bluuebunny/crossref_metadata_2025_split huggingface dataset:
PCR detection of MLOs in quick decline‐affected pear trees in Italy
Authors: GIUNCHEDI L , POLLINI C POGGI , BIONDI S , BABINI ANNA ROSA 
Published: February 2008

SummaryPolymerase chain reaction (PCR) amplification, using primers derived from the 16S rRNA gene, followed by restriction fragment length polymorphism (RFLP) analysis with Alu I restriction endonuclease was used to detect myc‐oplasma‐like organisms (MLOs) associated with pear decline. MLOs were consistently detected in pear trees that suddenly wilted and died within a few days during summer, as well as in pears of the same orchards with symptoms similar to the slow form of pear decline. In both cases the same RFLP pattern was obtained. Declining pear trees were 5 to 8‐yr‐old cvs Williams, Kaiser and Max Red Bartlett grafted on to Pyrus communis seedling rootstocks. All the orchards affected by quick decline had severe attacks of pear psyllid (Cacopsylla pyri) during the year this study was performed and during the previous year. The results showed the suitability of DNA amplification by the polymerase chain reaction for the detection of pear decline MLOs and established that MLOs can be detected in infected tissues of dead trees.
Virus‐vector relationships of chickpea chlorotic dwarf geminivirus and the leafhopper Orosius orientalis (Hemiptera: Cicadellidae)
Authors: HORN N M , REDDY S V , REDDY D V R 
Published: February 2008

SummaryChickpea chlorotic dwarf geminivirus (CCDV) is one of the viruses associated with chickpea stunt disease. It is transmitted by the leafhopper Orosius orientalis. The minimum acquisition access period (AAPmin) and inoculation access period (IAPmin) were found to be less than 2 min, while the minimum latency period (LPmin) was less than 2 h. The median AAP, IAP and LP were 8.0 h, 2.3 h and 27.7 h, respectively. No difference in transmission rates (proportion of leafhoppers able to transmit) was observed between male and female leafhop‐pers. In serial transmission experiments, transmission was shown to be persistent, and after a 2‐day AAP about 80% of the leafhoppers transmitted the virus for most of their life. The virus could be detected in individual leafhoppers by DAS‐ELISA. It did not multiply in the leafhopper, but, instead, decreased in concentration during leafhopper feeding on a non‐host of the virus.
Multiplication of English isolates of potato pale cyst‐ nematode, Globodera pallida, on potatoes of differing nematode resistance and the identity of potato cyst‐ nematode populations
Authors: WHITEHEAD A G , RUSSELL M D 
Published: February 2008

SummaryIn pots, 25 populations of potato pale cyst‐nematode, Globodera pallida Stone, differed significantly in their ability to multiply on potato clones P55/7 and ZC83/ 6, both fully resistant to G. pallida pathotype Pal. Neither clone was fully resistant to any of the populations. For 21 populations common to this and an earlier experiment, increase on the more resistant potatoes (P55/7, ZC83/6, cvs Sante, Paladin and Glenna) was correlated with their increase on less resistant potatoes (cvs Morag, Fingal and Valiant). Variation in virulence on these partially resistant potatoes was not matched by differences in the electrophoretic patterns of the nematodes' proteins. The identification of populations of G. rostochiensis (Woll.) Skarbilovich used in these experiments was confirmed by electrophoresis. All populations of G. pallida Stone, appeared to contain very small numbers of G. rostochiensis after subculture on susceptible potatoes (cv. Désirée).
The persistence and spread of Xiphinema diversicaudatum in cultivated and uncultivated biotopes
Authors: TAYLOR C E , BROWN D J F , NEILSON R , JONES A T 
Published: February 2008

SummaryThe distribution of Xiphinema diversicaudatum in an uncultivated woodland habitat in England and a cultivated soil in Scotland, was re‐investigated in 1991 after an interval of 30 and 24 years, respectively. In the undisturbed habitat, nematodes had a distribution similar to that in 1961 but with a lower population density. In the cultivated habitat, nematodes were aggregated in several discrete populations associated with the cultivation and change of cropping in the intervening years but had spread little further horizontally into the raspberry crop, planted in 1982. Although strawberry latent ringspot and arabis mosaic nepoviruses were present in 1966, only the latter virus was found in crop and weed plants in 1991.The X. diversicaudatum populations from the two locations were morphologically similar to each other and to other populations, including those used for a redescription of the species.
Induction of resistance mechanisms in barley by yeast‐derived elicitors
Authors: REGLINSKI T , LYON G D , NEWTON A C 
Published: February 2008

SummaryYeast cell‐wall extracts (YE) had high phytoalexin elicitor activity on soybeans and induced resistance against barley powdery mildew in the normally highly susceptible cv. Golden Promise. Following treatment with YE there was rapid stimulation of phenylalanine ammonia‐lyase (PAL) activity and faster formation of papillae in response to attempted fungal penetration. The spray adjuvants Agral and LI‐700 each had poor phytoalexin elicitor activity and caused a slight enhancement of papilla formation and a low level of mildew control. The addition of the adjuvant to YE did not affect phytoalexin elicitation on soybeans but significantly enhanced the speed and the extent of PAL activity, papilla formation and mildew control. It is proposed that this is due to greater coverage and improved persistence enabling increased uptake of YE into the barley leaves.
Morph identification in natural populations of alate female bird cherry aphids, Rhopalosiphum padi L., by multivariate methods
Authors: TAYLOR M S , TATCHELL G M , CLARK S J 
Published: February 2008

SummaryA discriminant analysis was done to determine which morphological characteristics contributed most to the identification of alate female morphs of Rhopalosiphum padi in natural populations collected from either Prunus padus or in suction traps. Twenty two characters were measured or counted, including wing dimensions, and three ratios were included. Analyses were done to separate morphs that might occur naturally together, i.e. emigrants and ‘early’ exules, or ‘late’ exules and gynoparae. Emigrants were distinguished readily from early exules, but gynoparae were not so easily separated from late exules. The biological significance of the morphological differences between morphs and the practical implications of being able to identify the different morphs are discussed.
Effects of water stress, nitrogen stress and certain sensory stimuli on infestation and damage by Chilo partellus (Swinhoe) to maize
Authors: KUMAR HARISH 
Published: February 2008

SummaryFoliar, stalk and dead heart damage caused by Chilo partellus (Swinhoe) (Lepidoptera: Pyralidae) to several maize genotypes (Inbred A, MBR 8637, Poza Rica 7832, ER‐29SVR, Across 7844, Bulk CG 4141, MMV 600 and ICZ2‐CM) subjected to water stress were significantly lower than those observed when plants were grown in the absence of water stress. Resistance of maize genotypes to C. partellus was distinguished clearly when there was no water stress to the plants. Resistance/susceptibility of maize genotypes Inbred A, MMV 400, MBR 8637 and Poza Rica 7832 to C. partellus was the same at 0, 60, 90 and 120 kg of N per hectare. At each nitrogen level, the genotypes MMV 400, MBR 8637 and Poza Rica 7832 suffered significantly lower damage than the susceptible Inbred A. The humidity stimuli from maize plants and the olfactory/hygro stimuli from the plants infested with larvae were the most important factors affecting host plant selection by ovipositing C. partellus females.
Genetic variation in resistance toFusarium oxysporumf.sp.liliiin the genusLilium
Authors: STRAATHOF Th P , van TUYL J M 
Published: February 2008

SummaryGenetic variation inFusariumresistance in 82Liliumgenotypes was studied. A high level of resistance was found in the Asiatic hybrids (sectionSinomartagon) and to a lesser extent in cultivars ofL. longiflorum(sectionLeucolirion). The Oriental hybrids (sectionArchelirion) showed only moderate resistance. In the sectionsSinomartagon, LeucolirionandMartagonspecies were detected with high levels of resistance. An accession ofL. dauricum(sectionSinomartagon) was the most resistant source. Possibilities for introgression ofFusariumresistance into cultivars by interspecific hybridisation, using the resistance found inLiliumgenotypes, are discussed.
In vitro spore germination and infection of cultivars of Rubus and Rosa by downy mildews from both hosts
Authors: BREESE WENDY A , SHATTOCK R C , WILLIAMSON B , HACKETT CHRISTINE 
Published: February 2008

SummaryThe cardinal temperatures for in vitro germination of conidia of imported and indigenous isolates of downy mildew from hosts in the genera Rubus and Rosa were similar. A high percentage of conidia germinated above 2°C and germination remained between 80% and 90% up to 15°C or 20°C, depending on the isolate. The highest incidence of disease on leaf disks of Tummelberry (blackberry × red raspberry) inoculated with an isolate of Peronospora rubi occurred at c. 15°C, with infection over a range from 2°C to 28°C. Tests on leaf disks in vitro, and leaflets of primocane and lateral shoots in plastic tunnels, with three hybrid berry (blackberry x red raspberry), six blackberry and nine red raspberry cultivars showed the hybrid berries to be most susceptible. In a plastic tunnel infected drupelets of red raspberry fruits developed more slowly and failed to ripen evenly compared with uninfected drupelets. Similar malformation of infected fruits occurred in a plantation of Tummelberry. An isolate of P. rubi attacked severely both Tummelberry and rose cv. Can Can. Fluorescence microscopy after staining with aniline blue showed that leaf disks of Tummelberry were extensively colonised by intercellular mycelium of P. sparsa isolated from rose, even though sporulation was sparse or absent. This supports the view that P. rubi and P. sparsa may be conspecific. Oospores of P. rubi were found routinely within leaf disks of Rubus cultivars inoculated in vitro and once in naturally infected leaflets of Tummelberry.
Genotypic influence on in vitro induction, dormancy length, advancing age and agronomical performance of potato microtubers (Solanum tuberosum L.)
Authors: RANALLI P , BIZARRI M , BORGHI L , MARI M 
Published: February 2008

SummaryMicrotubers of 13 cultivars, largely grown in Italy and other European countries, were induced. They were stored in the dark at 3°C for different periods (28, 56, 84 and 105 days), prior to being transferred to 20°C for between 4 and 17 weeks. Following removal to room temperature, sprouting was recorded and dormancy duration quantified. Dormancy decreased from 28.1 to 19.9, 11.1 and 7.8 days with reduced time of storage. Cvs Arsy, Nicola and Jaerla took consistently more time for dormancy release. The dormancy duration was linearly and inversely correlated with the length of storage. After sprouting, tubers were held at 20°C for various intervals and a range of physiological ages (0, 368, 720 and 1008 degree days) were accumulated. The field comparison of microtubers evidenced a plant growth response and tuber yield/plant affected by the cultivar and physiological age. In early cultivars (Jaerla), a better performance was shown by younger tubers; the opposite trend was noted in Alpha (a later cultivar) with an increase in stems/plant, tubers/plant and tuber yield/plant for tubers with greater physiological age. Like conventional seed tubers, microtubers showed differences in optimum physiological age associated with cultivar earliness. This study has provided some indications on how to enhance emergence and haulm development of plants from microtubers.
Genistein as an endogenous natural substrate of acidic peroxidases in lupin hypocotyls
Authors: FERRER M ANGELES , BARCELÓ A ROS 
Published: February 2008

SummaryThe localisation of peroxidase in the outermost cell layers of lupin (Lupinus albus L. cv. Multolupa) hypocotyls shows that peroxidase activity is present mainly in the epidermal cell layer in a similar way to isoflavones. The soluble peroxidase activity is due mainly to the presence of two peroxidase isoenzyme groups, one of an acidic nature (A1 and A2) and the other basic (B1 and B2). These isoenzymes, although present in epidermal tissues, are not tissue‐specific since they are also located in the soluble peroxidase fraction obtained from vascular tissues. These observations, and the fact that acidic peroxidases but not basic peroxidases are extremely active in the oxidation of genistein, a constitutive isoflavone of lupin hypocotyls, point to a role for acidic peroxidases in isoflavone turnover and degradation. Thus, manipulating peroxidase activity and/or its level would allow endogenous isoflavone levels to be controlled in order to grow lupins as a commercial fodder crop.
Interaction of bean leaf pubescence with rust urediniospore deposition and subsequent infection density
Authors: MMBAGA M T , STEADMAN J R , ROBERTS J J 
Published: February 2008

SummaryThe role of dense straight trichomes on bean leaves associated with race‐nonspecific resistance to rust was studied using a settling tower method for uniform inoculation. Abaxial leaf trichomes, which occur only on adult leaves, trapped significant numbers of urediniospores, especially those deposited in clusters, and resulted in reduced effective inoculum reaching the leaf surface. In the field where infection conditions are often less than optimum, leaf pubescence would partially explain the observed resistance. However, the observed increase in total number of spores as well as similar infection densities on fully expanded leaves of glabrous and pubescent genotypes cannot be explained by the trichomes. Other physical or chemical features of the leaf surface such as waxes or cations may play a role. The ecological fit of leaf pubescence is discussed.
Variation in cardinal temperatures for germination among wheat (Triticum aestivum) genotypes
Authors: ALI Z I , MAHALAKSHMI V , SINGH M , ORTIZ‐FERRARA G , PEACOCK J M 
Published: February 2008

SummaryIn most tropical regions where wheat is grown under irrigation, high temperatures at sowing adversely affect crop establishment and subsequent seedling survival. The objective of this study was to compare wheat (Triticum aestivum) genotypes for their ability to germinate and grow at high temperatures during the seedling stage. Twenty‐five seeds each of 14 spring wheat cultivars were placed on moist filter paper at different temperatures (5°C to 40°C) in a one‐way thermogradient plate to determine the cardinal temperatures for germination. Rate of germination at each temperature for each genotype was computed as the inverse of time taken for 50% of the seeds to germinate. Rate of germination for each genotype at different temperatures was modelled with temperature to determine the base (tb), and optimum (topt) temperatures. Response of germination to temperature for each genotype was calculated as the slope of a linear regression of the rate of germination on temperature below topt. Genotypes differed in their optimum temperatures and Mexipak (= Kalyansona) had the lowest. Range in base temperature among the genotypes was between 0°C and 2°C differences but were not statistically significant though they might be biologically significant. Genotypes differed in their response to temperature with Gomam having the lowest rate, implying that it was slow to respond to increasing temperatures. Debeira and Cham 6 showed a similar response. Three lines which had performed well in spring wheat evaluation trials for moderate rainfall areas under heat stress had the highest response rate.It is concluded that combining higher optimum temperatures with faster response rates would result in better‐adapted germplasm for regions where high temperatures persist at sowing.
Ultrastructure of the black currant gall mite, Cecidophyopsis ribis (Acari: Eriophyidae), the vector of the agent of reversion disease
Authors: ROBERTS I M , JONES A T , AMRINE J W 
Published: February 2008

SummaryElectron microscopy of ultrathin serial sections was used to determine the structure and anatomy of the eriophyid gall mite, Cecidophyopsis ribis, the vector of the agent of black currant reversion disease. The composite picture derived from these studies has determined the location of the food canal, and major internal organs of the mite. Detailed ultrastructural studies on the anterior of suitably orientated mites has also provided detailed information on the geometry and complex structure of three sets of stylets in the feeding apparatus. No evidence was found of structures resembling virus‐like particles or of other described plant pathogens in the feeding apparatus and food canal of mites obtained from black currant plants affected with reversion disease. However, little or no food was apparently present in the food canal of most mites examined. This is the first detailed report of the anatomy and the ultrastructure of the mouthparts of this important plant pest and vector.
Morphological factors of the central whorl leaf associated with leaf surface wetness and resistance in sorghum to shoot fly, Atherigona soccata*
Authors: SREE P S , NWANZE K F , BUTLER D R , REDDY D D R , REDDY Y V R 
Published: February 2008

SummaryEarlier studies showed that leaf surface water on the central whorl leaf of sorghum seedlings is associated with resistance to shoot fly. In this study, the results of an experiment to determine if leaf surface wetness (LSW) originates from atmospheric condensation or from the plant are described. Morphological structures: trichomes, stomata, leaf cuticle and quantity of surface wax of the central whorl leaf were also examined for their role in LSW production. The results suggest that LSW of the central whorl leaf originates from the plant and is not due to condensation of atmospheric moisture. The presence of trichomes was indirectly associated with LSW and resistance to shoot fly but stomatal density was not associated with LSW production. The amount of wax extracted per 100 mg of fresh weight varied significantly between genotypes and seedling age. It was more in susceptible than in resistant genotypes; however, cuticular thickness was not associated with resistance. It is suggested that LSW could be the result of some form of cuticular movement of water to the leaf surface.
Seasonal development of apothecia of the cereal eyespot pathogen Tapesia yallundae on straw stubble in the UK
Authors: DYER P S , BATEMAN G L , LUCAS J A , PEBERDY J F 
Published: February 2008

SummaryFive field sites growing winter wheat were inoculated with isolates of the W‐and R‐types of Tapesia yallundae in 1990 and 1991. After harvest, plots of uncultivated stubble were monitored for the production of apothecia during 1992 and 1993. Apothecia were found on the stem bases of straw stubble over a 9‐month period from mid‐October to July, but with a peak in numbers present during late January to March, 5 to 7 months after harvest. This was associated with mean monthly temperatures between 3°C and 8°C. Rainfall appeared to be less important than temperature in apothecial development. Single ascospore isolates obtained from apothecia collected from areas inoculated with W‐, R‐, or mixed W‐ and R‐type isolates all produced colonies with morphologies and growth rates characteristic of the W‐type. Thus there was no indication that the W‐ and R‐types are sexually compatible.
Thermal time and ecological strategies ‐ a unifying hypothesis
Authors: TRUDGILL D L , PERRY J N 
Published: February 2008

SummaryRates of embryogenesis and of development and growth in several nematodes are linearly related to temperature over a considerable range. On this basis, published data on the thermal time requirements are compared for a tropical and a temperate species of plant parasitic nematode Meloidogyne javanica and M. hapla respectively, the two being closely related and morphologically and biologically similar. M. hapla has a lower base temperature (Tb) and a higher thermal constant (S) than M. javanica with the relative values being almost inversed. Consequently, above their respective Tb values the slope of the relationship between rate of development and temperature was greater for the tropical species than that for the temperate species. A mathematical exploration of the relationship between Tb and S was made assuming that, over a narrow range, Tb×S was a constant. With this assumption, for any given average environmental temperature (Te) the optimum base temperature for minimum developmental duration was Te/2, and the temperature at which the duration of development was equal for the otherwise identical species was shown to be the sum of their base temperatures. The practical effect of the differences in Tb and S was to give M. hapla, the temperate species, a shorter life cycle and hence a competitive advantage at temperatures below 21ÅC and M. javanica, the tropical species, the advantage above that temperature. It is argued that a negative correlation between Tb and S is likely to be widespread, and provides a mechanism for regulating the distributions of related, competing organisms. Support for the hypothesis that the value of S tends to decrease as Tb increases is derived from data on the embryogenesis of an animal parasitic nematode Haemonchus contortus and from seed germination studies. Contrary results and exceptions are also briefly discussed. The observed interaction between Tb and S may be fundamental to many poikilothermic organisms and plants and provides an explanation for tropical species generally having higher Tb values than temperate ones. The ecological implications of different values of Tb and of S, including their relationship with organisms which are “r” or “K” strategists are briefly discussed.
Assessment of five cultivars of potato (Solatium tuberosum L.) in a competition diallel
Authors: BRADSHAW J E 
Published: February 2008

SummaryIn 1992 and 1993, potato cultivars Cara, Estima, Pentland Dell, Pentland Javelin and Torridon were assessed in all possible pairings in three consecutive drills, such that one member of the pair (the cultivar) was the centre‐drill, and the other member (the neighbour) was in the two adjacent drills. Each year the trial was a randomised complete block design with four replicates. Inter‐cultivar competition was present for height, total tuber yield, ware yield and dry matter content, but not for emergence and maturity. Cultivar heights and dry matter contents under inter‐cultivar competition and in pure‐stands were highly correlated, whereas for total and ware yields, the rankings of cultivars in pure‐stands were different from those under competition.Pure‐stand yields were predicted for the two years separately because of year × cultivar and year × neighbour interactions. When the average total yield of the outer‐drills was used as a covariate to adjust centre‐drill yields to pure‐stands, predicted yields were closer to those observed than were yields under competition, but there was little improvement in the correlations. In contrast, not only were the predicted values even closer to the observed ones when based on individual neighbour effects, the correlations were much higher (r = 0.76–0.94). Unfortunately, in plant breeding trials with large numbers of entries, precise estimation of individual neighbour effects would require an unrealistically large number of replicates. Hence, for the final stages of yield assessment of new cultivars, it is still desirable to use multiple‐drill plots and to discard the outside drills where inter‐cultivar competition can occur.