Prunus Cerasifera Ehrh Research Articles

Cell-to-cell transport through plasmodesmata in tree callus cultures

One factor that contributes to a successful fruit tree grafting is the establishment of symplasmic contacts in the graft interface to facilitate the transfer of compounds between scion and stock. Using novel experimental and theoretical approaches we investigated whether the localized incompatibility, experienced in some Prunus grafts, could be related to insufficient plasmodesmal coupling at an early stage of development within one of the partners. Dye-coupling analysis using fluorescent tracers combined with confocal laser scanning microscopy were performed in cultured callus from either the plum rootstock (Prunus cerasifera Ehrh. x Prunus munsoniana W. Wight et Hedr.) cv. 'Marianna 2624' or from the apricot (Prunus armeniaca L.) cv. 'Moniqui' growing in vitro. Fluorescein was loaded into callus cells in a caged form. Following photoactivation of fluorescence within single cells, the uncaged fluorescein could be traced as it was spreading cell-to-cell revealing the existence of functional plasmodesmata. This set of experiments was performed within the 'stock' partner in callus fusions ('callus grafts') as well as in ungrafted callus. The results indicated species-related as well as developmental-related differences in plasmodesmal conductivity. The results further pointed to a novel control factor of connectivity that reaches the graft partner and changes its innate rate of communication: when combining the poorly transporting apricot cultivar with the well-transporting plum cultivar, communication between plum callus cells was much reduced, compared to that in plum homografts. For further support of the hypothesis, we carried out a quantitative analysis in which fluorescein was esterloaded into the callus. Fluorescence redistribution after photobleaching of fluorescein in individual cells gave a measure for the plasmodesmal contact between the cells. We found significant differences between the species with regard to mobile fraction and halftime of redistribution, which confirmed that callus cells are not interconnected to the same extent in Marianna 2624 and Moniqui.

PRUNUS CERASIFERA AS A HOST OF PLUM POX VIRUS IN BULGARIA

SUMMARY Four hundred twenty-five trees of myrobalan (Prunus cerasifera Ehrh.) growing along the roads and small areas within residential spaces, private gardens, and parks in Sofia and around the town were visually inspected for virus symptoms and tested for the presence of PPV by DAS-ELISA. DASI-ELISA for strain differentiation was carried out for the identification of PPV isolates, using PPV-M and PPV-D specific monoclonal antibodies. A small number PPV isolates was tested with M/D specific primers targeting two different regions: cylindrical inclusion protein (CIP) and the coat protein (CP) amino terminal. The primers targeting the 3’-terminal region of the CP gene allowed the detection of a few unknown PPV isolates. While the inspected trees showed highly variable leaf symptoms, only a small number of them showed symptoms on the fruits. The overall detection of PPV was 49%, PPV-M was found in the majority (57%) of the samples, followed by PPVD (29%). Mixed infections occurred in 2% of the samples, and the diseased trees affected by the unknown PPV strain were 12%. PPV-Rec strain was identified in one infected tree. For the first time in Bulgaria two ornamental species, P. cerasifera var. rubrum and P. cerasifera cv. Pissardii were found to be natural hosts of PPV. Strains M and D alone or in mixture were identified in the infected trees of these species. IC-RT-PCR results showed the presence of mix infection of PPV-M and PPV-Rec strains in one tree of Armeniaca desicarpa (P. cerasifera x P. armeniaca). The presence of PPV in cultivated and uncultivated, edible and ornamental P. cerasifera species provides strong evidence that they are natural PPV reservoirs in Bulgaria.

Local plant resources in the ethnobotany of Theth, a village in the Northern Albanian Alps

An ethnobotanical field study was carried out in one of the most remote and poorest areas of Europe: the village of Theth, which is located in the upper Shala Valley in the Northern Albanian Alps. In this study, seventy-nine botanical taxa known and used by the local population were recorded in interviews with thirty-two informants. Among the local food species recorded, the most highly sought after were Prunus cerasifera Ehrh. and Cornus mas L. fruits, which are used for producing home-made raki. A few elderly women in the village still gather wild greens (Urtica, Chenopodium, Amaranthus, and Rumex species), which are used as fillings for home-made pies (byreke and laknur). Diverse vegetables (cabbage, turnips, tomatoes, peppers, and egg plants) are cultivated and harvested in spring and summer, and are conserved mainly via lacto-fermentation for consumption during the winter. Despite an almost total lack of medical assistance, the villagers of Theth gather only a few medicinal herbs on a regular basis, which they use internally to treat diverse minor ailments. These include the aerial parts of Origanum vulgare L., Hypericum maculatum Crantz, Agrimonia eupatoria L., and the roots of Gentiana lutea L. The findings from this field study could eventually stimulate sustainable plant gathering and harvesting activities in Theth for small-scale trade of a few food, medicinal, and handicraft products.

Leaf morphological and physiological adjustments to the spectrally selective shade imposed by anthocyanins in Prunus cerasifera

Prunus domestica L. has green leaves, whereas Prunus cerasifera Ehrh. var. atropurpurea has red leaves due to the presence of mesophyll anthocyanins. We compared morphological and photosynthetic characteristics of leaves of these species, which were sampled from shoots grafted in pairs on P. domestica rootstocks, each pair comprising one shoot of each species. Two hypotheses were tested: (1) anthocyanins protect red leaves against photoinhibition; and (2) red leaves display shade characteristics because of light attenuation by anthocyanins. Parameters were measured seasonally, during a period of increasing water stress, which caused a similar drop in shoot water potential in each species. As judged by predawn measurements of maximum PSII yield, chronic photoinhibition did not develop in either species and, despite the anthocyanic screen, the red leaves of P. cerasifera displayed lower light-adapted PSII yields and higher non-photochemical quenching than the green leaves of P. domestica. Thus, it appears that, in this system, anthocyanins afford little photoprotection. As predicted by the shade acclimation hypothesis, red leaves were thinner and had a lower stomatal frequency, area- based CO2 assimilation rate, apparent carboxylation efficiency and chlorophyll a:b ratio than green leaves. However, red leaves were similar to green leaves in conductivity to water vapor diffusion, dry-mass-based chlorophyll concentrations and carotenoid:chlorophyll ratios. The data for red leaves indicate adaptations to a green-depleted, red-enriched shade, rather than a neutral or canopy-like shade. Thus, green light attenuation by anthocyanins may impose a limitation on leaf thickness. Moreover, the selective depletion of light at wavelengths that are preferentially absorbed by PSII and chlorophyll b may lead to adjustments in chlorophyll pigment ratios to compensate for the uneven spectral distribution of internal light. The apparent photosynthetic cost associated with lost photons and reduced leaf thickness, and the absence of a photoprotective advantage, suggest that there are other, yet to be identified, benefits for permanently anthocyanic leaves of P. cerasifera.

INCOMPATIBILITY ASPECTR THAT APPEAR IN SCION-ROOTSTOCK ASSOCIATION AT SOME PEAR, PLUM AND SWEET CHERRY VARIETIES

Introduction. The present studies aim some aspects of the relations between photosynthetic apparatus and plant vital metabolism. A special attention was given to the assimilators pigments. There were analyzed the relations between grafting success percentage, shoots growing and thickness morphological index of the grafting zone as results of a good activity of photosynthetic apparatus (1). Material and Method. The researches were made during 2004 – 2007 and there were studied some pear, plum and sweet cherry varieties. Pear varieties are Cure, Euras, Contesa de Paris and Williams, plum varieties are Stanley, Pescarus, Centenar and Tuleu gras and sweet cherry varieties are Germersdorf, Van, Stella and Boambe de Cotnari. The grafting method used was T budding. The aim was observing the behaviour of those varieties grafted on two different rootstocks: Pyrus sativa Lam. and Cydonia oblonga Mill. for pear, for plum a selection of Prunus domestica L. and Prunus cerasifera Ehrh. and for sweet cherry a selection of Prunus avium L. and Prunus mahaleb L. Results and discussion. Plants photosynthetic activity is determined by complex physiologic processes and an important role in first stages of trees development have growth processes (2). While studying some physiological aspects of scion-rootstock association we find necessary to took into consideration some biometric parameters also. These allowed us to analyze the photosynthetic apparatus and also the whole plant. From the researches we made results that there is a direct correlation between the morphological index of the grafting zone and grafting success percentage. When the morphological index of the grafting zone has a small value, the grafting success percentage is also small and when the index’s value is high the success percentage is also high. The bigger differences on dry substance content that appear show a reduced capacity of dry substance synthesis and a lower flow of glucides through grafting zone. Also, these varieties registered a lower accumulation in chlorophyll and carotenes pigments. Conclusions. The disturbances that appear in assimilated circulation are the result of a low development of roots and glucides stagnation above joining line, fact that determines the scion growing in diameter and also the joining zone at incompatible associations or with a poor compatibility.

An Analysis of the Street Tree Population of Greater Melbourne at the Beginning of the 21st Century

An audit of the street tree population of Melbourne, Victoria, Australia, was undertaken to establish its size and botanical composition as a reference point for future studies. The 31 independent municipalities that comprise metropolitan Melbourne were approached to provide information on their respective street tree populations. Where available, data from individual municipalities on population, area, and total street length were also collected. Of the 31 municipalities surveyed, 23 had undertaken some form of street tree inventory or audit. These individual data sets were combined into a single database. Data queries were then undertaken to obtain a range of information. A total of 922,353 trees, comprising 1127 taxa, were captured in this superset of data. Australian native plants made up the majority of the trees with 60% of the total. Of the Australian native taxa, wattles (Acacia spp.), gums or eucalypts (Eucalyptus spp.), paperbarks (Melaleuca spp.), bottlebrush (Callistemon spp.), and Queensland brush box (Lophostemon confertus [R. Br.] Peter G. Wilson and Waterhouse) comprised 394,730 individuals (43% of all trees). Of the exotic taxa, Prunus spp. were the most common with 86,227 individuals (9% of the total). Queensland brush box was the most common taxon surveyed with 61,959 individuals. Purple-leaf cherry plum (Prunus cerasifera Ehrh. ‘Nigra’) was the most common exotic taxon with 35,402 individuals. An analysis of the diversity of this population showed that it meets a set of minimum diversity criteria apart from the dominance of the Myrtaceae at the family level.

MIROVAL - A NEW CLONAL ROOTSTOCK FOR EUROPEAN TYPE PLUM CULTIVARS

The plum rootstock 'Miroval' was registered in Romania in 1998. It is a hybrid selection originating from an open pollinated local biotype of Prunus cerasifera Ehrh. ('Myrobalan 5C'). Selection work was carried out at SCDP Valcea in 1982. The rootstock is clonally propagated through hardwood cuttings and, in special installations, proved to have a very good rooting rate (86-92%). 'Miroval' rootstock assures high vigour for the plum cultivars budded or grafted onto it and it has good compatibility with many European type cultivars ('Centenar', 'Carpatin', 'Minerva', 'Stanley', 'Agen 707', 'Anna Spath'). The budded or grafted plants are uniform and come into bearing in the fourth year. Production of the grafted plants is good (15-25 t/ha) and the fruit size is normal. 'Miroval' is less susceptible to viral (PPV) and fungal diseases. 'Miroval' has good behaviour on forest brown soils and on other soils with good drainage and less than 30% clay. It shows a good response to fertilizing and soil tillage through increased yields and growth vigour. 'Miroval' plum rootstock is recommended for the ecological zones suitable for European plum culture.

Impact of Water Treatment on Foliar Damage of Landscape Trees Sprinkle Irrigated with Reuse Water

Abstract An experiment was conducted on four container-grown tree species placed under five different irrigation reuse water treatments to determine the extent of foliar damage after a 14.5-month period. The tree species included Heritage oak (Quercus virginiana Mill. ‘Heritage’), desert willow (Chilopsis linearis (Cav.)/Sweet), flowering plum (Prunus cerasifera Ehrh ‘Atropurpurea’), and Chinese pistache (Pistacia chinensis Bunge). Plant response and an index of visual damage (IVD) were assessed at different times throughout the experiment. Ion concentrations in the leaf tissue were different for species (S) (p < 0.001), treatment (T) (Na, K, SO4, p < 0.05) and by a species by treatment interaction (S × T) (Na, Ca, Mg, K and SO4, p < 0.05). SPAD measurements varied by S (p < 0.001), T (p < 0.001) and by an S × T interaction (p < 0.045). SPAD measurements decreased as the leaf tissue Na concentration increased (SPAD = 47.49 – 12.46(Na), r2 = 0.38, p < 0.01). The IVD varied by S (p < 0.001), T (p < 0.001) and by an S × T interaction (p < 0.001). Na, Ca and SO4 tissue ion concentrations could account for 52% of the variability in the IVD (IVD =−1.93 + 4.63(Na) + 2.60(Ca)−0.001(SO4), p < 0.01). Because the irrigation treatment resulting in the lowest IVD was species dependent, irrigation treatment selection should be based upon an evaluation of the landscape species composition and the potential cost of implementing a given strategy. The response observed in this study suggests that a single universal irrigation strategy does not exist, indicating that emphasis must be placed on initial and replacement plant selection.

Genetic and phenotypic variability of cherry plum (Prunus cerasifera Ehrh) pomological characteristics

Cherry plum (Prunus cerasifera Ehrh) is one of the most widely spread fruit species in our country. The fruits are mostly used for brandy production and the seed is used for rootstock production in fruit culture. As cherry plum is resistant to plant diseases and pests, chemical protection is not required. Concerning that, cherry plum is reach and cheap source for the production of healthy food. The objective of this research was the analysis of genetic and phenotypic variability, as well as study on correlation of pomological traits of 49 cherry plum genotypes selected from the native population in Serbia. It was measured mat the highest genetic variance in total phenotypic variance was for the fruit height and total sugar content. The lowest genetic variance in total phenotypic variance was for the length of the stalk and dry matter content. The highest genetic variance coefficient (CVg = 22.93%) was calculated for the total acid content although the lowest value of genetic and phenotypic variance was for the fruit width (CVg = 0.69%; CVf = 0.80%). The highest coefficient of phenotypic and genetic correlation was calculated between the weight and height of the fruit. Native population of cherry plum in Serbia and Montenegro is specific because of the extensive variability of the forms which is highly important for the selection of raw material in breeding process.

Development of microsatellite markers in peach [ Prunus persica (L.) Batsch] and their use in genetic diversity analysis in peach and sweet cherry ( Prunus avium L.).

We report the sequence of 41 primer pairs of microsatellites from a CT-enriched genomic library of the peach cultivar 'Merrill O'Henry'. Ten microsatellite-containing clones had sequences similar to plant coding sequences in databases and could be used as markers for known functions. For microsatellites segregating at least in one of the two Prunus F(2) progenies analyzed, it was possible to demonstrate Mendelian inheritance. Microsatellite polymorphism was evaluated in 27 peach and 21 sweet cherry cultivars. All primer pairs gave PCR-amplification products on peach and 33 on cherry (80.5%). Six PCR-amplifications revealed several loci (14.6%) in peach and eight (19.5%) in sweet cherry. Among the 33 single-locus microsatellites amplified in peach and sweet cherry, 13 revealed polymorphism both in peach and cherry, 19 were polymorphic only on peach and one was polymorphic only on cherry. The number of alleles per locus ranged from 1 to 9 for peach and from 1 to 6 on sweet cherry with an average of 4.2 and 2.8 in peach and sweet cherry, respectively. Cross-species amplification was tested within the Prunus species: Prunus avium L. (sweet cherry and mazzard), Prunus cerasus L. (sour cherry), Prunus domestica L. (European plum), Prunus amygdalus Batsch. (almond), Prunus armeniaca L. (apricot), Prunus cerasifera Ehrh. (Myrobalan plum). Plants from other genera of the Rosaceae were also tested: Malus (apple) and Fragaria (strawberry), as well as species not belonging to the Rosaceae: Castanea (chestnut tree), Juglans (walnut tree) and Vitis (grapevine). Six microsatellites gave amplification on all the tested species. Among them, one had an amplified region homologous to sequences encoding a MADS-box protein in Malus x domestica. Twelve microsatellites (29.3%) were amplified in all the Rosaceae species tested and 31 (75.6%) were amplified in all the six Prunus species tested. Thirty three (80.5%), 18 (43.9%) and 13 (31.7%) gave amplification on chestnut tree, grapevine and walnut tree, respectively.

BEHAVIOUR OF MICROPROPAGATED OWN-ROOTED TREES OF PLUM CV. STANLEY IN THE ORCHARD. 1. GROWTH BEHAVIOUR

Own-rooted micropropagated plants of plum cv. Stanley, grown further for a single year in the nursery, were planted for comparison with trees, traditionally produced by grafting on clonal (GF655/2 - produced by micropropagation) and seedling (Dzhanka 4 - Prunus cerasifera Ehrh) rootstocks. In vitro plants of the same cultivar, grown further in the nursery for two vegetation periods, were also involved in the study. The following more important traits were observed: trunk cross-sectional area, crown volume and projection area, total and mean annual increment, as well as the first order branching angle. The objective of the study was to establish the growth characteristics of in vitro-produced plants of plum cv. Stanley, grown further for a single year, from their juvenile period to full bearing initiation. During the study years, the trunk cross-sectional area was largest in the control variant, budded on Dzhanka 4 seedling rootstock. The values of trunk thickening in the rapidly produced own-rooted trees were insignificantly higher than those of the trees that were further grown for two years, the difference between them being significant only during the second year after planting in the orchard. After the third vegetation, in spite of the different absolute values of this trait, no significant difference was found among the three aforementioned variants. The lowest increment was established for the trunk, the crown volume and area of trees budded on the clonal rootstock GF 655/2. The difference was significant both by value and statistically. The same regularity was established for the total annual trunk growth in length and thickness. An exception was observed during the second vegetation period when the variant produced rapidly surpassed significantly all other variants. The branching angle was larger in the in vitro-produced plants and particularly in those obtained by rapid production.

STUDY OF SOME LOCAL VARIETIES IN THE CENTRAL BALKAN REGION IN BULGARIA

The experiment included the following seven local varieties: 'Byala razgradska', 'Zimna karadzheyka', 'Tarkulka', 'Kraslanka', 'Sakarka' 'Drebna byala rakiynitsa' and 'Klestachka', grafted on Myrobalan seedlings (Prunus cerasifera Ehrh.). Trees of 'Drebna byala rakiynitsa' and 'Byala razgradska' have highest growth intensity. They form a larger crown and when plant in the orchards it is necessary to determine adequate distances. 'Byala razgradska' is fruitful and have moderate large fruits with very good taste. 'Drebna byala rakiynitsa' and 'Zimna karadzheyka' are fruitful, but their fruits are small and are suitable mainly for brandy production. The investigated seven local plum varieties can use in the breeding programme for resistant plums to Plum Pox Virus, Monilinia laxa and Monilinia fructigena.

Susceptibility of Purple-Versus Greenleaved Cultivars of Woody Landscape Plants to the Japanese Beetle

Twenty-six purple- or green-leaved cultivars representing 12 species of woody landscape plants were evaluated in the field for defoliation by Japanese beetles (Popillia japonica Newman) over three growing seasons. We further evaluated the hypothesis that, within closely-related plants, purple cultivars generally are preferred over green ones by comparing beetles' consumption of foliage in laboratory choice tests and their orientation to painted silk tree models baited with Japanese beetle lures. Cultivars of Prunus cerasifera Ehrh. and hybrids of that species [e.g., Prunus ×cistena (Hansen) Koehne, Prunus ×blireiana André] were more heavily damaged than nearly all other plants tested. Among maples, Acer palmatum Thunb. `Bloodgood' and A. platanoides L. `Deborah' and `Fairview' were especially susceptible. None of the cultivars of Berberis thunbergii DC, Cercis canadensis L., Cotinus coggygria Scop., or Fagus sylvatica L. were heavily damaged, regardless of foliage color. In the choice tests, purple Norway maples were preferred over green ones in three of four comparisons, but preference varied within the other plant genera. In fact, more beetles oriented to green-leaved tree models than to purple ones. Our results indicate that within a genus, purple-leaved plants do not necessarily sustain more damage than green-leaved ones. Widespread use of certain purple-leaved cultivars of generally susceptible plant species probably contributes to the perception that purpleleaved plants, overall, are preferred. Purple-leaved cultivars of redbud, European beech, smoketree, and barberry, or the purple-leaved Prunus virginiana L. `Canada Red' or Malus ×hybrida Lemoine `Jomarie' may be suitable substitutes for more susceptible purple-leaved plants in landscapes where Japanese beetles are a concern.

Performance of New Marianna Rootstocks in California for `French' Prune

Ten new marianna root-stocks [Prunus cerasifera Ehrh. × P. munsoniana Wight & Hedr.(?)] derived from open pollination of `Marianna 2616' (M series) were planted in 1987 and evaluated at four commercial orchard locations in California (Tehama, Butte, Sutter, and Merced counties) with `Improved French' prune (P. domestica L.) as the scion. These rootstocks were compared to three standard rootstocks: `Marianna 2624', myrobalan seedling (P. cerasifera Ehrh.) and `Myrobalan 29C'. Leaf potassium (K) and nitrogen (N), tree growth, fruit production and fruit quality were measured. Selection M40 in particular had high leaf N, high leaf K (equal to `Marianna 2624' and better than the myrobalan standards), higher yield efficiency per tree, fruit size, drying characteristics, and few root suckers when compared to the three standard rootstocks. M40 is being considered for patent and release by the Pomology Department at the University of California, Davis. Selection M58 had the highest yield efficiency of any tested rootstock. Several selections had characteristics that would make expanded planting worth considering.

Influence of arbuscular mycorrhizae and phosphate fertilization on shoot apical growth of micropropagated apple and plum rootstocks.

We studied the effects of phosphate fertilization and inoculation with the arbuscular mycorrhizal fungi Glomus mosseae (Nicol. and Gerd.) Gerdmann and Trappe, Glomus intraradices Schenck and Smith or Glomus viscosum Nicolson on shoot apical growth of plantlets that had been micropropagated from MM 106 apple (Malus pumila L.) and Mr.S. 2/5 plum (Prunus cerasifera Ehrh.) rootstocks. Unfertilized and non-mycorrhizal plantlets showed no apical growth during the post in vitro acclimation phase, whereas P fertilization induced early resumption of shoot apical growth. Growth enhancement and percentage of actively growing apices of mycorrhizal-inoculated plantlets were comparable to those obtained in plantlets fertilized with P. Furthermore, tissue P concentrations of mycorrhizal plantlets were similar to those of plantlets fertilized with P. We conclude that mycorrhizal inoculation can be used as a biotechnological tool to overcome blocked apical growth and to reduce chemical inputs, especially P inputs, to micropropagated fruit trees.

Graft establishment between compatible and incompatiblePrunusspp

Graft compatibility has been studied in apricot (Prunus armeniaca L.) grafted on Prunus cerasifera Ehrh. Two apricot cultivars, one compatible and one incompatible on this rootstock, were selected for this study. In these species incompatibility is only manifested by tree breakdown at a late phase of the tree's life. The process of graft union formation was observed for the first month following grafting. No differences were found either in the process of healing or in its kinetics. Thus, callus proliferation, callus differentiation and vascular connections are established in the same way and at the same time in both compatible and incompatible grafts. However, clear differences exist in the level of differentiation of the callus produced

A comparison of sap flux and water relations of leaves of various isolated trees with special reference to foundation movement in clay soil

Diurnal variation in sap flux (S) through stems of six trees, two each of Ulmus procera SALISB., Melaleuca styphelioides SM. and Prunus cerasifera EHRH. ‘Nigra’ (referred to hereafter by their generic names), were estimated from measurements of heat pulse velocities. Leaf water potential (ψ), stomatal conductance (g s ) and transpiration from leaves (T) of all replicate trees were measured at 1300–1500h, once during the summer. On two separate occasions measurements were made of S, ψ, (g s ) and T for one each of Ulmus and Melaleuca trees to study diurnal variations in these parameters. A 12×12 m2 area around each tree was kept covered to simulate the condition of trees growing on pavements adjacent to residential properties. Sap flux for these tree species was in the order Melaleuca>Ulmus>Prunus. It is suggested that the smaller canopy and sapwood area in Prunus compared to the other two species is responsible for lower water potential and lower transpiration rate than the other species. Detailed analysis of the diurnal variation in sap flux and water relation of leaves of Melaleuca and Ulmus indicated sap flux of Melaleuca to be greater than that of Ulmus at the same transpiration rate per unit leaf area although the sapwood area of the two species was marginally different. This may have been due either to the difference in canopy conductance or in leaf area between the two species. With the assumption that sap flux closely resembles the rate of soil water extraction for both species, results indicate that Melaleuca is likely to extract soil water at a higher rate than Ulmus and hence is capable of causing greater shrinkage and soil movement than Ulmus.

Effect of Cyanogenic Glycosides on Growth of Callus from Almond and Plum

Abstract The effects of the cyanogenic glycosides, amygdalin and prunasin, and their breakdown products, cyanide and benzaldehyde, on callus derived from ‘Marianna 2624’ plum (Prunus cerasifera Ehrh. × P. munsoniana Wight & Hedr.) and on that from 2 almond cultivars (P. amygdalus Batsch ‘Nonpareil’ and ‘Texas’) were compared. Prunasin (D-Mandelonitrile-β-D-glucoside) inhibited the growth of ‘Marianna 2624’ plum and ‘Nonpareil’ almond callus but not ‘Texas’ almond. Amygdalin (D-Mandelonitrile-β-D-gentiobioside) inhibited ‘Marianna 2624’ plum callus growth but promoted growth of both almond cultivars. All 3 cultivars were inhibited to the same extent by sodium cyanide, indicating that cyanide was not the differentiating inhibitory breakdown product of the cyanogenic glycosides. Benzaldehyde, another catabolite of prunasin and amygdalin, was strongly inhibitory to ‘Marianna 2624’ plum callus growth at 0.05 mm, but a concentration of 5 mm was required to inhibit similarly growth of either almond callus. The greater sensitivity of ‘Marianna 2624’ plum callus, compared to almond callus, to the cyanogenic glycosides and benzaldehyde, but not cyanide, suggests that benzaldehyde is an important factor in the almond/plum incompatibility.

Influence of Ca concentration on micronutrient imbalances inin vitropropagatedprunusrootstock

Abstract In vitro propagated plums of St. Julien GF 655–2 [Prunus insititia (L.)] (655–2), Damas GF 1869 [Prunus domestica (L.)] (D1869), and Clark Hill Redleaf [Prunus salicina (Until.) X Prunus cerasifera (Ehrh.)] (CHR), were grown in the greenhouse in nutrient solutions of 2, 6, 22, 66, 202, and 404 μM Ca for 96 days. 655–2 plants became severely chlorotic in Ca treatments of 66, 202, and 404 μM concentration after 86 days of growth. D1869 plants in 202 and 404 μM Ca exhibited slight interveinal chlorosis of new growth, while CHR exhibited no chlorosis at any Ca concentration. The best tissue nutrient indicator of chlorosis among rootstocks was foliar P/Fe and P/Zn ratios. 655–2 plants absorbed more P at higher Ca concentrations than did the other rootstock, resulting in the highest stem and leaf P/Fe, and P/Zn ratios. CHR plum may provide an easily propagated, chlorosis‐resistant rootstock for use on calcareous soils.

Samenübertragung des Nekrotischen Kirschenringflecken-Virus (Prunus necrotic ringspot virus) bei Schlehdorn (Prunus spinosa L.)

Summary Prunus necrotic ringspot virus (PNRV) proved as seed-transmissible in blackthorn (Prunus spinosa L.), by all means to a low extent. Progenies from seeds of three different experimentally infected blackthorn clones were PNRV-infected by 0, 1.9 and 3.5%, respectively. Seed transmission of PNRV, however, could be proved as a PNRV isolate originating from sour cherry (Prunus cerasus L.) only, but not as such a PNRV isolate from myrobalan (Prunus cerasifera Ehrh.).