Vaccinium Angustifolium Ait Research Articles

Comparative analysis of hypocotyl development in epiphytic, lignotuber-forming, and terrestrial Vaccinieae (Ericaceae)

A comparative analysis of hypocotyl development was undertaken with seedlings of three Vaccinieae (Ericaceae) species ( Macleania pentaptera Hoerold, Macleania rupestris (Kunth) A.C. Sm., and Vaccinium angustifolium Ait.) to determine the developmental basis for enlarged hypocotyls leading to the development of woody tubers (lignotubers) in M. pentaptera and M. rupestris. Differences in hypocotyl development are apparent after the first true leaves are visible in each species. Vascular tissue in M. rupestris and V. angustifolium is composed primarily of axial columns of secondary xylem. Secondary xylem tissues in M. pentaptera remain mostly parenchymatous and form radial columns of cells through numerous periclinal divisions. Furthermore, the secondary xylem of M. pentaptera comprises random networks of interconnected, small xylem elements in comparison with the secondary xylem of M. rupestris and V. angustifolium. These differences in hypocotyl development persist through the first 200 d of hypocotyl development, and ultimately lead to the development of a large lignotuber in M. pentaptera. Given the large amounts of parenchymatous tissue, a secondary xylem of relatively short secondary xylem elements, and the absence of adventitious buds, we propose that the lignotubers of M. pentaptera are used for short term water storage, rather than regeneration.

The relationships between Apocrita wasp populations and flowering plants in Maine's wild lowbush blueberry agroecosystems

This was the first study to have surveyed the spatial and temporal structure of Apocrita wasps in lowbush blueberry fields, a unique native agricultural landscape in Maine and eastern Canada. The relative abundances of wasps associated with lowbush blueberry (Vaccinium angustifolium Ait.) were investigated in 33 blueberry fields throughout Washington County, Maine, USA. Native wasps were captured during the springs and summers of 1997 and 1998 in Malaise traps erected along a transect in each field. Vegetation sampling was also conducted along these transects to quantify available floral resources. Data indicate the abundance of the total wasp community was positively associated with the abundance of sheep laurel (Kalmia angustifolia L.). Relationships between trap capture of 13 wasp morphospecies and other flowering weeds were also investigated. Most taxa in 1998 were positively associated with one or more of the following flowering plants: bunchberry (Cornus canadensis L.), bush honeysuckle (Diervilla lonicera P. Mill.), dogbane (Apocynum androsaemifolium L.), sheep laurel, and witherod (Viburnum nudum var. cassinoides L.). Similar results were not evident in 1997 because the method used to sample vegetation was not as extensive as that used in 1998. However, sheep laurel was positively associated with the wasp genera Microplitis spp. and Phanerotoma spp. during both years.

A Scale-up System for Lowbush Blueberry Micropropagation Using a Bioreactor

In an attempt to improve the micropropagation protocol for lowbush blueberry (Vaccinium angustifolium Ait.), a protocol using a bioreactor system combined with a semisolid gelled medium has been developed. Cultures of cultivar Fundy and two wild clones (‘NB1’ and ‘QB1’) were established in vitro on a gelled modified cranberry basal medium (BM) containing 5 μM zeatin or 10 μM N6-[2-isopentenyl]adenine. Multiple shoots were obtained within 8 weeks by transferring zeatin-induced shoots from the gelled BM to a bioreactor containing liquid BM with 1 to 4 μM zeatin. Genotypes differed significantly with respect to multiplication rate in liquid and gelled BM containing 1 μM zeatin with ‘NB1’ producing 8.5 ± 1.1 and 2.9 ± 0.3 shoots per explant in liquid and gelled media, respectively, after one subculture followed by ‘QB1’ (7.1 ± 0.6 and 2.6 ± 0.4 shoots per explant, respectively) and ‘Fundy’ (5.8 ± 0.4 and 2.0 ± 0.2 shoots per explant, respectively). With subculture, there was an increase of shoot multiplication rate for all genotypes. Bioreactor- and gelled medium-proliferated shoots were treated with 39.4 mm indole-3-butyric acid powder, rooted in a 2 peat:1 perlite (v/v) medium, plantlets acclimatized, and eventually established in the greenhouse with 64% to 74% rooting of microshoots and 90% to 99% survival of rooted shoots. Results obtained suggested the possibility of large-scale multiplication of lowbush blueberry shoots in bioreactors.

Spatial genetic structure of lowbush blueberry,Vaccinium angustifolium, in four fields in Maine

Expressed sequence tag – polymerase chain reaction (EST-PCR) molecular markers were used to infer spatial genetic structure of four lowbush blueberry ( Vaccinium angustifolium Ait.) fields in Maine. Genetic structure was quantified at three spatial scales: (1) within apparent clones (intrapatch), (2) among clones within a field, and (3) among fields separated by as much as 65 km. Of five “clones” or putative individuals examined in the intrapatch study, two showed complete genetic homogeneity within the patch, while three showed some band differences at their edges compared with their interiors. These differences at the edges, however, matched adjacent clones (so-called “intruders”), from which it was concluded that lowbush blueberry exhibits a fairly tight, phalanx clonal architecture with no evidence of invasive seedling establishment within clones. No significant correlation between genetic and physical distance was found among clones within fields via several statistical approaches. Significant among-field genetic differentiation was found via AMOVA (ΦPT= 8.4%; p ≤ 0.01) based upon transect samples across four fields ranging from 12.5 to 65 km apart. Principal component analysis and spatial autocorrelation (SA) corroborated these findings. Significant positive SA was found at the within-field distance class of <350 m, but SA decreased to an insignificant value by the first interfield distance of 12.5 km. A special form of SA analysis was employed to detect “hotspots” of genetic similarity between pairs of adjacent clones in two fields. Results indicated that 5 of 23 pairs of clones (21.7%) were genetically similar to each other, while the majority of pairs (18 of 23; 78.3%) showed random, decreasing patterns of genetic similarity. Results are discussed in terms of clonal dynamics including architecture, seedling recruitment, and inferred pollen or seed dispersal distances.

Effects of repeated applications of municipal solid waste compost and fertilizers to three lowbush blueberry fields

Field experiments were initiated in May 1999 and continued through 2002 to investigate the application of municipal solid waste (MSW) compost and fertilizers to lowbush blueberry ( Vaccinium angustifolium Ait.) fields. Three sites were selected: Debert, N.S. (Truro sandy loam) and two sites near Musquodoboit, N.S. (both Rawdon gravely loamy sands). Treatments at each site were in a randomized complete block design with six treatments (control [no fertilizer], NK fertilizer, NPK fertilizer, and three rates of MSW compost) blocked four times. Compost treatments provided the equivalent of 100, 200 and 400 kg ha −1 of total N. The experimental objectives were to evaluate soil and plant response to the compost and to determine whether it could be used as an alternative to the traditional chemical fertilizers. Yield, soil fertility, and leaf and fruit nutrients were examined following the four years of treatment applications. The MSW compost had a significant effect on pH and soil extractable levels of P, K and Ca, and influenced N and K levels in leaf samples. Fruit yield and nutrient content, except for Mn, were not affected by the treatments. In general, the compost treatments provided equivalent amounts of plant essential nutrients without negatively influencing trace element absorption.

Development of ISSR markers for genetic diversity studies in Vaccinium angustifolium

Understanding of the genetic relationship within wild lowbush blueberry (Vaccinium angustifolium Ait.) germplasm is important to establish a broad genetic base for safeguarding and for future use of the existing genetic resources. The objective of this study was to assess the genetic variability within 43 wild lowbush blueberry clones, collected from 10 communities of four Canadian provinces, and the cultivar ‘Fundy’ by using inter simple sequence repeat (ISSR) markers, with the hope to establish a reference set of lowbush blueberry germplasm for blueberry conservation, breeding and research. Thirteen primers generated 242 polymorphic ISSR‐PCR bands. A substantial degree of genetic similarity was found among the wild collections. Cluster analysis by the unweighted pair‐group method with arithmetic averages (UPGMA) separated the 41 genotypes into two main clusters, and identified the three remaining clones as outliers. Furthermore, within one main cluster, the genotypes tended to form sub‐clusters that were in agreement with the principal coordinate (PCO) analysis. Geographical distribution contributed to 27% of total variation as revealed by analysis of molecular variance (AMOVA). The ISSR‐PCR method was simple, fast and relatively inexpensive to produce useful DNA fragments and detected a sufficient degree of polymorphism to differentiate among lowbush blueberry clones, making this technology valuable for germplasm management and the more efficient choice of parents in current blueberry breeding program.

Optimum leaf nutrient concentrations of wild lowbush blueberry in Quebec

To evaluate the nutritional status of wild lowbush blueberry (Vaccinium angustifolium Ait.), optimum leaf nutrient concentrations were developed in earlier studies conducted in Canada's Maritime Provinces and in Maine. However, these concentrations have not been validated under the climatic and edaphic conditions of the Saguenay-Lac-Saint-Jean region of Quebec (Canada). These concentrations may not be necessarily correlated with the high productivity levels recorded in this region in recent years. The objective of the study was therefore to determine the minimum and maximum blueberry leaf nutrient concentrations under the conditions characterizing this region. These concentrations were derived using the boundary-line approach, which involves estimating the relationship between maximum fruit yield and leaf concentrations of N, P, K, Ca and Mg. The data were obtained from N and P fertilization trials carried out between 2001 and 2006 in eight blueberry fields in the Saguenay-Lac-Saint-Jean region. On average, more than 80% of the samples analyzed met the minimum leaf nutrient concentrations. Minimum leaf N and Mg concentrations were comparable to those obtained in earlier studies. Minimum leaf concentrations were revised downward for P and Ca. Only minimum K concentration was higher compared with published standards. Maximum leaf concentrations were revised downward for all nutrients. Minimum and maximum concentrations were 16.36–20.55, 1.19–1.66, 5.40–7.10, 2.93–3.88 and 1.34–1.81 mg g-1 for N, P, K, Ca and Mg respectively. These concentrations were used to establish sufficiency ranges suited to wild lowbush blueberry growing conditions in the Saguenay-Lac-Saint-Jean region. Key words: Vaccinium augustifolium Ait., nutritional standards, yield-nutrients relationship

EVALUATION OF VACCINIUM ARCTOSTAPHYLOS SELECTIONS FROM THE ARTVIN AND TRABZON PROVINCES OF TURKEY

This study was carried out to evaluate morphological and pomological characteristics of some little known blueberry types in Turkey during 2003–2006. Caucasian whortleberry (Vaccinium arctostaphylos L.) populations were collected from the coast area to high altitude in Trabzon and Artvin. The plant habit was generally shrub; growth habit was erect or prostrate; condensation wax on berries was high; berries were round, oblate or ovoid; berry taste ranged from sour to sweet; berry weight was 32.08–100.5 g/100 berries; total soluble solid was 7.43– 13.5%; cluster number of per plant was between 1 and 6. These wild selections will be evaluated in more detail. INTRODUCTION Turkey is a very important area for plant diversity. Many fruit species are grown and many different local or native fruit species and varieties are known. One of these is blueberries (Vaccinium) a fruit species from the Ericaceae family grown in temperate regions. Northern Turkey is a diversity hotspot for heathers (Ericaceae) and several little known Vaccinium species including blueberry, bilberry, lingonberry, bog blueberry, bog whortleberry or bog bilberry (Stevens, 1978; Agaoglu, 1986 and Celik, 2005). These species are widespread across Northeastern Anatolia and between 40 to 42° north, from Artvin to Canakkale. In the Black Sea Region, especially in plateaus, Vaccinium angustifolium Ait. and V. myrtilloides Michx. plants were endemic. These plants have economic importance (Celik et al., 2004). For many years wild blueberries have been harvested for commercial and home use in north-east and north-west Anatolia, in Turkey. The berry fruits of these Turkish species can be eaten. Those of V. arctostaphylos are especially appreciated (Stevens, 1978; Ayaz et al., 2001). Blueberries grow as a native fruit crop in the eastern Black Sea region of Turkey and are locally consumed fresh or as jam. The main crops in this region are hazelnut and tea. Annual rainfall is 1000 mm, distributed throughout the year. Annual mean temperature is 14.5oC and annual mean relative humidity is 75%. Although it is known that Ericaceae family like acidity soils, it is not cultivated blueberries for commercial plant in Black Sea region having natural acidity soil. The first research in Turkey was begun by Celik (2003, 2004, 2005) in the year 2000. Otherwise researches on blueberries were started around 1900. Now, several commercial species were grown in the world (Himelrick, 2002; Lyrene, 2002). Vaccinium fruit crops are potentially important crops for the Black Sea region of Turkey because of its natural acidic soils and ecology. There are many wild blueberry types in this region. The objective of this study was to evaluate wild blueberry populations and determine some of the pomological traits of little known blueberries collected from the Artvin and Trabzon Provinces.

A two-step procedure for adventitious shoot regeneration on excised leaves of lowbush blueberry

An efficient system to regenerate shoots on excised leaves of greenhouse-grown wild lowbush blueberry (Vaccinium angustifolium Ait.) was developed in vitro. The effect of thidiazuron (TDZ) on adventitious bud and shoot formation from apical, medial, and basal segments of the leaves was tested. Leaf cultures produced multiple buds and shoots with or without an intermediary callus phase on 2.3–4.5 μM TDZ within 6 wk of culture initiation. The greatest shoot regeneration came from young expanding basal leaf segments positioned with the adaxial side touching the culture medium and maintained for 2 wk in darkness. Callus development and shoot regeneration depended not only on the polarity of the explants but also on the genotype of the clone that supplied the explant material. TDZ-initiated cultures were transferred to medium containing 2.3–4.6 μM zeatin and produced usable shoots after one additional subculture. Elongated shoots were dipped in 39.4 mM indole-3-butyric acid powder and planted on a peat:perlite soilless medium at a ratio of 3:2 (v/v), which yielded an 80–90% rooting efficiency. The plantlets were acclimatized and eventually established in the greenhouse with 75–85% survival.

Comparison of consecutive and alternate fertilizer applications in wild blueberry production

Research has shown that improved nutrient uptake and yield of wild blueberries (Vaccinium angustifolium Ait) are very sporadic when fertilizers are applied. Growers are concerned with environment impacts and keeping fertilizer costs to a minimum. Two experiments were conducted to evaluate the response of wild blueberries to soil-applied fertilization over four cropping cycles in Prince Edward Island and Nova Scotia from 1997 to 2004. Commercial fertilizers (17-17-17, 1-46-0 and 13-26-5) were soil-applied in the sprout year either as a consecutive fertilizer application (every cropping cycle) or an alternate fertilizer application (every second cropping cycle). All fertilizers were applied at a rate of 200 kg ha-1. Fertilizer applications increased soil levels of P and K, leaf tissue concentrations of N and P and stem lengths of plants. Higher levels of soil P and leaf tissue concentrations of N, P and K were observed with consecutive than with alternate fertilizer applications. Average stem lengths, buds and blossoms per stem were higher over the length of the study when fertilizers were applied consecutively compared with alternately. Fruit yields were increased compared with the unfertilized control. Within applied fertilizers treatments, fruit yield was not affected when fertilizer was applied in either consecutive or alternate cropping cycles. Alternate fertilizer applications may reduce soil accumulation of P and production costs without comprising yields. Key words: Cropping cycles, fertilization, soil and tissue nutrients, yield

Effect of NPK fertilization and elemental sulphur on growth and yield of lowbush blueberry

The aim of the research was to determine the effect of fertilizers on the pH of former arable soils and on the growth and the yield of the lowbush blueberry (Vaccinium angustifolium Ait.). Lowbush blueberry fertilization experiments were established in 1999 at two locations – at Kärla, Saaremaa, West Estonia and at Vasula, Tartu County, South Estonia. Experimental sites were situated on different soils: soil pHKCl at Kärla was 5.5 and at Vasula 6.2. Elemental sulphur and acidifying fertilizers (ammonium sulfate, potassium sulfate and superphosphate) were used in both plantations. Fertilizers were applied based on nutrient in the soil and sulphur was applied at 100 g m–2. Plant growth was recorded in 2001, 2002 and 2003. A positive influence of NPK fertilization on yield was found in both Kärla and Vasula, and yield were 336 g and 41 g higher compared to the control, respectively. The vegetative growth and yield of blueberry depended significantly on soil pH. Elemental sulphur increased soil acidity and on loamy sand soil did not increase plant productivity. The sulphur effect on soil pH began to decrease three years after application. Sulphur can be recommended to increase soil acidity in nutrient-rich soil but, not nutrient poor soil with light texture, where only NPK fertilizers were effective.;

Suitability of EST-PCR Markers Developed in Highbush Blueberry for Genetic Fingerprinting and Relationship Studies in Lowbush Blueberry and Related Species

Little is known of the genetic structure and variability of wild fields, or of the dramatic differences in yield among clones (genetic individuals), of lowbush blueberry (Vaccinium angustifolium Ait.), Maine's most economically important fruit crop. Express sequence tag-polymerase chain reaction (EST-PCR) markers that were originally developed for genetic mapping purposes in highbush blueberry (Vaccinium corymbosum L.) are shown here to be valuable for genetic fingerprinting and relationship studies in the related species, V. angustifolium. As part of an interspecific genetic relationship study, 14 genotypes, including at least two specimens of each of four closely related Vaccinium L. species (V. pallidum Ait., V. corymbosum, V. boreale Hall & Aald., and V. myrtilloides Michx.) and the only four pedigreed cultivars of V. angustifolium, grouped out as expected in a genetic similarity dendrogram (matrix “r” correlation = 0.91). This work is ultimately aimed at using these markers in exploring how genetic relationship affects yield among proximal and distant breeding individuals via controlled field hand crosses. To help address this issue, a separate group of six individuals of V. angustifolium from two managed fields were also genotyped using the EST-PCR markers. The markers were very effective at intraspecific discrimination of individuals within the same field.

Effects of summer and fall applications of foliar boron on fruit bud winter injury in wild blueberry (Vaccinium angustifolium Ait.)

The effects of single and multiple applications of foliar B to two commercial wild blueberry sites during 1999 to 2001 were determined. The effects on tissue B concentrations and winter injury to developing fruit buds was evaluated. At one site, applications of foliar B in summer or fall or in both seasons increased tissue B levels in the first crop fruit buds, but the increases were not observed 1 yr later in the second crop fruit buds. At the other site, applications of foliar B in both the summer and fall of two successive cropping cycles reduced winter injury compared with untreated controls, indicating that multiple foliar B applications may be required to reduce winter injury to developing buds of wild blueberry. Key words: Extractable boron, bud damage, tissue boron concentration, Vaccinium angustifolium Ait.

Fermented Canadian lowbush blueberry juice stimulates glucose uptake and AMP-activated protein kinase in insulin-sensitive cultured muscle cells and adipocytesThis article is one of a selection of papers published in this special issue (part 1 of 2) on the Safety and Efficacy of Natural Health Products.

Extracts of the Canadian lowbush blueberry (Vaccinium angustifolium Ait.) have recently been demonstrated to possess significant antidiabetic potential, in accordance with the traditional use of this plant as an antidiabetic natural health product. Fermentation of blueberry juice with the Serratia vaccinii bacterium is known to modify the phenolic content and increase antioxidant activity. The present study evaluated the effects of fermented blueberry juice on glucose uptake, adipogenesis, and the signaling pathways that regulate glucose transport in muscle cells and adipocytes. A 6-hour treatment with fermented juice potentiated glucose uptake by 48% in C2C12 myotubes and by 142% in 3T3-L1 adipocytes, in the presence or absence of insulin, whereas nonfermented juice had no effect on transport. Fermented juice dramatically inhibited triglyceride content during adipogenesis of 3T3-L1 cells. Chlorogenic acid and gallic acid, both major phenolic components of fermented juice, had no effect on glucose uptake. Western blot analysis of the insulin-independent AMP-activated protein kinase revealed increased phosphorylation resulting from a 6-hour treatment. This activation or the increase in glucose uptake could not be explained by increased cytosolic calcium. Fermentation with S. vaccinii is concluded to confer antidiabetic activities to blueberry juice. Although the active principles and their mechanisms of action remain to be identified, transformed blueberry juice may nevertheless represent a novel complementary therapy and a source of novel therapeutic agents against diabetes mellitus.

Use of plant growth regulators to increase polyphenolic compounds in the wild blueberry

With increasing awareness of the antioxidant properties of the wild blueberry (Vaccinium angustifolium Ait.), more emphasis has been placed on d eveloping cultural management practices to enhance fruit polyphenolic levels and the use of processing byproducts as potential polyphenolic sources for the nutraceutical market. Trials were initiated in 2004 and 2005, with four plant growth regulators (methyl jasmonate, abscisic acid, riboflavin and Retain®) applied to maturing berries of the select clone Fundy at the Wild Blueberry Research Centre (Debert, NS). Berries were harvested 3 wk after treatment applications, with collections of green leaf tissues at harvest and red leaf tissues two weeks after harvest in 2005. Assessment of polyphenolic and anthocyanin levels within the berry and leaf tissues followed the Folin-Ciocalteu and pH differential methods, respectively. Overall, substantially higher levels of polyphenolic compounds were found within the leaf tissues, although anthocyanin content was highest in the berries. The application of methyl jasmonate resulted in a minor elevation in levels of bioactives within the harvested berry and red leaf tissues. This increase in bioactives occurred, however, at the expense of harvestable yields, with lower yield in plots treated with methyl jasmonate in 2004. Results thus suggest that the use of some plant growth regulators (PGR) may serve to increase bioactives, but their value must be assessed against a possible yield reduction. In addition, these studies indicate that leaf debris may provide a superior polyphenolic source for the nutraceutical market. Key words: Wild blueberry, plant growth regulator, anthocyanins, polyphenolics

Influence of indole-3-butyric acid and propagation method on growth and development of in vitro- and ex vitro-derived lowbush blueberry plants

The effects of four indole-3-butyric acid (IBA) concentrations and two propagation methods were studied in a lowbush blueberry (Vaccinium angustifolium Ait.) clone collected from natural stands in Newfoundland and Labrador, Canada. Lowbush blueberry cultures were established in vitro from nodal explants on a modified cranberry (V. macrocarpon Ait.) tissue culture medium containing zeatin (2 μM). Blueberry plants propagated by in vitro shoot proliferation (TC) and by conventional softwood cuttings (SC) were evaluated for growth and morphology. Significant interactions for morphological characteristics were observed among the treatments. The IBA concentration had an effect on morphology of propagated plants, increasing the concentration of IBA increased stem length and leaves per stem across propagation methods. Stems per plant increased with IBA concentration up to 20 μM in SC plants, but not in TC plants. Plant vigor was affected by neither IBA concentration nor propagation method. The TC plants produced longer and more stems with more leaves per stem than the conventional cuttings. In vitro culture on zeatin-containing nutrient medium apparently induces the juvenile branching characteristics that favored enhanced vegetative growth with more stems and leaf production. It is suggested that IBA may serve as a physiologically active form of auxin in contributing to increased stem and leaf production in lowbush blueberry SC plants but not in TC plants.

A single HPLC‐PAD‐APCI/MS method for the quantitative comparison of phenolic compounds found in leaf, stem, root and fruit extracts of Vaccinium angustifolium

A method was developed for the analysis of Vaccinium angustifolium Ait. (Lowbush blueberry), which is a widely used natural health product, particularly for the treatment of diabetic symptoms. While the anthocyanin content of the fruit has been well characterized, the chemistry of the vegetative parts used in supportive therapy for diabetes has been largely ignored. Using a metabolomics-based approach for compound identification with an emphasis on phenolic metabolites, a single HPLC-PAD-APCI/ MS method was developed for the separation and quantitation of the major metabolites found in the 95% ethanol extracts of leaf, stem, root and fruit. The leaf extract contained high concentrations of chlorogenic acid (approximately 100 microg/mg extract) and a variety of quercetin glycosides that were also detected in the fruit and stem extracts. Flavan-3-ol monomers (+)-catechin and (-)-epicatechin were found in all plant parts but their procyanidin dimers were exclusively identified in the stem and root. The accuracy and precision of the presented method were corroborated by low intra- and inter-day variations in quantitative results in all plant part extracts. Further validation of the extraction and analytical protocols focused on identified compounds with reputed anti-diabetic activity, revealing recoveries greater than 80% and detection limits of 0.12-2.73 microg/mL.

Second cropping of wild blueberries — Effects of management practices

Wild blueberries (Vaccinium angustifolium Ait.) are normally managed on a biennial basis. Pruning forces the plant into a vegetative year without fruit, followed by the first crop year, which provides the greatest harvest. In subsequent years, harvest levels drop dramatically. Prior to the introduction of selective herbicides, second crop yields were too low to allow the adoption of a double harvest. This study was initiated to compare production and incomes of a single cropping (2-yr management cycle, the present system) versus a double cropping system (3-yr management cycle), using systems that include herbicides. Total yields and net incomes over the 12-yr study were affected by fertilizer applications, but not by management system (2-yr management cycle versus 3-yr management cycle) or pruning (burning versus mowing). Yields in second crop plots were lower than those in first crop plots, even though blossom numbers were higher. Fertilizer affected many aspects of blueberry plant development, including stem length, numbers of buds and blossoms, and fruit yields. Over time, yields and net incomes in the 3-yr management cycle were similar to those for the standard 2-yr management cycle. Key words: Vaccinium angustifolium, 3-yr management, net income, fertilization, pruning

Anti-diabetic properties of the Canadian lowbush blueberry Vaccinium angustifolium Ait.

Incidence of type II diabetes is rapidly increasing worldwide. In order to identify complementary or alternative approaches to existing medications, we studied anti-diabetic properties of Vaccinium angustifolium Ait., a natural health product recommended for diabetes treatment in Canada. Ethanol extracts of root, stem, leaf, and fruit were tested at 12.5 microg/ml for anti-diabetic activity in peripheral tissues and pancreatic beta cells using a variety of cell-based bioassays. Specifically, we assessed: (1) deoxyglucose uptake in differentiated C2C12 muscle cells and 3T3-L1 adipocytes; (2) glucose-stimulated insulin secretion (GSIS) in beta TC-tet pancreatic beta cells; (3) beta cell proliferation in beta TC-tet cells; (4) lipid accumulation in differentiating 3T3-L1 cells; (5) protection against glucose toxicity in PC12 cells. Root, stem, and leaf extracts significantly enhanced glucose transport in C2C12 cells by 15-25% in presence and absence of insulin after 20 h of incubation; no enhancement resulted from a 1 h exposure. In 3T3 cells, only the root and stem extracts enhanced uptake, and this effect was greater after 1 h than after 20 h; uptake was increased by up to 75% in absence of insulin. GSIS was potentiated by a small amount in growth-arrested beta TC-tet cells incubated overnight with leaf or stem extract. However, fruit extracts were found to increase 3H-thymidine incorporation in replicating beta TC-tet cells by 2.8-fold. Lipid accumulation in differentiating 3T3-L1 cells was accelerated by root, stem, and leaf extracts by as much as 6.5-fold by the end of a 6-day period. Stem, leaf, and fruit extracts reduced apoptosis by 20-33% in PC12 cells exposed to elevated glucose for 96 h. These results demonstrate that V. angustifolium contains active principles with insulin-like and glitazone-like properties, while conferring protection against glucose toxicity. Enhancement of proliferation in beta cells may represent another potential anti-diabetic property. Extracts of the Canadian blueberry thus show promise for use as a complementary anti-diabetic therapy.

BLUEBERRY PRODUCTION AND RESEARCH TRENDS IN NORTH AMERICA

BLUEBERRY PRODUCTION AND RESEARCH TRENDS IN NORTH AMERICA