Glen Clova Research Articles

Kyanite and Cordierite‐Andalusite occurrences in parts of Barrow's Staurolite zones – The effects of high ferric iron

AbstractGeorge Barrow's maps (1893, 1912) of the metamorphic zones named after him in the south‐eastern Scottish Highlands, show a prominent staurolite zone running from the west of Glen Clova to the North Sea coast near Stonehaven in the east. Pelitic mica schists throughout this zone commonly show principal mineral assemblages of staurolite+biotite+garnet+muscovite +quartz (St + Bt + Grt), with sodic plagioclase, ilmenite and sometimes magnetite as common accessories; these schists have bulk compositions corresponding with those of common Dalradian metasediments. However, the mineral assemblages on the low‐ and high‐grade margins of the staurolite zone show evidence of changes from west to east. Lower grade assemblages near Stonehaven include chloritoid+biotite, which has not been found further west in the classic ‘Barrovian’ sequence; whilst the higher grade assemblages near Stonehaven lack kyanite, which is widely seen further west. The Stonehaven area has been suggested to have under gone metamorphism at lower pressure (P) than the classic region of the ‘Glens’ inland to the west.This paper describes the occurrence at middle grade in the broad staurolite zone, of unusual bulk rock compositions showing high ratios of Fe2O3/(Fe2O3 + FeO) and MgO/(MgO + FeO) (abbreviated to M/FM). The high M/FM assemblages are distinct from those of the common St‐Bt‐Grt schists. The high ratios of ferric to ferrous iron are thought to result from original sedimentary protolith compositions, that led to metamorphism at relatively high conditions of oxygen fugacity (ƒo2), and resulted in the formation of haematite‐bearing assemblages, rather than ones carrying accessory ilmenite and magnetite as in the common St + Bt + Grt rocks.In the west (Glen Lethnot), the haematite‐bearing pelites show the occurrence of kyanite at a distinctly lower grade than the common (haematite‐free) pelites, and a transition from staurolite‐biotite (St + Bt) through staurolite–kyanite‐biotite (St + Ky + Bt) to kyanite‐biotite (Ky‐Bt) assemblages occurs with increasing abundance of haematite and higher bulk M/FM values. In all bulk compositions, the upgrade formation of kyanite may be associated with the movement of the St + Ky + Bt assemblage to lower M/FM bulk compositions with increasing temperature (T). The difference in the temperature of lowest‐grade kyanite formation in haematite‐rich schists, compared with that in common haematite‐free schists may approach 50°C.In the east (Stonehaven section), the haematite‐bearing assemblages are much rarer than in Glen Lethnot, but those found so far are very distinctive in showing large porphyroblasts of probable cordierite (typically altered to chlorite and sericite). Occasional assemblages of andalusite‐cordierite‐biotite (And‐Crd‐Bt) also occur in the haematite‐bearing rocks and confirm lower pressures of metamorphism near Stonehaven than those seen further west in Glens Clova, Lethnot and Esk.

First report of Raspberry leaf mottle virus infecting raspberry in Poland.

Raspberry leaf mottle virus (RLMV) in Europe has been associated with raspberry mosaic disease (Martin et al. 2013) and crumbly fruit disease (Quito-Avila et al. 2014) in red raspberry (Rubus idaeus L.) beside Rubus yellow net virus (RYNV) and Black raspberry necrosis virus (BRNV). RLMV has also been reported infecting blackberry (Jones and McGavin 1998; Thekke-Veetil et al. 2016). A survey of virus diseases was conducted from 2016 to 2018 in 34 raspberry commercial plantations in Central and southeastern Poland. Some of the plants showed chlorotic spots, vein yellows, mosaic patterns and deformation of leaves and fruits. Leaf samples from 146 plants were tested using RT-PCR for RLMV, RYNV, BRNV, Raspberry vein chlorosis virus (RVCV), Raspberry leaf blotch virus (RLBV), and Raspberry bushy dwarf virus (RBDV). The pairs of primers CPhF and CPhR (Tzanetakis et al. 2007) as well as 1436F and 1437R (McGavin and MacFarlane 2010) were used to amplify a 452-bp fragment of the coat protein homologue (CPh) gene and a 681-bp of the 1 a helicase gene, respectively. RT-PCR products were obtained for five samples from cultivars: Malling Promise (MPrOK1 and MPrOk2; plantation A), Canby (CanKop; plantation B), Polka (PolKop; plantation B) and Malling Seedling (MSeWa; plantation C) grown in southeastern Poland. MPrOK1 and MSeWa were co-infected with RYNV while the other three samples were mixed infected with RBDV. Each of these plants showed chlorotic spots and mosaic symptoms of different intensity, leaf deformation and reduced growth. The RLMV-specific amplicons obtained for all five positive samples were directly sequenced at Genomed company, Warsaw, Poland. The obtained sequences were aligned using ClustalW of the Lasergene 7.1 software (DNASTAR Inc., USA) and were compared with sequences available in GenBank using the BLASTn algorithm. The identity of nucleotide (nt) sequences of Cph gene of RLMV isolates found in Poland was revealed. They shared 97.7% and 99% nt sequence similarity with 'HCRL Glen Clova' from USA (DQ357218) and 'SCRI stock' isolate from United Kingdom (FN391551) strains respectively The nucleotide sequence of isolates from Poland indicates a closer relationship with the strain found in UK. However, the amino acid (aa) sequence of both reference strains was identical and shared 99.2% identity with the corresponding fragment of the isolates from Poland. The representative sequence of PolKop isolate was deposited in GenBank under accession No. MT241265. The similarity of nucleotide sequence of the 1 a helicase gene ranged from 98.5% (between MseWa and four other isolates) to 100% (between MPrOk1 and MPrOk2). The amino acids sequences of MPrOk1, MPrOk2 and MSeWa isolates were identical whereas they shared 99.5% similarity with CanKop and PolKop isolates. The nt and aa sequences within this region of all five isolates were in 98% homologous with the sequences of 'HCRL Glen Clova' strain. Nucleotide sequences of the 1 a helicase gene of the CanKop, PolKop, MseWa, MPrOk1, MPrOk2 isolates were deposited in GenBank (acc. Nos. MT847633-MT8347637). Considering the low incidence of RLMV (five out of 146 positively tested), it can be assumed that there is no emergency of the RLMV large-scale occurrence in Poland. However, as RLMV is transmitted by Amphorophora idaei aphids found in our country, infected plants near raspberry plantations may play an important role in virus spread. This is the first report of RLMV infecting red raspberry in Poland. Acknowledgments This work was performed in the frame of multiannual programme 2015-2020 "Actions to improve the competitiveness and innovation in the horticultural sector with regard to quality and food safety and environmental protection" (task 2.1), financed by the Polish Ministry of Agriculture and Rural Development. I would like to thank Mrs. Dorota Starzec for technical assistance. References Jones, A. T, and McGavin, W. J. 1998. Ann. Appl. Biol. 132:239. https://doi.org/10.1111/j.1744-7348.1998.tb05200.x. Martin, R. R. et al. 2013. Plant Dis. 98:176. http://dx.doi.org/10.1094/PDIS-04-12-0362-FE. McGavin, W. J. and MacFarlane, S. A. 2010. Ann. Appl. Biol. 156:439. doi:10.1111/j.1744-7348.2010.00401.x. Quito-Avila, D. F., et al. 2014. Plant Dis. 98:176. http://dx.doi.org/10.1094/PDIS-05-13-0562-RE. Thekke-Veetil, T., et al. 2016. Plant Dis. 101:265. https://doi.org/10.1094/PDIS-07-16-1014-PDN Tzanetakis, I. E., et al. 2007. Virus Res. 127:26. doi:10.1016/j.virusres.2007.03.010.

Root Herbivores Drive Changes to Plant Primary Chemistry, but Root Loss Is Mitigated under Elevated Atmospheric CO2.

Above- and belowground herbivory represents a major challenge to crop productivity and sustainable agriculture worldwide. How this threat from multiple herbivore pests will change under anthropogenic climate change, via altered trophic interactions and plant response traits, is key to understanding future crop resistance to herbivory. In this study, we hypothesized that atmospheric carbon enrichment would increase the amount (biomass) and quality (C:N ratio) of crop plant resources for above- and belowground herbivore species. In a controlled environment facility, we conducted a microcosm experiment using the large raspberry aphid (Amphorophora idaei), the root feeding larvae of the vine weevil (Otiorhynchus sulcatus), and the raspberry (Rubus idaeus) host-plant. There were four herbivore treatments (control, aphid only, weevil only and a combination of both herbivores) and an ambient (aCO2) or elevated (eCO2) CO2 treatment (390 versus 650 ± 50 μmol/mol) assigned to two raspberry cultivars (cv Glen Ample or Glen Clova) varying in resistance to aphid herbivory. Contrary to our predictions, eCO2 did not increase crop biomass or the C:N ratio of the plant tissues, nor affect herbivore abundance either directly or via the host-plant. Root herbivory reduced belowground crop biomass under aCO2 but not eCO2, suggesting that crops could tolerate attack in a CO2 enriched environment. Root herbivory also increased the C:N ratio in leaf tissue at eCO2, potentially due to decreased N uptake indicated by lower N concentrations found in the roots. Root herbivory greatly increased root C concentrations under both CO2 treatments. Our findings confirm that responses of crop biomass and biochemistry to climate change need examining within the context of herbivory, as biotic interactions appear as important as direct effects of eCO2 on crop productivity.

Pressure–temperature evolution and thermal regimes in the Barrovian zones, Scotland

Abstract: We constrain the P – T evolution of the Barrovian metamorphic zones from the southwestern to the northeastern coasts of Scotland using thermobarometry and pseudosection analysis based on mineral composition data, garnet zoning profiles and 2D garnet maps. Twenty-five samples were investigated from the garnet to the sillimanite zones. In the western half of the field area there was relatively high- P metamorphism (0.9–1.1 GPa) followed by near-isothermal decompression. In and around the Barrovian type area of Glen Clova maximum pressures were also high ( c . 0.8–0.9 GPa); however, peak- T conditions were driven by a brief (of the order of 1 Ma or less) thermal pulse or pulses during exhumation at c . 0.6 GPa. Pressures at peak- T conditions along the eastern coast were the lowest observed, c . 0.4–0.5 GPa. These rocks were probably affected by the same thermal pulse activity evident around Glen Clova. All three regions initially developed during regional metamorphism associated with thermal relaxation of tectonically overthickened crust. The eastern part of the sequence, including Glen Clova, is fundamentally different from the western part because it required additional advective heat input to achieve peak thermal conditions. This heat was probably supplied by synorogenic magmas (e.g. Newer Gabbros) and the associated elevated crustal heat flow. Supplementary material: Electron microprobe methods, mineral and rock analyses, mineral activity–composition relations, criteria for identifying prograde mineral compositions, pseudosection and diffusion modelling methods, and profiles of X Alm and X Prp from garnets in Figures 7 , 8 , 9 , 10 are available at http://www.geolsoc.org.uk/SUP18491 .

CHARACTERIZATION OF THREE NOVEL VIRUSES INFECTING RASPBERRY

During routine graft indexing at the USDA-ARS Horticultural Crops Research Laboratory in Corvallis, Oregon, USA, a ‘Glen Clova’ plant that originated in Europe, induced severe symptoms on indicator plants causing mottling, epinasty and apical necrosis. Testing for all Rubus viruses with available laboratory based detection tests failed to identify a known virus in the plant. In an effort to determine the causal agent(s) of the symptoms, dsRNA was extracted from the ‘Glen Clova’ plant and cloned. Sequence analysis revealed the presence of three novel viruses in the plant, temporarily designated as Glen Clova virus -1, -2 and -3 (GC-1, -2, -3). GC-1 is a novel closterovirus with sequence similarity to Citrus tristeza virus, GC-2 is a member of the family Flexiviridae and shares greatest similarity with members of the virus family that infect rosaceous hosts. GC-3, a unique plant virus, belongs to the Dicistroviridae, a family of picorna-like insect viruses and is similar to a virus identified recently in strawberry. RT-PCR based detection protocols have been developed for the three viruses. GC-1 has been identified in several raspberry plants from the state of Washington. One of these plants, a yellow raspberry, did not have any other detectable viruses. When leaves from this plant were used to graft R. occidentalis, a standard indicator for most viruses of Rubus, the plant developed mosaic symptoms but not the tip necrosis and epinasty. Testing of the graft and aphid transmissible virus-like agents of Rubus from the UK is currently underway through a collaborative project with colleagues at SCRI in Invergowrie, Scotland. Also, transmission studies are currently underway.

DIFFERENT RATES OF SPREAD OF RASPBERRY BUSHY DWARF VIRUS AND SOME APHID-BORNE VIRUSES INTO RED RASPBERRY CULTIVARS CONTAINING DIFFERENT RESISTANCE GENES

The incidence of infection with the pollen-borne Raspberry bushy dwarf virus (RBDV) and some aphid-borne viruses was assessed in 6 red raspberry cultivars in a field experiment at Invergowrie, Dundee. The cultivars differed in their resistance to RBDV, and to strains of the main aphid virus vector, Amphorophora idaei. Six years after planting as healthy plants, cv. Glen Clova, that contains the RBDV-resistance gene Bu, was not infected with RBDV, whereas all 5 RBDV-infectible cultivars became infected with RBDV but the virus incidence varied greatly from 2 - 78%. Seemingly, factors other than the presence of gene Bu influence the level of resistance to natural infection with RBDV under field conditions. All cultivars contained genes for resistance to strains of Am. idaei present in the UK and, in PCR assays for Rubus yellow net virus (RYNV) transmitted by this aphid species, the incidence of infection varied greatly. The percent infection with RYNV in cvs Glen Rosa and Leo, that contain the strongest resistance gene A10, was 0 and 9 respectively, in cvs Glen Ample, Glen Prosen and Malling Landmark, that contain gene A1, it was 9, 53 and 19 respectively, and in cv. Glen Clova, that has only minor gene resistance, it was 22. In the four cultivars sensitive to the viruses inducing Raspberry leaf spot mosaic disease, the lowest incidence of disease was 0.6% in the gene A10-containing cv. Glen Rosa and the highest was 80% in the gene A1-containing cv. Malling Landmark. Clearly, there are factors other than the major aphid resistance genes that influence resistance to virus inoculation by Am. idaei under field conditions. None of the raspberry cultivars studied were resistant to Raspberry vein chlorosis virus (RVCV) or to its aphid vector, Aphis idaei. Based on symptomatology, all cultivars became infected with RVCV but the incidence of infection varied from 1 - 100%.

Prograde temperature–time evolution in the Barrovian type–locality constrained by Sm/Nd garnet ages from Glen Clova, Scotland

Abstract: The timing of garnet growth during metamorphism associated with the Grampian Orogeny in the sillimanite zone of the Barrovian type-locality in Glen Clova, Scotland, was determined by Sm/Nd geochronology. Two high precision garnet-whole-rock ages were achieved by employing HF partial dissolution of garnet separates to optimize purity. Multiple garnet growth generations were identified on the basis of the geochronology and detailed textural and chemical data: an early stage, at 472.9 ± 2.9 Ma, during D 2 deformation under garnet zone conditions (c. 500–550 °C), and a later stage, at 464.8 ± 2.7 Ma, during or slightly after D 3 deformation mostly under sillimanite zone conditions (peak temperature of c. 660 °C), but possibly including some growth during kyanite zone conditions. When combined with recently published garnet ages from the kyanite and garnet zones the data suggest that peak metamorphic temperatures in at least these three of Barrow's zones were achieved roughly contemporaneously. The difference between garnet zone and sillimanite zone peak temperature attainment is 2.8 ± 3.7 Ma. The near contemporaneity of peak temperature attainment in different metamorphic zones requires an additional source of heat beyond thermal relaxation of a variably over-thickened crust. We suggest that local igneous intrusions, with synmetamorphic ages, provided that additional heat.

Incidence and Distribution of Raspberry bushy dwarf virus in Commercial Red Raspberry (Rubus idaeus) Crops in Scotland

A survey was done in 1998 to determine whether Raspberry bushy dwarf virus (RBDV) was established in raspberry fruiting plantations in Scotland. Raspberry-producing holdings were selected according to geographical area and size. Samples (201), each comprising 60 shoots per stock, were obtained from 77 holdings and tested by enzyme-linked immunosorbent assay (ELISA). ELISA-positive shoots from each infected stock were grafted onto cultivar Glen Clova, which is resistant to the Scottish-type isolate of RBDV (RBDV-S), to establish whether the virus is a resistance-breaking (RB) isolate. RBDV was detected in 22% of the stocks sampled, with 2 to 80% incidence of infection. No RBDV was in any of the 40 plantations containing cultivars resistant to RBDV-S or in Glen Clova plants, which were grafted successfully with samples from 15 infected plantations, indicating that no RB isolates were detected. The percentage of infected plantations increased with time from the planting date. In order to investigate possible sources of infection, ELISA for RBDV was made in 1999 on samples of stocks of raspberry cultivars entered for the lowest certified grade (Standard Grade) in Scotland and, in 1994 to 1997, on certified stocks planted with material originating from outside Scotland. No RBDV was detected in any of the samples. RBDV was found only rarely in samples of wild raspberry in Angus and Perthshire.

High fO2 During Sillimanite Zone Metamorphism of Part of the Barrovian Type Locality, Glen Clova, Scotland

The redox state of sillimanite zone (650–700°C, 5–6 kbar) metasediments of the Barrovian type area, Scotland, was investigated using estimates of metamorphic oxygen fugacity (fO2), sulfur fugacity (fS2), and fluid chemistry based on new determinations of mineral and rock compositions from 33 samples. A total of 94% of the samples lack graphite, contain both ilmenite–hematite solid solutions (RHOMOX) and magnetite, and had metamorphic fO2 about 2 log10 units above the quartz–fayalite–magnetite (QFM) buffer. The regional variation in metamorphic fO2 for these rocks was minimal, about ±0·3 log10 units, reflecting either a protolith that was homogeneous with respect to redox state, or an initially variable protolith whose redox state was homogenized by metamorphic fluid–rock interaction. RHOMOX inclusions in garnet porphyroblasts that become richer in ilmenite from the interior to the edge of the host porphyroblast suggest that at least some syn-metamorphic reduction of rock occurred. Significant variations in bulk-rock oxidation ratio (OR) that are probably inherited from sedimentary protoliths are found from one layer to the next; OR ranges mostly between ∼20 and ∼50 [OR = molecular 2Fe2O3 × 100/(2Fe2O3 + FeO)]. These OR variations are uncorrelated with fO2 and do not indicate that large, order-of-magnitude gradients in fO2 and redox state existed or were preserved between layers during metamorphism. The other 6% of the samples contain ilmenite, lack magnetite, and had low fO2 0–1 order of magnitude below QFM in the stability field of graphite. They are characterized by combinations of the following: large fluid HF/H2O; metasomatic, tourmaline-bearing veins; absence or rarity of primary organic matter; and crosscutting late metamorphic shear zones rich in carbonaceous material. Such observations suggest that locally low fO2 conditions may have been related to the influx of reducing fluids from elsewhere in the area.

Ripening-related changes in raspberry cell wall composition and structure

Cell walls were prepared from the fruit of two cultivars of raspberry at three stages of ripening; green, white and red (ripe). The cultivars, Glen Clova and Glen Prosen, are subjectively classified, at harvest by growers, as soft and firm fruit, respectively. The cell walls were analysed for neutral sugar composition, uronic acid content, degree of methyl esterification, lignin and ferulic acid-derived dehydrodimers. Solid-state 13C NMR and diffuse reflectance infrared (DRIFT) spectra were acquired for the cell wall residues. For both cultivars the progression from green to white produced minimal changes, save for a reduction in pectin. NMR analyses indicated that the solubilized pectin was acetylated. Progression to the red (ripe) stage, in both cultivars, was accompanied by a reduction in the ordered cellulose and a dramatic reduction in pectin content and the degree of methyl-esterification. Significantly, the softer fruit (Glen Clova) exhibited greater reductions in both parameters, implicating increased pectin hydrolysis, as one of the main factors contributing to the difference in firmness between the cultivars. A relative increase in cell wall-associated protein was seen at the red stage. The nature and function of the protein(s) are, as yet unknown.

A causal role for ethylene and endo‐β‐1,4‐glucanase in the abscission of red‐raspberry (Rubus idaeus) drupelets

During raspberry (Rubus ideaus L. cv Glen Clova) fruit ripening, endo‐β‐1,4‐glucanase (EGase; EC 3.2.1.4) specific activity (per g fresh weight) increases approximately 15‐fold. Highest activity was associated with the surfaces of the receptacles where the weakening abscission zones are located. Immunoblotting using antibodies raised against a bean abscission‐EGase (ab.‐EGase) identified a single protein of Mr 52 kDa that was present only in ripe fruit and was most prominent in the receptacle. Using reverse transcription‐polymerase chain reaction (RT‐PCR), two 497‐bp partial putative EGase clones were obtained from ripe receptacle mRNA (termed RI‐EGL1 and 2) which share 53% amino acid identity. The more abundant RI‐EGL1 was used to obtain its full length clone from a ripe receptacle cDNA library. The deduced amino acid sequence of RI‐EGL1 was similar to other ab.‐EGase sequences (ca 67%) and contained the conserved motifs present in all E2‐class EGases. Northern analysis revealed that RI‐EGL1 expression was limited to ripe‐fruit receptacles. Application of the ethylene antagonist 1‐methylcyclopropene (1‐MCP) to green fruits indicated that endogenous ethylene accelerates raspberry abscission and increases both EGase activity and RI‐EGL1 expression.

The role of ethylene and cell wall modifying enzymes in raspberry (Rubus idaeus) fruit ripening

This study focuses on four raspberry (Rubus idaeus) genotypes from two different genetic backgrounds: cvs Glen Prosen and Glen Clova, bred at the Scottish Crop Research Institute (SCRI) and genotypes bred at Horticulture Research International (HRI), East Malling (EM), EM 4997 and EM 5007. The ripe fruit of each genotype pair were characterised subjectively by raspberry breeders as relatively firm or soft, respectively. Different stages of fruit development from each genotype were used to quantify fruit firmness, rates of ethylene evolution and ripening rate. Penetrometry data confirmed suspected firmness differences. Firmness correlated with rates of ethylene evolution. Rates of ethylene production also correlated with receptacle size. Storage of green fruits in 20 μl l−1 ethylene reduced fruit firmness, enhanced respiration rate and colour (anthocyanin) development and stimulated the development of cell wall hydrolase activities. However, during natural ripening in the field, fruit respiration rate declined, which indicates a non‐climacteric ripening pattern. In drupelets, the activities of polygalacturonase (PG), pectin methylesterase (PME), Cx‐cellulase (Cx) and β‐galactosidase (β‐gal.) increased substantially as ripening progressed. More detailed studies with ripe fruit of cv. Glen Clova indicated major isoforms of PG at pIs 3.3, 8.6 and 10.1; of PME at pIs 7.2, 8.5, 8.7, 8.8; of Cx at pI 2.4; and of β‐gal. at pIs 6.3 and 6.7.

Genotype, Location, and Harvest Date Effects on the Sensory Character of Fresh and Frozen Red Raspberries

Fruit from three red raspberry (Rubus idaeus L.) cultivars—`Glen Clova', `Glen Lyon', and `Glen Moy'—were harvested from four sites on two harvest dates and evaluated fresh or following storage at -20 °C to determine the relative importance of genotype, harvest date, location and freezing effects on 19 sensory attributes using a trained sensory panel. Freezing and cultivar × freezing interaction effects were relatively large while site, harvest date, and other interactions were of minor importance. The cultivar × freezing interaction was caused by differential responses among cultivars for the sensory attributes purple, juicy, sweet, and raspberry aroma with less discrimination among cultivars postfreezing. `Glen Clova' fresh fruit received the highest values for juicy, fruity, sweet, and raspberry aroma; `Glen Moy' fresh fruit received the highest values for purple; `Glen Lyon' fresh fruit received the lowest values for juicy, postfreezing, `Glen Lyon' received the highest values for purple and sweet and all three cultivars were similar for the other attributes. These data suggest that selection for improved postfreezing sensory characteristics should not rely solely on fresh fruit evaluations although further study of a more genetically diverse group of genotypes would be beneficial. The significant cultivar and minimal harvest date and location effects suggest that these fruit sensory analysis methods should be useful in selecting raspberry genotypes with superior fruit quality.

Flower choices by raspberry beetles: cues for feeding and oviposition

Raspberry beetles,Byturus tomentosus, use raspberry as the host plant for feeding, mating and oviposition; the larvae are a major pest on the fruit. This study seeks reasons for their choices between flowers of different cultivars. Beetles showed consistent diurnal movements between different cultivars of raspberry, which were linked to differential behavioural patterns; they fed predominantly on Glen Clova canes in the morning and moved to Glen Prosen later in the day where oviposition behaviour was commoner and substantially more effective. Hence two closely similar cultivars of the same plant species received very different levels of flower damage (from adult feeding) and of fruit damage (from larval infestation). These patterns were linked to subtle differences in cues from the host plant; Glen Clova produces unusually copious nectar which may limit oviposition opportunities because of osmotic threats to eggs and larvae, whereas Glen Prosen has drier flowers for egg laying and apparently emits a short-lived volatile cue that principally attracts female beetles. Selective breeding of the host plant has therefore had unexpected side-effects on interactions with a major pest species, mediated by the behaviour of the insect, and perhaps accentuating natural behavioural preferences that serve to reduce competition between adult and larval stadia.

Cloning of three genes up-regulated in ripening raspberry fruit ( Rubus idaeus cv. Glen Clova)

Summary cDNA clones of three genes, up-regulated as raspberry ( R. idaeus cv. Glen Clova) fruit ripen, were isolated by differential screening of a cDNA library constructed from RNA extracted from ripe fruit. The expression patterns of these genes were determined in ripening fruit and in other tissues of the raspberry plant. When compared with sequences in databases, the genes were identified on the basis of sequence similarity. The predicted polypeptides coded for by the three clones show similarity to major latex proteins, a class of fruit-specific metallothionein-like proteins, and fruit-ripening associated endo-polygalactu-ronases, respectively. The potential roles of these gene products in fruit-ripening is discussed.

Spatially dependent genetic diversity within and between colonies of wild raspberry Rubus idaeus detected using RAPD markers

In the Tayside region of Scotland, red raspberry Rubus idaeus exists both as extensive plantations of clonally propagated cultivars, and as wild populations that inhabit both the cultivated areas and uncultivated uplands to the north. In order to explore the genetic diversity of the wild populations and their degree of similarity to the plantation clones, individual plants in wild populations were sampled from four distinct sites along a 25‐km transect northwards from the area of cultivation. The genetic material of each of 45 individuals and the commercial cv. Glen Clova were examined using six RAPD primers giving a total of 63 variable bands. Some identical banding patterns were observed, suggesting vegetative growth up to 20 m, but populations consisted mainly of genetically distinct individuals. Similarity matrices based on the marker bands showed, without exception, that plants were more similar within a site than between sites. None of the populations was closely related to the cv. Glen Clova. Although the most northerly site had the largest proportion of rare bands, there was no general trend between within‐site diversity, or similarity to the cultivar, and position on the north‐south line. All four sites had unique bands and bands not displayed by the cultivar. However, the genetic diversity of a site appeared to increase as the extent of the sampled area increased, implying that the genetic variation was spatially dependent. For example, maximum and minimum similarities were 100 and 80%, respectively, at interplant distances of 2 m; 100 and 60% at distances of 20 m; 85 and 55% at 200 m and 70 and 40% at 20 km.

Cellulase, Fruit Softening and Abscission in Red RaspberryRubus idaeusL. cv Glen Clova

Abstract The ripening of raspberry fruit ( Rubus ideaus L. cv Glen Clova) is associated with a climacteric rise in ethylene production. As the fruit pigments change from green to red there is a progressive softening, loss of skin strength and a breakdown of cell walls in the mesocarp. An increase in cellulase (endo-1,4-β- d -glucanase) in both drupelets and receptacles accompanies these changes. The localization of cellulase in the regions of the fruit associated with abscission zones suggest the enzyme may be involved in fruit separation as well as softening.

Development of two spotted spider mite (Acari: Tetranychidae) populations on strawberry and raspberry cultivars

Summary.Five strawberry (Fragaria sp.) and five raspberry (Rubus ideaus L.) cultivars were evaluated for resistance to two spotted spider mite (Tetranychus urticae Koch.). Two methods of assessing the development of two spotted mite populations using detached leaves were compared. The number of eggs laid and mites which developed were compared. The strawberry cvs Hapil and Pegasus had significantly greater development of two spotted mite populations than the cvs Rhapsody, Symphony and Elsanta. The raspberry cv. Joan Squires had higher populations of two spotted mite whilst the raspberry cv. Leo the least, when compared with cvs Glen Clova, Glen Moy and Glen Prosen. Differences were observed in oviposition sites and mite distribution when comparing raspberries with strawberries. The method of assessing the populations development of two spotted mite which involved maintaining the cut leaf stem in water may be of potential use for studying population dynamics of both two spotted mite and possible predators over extended periods of time.

Ethylene Co-ordinates Petal Abscission in Red Raspberry (Rubus idaeus L.) Flowers

The time-course of flower development of Rubus idaeus L. cv. Glen Clova was studied on detached buds opened in the laboratory. After sepal and petal opening petal abscission occurred with the petals from an individual flower being shed over 3-4 h. Abscission was accompanied by a peak in ethylene production. Treatment of flowers with aminoethoxyvinylglycine eliminated the peak in ethylene production but did not prevent petal abscission. However, petal loss was much slower, taking place over a period of days rather than hours. Abscission was more effectively retarded by silver thiosulphate. Exogenous ethylene accelerated the rate of petal abscission and senescence. The increase in ethylene production coincident with petal abscission appears to accelerate and co-ordinate the shedding of the separate petals on an individual flower. If ethylene is important in the induction of abscission it would appear that the low rate of production sustained in the presence of aminoethoxyvinylglycine must be sufficient.

Root Rot of Red Raspberry Caused byPhytophthora citricolaandP. citrophthorain Chile

Outbreaks of root rot on red raspberry occur frequently in Chile and often are related to excess soil moisture. Aerial symptoms, including leaf chlorosis, wilting of primocanes and floricanes, poor growth of floricanes, and poor emergence of primocanes, are always associated with root necrosis. Diseased plants eventually die. Phytophthora citricola and P. citrophthora were consistently recovered from the roots of symptomatic plants of the cultivars Willamette and Glen Clova