the light at 15CC for 14 days in a polyethylene glycol ‘6000’ solution giving an osmotic potential of either ‐10 or ‐15 bars. Priming had a highly significant effect on speed of germination reducing the median germination time by 2.8 ± 0.27 days in the ‐10 bar treatment and 1.6 ± 0.27 days in the ‐15 bar treatment. At the species level, 28 species had significantly reduced median germination times following priming. Priming significantly enhanced the final germination percentage in 15 species and significantly reduced it in eight species, with the adverse effect being more pronounced at ‐15 bars than at ‐10 bars. Non‐hierarchical cluster analysis showed no clear patterns in response to priming either in relation to the comparative ecology or the plant family of the species tested, with the possible exception of the Leguminosae species. Only one out of six members of this family showed any enhancement in germination rate or percentage.The study demonstrates that a priming treatment could improve speed of germination, in a wide range of commonly sown semi‐natural grassland species.
Analysis of potential sources of variation in tissue culture derived celery plants
Authors: DONOVAN ANNE , COLLIN HAMISH A , ISAAC SUSAN , MORTIMER A MARTIN 
Published: February 2008

SummarySomaclonal variation derived from tissue culture is a potential source of variation that can be used in crop improvement programmes. The characteristics of this variation are first shown in the regenerant generation and their heritability is then confirmed by examination of the progeny. There would be savings of time, space and labour if this variation could be detected in vitro using easily assessed visual cues. The aim of this study was to relate variation in the source of explant and the morphology of the newly initiated callus to the characteristics of the regenerant plant, of which the most important was resistance to leaf spot disease caused by Septoria apiicola. Associations were investigated by isolating four stem explants from each of 564 surface sterile seedlings, var. Celebrity, on a callus initiation medium (MS medium, 30 g litre‘1sucrose, 0.5 mg litre’12,4‐D, 0.6 mg litre‘1kinetin) and assessing the morphology and colour of the callus. After this initial culture (8 wk), each callus was transferred to a regeneration medium (MS medium, 30 g litre“1sucrose). Plantlets were regenerated from many of the callus cultures and these were transferred to the glasshouse. When all of the surviving regenerant plants (276) were mature, leaf shape, amount and composition of the essential oils and resistance to late blight were assessed. Statistical analysis revealed that the character of the newly initiated callus (width, height, colour, organogenesis) showed poor correlation with all aspects of the regenerated plant measured. However, it was shown that increased variation resulted from different seedlings more than from plants derived from within seedlings or within callus.
The detection of salivary enzymes of phytophagous Hemiptera: a compilation of methods
Authors: MADHUSUDHAN V V , TAYLOR G S , MILES P W 
Published: February 2008

SummaryThe role of Hemipteran saliva and salivary enzymes is central to an understanding of the etiology of damage that these insects cause to plants. The dilute nature of the salivary secretions and the minute quantities in which they are often obtainable have made analysis and detection of salivary components very difficult. Such investigations in this laboratory have led us to formalise the techniques involved and we believe that the compilation of these methods presented herein may be useful to other research workers in this area. Methods are described for acid and alkaline phosphatase, esterase, /S‐glucosidase, carbohydrases, invertase, amylase, proteinase, pectinase, cellulase, catalase, peroxidase, catechol oxidase, superoxide dismutase and ascorbic oxidase.
Influence of fluctuating temperatures and interrupted periods of plant surface wetness on infection of bean leaves by ascospores of Sclerotinia sclerotiorum
Authors: PHILLIPS A J L 
Published: February 2008

SummaryIn artificial inoculations of bean leaves (Phaseolus vulgaris), the minimum period of plant surface wetness (PSW) required for the start of infection was temperature dependent. Infection was most rapid at 20–25oC and no infection occurred at 5oC or 27oC. In experiments conducted in a glasshouse or controlled environment chamber, the influence of fluctuating temperatures was taken into account by calculating degree hours (oh) of PSW. A continuous period of PSW was not necessary for successful infection. Successive short periods of PSW were not strictly additive. A dry period following a wet period delayed the start of infection for longer than the duration of the dry period. The length of the delay depended on the preceding oh PSW and on the duration of the dry period. From this information, a model was constructed to predict when first infections could be expected. This model was tested in small plot field experiments in two seasons. The date on which infection was first noticed coincided closely with the date on which oh PSW first exceeded 1200. The use of this model in disease control is discussed.
Characteristics of resistance in rice to rice hoja blanca virus (RHBV) and its vector, Tagosodes orizicolus (Muir)
Authors: ZEIGLER R S , PANTOJA A , DUQUE M C , WEBER G 
Published: February 2008

SummaryThis paper characterises resistance to rice hoja blanca virus (RHBV) which is transmitted by the planthopper Tagosodes orizicolus (Muir). Resistance is expressed as decreased proportion of plants infected compared to susceptible lines, although severity of symptom expression is similar in both types. This resistance is not due to differences in vector feeding behaviour. Vectors reared eight generations on resistant plants showed no increased ability to transmit to resistant lines or decreased ability to transmit to susceptible ones. Longevity of vectors was similar when reared either on virus‐resistant or susceptible plants. Incubation period of the virus in resistant plants are significantly longer than in susceptible plants. Resistance increased with plant age in resistant and susceptible cultivars. Increased virus dosage, as determined by increased number of viru‐liferous vectors per inoculated plant, caused an increase in transmission to both resistant and susceptible cultivars. However, the ranking of resistant and susceptible remained the same across the experimental range of dosage and plant age. It is concluded that the resistance studied is to virus infection and there is little risk of “breakdown” occurring as a result of genetic or behavioural changes in the vector population. This will permit the use of economic thresholds to planthopper feeding damage with little risk of RHBV epidemic outbreak.
Effects of beet cryptic virus infection on sugar beet in field trials
Authors: XIE W S , ANTONIW J F , WHITE R F , JOLLIFFE T H 
Published: February 2008

SummaryThe effects of beet cryptic virus (BCV) infection on sugar beet crops were investigated in field trials in 1990. Two sugar beet breeding stock lines were screened for infection by BCV. Seed lots containing different proportions of seed infected with BCV1 & 2 were obtained by crossing the stock lines and used in field trials at five different sites. Five characteristics of the infected plants were assessed. BCV infection appeared to have no significant effects on the sugar beet crop at four locations which suffered from drought stress but significant effects were found at one site where the crop was grown on grade 1 land with good moisture retention properties. Root yield and sugar yield were reduced by up to 17% and 20%, respectively, by BCV infection.
The effects of control on the biomass, carbohydrate content and bud reserves of bracken (Pteridium aquilinum (L.) Kuhn), and an evaluation of a bracken growth model
Authors: PAKEMAN R J , MARRS R H 
Published: February 2008

SummaryThis paper examines the initial effects of bracken control on frond numbers and biomass, and the biomass, carbohydrate reserves and bud densities of bracken stands cut once per year, twice per year, subject to a single application of asulam or left untreated. The seasonal dynamics of these parameters are displayed; carbohydrate and biomass are both removed from the rhizome system to produce frond tissue, and are replenished at the end of the growing season. Asulam application reduced densities of both active and dormant buds, and both frond biomass and density. It did not significantly reduce rhizome biomass or carbohydrate reserves in the two years after treatment. Cutting, either once or twice per year reduced both rhizome biomass and rhizome carbohydrate reserves, as well as bud densities, though the latter were reduced in proportion to biomass. Cutting twice a year reduced the production of fronds, both in numbers and biomass. The collected data were used to evaluate a model of bracken growth, and subsequently to improve estimates of some of the model parameters. The model simulations of control treatments were compared to field data. The effects of cutting once per year and spraying with asulam were predicted accurately, but the bracken stand was more resilient to cutting twice per year than would be expected from model predictions. The combination of cutting and spraying is discussed as a potential tool in land management and the deficiencies of the model are discussed in relation to the need for future research into the biology of bracken.
Changes in glucosinolates during crop development in single‐ and double‐low genotypes of winter oilseed rape (Brassica napus): I. Production and distribution in vegetative tissues and developing pods during development and potential role in the recycling of sulphur within the crop
Authors: FIELDSEND JANE , MILFORD G F J 
Published: February 2008

SummaryThe distributions of glucosinolates and sulphur were measured in the vegetative and reproductive tissues in a series of single‐ and double‐low cultivars of oilseed rape (Bienvenu, Ariana, Cobra and Capricorn) grown on a sulphur‐sufficient soil at Rothamsted in 1987/88, and in crops of the cv. Libravo grown with none or 40 kg/ha of sulphur on a sulphur‐deficient soil at Woburn in 1990/91.The glucosinolate measurements demonstrated large differences in the abilities of single‐ and double‐low cultivars to synthesise glucosinolates, and showed that the biosynthetic differences were associated more with the developing pods than the vegetative tissues. It indicated that potential contribution of intact glucosinolates from vegetative tissues to the seed was likely to be small, but did not preclude the possibility that the vegetative tissues were a source of glucosinolate precursors. The sulphur measurements showed that the glucosinolates contained only a small proportion of the crop's total sulphur and that they were unlikely to be a major source of recyclable sulphur, even under conditions of severe sulphur deficiency.
Changes in glucosinolates during crop development in single‐ and double‐low genotypes of winter oilseed rape (Brassica napus): II. Profiles and tissue‐water concentrations in vegetative tissues and developing pods
Authors: FIELDSEND JANE , MILFORD G F J 
Published: February 2008

SummaryThe concentrations of glucosinolates in the tissue water of leaves, stems, floral buds and developing pods were measured at defined stages of development in four oilseed rape cultivars known to have different seed glucosinolate concentrations (Bienvenu, Ariana, Cobra and Capricorn). Five alkenyl, two aromatic and three indolyl compounds were identified in the vegetative and reproductive organs. Substantial differences developed in the profiles of compounds present during vegetative growth. The 2‐hydroxy‐3‐butenyl glucosinolate was primarily associated with developing and mature seeds and germinated seedlings. The 4‐pentyl glucosinolate occurred mainly during the later stages of vegetative growth in spring, when leaves contained higher concentrations than stems, and during the early stages of flowering. The 2‐phenylethyl and 3‐indolymethyl glucosinolates were present earlier in vegetative growth when similar concentrations were present in leaves and stems. Differences between cultivars in the tissue‐water concentrations of individual glucosinolates were small during vegetative growth. The leaves of Cobra and Capricorn had smaller concentrations of the 3‐pentyl glucosinolate than Bienvenu and Ariana especially early in spring, and the stems of Capricorn had smaller concentration of the 3‐pentyl and 2‐phenylethyl glucosinolates. Greater differences between cultivars developed during pod growth and involved large increases in the concentrations of the 2‐hydroxy‐3‐butenyl and 3‐butenyl glucosinolates, especially in Bienvenu and Ariana. The implications of these changes in the types and concentrations of glucosinolates in the different organs for the incidence of pests and diseases are discussed.
Blackleg potential of potato seed: determination of tuber contamination by Erwinia carotovora subsp. Atroseptica by immunofluorescence colony staining and stock and tuber sampling
Authors: JONES D A C , HYMAN L J , TUMESEIT M , SMITH P , PÉROMBELON M C M 
Published: February 2008

SummaryTwo methods to determine numbers of the blackleg pathogen, Erwinia carotovora subsp. atroseptica, in tuber peel extract were compared; (1) growth and cavity formation on crystal violet pectate (CVP) medium (Pérombelon, Lumb & Hyman, 1987) and (2) immunofluorescent colony (IFC) staining (Van Vuurde & Roozen, 1990) using an antiserum against the bacterium conjugated with fluorescein isothiocyanate. Detection, identification and quantification of the bacterium based on the differential effect of temperature on growth in the CVP method were severely restricted and in some cases could not be done at low peel extract dilutions containing > 106 saprophytic bacteria ml“1 and > 103 cells ml‐1 of E. carotovora subsp. carotovora. In contrast, although recovery was c. 50% relative to growth of E.c. atroseptica alone on nutrient agar, numbers of the bacteria could be determined by the IFC method regardless of numbers of saprophytic bacteria and E.c. carotovora present. Moreover, the tedium of counting colonies on a UV microscope could be avoided by automation using an imaging system on photograph film negatives of the microscope fields.Readily accessible tubers from the top layer of one tonne boxes in commercial stores were c. 10 times less contaminated than those from the middle of the boxes. For the two methods of peel extract preparation examined, the estimated sample size needed with an allowable error of log1010 E.c. atroseptica cells ml“1 extract with 95% confidence, was c. five tubers per box and 14 boxes for extract prepared from individual tubers and c. three lots of 10 tubers per box and 10 boxes for extract from 10 pooled tubers. A blackleg potential index for seed stocks was proposed based on the summation of the weighted number of individually tested tubers in different classes of contamination level.
Properties of an unusual isolate of raspberry ringspot virus from grapevine in Germany and evidence for its possible transmission by Paralongidorus maximus
Authors: JONES A T , BROWN D J F , McGAVIN WENDY J , RÜDEL MARIA , ALTMAYER B 
Published: February 2008

SummaryAn isolate of raspberry ringspot nepovirus (RRV‐P) commonly found infecting grapevine in localised areas of the German Palatinate, was serologically closely related to, but distinguishable from, the English type strain of this virus (RRV‐E) which is transmitted by Longidorus macrosoma. However, unlike RRV‐E, RRV‐P had a restricted herbaceous host range and produced symptoms reliably in only two hosts, Chenopodium quinoa and Nicotiana occidentalis‐accession 37B: these symptoms were a faint systemic vein clearing which, on most occasions in C. quinoa, was transient. In in vitro studies with herbaceous plant sap, RRV‐P infectivity was lost after diluting 1/100‐1/500, after storage at 20oC for 1–3 days and at 4oC for 45 days: for similar studies with RRV‐E, the values were 1/125 000, and more than 15 days at 20oC and 4oC, respectively. RRV‐P was difficult to purify in quantity and in most preparations seemed to sediment as a single component corresponding to ‘bottom’ component of RRV‐E. Purified particles of RRV‐P, like those of RRV‐E, contained a major polypeptide and two RNA species of Mx 54 000, 2.6 × 106 and 1.6 × 106 respectively. There was no evidence from RNA preparations from purified virus particles or, from analysis of dsRNA from infected plants, that RRV‐P contained a satellite RNA. The incidence of RRV‐P in vineyards was not associated with the presence in soils of Longidorus nematodes, but was associated with the distribution in the Palatinate of Paralongidorus maximus. Furthermore, results from an experiment in Germany in a vineyard planted with healthy grapevines in soil fumigated to destroy nematodes, showed spread of RRV‐P into these plants from an adjoining source of infected grapevines and soil infested with P. maximus. In laboratory studies, RRV‐P was transmitted by P. maximus at a very low level between grapevines (used as the virus source and test plants) but not to, or between, herbaceous hosts.
Partial replacement of local common bean mixtures by high yielding angular leaf spot resistant varieties to conserve local genetic diversity while increasing yield
Authors: TRUTMANN PETER , PYNDJI MUKISHI M 
Published: February 2008

SummaryThe effect of replacing proportions of local farmer bean (Phaseolus vulgaris) mixtures with varieties resistant to angular leaf spot on grain yield was evaluated under local disease pressure in the Kivu region of Zaire. Local bean mixtures in on‐station and in multi‐locational trials containing respectively 25%, or 50% of Centro Internacional de Agricultura Tropical (CIAT) breeding lines BAT76, or A285, resistant to angular leaf spot yielded significantly more than the local mixture alone. Yields exceeded expected values in three seasons of on‐station testing and in two seasons of multi‐locational trials. Yield over the expected was found to be a property of new mixtures not protected with fungicide and were attributed to disease control. Relative to expected yields non‐protected farmer mixture components performed 17% and 16% better than in protected plots and A285 components yielded 24% and 16% better at respectively 25% and 50% A285 supplementation levels. A285 increased yields of the local mixture components and benefitted from the local mixture when not protected by fungicide. Yield increases in multi‐locational trials were largely attributed to the higher yield potential of the resistant variety A285, although angular leaf spot severity was significantly reduced. It was concluded that high yielding, resistant varieties were able to increase bean yield in the region, but probably at a substantial cost in genetic diversity in farmer bean mixtures. That said, a partial replacement strategy is preferable to strategies which encourage complete replacement of local germplasm with one or few high yielding varieties.
Infection of cereals and grasses by isolates of Polymyxa graminis (Plasmodiophorales)
Authors: ADAMS M J , JACQUIER C 
Published: February 2008

SummaryThe host range of isolates of Polymyxa was tested in mono‐fungal sand cultures. Fourteen isolates of P. graminis, obtained from barley, wheat, oats or Poa annua and from several different countries, all infected barley and all but one infected wheat. Rye was also a good host, whereas oats (nine cultivars), Lolium multiflorum and Poa pratensis became only slightly infected. Wheat cultivars differed in susceptibility, with Galahad much more resistant than Avalon. Several common weed and pasture grasses were not infected by the two isolates tested. A range of wild Hordeum spp. were mostly susceptible to P. graminis and/or barley mild mosaic virus, which it transmits. An isolate of P. betae, used for comparison, caused slight infection on oats but not on other cereals. The variation within and between species of Polymyxa needs more detailed investigation.