bluuebunny/crossref_metadata_2025_split huggingface dataset:
Cloning and molecular analysis of double‐stranded RNA associated with grapevine leafroll disease*
Authors: HABILI N. , REZAIAN M. A. 
Published: February 2008

SummaryEight major dsRNA species ranging from 1.0 to 19.5 kbp were detected in a low‐yielding clone of Sultana (Thompson seedless) grape (Vitis vinifera L., cv. Sultana, clone B4L) affected leafroll disease. Using total dsRNA from this Sultana line as template, a number of cDNA clones were produced. The clones were used as probes for northern blot analysis of dsRNA extracted from Sultana B4L, and from six other grapevine leafroll‐infected Sultana sources differing in yield performance. Based on the hybridisation of each probe with dsRNA bands from various Sultanas, the cDNA clones could be divided into three groups. One group of cDNA clones hybridised to high molccular weight dsRNA (19.5 kbp) from two low‐yielding Sultanas, another group hybridised to high Mr dsRNA from three low‐yielding Sultanas and the third group hybridised to a number of smaller dsRNA species ranging in size between 1.15 and 6.5 kbp. Using the latter cDNA clones, the sequence of 965 nucleotides at the 5′‐end of a 1.15 kbp dsRNA (dsRNA 6) of B4L Sultana was determined. This RNA contains an open reading frame encoding a putative protein of M, = 33 441 with no homology to known protein sequences. The sequence of dsRNA 6 was found to overlap larger dsRNAs of sizes between 2.2 to 6.5 kbp. This allowed us to determine the sequence upstream of the 5′‐end of the positive strand of dsRNA 6. The nucleotide sequence neighbouring the 5′‐end of the positive strand of dsRNA 6 conforms to a consensus sequence proposed as a subgenomic promoter element for the coat protein gene of positive strand RNA plant viruses. The results indicate that more than one virus was present in Sultana B4L and that dsRNA 6 may be a subgenomic species of viral origin.
Beet luteovirus coat protein sequence variation
Authors: de MIRANDA J. R. , STEVENS M. , de BRUYNE E. , SMITH H. G. , BIRD C. , HULL R. 
Published: February 2008

SummaryThe 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.
Mode of action of chlorsulfuron in a sensitive wheat (Triticum aestivum) cultivar: primary and secondary effects on nitrogen assimilation
Authors: DASTGHEIB F. , ANDREWS M. , MORTON J. D. , BARNES M. F. 
Published: February 2008

SummaryChlorsulfuron (15 g a.i. ha‐1) inhibited growth of wheat (Triticurn aestivum L. cv. Rongotea) especially on high nitrate (NO3) supply. Decreased growth at high NO‐3 was associated with higher concentrations of reduced nitrogen (N) and NO‐3 in the shoots. Seven days after spraying (DAS), shoot dry weight (dry wt) of sprayed plants was similar with NO‐3 or branched chain amino acids as main N supply but 28 DAS, shoot dry wt was greater with the amino acid treatment.One DAS, chlorsulfuron caused substantial decreases in extension of the youngest leaf and acetolactate synthase activity and valine content of shoots of plants supplied with NO‐3 or branched chain amino acids. Total amino acid content of shoots was greater in sprayed plants than in unsprayed plants 1 DAS. Acetolactate synthase activity of sprayed plants supplied low NO‐3 returned to normal 14–21 DAS. For sprayed plants transferred from low to high NO‐3 supply 7, 14 or 21 DAS, shoot dry wt 50 DAS increased with increased time of transfer to high NO‐3 while shoot NO‐3 content decreased. Shoot NO3 content of sprayed plants transferred to high NO‐3 supply 7 or 14 DAS was similar to that in unsprayed plants at applied NO‐3 concentrations which inhibited growth. It is concluded that inhibition of acetolactate synthase is likely to be the primary mode of action of chlorsulfuron in this wheat cultivar; data are consistent with the proposal that subsequent NO‐3 accumulation can also inhibit growth.
Development of cercospora blight epidemics and effect on the summer annual Heliotropium europaeum in the field
Authors: BRUN L. A. , SHEPPARD A. W. , DELMOTTE E. , HASAN S. , JOURDAN M. 
Published: February 2008

SummaryHeliotropium europaeum, common heliotrope, is a serious economic weed in southern Australia. Cercospora blight occurs on H. europaeum in both its native (Mediterranean) and non‐native (Australian) range. The causal agents are genetically different forms of an asexual pathogen in the form‐genus Cercospora in each region. Natural epidemics of cercospora blight killed weed infestations in both Australia and France. The epidemiology of the disease did not differ between the two regions once differences in rainfall had been considered. Rainfall was important for disease spread. In France, field inoculation experiments were conducted using different concentrations of conidia prepared from a monospore isolate. Cercospora blight reduced seed production 89%, but did not reduce viability. Increased inoculum concentration and inoculation of younger plants encouraged an early epidemic, but did not affect the rate of disease development once the epidemic took hold. In order to be effective at controlling this weed in Australia, these pathogens need to attack young hosts and have regular rain‐splash to facilitate spread to new growth.
The effects of inbreeding on the parental values of potato dihaploids
Authors: MAINE M J DE. 
Published: February 2008

SummaryDihaploids obtained from a somatically chromosome‐doubled dihaploid potato were crossed with Solanum phureja clones. To test the effect of inbreeding, measurements were made of their seed production and the tuber yield, tuber number and mean tuber weight of their offspring. On average, seed production of the second generation dihaploids was higher than that of the original dihaploid progenitor. Progeny tuber yield and its components were little different from those of the original dihaploid's progeny. Tuber flesh quality, as measured lack of blemishes, was better in the offspring of second generation dihaploids.It is suggested that the negative effects of producing second generation dihaploids are minor compared with producing the first generation dihaploid from a tetraploid, because most deleterious recessives have already been unmasked. The results indicated residual variation within the original dihaploid which could be exploited for plant breeding purposes.An indicator of inbred status, alternative to the inbreeding coefficient, is suggested which could be applied to both diploids and tetraploids.
Effects of activated charcoal effects on induction and development of microtubers in potato (Solanurn tuberosum L.)
Authors: BIZARRI M. , BORGHI L. , RANALLI P. 
Published: February 2008

SummaryThe aim of this research was to compare hormone‐free medium with media with regulator substances (activated charcoal, cytokinins, polyamine biosynthesis inhibitor and chlorocholine chloride) used for microtuber induction and development. Explants of cvs Monalisa, Primura and Spunta were multiplied subculturing nodal segments on plant growth regulator‐free Murashige & Skoog (1962) (MS) medium. When the plantlets had 6–8 nodes, single‐node stem segments were excised and transferred to eight tuberisation media, each consisting of MS basal components supplemented with sucrose (8% w/v) and various regulator substances. The control was a regulator‐free medium including only sucrose. Results were expressed as the number and weight of microtubers per nodal explant.The cultivars showed wide variations in the mean weight of microtubers, ranging from 44.6 mg (Primura) to 77.5 mg (Spunta), and nearly all plants produced tubers. Medium containing activated charcoal gave the highest rate of tuberisation and the largest microtubers. It thus played a role in optimising conditions for rapid, mass tuberisation of these cultivars, and produced large microtubers for field planting.
Distribution and abundance of three species of Sitona (Coleoptera: Curculionidae) in grassland in England
Authors: MURRAY P. J. , CLEMENTS R. O. 
Published: February 2008

SummaryThe distribution and abundance of weevils of the genus Sitona was assessed at 16 sites in England. The sites were chosen to cover a wide range of geographical and agricultural regions. Adult weevils were sampled on four occasions, from May to August 1993. Numbers of adults, larvae and pupae were determined for each site on four occasions from June to September 1994. Numbers of larvae declined throughout the year in which they were sampled and pupae were most numerous in July. The population density of adults increased through the sampling period in both years. Sites close to pulse crops had the largest population levels of weevils, with Sitona lineatus L. the dominant species. No differences in the population levels of Sitona hispidulus (F.) or S. flauescens (Marsh.) were detected. Evidently populations of the latter two species are fairly constant in grassland and most of the variation in the population densities of these three species found in English grassland can be attributed to the migratory behaviour of S. lineatus and the proximity of pulse crops.
Partial application of insecticide to broad bean (Vicia fabae) as a means of controlling bean aphid (Aphis fabae) and bean weevil (Sitona lineatus)
Authors: WARD A. , MORSE S. 
Published: February 2008

SummaryThe effects upon the nature of insect pest attack of treating only a certain proportion (0%, 25%, 50%, 75% and 100%) of the plants in a field bean (Vicia fabae) stand, with a systemic insecticide (aldicarb as Temik 10G, Rhone Poulenc Drugs Ltd; 10% a.i.) were assessed. Numbers of both the black bean aphid (Aphis fabae) and the bean weevil (Sitona lineatus) were proportionally reduced on untreated plants in plots with an increasing proportion of insecticide treated plants. A similar response was also observed with bean weevil leaf damage scores.It is postulated that the observed effects are due to a reduction in insect numbers per plot brought about by redistribution of insects after initial invasion. Insects initially alighting on untreated plants later migrate to treated plants and either die or leave the plot altogether. This resulted in proportionally fewer insects on the untreated plants than would be expected.
In vitro screening of coffee genotypes for resistance to coffee berry disease (Colletotrichum kahawae)
Authors: NYANGE N. E. , WILLIAMSON B. , McNICOL R. J. , HACKER CHRISTINE A. 
Published: February 2008

SummaryAn in vitro protocol was developed to screen Coffea arabica genotypes for resistance to coffee berry disease caused by Colletotrichum kahawae. Initially, cultural conditions which influenced the growth of isolates of C. kahawae on agar media suitable for callus growth were determined. The growth of the fungus on the callus derived from susceptible and resistant genotypes was then assessed. This ensured that no detrimental competition for nutrients between the pathogen and the calli occurred. Optimisation of the concentration of the phytohormones added to the media, the temperature and incubation period were found to be important in the expression of differential responses of calli to inoculation with the pathogen as detected by measurement of hyphal growth. The screening of calli of nine C. arabica genotypes showed that this method identified genotypes highly resistant or susceptible to the disease and was sufficiently sensitive to distinguish those genotypes with moderate or low resistance.
Assessing linseed (Linum usitatissimum) resistance to Alternaria linicola using a detached cotyledon assay
Authors: EVANS N. , McROBERTS N. , HITCHCOCK D. , MARSHALL G. 
Published: February 2008

SummaryLevels of resistance to the seed‐borne pathogen Alternaria linicola in linseed and Linum accessions were characterised using an in vitro detached cotyledon bioassay. The response of four marketed varieties to seven isolates showed that differences between the isolates accounted for the majority of the variance. There was no significant interaction between varieties and isolates so that levels of response to the isolates showed a consistent trend. In a more comprehensive study, 102 different linseed and Linum accessions were challenged with an aggressive and a non‐aggressive isolate. Differences between accessions were significant (P > 0.001). Much of the material gave a moderate response to the two isolates although there was a continuous distribution of resistance from susceptible to resistant. The response of a sub‐set of tested material to the two isolates in a whole plant assay was positively correlated to the scores achieved in the in vitro bioassay, indicating that the resistance response of material could be predicted by the in vitro bioassay. Since large isolate‐line interactions with respect to resistance scores were not observed in either test, resistance appears to be polygenically determined. The results suggest that an improvement in the resistance of linseed to A. linicola would be possible and beneficial.
Evaluating between‐plant interference in field trials for assessing potato genotypes for resistance to late blight
Authors: CONNOLLY T. , McNICOL J. W. , WASTIE R. L. , STEWART HELEN E. 
Published: February 2008

SummaryField trials were done with four cultivars over 3 years to assess the extent to which the amount of late blight on the foliage of a potato plant could be influenced by that on a neighbouring plant of the same or a different cultivar. Drills containing the test plants were interspersed with those of spreader plants (cv. King Edward) which were artificially inoculated with Phytophthora infestans. The intensity of blight on the test plants was recorded on several occasions.Resistant cultivars tended to be scored as less resistant in mixtures with other cultivars than in pure stands, and susceptible cultivars tended likewise to be scored as more resistant in mixed stands. However, standard analysis of variance indicated no systematic evidence of a significant effect due to neighbour cultivars, nor of interaction between cultivars and neighbour cultivars. In contrast, Kempton's (1982) neighbour model indicated a significant and positive interference coefficient (β) in each trial, which generally decreased over time. Predicted pure stand scores for each cultivar indicated that the adjustment was greatest for the most resistant and most susceptible cultivars. There was no advantage in using two‐plant rather than one‐plant plots in withstanding neighbour effects.
Evidence from the virobacterial agglutination test for the existence of eight serogroups of cocoa swollen shoot virus
Authors: HUGHES J. d'A. , ADOMAKO D. , OLLENNU L. A. A. 
Published: February 2008

SummaryMany isolates of cocoa swollen shoot virus (CSSV) have been found in Ghana. Relationships between these isolates have been based on symptom expression and limited serological information. This paper reports on the serological relationships between 44 accessions of CSSV using the virobacterial agglutination test. The CSSV group is differentiated into eight groups using seven antibody ‘types’. The largest group comprising those isolates closely related to CSSV 1A is sub‐divided into four further groups. These groupings are compared with previous results. Differences are seen between accessions of the same isolate which may be due to contamination of the source plants. These serological results can be used for studying mixed isolate infections as well as for determining the most closely related CSSV mild isolate for appropriate cross‐protection against severe isolates.
Critical factors required by the nematode Steinernema feltiae for the control of the leafminers Liriomyza huidobrensis, Liriomyza bryoniae and Chromatomyia syngenesiae
Authors: WILLIAMS E. C. , MACDONALD O. C. 
Published: February 2008

SummaryThe critical factors required by entomopathogenic nematodes for the control of dipteran leafminers were investigated and compared. The foliar application of Steinernema feltiae and Heterorhabditis sp. (strain UK 211) caused a significant reduction in the numbers of dipteran leafminer larvae. There was no significant difference in efficacy between these nematode species against Liriomyza huidobrensis at 20°C and 85–90% r.h. Application of S. feltiae to all three larval instars of L. huidobrensis significantly reduced larval survival, with application to the second instar being the most effective at 20 ± 2°C and 80 ± 10% r.h. Humidities of >90% significantly enhanced the efficacy of S. feltiae. When S. feltiae was applied to second instar larvae, it was equally effective throughout the temperature range 10–30°C. At 20°C and >90% r.h., sufficient nematodes were able to enter the leaf tissues within the first 12 h after application to reduce larval survival to c. 15%. A comparison between L. huidobrensis, L. bryoniue and Chromatomyia syngenesiue indicated that the efficacy of S. feltiae was affected by the same critical factors for all three species.
Shelf‐life enhancement of fresh ginger rhizomes at ambient temperatures by combination of gamma‐irradiation, biocontrol and closed polyethylene bag storage
Authors: MUKHERJEE P. K. , THOMAS PAUL , RAGHU K. 
Published: February 2008

SummaryThe feasibility of a combination process involving gamma‐irradiation, packing in closed polyethylene bags and biological control of fungi causing storage rot was evaluated as a means of extending the shelf‐life of fresh ginger rhizomes at ambient temperatures (25–30°C). Storage in closed polyethylene bags reduced weight loss but increased sprouting and rooting, which could be prevented by gamma irradiation to 60 Gy. Rotting caused by Sclerotium rolfsii was, however, a major cause of spoilage during extended storage.Four isolates of Trichoderma sp. isolated from sclerotia of S. rolfsii infecting ginger rhizomes, one of Gliocfadium uirens, and four isolates of fluorescent Pseudomonas were tested, out of which, one isolate of Trichoderma was found to be highly effective in suppressing the growth of S. rolfsii. The efficacy of the antagonist was demonstrated under simulated market conditions using artificially inoculated rhizomes. The recommended procedure consists of dipping washed, air dried rhizomes in Trichoderma suspension (108spores ml‐1), air‐drying, packing in 250 gauge LDPE bags followed by irradiation to 60 Gy. Rhizomes thus treated remained in good marketable condition for up to 2 months at ambient temperature without sprouting or significant loss of quality and less than 5% weight loss.An in vitro bioassay system was developed to demonstrate the efficacy of the antagonist to protect the cut surface of sliced rhizomes inoculated with the pathogen. The method could be used for rapid screening of antagonists.
In vitro selection of Coffea arabica callus for resistance to partially purified phytotoxic culture filtrates from Colletotrichum kahawae
Authors: Nyange N E. , Williamson B. , McNicol R J. , Lyon G D. , Hackett Christine A. 
Published: February 2008

SummaryCalli derived from hypocotyl explants of a susceptible and resistant genotype of Coffea arabica were evaluated for their response to different concentrations of partially purified culture filtrates (PPCFs) produced by Colletotrichum kahawae which are phytotoxic. The size of calli was measured non‐destructively by automated image analysis. Differential responses of calli ranged from complete necrosis or reduced growth in the susceptible genotype (N39) to an absence of necrosis and rapid growth in the resistant genotype (cv. Hybrido de Timor). Subsequently, one selection cycle in the presence of PPCF was devised and applied to calli of nine C. arabica genotypes. Normal plants were regenerated through somatic embryogenesis of callus lines that survived the phytotoxin treatment and in vitro and in vivo testing of these plants against the PPCF showed that increased resistance to the toxin had been obtained. These studies suggest that in vitro selection of calli may be a feasible approach to acquiring germplasm with improved resistance to coffee berry disease.
Genetics of resistance to Fusarium oxysporum f.sp. cucumerinum races 1 and 2 in cucumber line Wisconsin‐2757
Authors: Vakalounakis D J. , Smardas K. 
Published: February 2008

SummaryThe mode of inheritance of resistance to Fusarium oxysporum f.sp. cucumerinum races 1 and 2 in Wisconsin‐2757 (WI‐2757), a gynoecious cucumber (Cucumis sativus L.), was determined by analysing segregation of F1, F2 and BC1 populations of crosses with susceptible cultivar Straight‐8. Resistance to either race 1 or race 2 in WI‐2757 was conferred by a single dominant gene. In allelism tests, resistance to either race in WI‐2757 was determined by the gene Fcu‐1, which also confers resistance in line SMR‐18.
Occurrence of potato virus X strain group 1 in seed stocks of potato cultivars lacking resistance genes
Authors: Wilson C R. , Jones R A C. 
Published: February 2008

SummaryPotato virus X (PVX) isolates were obtained from a simple seed potato production scheme or from ware potatoes produced by seed potatoes obtained from it. In this scheme, PVX infection is widespread in seed stocks and most of the potatoes grown lack PVX resistance genes. Thirteen PVX isolates were typed to strain group by inoculation to potato cultivars containing different combinations of hypersensitivity genes Nx and Nb. Six failed to overcome either gene and therefore belonged to strain group 1, four overcame Nb only and were placed in strain group 3 and three were mixtures of the two. All 13 isolates failed to overcome extreme resistance/immunity gene Rx. Naturally infected cultivars of genotype nx.nb contained strain group 1 alone or strain groups 1 and 3, while those of genotype nx:Nb contained only strain group 3. The widespread occurrence of strain group 1 contrasts with the predominant occurrence of strain group 3 in potatoes in the UK. However, it resembles the UK situation before sophisticated seed potato production schemes were introduced and before PVX hypersensitivity genes Nx and Nb were deliberately exploited in potato breeding. Prior infection with potato leafroll virus (PLRV) did not affect expression of hypersensitivity to PVX in inoculated leaves of an nx:Nb genotype.