Shoot regeneration from tissue-cultured leaves of the American cranberry (Vaccinium macrocarpon)

A method for shoot regeneration from leaf explants in two cultivars of cranberry (Vaccinium macrocarpon Ait.) is described. Modified Anderson's medium supplemented with combinations of thidiazuron (TDZ) with or without 1 M NAA (-naphthaleneacetic acid) was used to optimize shoot regeneration. The effect of light or dark incubation was also determined. Maximum regeneration was obtained in the light in the presence of 10 M TDZ and 1 M NAA. While this medium was suitable for leaf explants obtained from shoot cultures, regeneration did not occur from leaves collected from greenhouse-grown plants. Elongation of the regenerated shoot tips did not occur until explants were transferred to growth regulator-free medium at which time only a minority of shoots elongated. Elongated shoots could be dissected away from leaf tissue, rooted easily, and acclimitized to ambient conditions.Abbreviations NAA -naphthaleneacetic acid - TDZ 1-phenyl-3-(1,2,3-thiadiazol-5-yl) urea     

Fruit production in cranberry (Ericaceae: Vaccinium macrocarpon): a bet-hedging strategy to optimize reproductive effort

In the cultivated cranberry (Vaccinium macrocarpon), reproductive stems produce 1-3 fruit even though they usually have 5-7 flowers in the spring. We undertook experiments to test the hypothesis that this was an adaptive life history strategy associated with reproductive effort rather than simply the result of insufficient pollination. We compared fruit production on naturally pollinated plants with those that were either manually pollinated or that were caged to exclude insects. Clearly, insects are necessary for the effective pollination of cranberry plants, but hand pollination of all flowers did not result in an increase in fruit number. Most of the upper flowers, which had significantly fewer ovules than did the lower flowers, aborted naturally soon after pollination. However, when the lower flower buds were removed, the upper flowers produced fruit. This suggests that the upper flowers may serve as a backup if the earlier blooming lower ones are lost early in the season. Furthermore, the late-blooming flowers may still contribute to the plant's reproductive success as visiting pollinators remove the pollen, which could serve to sire fruit on other plants. These results are discussed in the context of their possible evolutionary and proximate causes.     

Isolation of parasorbic acid from the cranberry plant,Vaccinium macrocarpon

Parasorbic acid, 5,6-dihydro-6(S)-methyl-2H-pyran-2-one, has been isolated from whole plant extracts of the cranberry, Vaccinium macrocarpon. This antibiotic lactone, which also inhibits seed germination, has been reported previously only from the fruit of the mountain ash, Sorbus aucuparia.     

Inoculation of cranberry (Vaccinium macrocarpon) with the ericoid mycorrhizal fungus Rhizoscyphus ericae increases nitrate influx

Despite the ubiquitous presence of ericoid mycorrhizal (ERM) fungi in cranberry (Vaccinium macrocarpon), no prior studies have examined the effect of ERM colonization on NO(3)(-) influx kinetics. Here, (15)NO(3)(-) influx was measured in nonmycorrhizal and mycorrhizal cranberry in hydroponics. Mycorrhizal cranberry were inoculated with the ERM fungus Rhizoscyphus (syn. Hymenoscyphus) ericae. (15)NO(3)(-) influx by R. ericae in solution culture was also measured. Rhizoscyphus ericae NO(3)(-) influx kinetics were linear when mycelium was exposed for 24 h to 3.8 mm NH(4)(+), and saturable when pretreated with 3.8 mm NO(3)(-), 50 microm NO(3)(-), or 50 microm NH(4)(+). Both low-N pretreatments induced greater NO(3)(-) influx than either of the high-N pretreatments. Nonmycorrhizal cranberry exhibited linear NO(3)(-) influx kinetics. By contrast, mycorrhizal cranberry had saturable NO(3)(-) influx kinetics, with c. eightfold greater NO(3)(-) influx than nonmycorrhizal cranberry at NO(3)(-) concentrations from 20 microm to 2 mm. There was no influence of pretreatments on cranberry NO(3)(-) influx kinetics, regardless of mycorrhizal status. Inoculation with R. ericae increased the capacity of cranberry to utilize NO(3)(-)-N. This finding is significant both for understanding the potential nutrient niche breadth of cranberry and for management of cultivated cranberry when irrigation water sources contain nitrate.     

An efficient in vitro shoot propagation of cranberry (Vaccinium macrocarpon ait.) by axillary bud proliferation

Summary Cultures of two eranberry (Vaccinium macrocarpon Ait.) cultivars, ‘Ben Lear’ and ‘Pilgrim’, and three eranberry clones from natural stands in Newfoundland were established in a nutrient medium containing N⁶[2-isopentenyl]adenine (2iP) from nodal and/or shoot-tip explants obtained under aseptic conditions. The cultivars differed in shoot regeneration in terms of shoot number per explant with various concentrations of 2iP over two culture periods. Best total shoot production was obtained when nodal segments were cultured in the medium supplemented with 2.5–5.0 mg 2iP l⁻¹ (12.3–24.6 μM). With higher 2iP levels, shoots did not expand and had a high mortality rate. Nodal explants of the three clones cultured in the same nutrient medium supplemented with 2.5 mg 2iP l⁻¹ (12.3 μM) produced three to five healthy axillary shoots per explant. In another experiment, nodal explants were more productive than shoot tips. In all experiments with subculture, there was an increase in shoot multiplication rate for all genotypes. Shoots were rooted in vitro in the same media used for shoot proliferation, but without any growth regulators. After their transfer to potting medium, almost all of the rooted plants survived. Cranberry genotypes can be efficiently propagated and maintained through nodal culture in a nutrient medium without auxin that contains 2.5–5 mg 2iP l⁻¹ (12–25 μM).     

RAPDs identify varietal misclassification and regional divergence in cranberry [Vaccinium macrocarpon (Ait.) Pursh]

The majority of cultivated cranberry varieties were selected from native populations in the 1800s and early 1900s from sites in Massachusetts, New Jersey, and Wisconsin. Since their initial selections 100–150 years ago, varietal identities have become increasingly confused; primarily the result of there being a paucity of qualitative markers to effectively distinguish among varieties. Random amplified polymorphic DNA (RAPD) technology has the potential for allowing a more definitive classification of varieties and was used in this study to characterize 22 cranberry varieties. Twenty-two decamer primers amplified 162 scorable DNA fragments, of which 66 (41%) were polymorphic. On the basis of these 66 silver-stained RAPDs (ssRAPDs), 17 unique profiles were identified rather than the expected 22. Fourteen varieties had unique ssRAPD profiles, while the remaining 8 were represented by 3 ssRAPD profiles. Permuational analyses of the data suggest that the observed ssRAPD profile duplications are examples of varietal misclassification. Further analyses identified 2 ssRAPD markers that were found only in Eastern varieties (from Mass. and N. J.) and not in Wisconsin varieties. With varieties differing on average by 22 bands, ssRAPDs are shown to be effective in varietal identification and the assessment of genetic diversity in cranberry.New Jersey Agricultural Experiment Station, Publ No. D-12163-8-93, Supported by State funds.     

Dose-response relationships between pollination and fruiting refine pollinator comparisons for cranberry (Vaccinium macrocarpon [Ericaceae])

Comparisons of pollinator efficacy using pollen received on stigmas can be refined by incorporating experimental dose-response relationships for pollen deposition and fruiting responses. A range of discrete pollen doses applied to cranberry stigmas resulted in decelerating curvilinear responses for fruiting, berry size, and seed set. Minimum thresholds and maximum asymptotes bounded reproductive responses to incremental stigmatic pollen loads. Four bee species were compared for their pollination efficacies on commercial cranberries, using counts of pollen received by stigmas during single bee visits to previously virgin flowers. Differences between these bee species were found to be exaggerated when raw pollen counts were used for comparison because foragers of some species often delivered pollen in excess of that needed to maximize fruit and seed production. Sixfold differences between species in mean pollen deposition translated into 1.5-2-fold differences in predicted cranberry fruit set and size. Implications for pollen tube competition and agricultural production are discussed.     

Assessing population genetic structure and variability with RAPD data: Application to Vaccinium macrocarpon (American Cranberry)

A method for estimating and comparing population genetic variation using random amplified polymorphic DNA (RAPD) profiling is presented. An analysis of molecular variance (AMOVA) is extended to accomodate phenotypic molecular data in diploid populations in Hardy-Weinberg equilibrium or with an assumed degree of selfing. We present a two step strategy: 1) Estimate RAPD site frequencies without preliminary assumptions on the unknown population structure, then perform significance testing for population substructuring. 2) If population structure is evident from the first step, use this data to calculate better estimates for RAPD site frequencies and sub-population variance components. A nonparametric test for the homogeneity of molecular variance (HOMOVA) is also presented. This test was designed to statistically test for differences in intrapopulational molecular variances (heteroscedasticity among populations). These theoretical developments are applied to a RAPD data set in Vaccinium macrocarpon (American cranberry) using small sample sizes, where a gradient of molecular diversity is found between central and marginal populations. The AMOVA and HOMOVA methods provide flexible population analysis tools when using data from RAPD or other DNA methods that provide many polymorphic markers with or without direct allelic data.     

Reproductive trade-offs in genetically distinct clones ofVaccinium macrocarpon,the American cranberry

Patterns of resource allocation to growth, current reproduction, and potential future reproduction were quantified in six genetically distinct cultivars ofVaccinium macrocarpon. For all cultivars (genotypes), vegetative size is positively correlated with some measures of current reproduction (fruit and flower number) but negatively correlated with others (seed number per fruit, seed weight per fruit). Vegetative growth in the current year is significantly related to the production of reproductive terminal buds, a measure of the potential for reproduction in the following year. Stems with low levels of current reproduction — lower flower number, fruit number, and seed weight — were more likely to form reproductive terminal buds than stems with higher levels of current reproduction. Individual genotypes differed significantly for vegetative size, fruit number, fruit weight, seed number, and seed weight, as well as for the frequency of fruiting stems and reproductive terminal buds produced. Genotypes were segregated in principal component space, indicating overall differences between them in allocation to the suite of variables measured. These results indicate the possibility of fitness differences among cultivars due to genetically determined allocation strategy, which has implications for fitness differences among genotypes within natural populations.     

Metabolic adaptation to prolonged exercise.

A study was undertaken to evaluate and to examine the role of substrate supply in 50 healthy subjects after long distance events, such as 10 km, 25 km, and marathon races. The metabolic, variables of carbohydrate metabolism were greatest in 10-km runners, with the highest increase in glucose, lactate, and pyruvate, while in marathon runners only moderate changes were observed. Marathon competitors gave the greatest decrease in insulin concentration whereas glucagon and cortisol showed a contrary tendency. As for lipid concentrations, the most remarkable point was that after the marathon competition the best runners had the highest increase in free fatty acids; the longer the race, the higher were the beta-hydroxybutyrate and acetoacetate levels after the competition. It is important to emphasize that the limiting factor up to 90 min duration is the competitor's ability to deplete the stores of glycogen. Beyond 90 min (or 25 km) the decrease in insulin, the rise in cortisol and the higher concentration of ketnne bodies found indicate a change in metabnlic response.     

The role of mycorrhizal infection in the resistance of Vaccinium macrocarpon to manganese

The role of mycorrhizal infection in the resistance of Vaccinium macrocarpon to manganese was investigated in perlite culture containing nutrient solution amended with Mn at 0, 250, 500 or 1000 g/ml. Shoot and root dry weights of the mycorrhizal plants were higher than nonmycorrhizal plants. The mycorrhizal plants produced significantly longer main roots than the nonmycorrhizal plants. Differences between shoot and root Mn concentrations of mycorrhizal and nonmycorrhizal plants arose by reduction of Mn in the leaves of mycorrhizal plants and a corresponding increase in root tissues.     

The role of mycorrhizal infection in the tolerance of Vaccinium macrocarpon to iron

Hymenoscyphus ericae survived in liquid media containing up to 500 g/ml iron (Fe), Mycorrhizal seedlings of Vaccinium macrocarpon showed higher yields and lower shoot Fe levels and exhibited less severe toxicity symptoms than nonmycorrhizal seedlings.     

Pollinator genetics and pollination: do honey bee colonies selected for pollen‐hoarding field better pollinators of cranberry Vaccinium macrocarpon?

1. Genetic polymorphisms of flowering plants can influence pollinator foraging but it is not known whether heritable foraging polymorphisms of pollinators influence their pollination efficacies. Honey bees Apis mellifera L. visit cranberry flowers for nectar but rarely for pollen when alternative preferred flowers grow nearby. 2. Cranberry flowers visited once by pollen‐foraging honey bees received four‐fold more stigmatic pollen than flowers visited by mere nectar‐foragers (excluding nectar thieves). Manual greenhouse pollinations with fixed numbers of pollen tetrads (0, 2, 4, 8, 16, 32) achieved maximal fruit set with just eight pollen tetrads. Pollen‐foraging honey bees yielded a calculated 63% more berries than equal numbers of non‐thieving nectar‐foragers, even though both classes of forager made stigmatic contact. 3. Colonies headed by queens of a pollen‐hoarding genotype fielded significantly more pollen‐foraging trips than standard commercial genotypes, as did hives fitted with permanently engaged pollen traps or colonies containing more larvae. Pollen‐hoarding colonies together brought back twice as many cranberry pollen loads as control colonies, which was marginally significant despite marked daily variation in the proportion of collected pollen that was cranberry. 4. Caloric supplementation of matched, paired colonies failed to enhance pollen foraging despite the meagre nectar yields of individual cranberry flowers. 5. Heritable behavioural polymorphisms of the honey bee, such as pollen‐hoarding, can enhance fruit and seed set by a floral host (e.g. cranberry), but only if more preferred pollen hosts are absent or rare. Otherwise, honey bees' broad polylecty, flight range, and daily idiosyncrasies in floral fidelity will obscure specific pollen‐foraging differences at a given floral host, even among paired colonies in a seemingly uniform agricultural setting.     

Is the polyploid cranberry (Vaccinium sp.) in Finland tetraploid or hexaploid?

Only the hexaploid chromosome number of 2n=72 has been reported with convincing documentation for polyploid cranberry ( Vaccinium ) clones in Finland. Meiosis is regular in those cases which have been checked and dispersal by seeds is apparently efficient. The recent documented determinations of hexaploidy in Central Europe and N Asia and the reports in N America and N Europe may mean a circumpolar distribution of hexaploid cranberry.     

Allozyme evidence for genetic autopolyploidy and high genetic diversity in tetraploid cranberry, Vaccinium oxycoccos (Ericaceae)

Polyploidy has been important in the evolution of angiosperms and may significantly affect population genetic diversity and structure. Nineteen isoenzyme loci were studied in diploid and tetraploid populations of Vaccinium oxycoccos (Ericaceae), and the results are compared with data previously reported for the related V. macrocarpon. Diploid V. oxycoccos and V. macrocarpon were readily discriminated based on their allozymic variation. No evidence for fixed heterozygosity was found in tetraploid V. oxycoccos. In contrast, all polymorphic loci exhibited both balanced and unbalanced heterozygotes, with some individuals exhibiting a pattern consistent with the presence of three alleles. These results support an autopolyploid origin for tetraploid V. oxycoccos. However, tetraploid V. oxycoccos possessed a suite of alleles not found in diploid V. oxycoccos; half of these alleles were shared with V. macrocarpon. This suggests that autotetraploid V. oxycoccos may have undergone hybridization with V. macrocarpon or that the autotetraploid retained the genetic variation present in an ancestral diploid species. Following theoretical expectations, proportion of polymorphic loci, mean number of alleles, and observed heterozygosity were significantly higher for the autotetraploid than for the diploid. Mean inbreeding (F(IS)) was similar for diploid and tetraploid V. oxycoccos. The latter exhibited population differentiation (F(ST)) exceeding both diploid species.     

Metabolic evidence for stelar anoxia in maize roots exposed to low o(2) concentrations

This investigation presents metabolic evidence to show that in 4- to 5-day-old roots of maize (Zea mays hybrid GH 5010) exposed to low external O₂ concentrations, the stele receives inadequate O₂ for oxidative phosphorylation, while the cortex continues to respire even when the external solution is at zero O₂ and the roots rely solely on aerenchyma for O₂ transport. Oxygen uptake rates (micromoles per cubic centimeter per hour) declined at higher external O₂ concentrations in excised segments from whole roots than from the isolated cortex; critical O₂ pressures for respiration were greater than 0.26 moles per cubic meter O₂ (aerated solution) for the whole root and only 0.075 moles per cubic meter O₂ for the cortex. For plants with their shoots excised and the cut stem in air, ethanol concentrations (moles per cubic meter) in roots exposed to 0.06 moles per cubic meter O₂ were 3.3 times higher in the stele than in the cortex, whereas this ethanol gradient across the root was not evident in roots exposed to 0 moles per cubic meter O₂. Alanine concentrations (moles per cubic meter) in the stele of roots exposed to 0.13 and 0.09 moles per cubic meter O₂ increased by 26 and 44%, respectively, above the levels found for aerated roots, whereas alanine in the cortex was unchanged; the increase in stelar alanine concentration was not accompanied by changes in the concentration of free amino acids other than alanine. For plants with their shoots intact, alcohol dehydrogenase and pyruvate decarboxylase activities (micromoles per gram protein per minute) in roots exposed to 0.13 moles per cubic meter O₂ increased in the stele by 40 to 50% over the activity in aerated roots, whereas there was no appreciable increase in alcohol dehydrogenase and pyruvate decarboxylase activity in the cortex of these roots. More convincingly, for roots receiving O₂ solely from the shoots via the aerenchyma, pyruvate decarboxylase in the cortex was in an “inactive” state, whereas pyruvate decarboxylase in the stele was in an “active” state. These results suggest that for roots in O₂-free solutions, the aerenchyma provides adequate O₂ for respiration in the cortex but not in the stele, and this was supported by a change in pyruvate decarboxylase in the cortex to an active state when the O₂ supply to the roots via the aerenchyma was blocked.     

In vitro inhibitory effect of cranberry (Vaccinium macrocarpom Ait.) juice on pathogenic microorganisms

The purpose of this study was to determine the inhibitory effects of cranberry juice on pathogenic microorganisms. The microorganisms analyzed were Escherichia coli from patients with urinary infections, Salmonella spp., Listeria monocytogenes, Pseudomonas aeruginosa, and Staphylococcus aureus. The disc method was used to determine the sensitivity of bacteria to cranberry juice (CJ, both concentrated and diluted). A lawn of 10(6) cfu/ml was grown on agar surfaces in Petri dishes and on Whatman discs that had been previously saturated with CJ and CJ : water 1 : 1 to 1 : 50 juice solutions had been placed on the discs, which were cultured and incubated. The results indicated that S. aureus was more susceptible to cranberry juice inhibition than the other microorganisms. L. monocytogenes was the most resistant to the inhibitory action of cranberry juice, showing a significant difference from the inhibition of P. aeruginosa, uropathogenic E. coli, Salmonella spp., and S. aureus. This study also demonstrated that the inhibitory activity of cranberry juice for E. coli took place up to a dilution of 1 : 20.     

Compensatory response of cranberry to simulated damage by cranberry weevil (Anthonomus musculus Say) (Coleoptera: Curculionidae)

Cranberry weevil (Anthonomus musculus Say), a key pest of cranberry (Vaccinium macrocarpon Aiton) in Massachusetts, deposits eggs in unopened flowers and often severs the flower pedicel from the peduncle. The compensatory response of cranberry to simulated cranberry weevil damage was investigated by severing the pedicel of unopened flowers with scissors. When intensity of damage was varied on the cultivar Early Black, complete compensation was observed at three of four sites after removal of 33% of a peduncle's unopened flowers, but a approximately 37% decline in number of fruit and weight of berries per peduncle was observed when 67% of unopened flowers were removed. When timing of damage was varied at sites planted to the cultivar Howes, no differences were observed when 50% of unopened flowers were clipped from a peduncle early versus late in preblossom peduncle growth. However, both the early and late clipping treatments resulted in a 30% decrease in the number and weight of berries per peduncle when compared with the no clipping treatment. These results suggest that cranberry has the ability to tolerate low to moderate levels of weevil damage, but a substantial data base will be required to determine any appropriate changes in threshold recommendations.