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PubMed2003

Mapping quantitative physiological traits in apple (Malus x domestica Borkh.).

Efficient breeding and selection of high-quality apple cultivars requires knowledge and understanding of the underlying genetics. The availability of genetic linkage maps constructed with molecular markers enables the detection and analysis of major genes and quantitative trait loci contributing to the quality traits of a genotype. A segregating population of the cross between the apple varieties 'Fiesta' (syn. 'Red Pippin') and 'Discovery' has been observed over three years at three different sites in Switzerland and data on growth habit, blooming behaviour, juvenile period and fruit quality has been recorded. QTL analyses were performed, based on a genetic linkage map consisting of 804 molecular markers and covering all 17 apple chromosomes. With the maximum likelihood based interval mapping method, the investigated complex traits could be dissected into a number of QTLs affecting the observed characters. Genomic regions participating in the genetic control of stem diameter, plant height increment, leaf size, blooming time, blooming intensity, juvenile phase length, time of fruit maturity, number of fruit, fruit size and weight, fruit flesh firmness, sugar content and fruit acidity were identified and compared with previously mapped QTLs in apple. Although 'Discovery' fruit displayed a higher acid content, both acidity QTLs were attributed to the sweeter parent 'Fiesta'. This indicated homozygosity at the acidity loci in 'Discovery' preventing their detection in the progeny due to the lack of segregation.

Chromosome Mapping↗
PubMed2004

The predatory mite Typhlodromus pyri (Acari: Phytoseiidae) causes feeding scars on leaves and fruits of apple.

Typhlodromus pyri Scheuten (Acari: Phytoseiidae) is the most important predator of Panonychus ulmi (Koch) (Acari: Tetranychidae) in orchards and vineyards. It was recently found that adult T. pyri females cause microscopic scars on apple leaves. The present laboratory experiments were carried out to confirm the production of scars on apple leaves and to assess if females cause scars on fruits as well. Scar production on apple leaves and/or fruits was investigated under various nutritional conditions: no food, pollen of Scots pine (Pinus sylvsestris L.) only, nymphs of P. ulmi only, and pollen + prey. Both on leaves and fruits, either offered alone or in combination, feeding scars were produced under all nutritional conditions, but mostly in the 'no food' treatment. The predators consumed significantly more P. ulmi nymphs when offered alone than when offered in combination with pollen. T. pyri laid eggs under all nutritional conditions, but mostly in the 'pollen + prey' treatment and least when no food was offered. T. pyri females caused scars on both leaves and fruits when offered simultaneously, but more on leaves than on fruits. The scars were also bigger on leaves than on fruits in all experiments. T. pyri survived and reproduced on plant material in the absence of other food sources. Whether the scars produced on leaves and fruits harm the quality of fruits or the yield of apple cannot be concluded from the present experiments.

Animals↗
PubMed2004

Phytoseiid mites on unsprayed apple trees in Oregon, and other western states (USA): distributions, life-style types and relevance to commercial orchards.

In unsprayed apple trees in eastern Oregon, Galendromus flumenis (Chant), Galendromus occidentalis (Nesbitt), Typhlodromus caudiglans Schuster and Metaseiulus citri (Garman and McGregor) were common phytoseiid mites; common plant-feeding mites were the eriophyid, Aculus schlechtendali Nalepa, the brown mite, Bryobia rubrioculus (Scheuten) and Eotetranychus spp.; apple rust mites seemed to be the primary prey for phytoseiids; the spider mites, Tetranychus urticae Koch and Panonychus ulmi (Koch) were scarce except for a few local outbreaks; the stigmaeid Zetzellia mali (Ewing) was at 10% of sites and its densities were inversely related to phytoseiid densities; phytoseiids were absent at some sites, particularly at high elevations where winters are severe. In seven Oregon ecoregions, G. flumenis was often at lower elevations in valleys with moderate winters; T. caudiglans was often at higher elevations; G. occidentalis was often at intermediate elevations, in young trees, and near where pesticides were used; it dominated in unsprayed trees only in almost treeless, sage-covered areas; M. citri was usually in older apple trees near agriculture. In mixed phytoseiid populations, M. citri, a generalist, and G. occidentalis, a specialist, occurred more often than expected; G. occidentalis was mostly found with T. caudiglans, a generalist; G. flumenis, a generalist, occurred less with others, possibly because it competes with both specialists and generalists. Analyses of species' distributions with multiple regression and genetic models gave explanatory r2s of 0.019-0.318. Of 29 variables, altitude of site, intensity of agricultural management, tree age, plant types, and Z. mali levels helped explain phytoseiid species presence. In the western USA, G. flumenis dominated in middle-southern latitudes; T. caudiglans dominated in the north near the Canadian border; G. occidentalis dominated in middle latitudes in parts of Washington, Idaho, Montana, and Wyoming; M. citri was at a few sites in these four states. Distributional and independent variable data were used to predict species presence at sites in Oregon with a 70% success rate. We discuss phytoseiid life-style types, community dynamics, presence in organic/conventional orchards, and trends as more selective IPM methods are used in apple orchards.

Animals↗
PubMed2000

Natural selection and sympatric divergence in the apple maggot Rhagoletis pomonella.

In On the Origin of Species, Darwin proposed that natural selection had a fundamental role in speciation. But this view receded during the Modern Synthesis when allopatric (geographic) models of speciation were integrated with genetic studies of hybrid sterility and inviability. The sympatric hypothesis posits that ecological specialization after a host shift can result in speciation in the absence of complete geographic isolation. The apple maggot, Rhagoletis pomonella, is a model for sympatric speciation in progress. Hawthorn (Crataegus spp.) is the native host for R. pomonella in N. Americas. But in the mid-1800s, a new population formed on introduced, domesticated apple (Malus pumila). Recent studies have conferred 'host race' status on apple flies as a potentially incipient species, partially isolated from haw flies owing to host-related adaptation. However, the source of selection that differentiates apple and haw flies is unresolved. Here we document a gene-environment interaction (fitness trade-off) that is related to host phenology and that genetically differentiates the races.

Animals↗
PubMed2002

Post-harvest biological control by Pantoea agglomerans (CPA-2) on Golden Delicious apples.

AIMS: To investigate the potential of Pantoea agglomerans to control the major post-harvest diseases on Golden Delicious apples. METHODS AND RESULTS: In laboratory trials, a high level of control of Penicillium expansum, Botrytis cinerea and Rhizopus stolonifer was obtained with P. agglomerans. In semi-commercial trials at 1degrees C in air and a low oxygen atmosphere, the reduction of blue mould was 81% and 100%, respectively, and control of grey mould was achieved equally with P. agglomerans and imazalil. In trials at 1degrees C and seven atmosphere conditions, maximum reduction in decay was 80% obtained at 3% O2-6% CO2. The population of P. agglomerans on apples followed the same pattern under all three atmosphere conditions studied. CONCLUSIONS: Pantoea agglomerans could be used effectively on apples under a wide range of temperature and atmosphere conditions. SIGNIFICANCE AND IMAPCT OF THE STUDY Pantoea agglomerans can be used as a biocontrol agent on apples at 8 x 10(7) cfu ml-1, the same concentration as in pears. This will facilitate the application of this biological control agent by the growers in packing houses.

Food Preservation↗
PubMed2000

A novel alpha-amylase gene is transiently upregulated during low temperature exposure in apple fruit.

An alpha-amylase gene product was isolated from apple fruit by reverse-transcriptase PCR using redundant primers, followed by 5' and 3' RACE. The gene is a member of a small gene family. It encodes a putative 46.9 kDa protein that is most similar to an alpha-amylase gene from potato (GenBank accession M79328). In apple fruit this new gene was expressed at low levels, as detected by reverse-transcriptase PCR, in a number of plant tissues and during fruit development. Highest levels of mRNA for this transcript were observed 3 to 9 days after placing apple fruit at 0.5 degrees C. Phylogenetic analysis of amino acid sequence places the potato and apple proteins as a distinct and separate new subgroup within the plant alpha-amylases, which appears to have diverged prior to the split between monocotyledonous and dicotyledonous plants. These two divergent alpha-amylases lack the standard signal peptide structures found in all other plant alpha-amylases, and have sequence differences within the B-domain and C-domain. However, comparisons with structures of known starch hydrolases suggest that these differences are unlikely to affect the enzymatic alpha-1,4-amylase function of the protein. This is the first report of upregulation of a dicotyledonous alpha-amylase in response to low temperature, and confirms the presence of a new family of alpha-amylases in plants.

Amino Acid Sequence↗
PubMed2004

The HcrVf2 gene from a wild apple confers scab resistance to a transgenic cultivated variety.

The Vf gene from the wild species Malus floribunda 821 is the most studied apple scab resistance gene. Several molecular markers mapping around this gene were the starting point for a positional cloning project. The analysis of the bacterial artificial chromosome clones spanning the Vf region led to the identification of a cluster of genes homologous to the Cladosporium fulvum resistance gene family of tomato. One of these genes, HcrVf2 (homologue of the C. fulvum resistance genes of the Vf region), was used to transform the susceptible apple cultivar Gala. Four independent transformed lines resistant to apple scab were produced, proving that HcrVf2 is sufficient to confer scab resistance to a susceptible cultivar. The results show that direct gene transfer between cross-compatible species can be viable when, as in apple, the use of backcrosses to introduce resistance genes from wild species cannot exactly reconstitute the heterozygous genotype of clonally propagated cultivars.

Ascomycota↗
PubMed1995

Overhead work and shoulder-neck pain in orchard farmers harvesting pears and apples.

The effects of overhead work were studied by comparing orchard farmers' musculoskeletal symptoms while bagging pears with those same symptoms while bagging apples. The subjects were 52 Japanese female farmers, who were examined twice an evening in late June for bagging pears, and during another evening of late July for bagging apples, when each task had been almost finished. They were questioned about musculoskeletal complaints of stiffness and pain during each job, and examined for muscle tenderness and pain from joint movement. Arm elevation angles during the work were measured for each type of bagging. The prevalence of stiffness and pain in the neck and shoulder, muscle tenderness in the shoulder regions, and pain in neck motion were found to be significantly higher when bagging pears than apples. Musculoskeletal symptoms of parts other than the neck and shoulder did not differ between the two types of bagging. The working posture of elevating the arm more than 90 degrees was assumed to account for 75% of the time bagging pears, against 40% for bagging apples. Overhead work requiring arm elevation and head extension was considered to be closely related with shoulder-neck disorders among farmers.

Adult↗
PubMed2006

Monitoring of pesticide residues in apples, lettuce and potato of the Slovene origin, 2001-04.

Apples, lettuce and potatoes (404 samples) produced in the Republic of Slovenia were analysed for pesticide residues at the Agricultural Institute of Slovenia, Ljubljana, in 2001-04. Sampling from eight agricultural production areas was performed at market producers at the harvesting of products or in storehouses after the pre-harvest interval of plant protection products used. Samples exceeding the maximum residue levels were the following: three apple samples (2.0%) containing 0.33-2.24 mg kg(-1) (phosalone and tolylfluanid), three lettuce samples (3.1%) containing 0.14-6.36 mg kg(-1) (dimethoate, dithiocarbamates and metalaxyl) and 36 potato samples (23.1%) containing 0.06-0.51 mg kg(-1) (dithiocarbamates). Residues of two or more active substances were found in 73 apple samples (48.3%), of which the maximum residue limit (MRL) was exceeded by three samples (2.0%) with the values ranging from 0.33 to 2.24 mg kg(-1), and nine lettuce samples (9.3%), for which the MRL was exceeded by three samples (3.1%) with values from 0.14 to 6.36 mg kg(-1). In potato samples, only residues of dithiocarbamates or no residues at all were found. Residues of the dithiocarbamate group were the most frequently found, i.e. in 66 apple samples (43.7%), 30 lettuce samples (30.9%) and 38 potato samples (24.4%).

Agriculture↗
PubMedDate not supplied

Production of patulin by different strains of Penicillium expansum in pear and apple cultivars stored at different temperatures and modified atmospheres.

It was shown that the ability of three different strains of Penicillium expansum (NRRL 2034, NRRL 6069, and CBS 481.84) to grow and to produce patulin in pears (cv. Spadona) and apples (cv. Starking) varied under the different temperatures tested (0, 3, 6, 17 and 25 degrees C). Strain NRRL 2034 did not produce patulin at 0 or 25 degrees C while the two other strains produced the toxin at all temperatures, the maximum production occurring at 25 degrees C (for pears) and 17 degrees C (for apples). No significant differences in pathogenicity, as determined by lesion diameter, was recorded among the strains. Patulin production was totally inhibited when the fungi were grown in apples stored under 3% CO2/2% O2 (25 degrees C). The weight of infected tissue in apples contaminated with any of the strains and stored at that modified atmosphere was 70% that of the control. Under 3% CO2/10% O2 or 3% CO2/20% O2, strain NRRL 2034 did not produce patulin while the two other strains produced the toxin in different amounts.

Carbon Dioxide↗
PubMedDate not supplied

Reduction in phosalone residue levels during industrial dehydration of apples.

Dehydrated fruits and vegetables, which may well be used in baby foods, must be of excellent bacteriological quality with an absence of contamination. In order to define the effects of the industrial dehydration process, according to the 'Hatmacker' drying method, on an organophosphorus pesticide, we have studied phosalone in Golden Delicious apples as an example. The technological process undertaken leads to a reduction in phosalone levels on the apples of more than 80%, whatever the initial dose between 0 and 4.29 micrograms/kg. Washing brings about a reduction of 30-50%, probably by the dissolution of the phosalone in the water. The cooking and especially the filtration of the puréed apple mechanically eliminates, without notable deterioration, 40-70% of the phosalone. However, drying, which takes place at the end of the process, does not lead to significant variations in phosalone levels. Consequently, the reduction in phosalone residue levels in dehydrated apple products manufactured by this process provides the consumer with a greater degree of security with respect to this contaminant. In addition, we have presented several possibilities to add to the quality of dehydrated products.

Desiccation↗
PubMed2000

Effects of five insecticides used in apple orchards on Hyaliodes vitripennis (Say) (Hemiptera: Miridae).

Azinphos-methyl, carbaryl, dimethoate, phosmet and phosalone were used in apple orchards to manage apple aphid, apple maggot, woolly apple aphid and leaf eating caterpillars. Among the five insecticides evaluated, dimethoate, carbaryl and azinphosmethyl were the most toxic to the nymphs and adults of Hyaliodes vitripennis (Say) from two regions. Phosalone was the least toxic. Nymphs were more resistant than the adults. While the LC50 for dimethoate was 130 ppm for nymphs, it was 3 ppm for adults from St. Jean-Baptiste-de-Rouville. There were also significant differences in the level of resistance between the two regions where the H. vitripennis were collected. At St. Alexandre the LC50 for phosalone on nymphs was 19,250 ppm whereas, at St. Jean-Baptiste-de-Rouville it was 160,000 ppm.

Agriculture↗
PubMed1996

Calcium absorption from apple and orange juice fortified with calcium citrate malate (CCM).

OBJECTIVE: Determine calcium (Ca) absorption from Ca fortified orange and apple juice. METHODS: Absorbability was assessed by measuring 45Ca absorption in healthy women (mean age 57 years, n = 57/group) and whole body 47Ca retention in adult female beagle dogs (n = 6/group) and young adult male rats (n = 6/group). Women received 6.24 mmol (250 mg) Ca as calcium citrate malate fortified orange juice (CCM-OJ) or apple juice (CCM-AJ). Dogs received 3.12 mmol (125 mg) Ca as CCM-OJ or CCM-AJ. Rats were administered 0.15 mmol (6 mg) Ca as either milk, CCM-OJ, or CCM-AJ. Additional 47Ca whole body retention experiments in rats measured the effects of differences in the carbohydrate and organic acid contents of the juices on Ca absorption. RESULTS: Mean +/- SEM percent Ca fractional absorption was greater (p < 0.003) in women who consumed CCM-AJ (42 +/- 2%) than those who consumed CCM-OJ (36 +/- 1%). Ca retention in dogs was 15 +/- 1% for CCM-OJ and 29 +/- 2% for CCM-AJ (p < 0.001). Ca retention was significantly different (p < 0.05) in rats administered milk (42 +/- 2%), CCM-OJ (52 +/- 2%), or CCM-AJ (61 +/- 2%). By manipulating the carbohydrate and organic acid concentrations of test solutions to mimic the composition of Ca fortified juices, we found that the greater fructose and lower organic acid content of apple juice accounted for its greater Ca absorbability. CONCLUSIONS: CCM fortified versions of orange and apple juice have high Ca absorbability and are potentially important vehicles for increasing dietary Ca intake. The greater Ca absorption from CCM-AJ compared with CCM-OJ is accounted for by differences in the carbohydrate and organic acid content of the juices. These data suggest that by modifying common beverage ingredients, products with even greater Ca absorbability could be formulated.

Absorption↗
PubMed2003

Field and laboratory tests of new insecticides against the apple maggot, Rhagoletis pomonella (Walsh) (Diptera: Tephritidae).

Laboratory bioassays and field tests were conducted to compare the effectiveness of the new insecticides, imidacloprid, indoxacarb, pyriproxyfen, spinosad, thiacloprid, and thiamethoxam, against apple maggot. The activity ranking of the compounds in reducing oviposition in laboratory bioassays was: imidacloprid, 95% reduction at 11 ppm > thiamethoxam, 91% and thiacloprid, 89% reduction at 100 ppm > spinosad, 98% reduction at 316 ppm > indoxacarb, 80% reduction at 1000 ppm > pyriproxyfen, 0% reduction at 38 ppm. In laboratory bioassays, the only insecticides that were toxic to flies at concentrations equal to or below the recommended field rates were imidacloprid, (50% of flies at 11 ppm), spinosad (90% of flies at rates > 10 ppm), and thiamethoxam (approximately 50% of flies at 32 ppm). In field trials, thiacloprid was the only material that consistently controlled apple maggot fruit infestation that was comparable to standard treatments of organophosphate insecticides. Spinosad applied at weekly intervals, and indoxacarb applied as biweekly sprays provided adequate control of apple maggot damage when infestation levels in the field were low, but were not effective in preventing damage in small plots when apple maggot pressure was high.

Animals↗
PubMed2005

Effect of a plant growth regulator prohexadione-calcium on insect pests of apple and pear.

The effect of prohexadione-calcium, a plant growth regulator that inhibits gibberellin metabolism, on Cacopsylla pyricoloa (Foerster) in pear trees, and Choristoneura rosaceana (Harris) and Aphis spireacola Patch, in apple trees was studied. C. pyricoloa and A. spireacola populations were significantly reduced in prohexadione-calcium-treated pear and apple, respectively. Insecticide control of both pests with imidacloprid was synergized in treatments with prohexadione-calcium. In apples treated with prohexadione-calcium, there was a significant reduction in the number of C. rosaceana shelters per tree and amount of fruit injury at harvest attributable to the C. rosaceana. There was an additive effect when tebufenozide was used to control C. rosaceana in trees treated with prohexadione-calcium. Prohexadione-calcium significantly reduced vegetative growth in both pears and apples. Synergistic and additive treatment effects of prohexadione-calcium and pesticides used in this study may be due to better penetration and coverage of pesticides due to reduced foliar growth or to changes in the nutritional quality of the host plants.

Animals↗
PubMed2005

Effects of seasonal mineral oil applications on the pest and natural enemy complexes of apple.

This 3-yr study examined the use of two different apple, Malus domestica Borkhausen, pest management programs based on horticultural mineral oil. Whereas oil provided some additional control of codling moth, Cydia pomonella (L.), when targeting eggs of both generations (Oil/Direct Pest program, typically six applications per season), the additional benefit was difficult to detect when densities were high. With moderate densities, oil reduced the number of fruit infestations, but not stings (unsuccessful entries). There also were some measurable benefits to leafroller, Pandemis pyrusana Kearfott control. Oil was most useful, however, in suppression of secondary pests. White apple leafhopper, Typhlocyba pomaria McAtee, was the primary target of oil applications in the Oil/Indirect Pest program (typically three applications per season). However, leafhopper suppression in the Oil/Direct Pest program was generally greater because of the higher number of applications. Phytophagous tetranychid and eriophyid mites also were suppressed by more oil applications. Predatory mite populations were lower in both oil programs than in the check, but it is difficult to determine whether direct toxicity or reduction of prey was responsible for lower predator populations. There also was some evidence that oil suppressed woolly apple aphid, Eriosoma lanigerum Hausman. The six-spray oil program largely prevented a woolly apple aphid outbreak that occurred in July and August 1998 in the check, although the three-spray program seemed to provide some suppression despite the nonspecific spray timing.

Animals↗
PubMed2002

Cloning and characterization of four apple MADS box genes isolated from vegetative tissue.

With the aim of finding genes involved in the floral transition of woody species four MADS box genes containing cDNAs from apple (Malus domestica) have been isolated. Three genes were isolated from vegetative tissue of apple, but were homologues of known genes that specify floral organ identity. MdMADS13 is an AP3-like B class MADS box gene, and was mainly expressed in petals and stamens as demonstrated by Northern blot analysis. MdMADS14 and -15 are AGAMOUS-like genes. They differed slightly in expression patterns on Northern blots, with MdMADS15 mRNA levels equally high in stamens and carpels, but MdMADS14 preferably expressed in carpels. MdMADS14 is likely to be the apple orthologue of one of the Arabidopsis thaliana SHATTERPROOF genes, and MdMADS15 closely resembled the Arabidopsis AGAMOUS gene. It has been shown with RT-PCR that the three floral apple MADS box genes are expressed in vegetative tissues of adult as well as juvenile trees, albeit at low levels. MdMADS12 is an AP1-like gene that is expressed at similar levels in leaves, vegetative shoots, and floral tissues, and that may be involved in the transition from the juvenile to the adult stage.

Amino Acid Sequence↗
PubMed2005

Expression of arginine decarboxylase and ornithine decarboxylase genes in apple cells and stressed shoots.

Arginine decarboxylase (ADC) and ornithine decarboxylase (ODC) are two important enzymes responsible for putrescine biosynthesis. In this study, a full-length ADC cDNA (MdADC) was isolated from apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. Meanwhile, a partial ODC (pMdODC) could be amplified only by a second RCR from the RT-PCR products, whereas a full-length ODC could not be obtained by either cDNA library screening or 5'- and 3'-RACEs, suggesting quite low expression. Moreover, D-arginine, an ADC inhibitor, caused a decrease in ADC activity and severely inhibited the growth of apple callus, which could be partially resumed by exogenous addition of putrescine, whereas alpha-difluoromethylornithine (DFMO), an inhibitor for ODC, caused the incomplete repression of callus growth without changing ODC activity. RNA gel blot showed that the expression level of MdADC was high in young tissues/organs with rapid cell division and was positively induced by chilling, salt, and dehydration, implying its involvement in both cell growth and these stress responses. By contrast, the transcript of ODC could not be detected by RNA gel blot analysis. Based on the present study, it is possible to conclude that (i) the ODC pathway is active in apple, although the expression level of the pMdODC gene homologous with its counterparts found in other plant species is quite low; and (ii) MdADC expression correlates with cell growth and stress responses to chilling, salt, and dehydration, suggesting that ADC is a primary biosynthetic pathway for putrescine biosynthesis in apple.

Amino Acid Sequence↗