Altered expression of a raspberry homologue of VRN1 is associated with disruption of dormancy induction and misregulation of subsets of dormancy-associated genes.

Winter dormancy is a key process in the phenology of temperate perennials. Climate change is severely impacting its course leading to economic losses in agriculture. A better understanding of the underlying mechanisms, as well as the genetic basis of the different responses, is necessary for the development of climate-resilient cultivars. This study aims to provide an insight into winter dormancy in red raspberry (Rubus idaeus L). We report the transcriptomic profiles during dormancy in two raspberry cultivars with contrasting responses. The cultivar 'Glen Ample' showed a typical perennial phenology, whereas 'Glen Dee' registered consistent dormancy dysregulation, exhibiting active growth and flowering out of season. RNA-seq combined with weighted gene co-expression network analysis identified gene clusters in both genotypes that exhibited time-dependent expression profiles. Functional analysis of 'Glen Ample' gene clusters highlighted the significance of the cell and structural development prior to dormancy entry as well the role of genetic and epigenetic processes such as RNAi and DNA methylation in regulating gene expression. Dormancy release in 'Glen Ample' was associated with up-regulation of transcripts associated with the resumption of metabolism, nucleic acid biogenesis, and processing signal response pathways. Many of the processes occurring in 'Glen Ample' were dysregulated in 'Glen Dee' and 28 transcripts exhibiting time-dependent expression in 'Glen Ample' that also had an Arabidopsis homologue were not found in 'Glen Dee'. These included a gene with homology to Arabidopsis VRN1 (RiVRN1.1) that exhibited a sharp decline in expression following dormancy induction in 'Glen Ample'. Characterization of the gene region in the 'Glen Dee' genome revealed two large insertions upstream of the ATG start codon. We propose that expression below detection level of a specific VRN1 homologue in 'Glen Dee' causes dormancy misregulation as a result of inappropriate expression of a subset of genes that are directly or indirectly regulated by RiVRN1.1.

Impact of Background Fruit Odors on Attraction of Drosophila suzukii (Diptera: Drosophilidae) to Its Symbiotic Yeast.

Background odors produced by plants in the environment can interfere with the response of insects to a point-releasing attractant, especially when their compositions overlap. In this study, a series of binary choice tests was conducted in a wind tunnel to investigate whether background odors emitted from cherry, blueberry, blackberry, or raspberry fruits would affect the level of Drosophila suzukii (Matsumura) attraction to its symbiotic yeast, Hanseniaspora uvarum (Niehaus) (Saccharomycetales: Saccharomycetaceae). Whether an increase in the intensity of background odors would affect the attractiveness of H. uvarum to D. suzukii was also investigated, either by increasing the number of cherry or raspberry fruit per cup or by increasing the number of fruit cups surrounding the cup baited with the yeast. In wind tunnel assays, background fruit odors interfering with D. suzukii attraction to the yeast varied among fruit types. Raspberry odor inhibited the attractiveness of H. uvarum to the fly the most, followed by blackberry odor, whereas cherry and blueberry odors had no significant impact on the attraction. An increase in the intensity of odors by adding more cherry or raspberry fruit per cup did not increase the impact of fruit odor on the attraction; however, adding more raspberry cups around H. uvarum linearly decreased its attractiveness, suggesting that background host fruit abundance and likely increase in host odor may influence D. suzukii attraction to yeast odor depending on host species.

The cholesterol-lowering effect of unripe Rubus coreanus is associated with decreased oxidized LDL and apolipoprotein B levels in subjects with borderline-high cholesterol levels: a randomized controlled trial.

BACKGROUND: Rubus coreanus (R. coreanus) possesses properties that may decrease cholesterol levels. METHODS: The effects of unripe R. coreanus (uRC) consumption on low-density lipoprotein (LDL) and total cholesterol levels related to decreased circulating apolipoprotein (Apo) B and oxidized LDL levels were evaluated. This randomized, double-blind, placebo-controlled study included subjects with borderline-high cholesterol levels (between 200 and 239 mg/dL) who consumed one capsule daily containing 600 mg of freeze-dried uRC extract (n = 39) or the placebo (n = 38). RESULTS: After 12 weeks, the uRC group showed reductions of 21.23 ± 4.36 mg/dL in total cholesterol levels (P = 0.007) and 15.61 ± 4.16 mg/dL in LDL cholesterol levels (P = 0.032). In addition, significantly greater reductions in Apo B levels were observed in the uRC group (- 3.48 ± 3.40 mg/dL), but Apo B levels were increased in the placebo group (6.21 ± 2.84 mg/dL; P = 0.032). Furthermore, a remarkably lower oxidized LDL level was detected in the uRC group (57.76 ± 2.07 U/L) than in the placebo group (66.09 ± 3.47 U/L) after 12 weeks of consumption (P = 0.044). CONCLUSIONS: Because of its cholesterol-lowering effect, uRC shows great promise as a therapeutic agent for subjects with borderline-high total blood cholesterol levels. TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT03649620 (8/28/2018, retrospectively registered).

The raspberry bushy dwarf virus 1b gene enables pollen grains to function efficiently in horizontal pollen transmission.

Horizontal pollen transmission by the raspberry bushy dwarf virus 1b deletion mutant (RBΔ1bstop), which is defective in virus virulence, was significantly decreased compared to wild-type raspberry bushy dwarf virus (wtRBDV). We assessed accumulation of viral genomic (g) RNAs in pollen grains from RBΔ1bstop-infected plants and found that the pollen grains had less viral gRNA than those from wtRBDV-infected plants. In addition, pollen grains from 1b-expressing transgenic plants (1b-plants) infected with RBΔ1bstop were more efficient in horizontal virus transmission to healthy plants after pollination than pollen from RBΔ1bstop-infected wild type plants. Moreover, viral gRNA accumulation in pollen grains from RBΔ1bstop-infected 1b-plants was higher than in pollen from RBΔ1bstop-infected wild type plants. We suggest that 1b increases the amount of viral gRNAs released from elongating pollen grains.

Attenuation of Postmeal Metabolic Indices with Red Raspberries in Individuals at Risk for Diabetes: A Randomized Controlled Trial.

OBJECTIVE: This study investigated the effect of red raspberry intake on meal-induced postprandial metabolic responses in individuals who have overweight or obesity with prediabetes and insulin resistance (PreDM-IR), and in metabolically healthy individuals (Reference). METHODS: Thirty-two adults (PreDM-IR, n = 21; Reference, n = 11) were randomized to a controlled, three-arm, single-blinded, crossover trial. Participants were provided 0 g of frozen red raspberries (Control), 125 g of frozen red raspberries (RR-125) (~1 cup), or 250 g of frozen red raspberries (RR-250) (~2 cups), with a challenge breakfast meal (high carbohydrate/moderate fat) on three separate days. Multiple blood samples were collected up to 8 hours post breakfast with a final blood sample at 24 hours. A snack was provided at 6 hours. RESULTS: Breakfast containing RR-125 and RR-250 significantly reduced 2-hour insulin area under the curve, and RR-250 reduced peak insulin, peak glucose, and 2-hour glucose AUC compared with Control in the PreDM-IR group (P < 0.05). Postprandial triglycerides were significantly lower after RR-125 versus RR-250 (P = 0.01) but not different from Control (P > 0.05). No significant meal-related differences were observed for oxidative stress or inflammatory biomarkers. CONCLUSIONS: Our findings suggest that red raspberries aid in postmeal glycemic control in individuals with PreDM-IR, reducing glycemic burden with less insulin, which may be related to improved tissue insulin sensitivity.

Vertical and temporal distribution of spotted-wing drosophila (Drosophila suzukii) and pollinators within cultivated raspberries.

BACKGROUND: Drosophila suzukii (Diptera: Drosophilidae) is the most prominent arthropod pest of caneberries. Current management practices rely on chemical control, which has raised concerns over the sustainability of this approach. We currently understand little about D. suzukii activity, and whether activity patterns can be exploited to improve management. In this study, we investigated the vertical and temporal distribution of D. suzukii, as well as pollinators, in cultivated raspberries. RESULTS: D. suzukii were generally crepuscular, and most active in the morning within the bottom half of the crop, and in the evening within the top half of the crop. Pollinators were most active during the day and within the top half of the canopy. Humidity and temperature were correlated with insect activity. CONCLUSION: Pesticides applied during twilight that ensure coverage in the bottom half of the crop, or if applied in the late afternoon cover the entire crop, should improve the pesticide efficacy. However, previous studies suggest that specific D. suzukii (e.g. sex, mating status, age) may exploit different areas in the crop at different times, and more work needs to be done to understand how these aspects before a specific management program can be recommended. © 2019 Society of Chemical Industry.

The costs and benefits of pollinator dependence: empirically based simulations predict raspberry fruit quality.

Globally, agriculture increasingly depends on pollinators to produce many seed and fruit crops. However, what constitutes optimal pollination service for pollinator-dependent crops remains unanswered. We developed a simulation model to identify the optimal pollination service that maximizes fruit quality in crops. The model depicts the pollination (i.e., autonomous self-fertilization, pollen deposition) and post-pollination (i.e., pollen germination, and time from germination to ovule fertilization) processes leading to fruit and seed set and allows for negative flower-pollinator interactions, specifically pistil damage. We parameterized and validated the model based on empirical observations of commercial raspberry in western Argentina. To assess the effects of pollination intensity for fruit production, we conducted simulations over a range of visit number per flower by the two primary managed pollinators worldwide, Apis mellifera and Bombus terrestris. Simulations identified that ~15-35 visits per flower by A. mellifera or ~10-20 visits by B. terrestris provide adequate pollination and maximize raspberry fruit quality (i.e., estimated as the proportion of ovules that develop into drupelets). Visits in excess of these optima reduce simulated fruit quality, and flowers receiving >670 honey bee visits or >470 bumble bee visits would produce fruits of poorer quality than those receiving no bee visits. The simulations generated consistent, unbiased predictions of fruit quality for 12 raspberry fields. This model could be adapted easily to other animal-pollinated crops and used to guide efficient pollinator management in any agro-ecosystem.

Transfer of plant protection products from raspberry crops of Laszka and Seedling varieties to beehives.

Field studies were conducted to evaluate the transfer of active ingredients (AIs) of plant protection products (PPPs) to beehives. They were applied in two commodity red raspberry plantations of two varieties: Laszka (experiment 1) and Seedling (experiment 2). Samples of flowers, leaves, bees, brood, and honey were examined for the presence of chlorpyrifos, cypermethrin, difenoconazole, cyprodinil, and trifloxystrobin (experiment 1) and chlorpyrifos, boscalid, pyraclostrobin, cypermethrin, difenoconazole, and azoxystrobin (experiment 2). In experiment 1, the highest levels of trifloxystrobin were observed on the surface of flowers, (0.04 µg/flower) and for difenoconazole on the inside (0.023 µg/flower). Leaves contained only trace residues of cypermethrin and cyprodinil (0.001 µg/cm2 of leaves each) and trifloxystrobin (0.01 µg/cm2 of leaves) on the surface; inside the leaves, the highest levels of trifloxystrobin were observed (0.042 µg/cm2 of leaves). In experiment 2, boscalid was found on the surface and inside the flowers and leaves (0.063 and 0.018 µg/flower and 0.057 and 0.033 µg/cm2 of leaves, respectively). In bees, brood, and honey (experiment 1), chlorpyrifos was present in the highest quantity (7.3, 1.6, and 4.7 µg/kg, respectively). Additionally, cypermethrin and trifloxystrobin were found in bees, and trifloxystrobin was present in honey. Bees, brood, and honey from plantation 2 contained all studied AIs, with the highest levels of boscalid (28.6 µg/kg of bees, 37.0 µg/kg of brood, and 33.9 µg/kg of honey, respectively). In no case did the PPP residues in honey exceed acceptable maximum residue levels (MRLs)-from a formal and legal point of view, in terms of the used plant protection products, the analysed honey was fit for human consumption.

Evaluation of the Nutraceutical and Cosmeceutical Potential of Two Cultivars of Rubus fruticosus L. under Different Cultivation Conditions.

BACKGROUND: The starting point for the development of new, functional products derived from Rubus fruticosus L. is to determine the optimal cultivation conditions that produce maximal yield of fruits containing desirable bioactive properties. Towards that goal, the effect of soil, soil/peat mixture and light intensity on the nutraceutical and cosmeceutical potential of two cultivars ('Thornfree' and 'Loch Ness') of Rubus fruticosus L. were evaluated. METHODS: The assessment was carried out employing a range of methods for evaluating fruit properties associated with promoting good health such as total antioxidant capacity, secondary metabolites content (vitamin C, polyphenols, flavonoids and anthocyanins) and inhibition analysis of skin-regulating enzymes. RESULTS: 'Thornfree' cultivar produced fruits in all light conditions, while 'Loch Ness' did not produce fruits in low light conditions. The results showed that in Rubus fruticosus L. fruit, the chemical composition and bioactivity are strongly affected by both genetics factors and growing conditions. Extract from 'Thornfree' fruits obtained under low light and soil/peat conditions displayed superior properties such as high antioxidant capacity, high concentrations of phenolics, flavonoids and anthocyanins and high inhibitory potency towards the enzymes tyrosinase and elastase. This extract was used for the development of a topical skin care cream with excellent compatibility and stability. CONCLUSION: Our findings conclude that Rubus fruticosus L. cultivation may be efficiently and effectively manipulated through conventional cultivation techniques to produce promising bioactive ingredients with potential use in commercial cosmetics and pharmaceuticals.

Persistent negative temperature response of mesophyll conductance in red raspberry (Rubus idaeus L.) leaves under both high and low vapour pressure deficits: a role for abscisic acid?

The temperature dependence of mesophyll conductance (gm ) was measured in well-watered red raspberry (Rubus idaeus L.) plants acclimated to leaf-to-air vapour pressure deficit (VPDL) daytime differentials of contrasting amplitude, keeping a fixed diurnal leaf temperature (Tleaf ) rise from 20 to 35 °C. Contrary to the great majority of gm temperature responses published to date, we found a pronounced reduction of gm with increasing Tleaf irrespective of leaf chamber O2 level and diurnal VPDL regime. Leaf hydraulic conductance was greatly enhanced during the warmer afternoon periods under both low (0.75 to 1.5 kPa) and high (0.75 to 3.5 kPa) diurnal VPDL regimes, unlike stomatal conductance (gs ), which decreased in the afternoon. Consequently, the leaf water status remained largely isohydric throughout the day, and therefore cannot be evoked to explain the diurnal decrease of gm . However, the concerted diurnal reductions of gm and gs were well correlated with increases in leaf abscisic acid (ABA) content, thus suggesting that ABA can induce a significant depression of gm under favourable leaf water status. Our results challenge the view that the temperature dependence of gm can be explained solely from dynamic leaf anatomical adjustments and/or from the known thermodynamic properties of aqueous solutions and lipid membranes.​.

Two Pests Overlap: Drosophila suzukii (Diptera: Drosophilidae) Use of Fruit Exposed to Halyomorpha halys (Hemiptera: Pentatomidae).

Drosophila suzukii (Matsumura) (Diptera: Drosophilidae) and brown marmorated stink bug, Halyomorpha halys (Stål) (Hemiptera: Pentatomidae), are global economic pests that may co-occur on small fruits. We investigated whether fruit recently exposed to H. halys affected subsequent host use by D. suzukii. Laboratory no-choice and choice tests presented D. suzukii with H. halys-fed and unfed raspberries and blueberries immediately or 3 d after H. halys feeding. Resulting D. suzukii eggs, or larvae and pupae, were counted. The number of D. suzukii immatures among fed and unfed fruit was not significantly different in lab studies. There was no relationship between the intensity of H. halys feeding, as estimated by the number of stylet sheaths, and D. suzukii oviposition on blueberry. Lastly, field studies compared D. suzukii infestation between H. halys-fed and unfed raspberries. Raspberries were previously exposed to H. halys for 3 d or simultaneously exposed to both pests for 7 d. Natural infestation by D. suzukii in the field was similar among raspberries previously or simultaneously exposed to H. halys compared to control fruit.

Adaptation of primocane fruiting raspberry plants to environmental factors under the influence of Bacillus strains in Western Siberia.

In geographical locations with a short vegetative season and continental climate that include Western Siberia, growing primocane fruiting raspberry varieties becomes very important. However, it is necessary to help the plants to overcome the environmental stress factors. This study aimed to evaluate the impact of the pre-planting treatment of primocane fruiting raspberry root system with Bacillus strains on the following plant development under variable environmental conditions. In 2012, Bacillus subtilis RCAM В-10641, Bacillus amyloliquefaciens RCAM В-10642, and Bacillus licheniformis RCAM В-10562 were used for inoculating the root system of primocane fruiting raspberry cultivar Nedosyagaemaya before planting. The test suspensions were 105 CFU/ml for each bacterial strains. The effects of this treatment on plant growth and crop productivity were estimated in 2012-2015 growing seasons differed by environmental conditions. The pre-planting treatment by the bacterial strains increased the number of new raspberry canes and the number of plant generative organs as well as crop productivity compared to control. In addition, these bacilli acted as the standard humic fertilizer. Variable environmental factors such as air temperature, relative humidity, and winter and spring frosts seriously influenced the plant biological parameters and crop productivity of control plants. At the same time, the pre-planting primocane fruiting root treatment by Bacillus strains decreased the negative effects of abiotic stresses on plants in all years of the research. Of the three strains studied, B. subtilis was shown to reveal the best results in adaptation of primocane fruiting raspberry plants to environmental factors in Western Siberia. For the first time, the role of Bacillus strains in enhancing frost resistance in primocane fruiting raspberry plants was shown. These bacilli are capable of being the basis of multifunctional biological formulations for effective plant and environmental health management in growing primocane fruiting raspberry.

Mapping and expression of genes associated with raspberry fruit ripening and softening.

KEY MESSAGE: QTL mapping identifies a range of underlying and unrelated genes with apparent roles in raspberry fruit ripening and softening that show characteristic developing fruit expression profiles. Fruit softening is an important agronomical trait that involves a complex interaction of plant cell processes. We have used both qualitative and quantitative scoring of fruit firmness, length, mass, and resistance to applied force to identify QTL in a raspberry mapping population. QTLs were located primarily on linkage group (LG) 3 with other significant loci on LG 1 and LG 5 and showed mostly additive effects between the two parents. The expression of key genes that underlie these QTLs with roles in cell-wall solubility, water uptake, polyamine synthesis, transcription, and cell respiration was tested across five stages of fruit development, from immature green to red ripe fruit, using real-time RT-qPCR. Gene expression patterns showed variable expression patterns across fruit development with a highly significant positive and negative correlation between genes, supporting precise regulation of expression of different cell processes throughout raspberry fruit development. Variable timing in expression was also found in some genes at different fruit development stages between soft and firm cultivars. Multiple processes have a role to play in fruit softening and this will require development of multiple marker combinations to genes that characterise raspberry fruit softening.

Does the Slow-Growth, High-Mortality Hypothesis Apply Below Ground?

Belowground tri-trophic study systems present a challenging environment in which to study plant-herbivore-natural enemy interactions. For this reason, belowground examples are rarely available for testing general ecological theories. To redress this imbalance, we present, for the first time, data on a belowground tri-trophic system to test the slow growth, high mortality hypothesis. We investigated whether the differing performance of entomopathogenic nematodes (EPNs) in controlling the common pest black vine weevil Otiorhynchus sulcatus could be linked to differently resistant cultivars of the red raspberry Rubus idaeus. The O. sulcatus larvae recovered from R. idaeus plants showed significantly slower growth and higher mortality on the Glen Rosa cultivar, relative to the more commercially favored Glen Ample cultivar creating a convenient system for testing this hypothesis. Heterorhabditis megidis was found to be less effective at controlling O. sulcatus than Steinernema kraussei, but conformed to the hypothesis. However, S. kraussei maintained high levels of O. sulcatus mortality regardless of how larval growth was influenced by R. idaeus cultivar. We link this to direct effects that S. kraussei had on reducing O. sulcatus larval mass, indicating potential sub-lethal effects of S. kraussei, which the slow-growth, high-mortality hypothesis does not account for. Possible origins of these sub-lethal effects of EPN infection and how they may impact on a hypothesis designed and tested with aboveground predator and parasitoid systems are discussed.

Learning through the waste: olfactory cues from the colony refuse influence plant preferences in foraging leaf-cutting ants.

Leaf-cutting ants learn to avoid plants initially harvested if they prove to be harmful for their symbiotic fungus once incorporated into the nest. At this point, waste particles removed from the fungus garden are likely to contain cues originating from both the unsuitable plant and the damaged fungus. We investigated whether leaf-cutting ant foragers learn to avoid unsuitable plants solely through the colony waste. We fed subcolonies of Acromymex ambiguus privet leaves treated with a fungicide undetectable to the ants, then collected the produced waste, and placed it into the fungus chamber of naive subcolonies. In individual choice tests, naive foragers preferred privet leaves before waste was put into the fungus chamber, but avoided them afterwards. Evidence on the influence of olfactory cues from the waste on decision making by foragers was obtained by scenting and transferring waste particles from subcolonies that had been fed either fungicide-treated or untreated leaves. In choice experiments, foragers from subcolonies given scented waste originating from fungicide-treated leaves collected fewer sugared paper discs with that scent compared with foragers from subcolonies given scented waste from untreated leaves. The results indicate that foragers learn to avoid plants unsuitable for the fungus by associating plant odours and cues from the damaged fungus that are present in waste particles. It is argued that waste particles may contribute to spread information about noxious plants for the fungus within the colony.

Long-Term Effects of White-Tailed Deer Exclusion on the Invasion of Exotic Plants: A Case Study in a Mid-Atlantic Temperate Forest.

Exotic plant invasions and chronic high levels of herbivory are two of the major biotic stressors impacting temperate forest ecosystems in eastern North America, and the two problems are often linked. We used a 4-ha deer exclosure maintained since 1991 to examine the influence of a generalist herbivore, white-tailed deer (Odocoileus virginianus), on the abundance of four exotic invasive (Rosa multiflora, Berberis thunbergii, Rubus phoenicolasius and Microstegium vimineum) and one native (Cynoglossum virginianum) plant species, within a 25.6-ha mature temperate forest dynamics plot in Virginia, USA. We identified significant predictors of the abundance of each focal species using generalized linear models incorporating 10 environmental and landscape variables. After controlling for those predictors, we applied our models to a 4-ha deer exclusion site and a 4-ha reference site, both embedded within the larger plot, to test the role of deer on the abundance of the focal species. Slope, edge effects and soil pH were the most frequent predictors of the abundance of the focal species on the larger plot. The abundance of C. virginianum, known to be deer-dispersed, was significantly lower in the exclosure. Similar patterns were detected for B. thunbergii, R. phoenicolasius and M. vimineum, whereas R. multiflora was more abundant within the exclosure. Our results indicate that chronic high deer density facilitates increased abundances of several exotic invasive plant species, with the notable exception of R. multiflora. We infer that the invasion of many exotic plant species that are browse-tolerant to white-tailed deer could be limited by reducing deer populations.