Flemish Beauty Research Articles

Comparative performance of some pear cultivars on southern aspect of wet temperate zone in Western Himalaya

The studies were conducted at experimental farm of Temperate Horticultural Research Station, Kotkhai to compare the performance of 12 pear cultivars for their fruit quality and leaf nutritional status. Various cultivars under study differed significantly with respect to their fruit physico-chemical characteristics and leaf nutrient contents. Cultivar Red Bartlett had highest fruit length (82.37 mm, whereas, fruit diameter (76.65 mm) and fruit weight (193.50 g) were recorded significantly higher in cultivar Max Red Bartlett. Cultivar Starking Delicious exhibited highest total soluble solids (16.05°Brix), TSS/acid ratio (66.27) and minimum titratable acidity (0.28%). The highest fruit firmness (15.40 lbs/inch2) was recorded in cv. Beurre Hardy, whereas significantly higher total sugars content (5.95%) and reducing sugars content (5.03) were registered by Doyenne du Comice and Kala Hathi, respectively. The cultivars Aval Number, Max Red Bartlett and Flemish Beauty exhibited highest leaf nitrogen (2.31%), phosphorus (0.212%) and potassium (1.96%) contents, respectively. On the basis of fruit physicochemical characteristics, Red Bartlett, Max Red Bartlett, Starking Delicious, Doyenne du Comice and Beurre Hardy were found suitable for cultivation in zone III of Himachal Pradesh.

Quality characteristics and phenolic compounds of European pear cultivars

Background: Pear fruits are an important source of plant secondary metabolites and one of the major sources of dietary phenolic compounds.Materials and Methods: The aim of this study was to determine the individual phenolic compounds and some quality characteristics of the flesh and peel of the fruit in four pear cultivars. The phenolic composition of these pear cultivars was determined by high performance liquid chromatography with diode array detection (HPLC-DAD).Results: The fruit flesh firmness ranged from 35.2 to 85.8 N in the pear cultivars. The soluble solids content was higher in the flesh, while titrate-able acidity, vitamin C, individual phenolic compounds and total phenolics were generally higher in the peel. Arbutin, chlorogenic acid and epicatechin were detected as major phenolic compounds in the peel and flesh of pear fruits. Arbutin, chlorogenic acid and epicatechin of the flesh and peel ranged from 834.8 to 937.9 mg kg-1; from 332.1 to 460.7 mg kg-1; and from 77.2 to 104.0 mg kg-1 for ‘Seckel’ pear fruits, respectively. The highest total phenolics were found to be in the peel and flesh of the ‘Flemish Beauty’ pear fruits.Conclusion: Because of the higher level of antioxidant components in the peel of pear fruits (all phenolic compounds and vitamin C) consumption of unpeeled pears, after proper washing, is recommended to maximize the dietary benefit.Key words: Arbutin, Chlorogenic acid, Flesh and Peel, HPLC, Pear cultivars, Vitamin C

SOME QUALITY CHARACTERISTICS AND INDIVIDUAL PHENOLIC COMPOUNDS OF EUROPEAN PEAR CULTIVARS

Background: Pear fruits are an important source of secondary plant metabolites and one of the major sources of dietary phenolic compounds. 
 Materials and Methods: The aim of this study was to determine the individual phenolic compounds and some chemical characteristics of the flesh and peel of the fruit in the four pear cultivars. The phenolic composition of these pear cultivars was determined by high performance liquid chromatography with diode array detection (HPLC-DAD). 
 Results: The fruit flesh firmness ranged from 35.2 to 85.8 N in the pear cultivars. The soluble solids content was higher in the flesh, while titratable acidity, vitamin C, individual phenolic compounds and total phenolics were generally higher in the peel. Arbutin, chlorogenic acid and epicatechin were detected as major phenolic compounds in the peel and flesh of pear fruits. Arbutin, chlorogenic acid and epicatechin of the flesh and peel ranged from 834.8 to 937.9 mg kg-1; from 332.1 to 460.7 mg kg-1; and from 77.2 to 104.0 mg kg-1 for ‘Seckel’ pear fruits, respectively. The highest total phenolics were found to be in the peel and flesh of the ‘Flemish Beauty’ pear fruits. 
 Conclusion: Because of the higher level of antioxidant components in the peel of pear fruits (all phenolic compounds and vitamin C) consumption of unpeeled pears, after proper washing, is recommended to maximize the dietary benefit.

English

The genetic divergence among twenty-three pear genotypes under the present study was of medium quantum. The studied genotypes, on the basis of total variability were grouped into three distinct clusters. Maximum number of cultivars were accommodated in Cluster II (Ishiwase, Seckel, Anjou, Beurre Hardy, Lisnova Karavista, Jargonelle, Kala Hathi, Autumn of Yaklove, Kashmir Pear, Hengal, Flemish Beauty, Awal Number and Basuidse Favourite) followed by Cluster III (William Bon Chretien, Luhimtsa Kalapa, Manning Elizabeth, Red Bartlett, Max Red Bartlett and Starkrimson) and Cluster I (Kiskusui, Yakumo, Bodde Cappiament and Nouveau Poiteau). Cluster II had highest intra cluster value and was therefore the most divergent and Cluster III had least intra cluster value so was least divergent. Highest value for inter cluster distance was recorded between Cluster I and III while it was lowest between Cluster I and II. Cluster means were maximum in Cluster II. Kala Hathi was found to be best cultivar for fruit yield/tree and tree height while Red Bartlett was for fruit length and breadth. Cultivars Beuree Hardy and Ishiwase proved best for different vegetative characters. Key words: Pear, Pyrus commmunis L., cluster analysis, D2 statistics, genetic divergence.

Changes in Leaf Water Potential, Electrolyte Leakage, Antioxidant System and Anatomical Characteristics in Flemish Beauty Pear Induced by Paclobutrazol During Drought Stress

Changes in Leaf Water Potential, Electrolyte Leakage, Antioxidant System and Anatomical Characteristics in Flemish Beauty Pear Induced by Paclobutrazol During Drought Stress

Rootstocks affect growth, water relations, gas exchange, and anatomy of ‘Flemish Beauty’ pear under water stress

SummaryOne-year-old ‘Flemish Beauty’ pear (Pyrus communis L.) trees, grafted on two Pyrus seedling rootstocks [‘Kainth’ (P. pashia Buck and Ham.) and ‘Shiara’ (P. serotina Redh.)] and three clonal quince rootstocks [BA 29, Quince A and Quince C], were studied under two moisture levels for 6 months, in order to evaluate the physiological and anatomical changes induced by water stress. Irrigation was applied when the soil water potential reached –0.05 MPa for control trees, and –0.5 MPa for water-stressed trees. Growth data suggested that pear trees on ‘Kainth’ and on BA 29 were less affected by water stress than those on the other rootstocks. Leaf water potential declined to 1.48 MPa for trees on ‘Kainth’, and to 1.50 MPa for those on BA 29. Trees on ‘Kainth’ and BA 29 showed less reduction in their relative water content, photosynthetic rate, xylem vessel diameter, and the width of their secondary xylem zone, compared to trees on the other rootstocks under water stress conditions.

Rootstock Affects Growth, K+ Uptake, Antioxidant Enzyme Activity, and Endogenous Cytokinin Levels of Flemish Beauty Pear During Water Stress Conditions.

Rootstock Affects Growth, K+ Uptake, Antioxidant Enzyme Activity, and Endogenous Cytokinin Levels of Flemish Beauty Pear During Water Stress Conditions.

Ultrastructural study on scab resistance expressed in epidermal pectin layers of pear leaves

Proliferation and collapse of subcuticular hyphae of Venturia nashicola race 1 were studied ultrastructurally, after inoculation of susceptible Japanese pear cv. Kousui, resistant Japanese pear cv. Kinchaku, resistant Asian pear strain Mamenashi 12 and nonhost European pear cv. Flemish Beauty leaves, to understand the nature of the resistance mechanism. After cuticle penetration by the pathogen, the hyphae were observed at lower frequency in epidermal pectin layers and middle lamellae of leaves of the three resistant plants than in those of susceptible ones. This result suggested that fungal growth was suppressed in the incompatible interaction between pear and V. nashicola race 1. In the pectin layers of all inoculated plants, some hyphae had modifications such as breaks in the plasmalemma with plasmolysis, necrotic cytoplasm and degraded cell walls. More hyphae had collapsed in the leaves of the three resistant plants than in those of the susceptible cv. Kousui. In collapsed hyphae, the polymerized cell walls broke into numerous fibrous and amorphous pieces, showing that the scab resistance might be associated with cell wall-degrading enzymes from pear plants.

Characterization of a leucine-rich repeat receptor-like protein kinase (LRPK) gene from Japanese pear and its possible involvement in scab resistance

A gene encoding a leucine-rich repeat receptor-like protein kinase (LRPK) was identified from Japanese pear (Pyrus pyrifolia var. culta) using reverse transcription-polymerase chain reaction (RT-PCR) and rapid amplification of cDNA ends (RACE) PCR. The Japanese pear LRPKp protein was composed of a leucine-rich extracellular ligand-binding domain, a transmembrane-spanning segment, and a cytoplasmic kinase domain; it had the highest sequence homology with apple LRPKm and Arabidopsis receptor-like protein kinase (RLK). Southern blot analysis revealed that the LRPKp belongs to a multigenic family, and a polymorphism in restriction fragment length was observed among Asian and European pear cultivars. The LRPKp transcripts were present at a high level in leaves and at a low level in flowers, while no expression was detected in fruits. The expression pattern of LRPKp was also studied by real-time RT-PCR in the scab susceptible cv. Kousui and resistant cvs. Kinchaku and Flemish Beauty after challenge inoculation with Venturia nashicola, the causal agent of Japanese pear scab. Transcripts of LRPKp were transiently enhanced in both the susceptible Kousui and to a great extent in the non-host-resistant Flemish Beauty. However, in resistant Kinchaku, expression of this gene was only weakly enhanced. Moreover, treatment with a resistance inducer, acibenzolar-S-methyl (ASM), which significantly reduces scab severity on potted trees of Kousui, was also able to induce and to potentiate the expression of this gene after inoculation. This suggests that the LRPKp gene is possibly involved in ASM-induced resistance.

Parthenocarpy and Self- and Cross-incompatibility in Ten European Pear Cultivars

Self- and cross-incompatibility in European pear (Pyrus communis L.), which is estimated by the fruit set and seed formation, is yet unclear. We carried out self-, cross- and non-pollinations with one flower per cluster on 10 European pear cultivars, and estimated their parthenocarpic potential, and self- and cross-incompatibility. Most cultivars exhibited parthenocarpy, which suggests that the fruit set is not a suitable criterion for distinguishing incompatibility from compatibility. However, clear judgment could be provided by using the self-incompatibility (SI) index, (the number of viable seeds per flower obtained from test pollination / the number of viable seeds per flower resulting from compatible cross-pollination) × 100, as a new criterion. Based on this index, ‘Grand Champion’ has proven to be partially self-compatible, whereas others were classified as self-incompatible. Traits of the seeded fruits, such as weight, size, and soluble solids content, were superior to those of the parthenocarpic fruits. Thus, cross-compatible pollination is necessary for a stable fruit set and production of large, good quality fruits in cultivars with a high parthenocarpic potential. Two cross-incompatible combinations were found between ‘Flemish Beauty’ and ‘Starkrimson’, and ‘Bartlett’ and ‘Seigneur d' Espéren’, respectively.

Expression of potential defense responses of Asian and European pears to infection with Venturia nashicola

In order to determine if differences in timing or levels of gene and enzyme activations were likely to account for differences in resistance of pear cultivars against Japanese pear scab, time course analyses of several potential defense genes and enzymes as well as salicylic acid (SA) accumulation were carried out using leaf tissue of susceptible Japanese pear cv. ‘Kousui’ and resistant pear cvs. ‘Kinchaku’, ‘Mamenashi 12’ and ‘Flemish Beauty’ upon inoculation with the race 1 of Venturia nashicola. A phenylalanine-ammonia lyase gene ( pal) expression was not significantly affected by pathogen regardless of the compatible or incompatible interaction. Accumulation of pathogenesis-related protein 1 ( pr1) and chitinase ( chi) transcripts was early and highly elicited in the host resistant cv. ‘Kinchaku’, while in the other interactions it was delayed. In general, enhancement of SA accumulation and increase in the expression of pr1 gene in ‘Kinchaku’ are positively correlated, suggesting that this resistance is SA-dependent. The activity of four antioxidant enzymes (superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) and guaiacol peroxidase (GPX)) was significantly enhanced only in resistant cultivars with a differential pattern of induction according to the cultivar. Superoxide anion ( O 2 ˙− ) was highly detected in inoculated leaves of the resistant cvs. ‘Kinchaku’ and ‘Mamenashi 12’ when compared to the susceptible cv. ‘Kousui’. The involvement of the oxidative burst as well as its relationship with the activity of the antioxidant enzymes and with resistance is discussed.

Polygalacturonase-inhibiting protein (PGIP) from Japanese pear: possible involvement in resistance against scab

Venturia nashicola is the causal agent of scab, a fungal disease affecting Asian pears. The Japanese pear cv. ‘Kousui’ is highly susceptible to the race 1 of this fungus whereas the cv. ‘Kinchaku’ and the non-host European pear cv. ‘Flemish Beauty’ are resistant. The aim of this work is to investigate the role of polygalacturonase-inhibiting proteins (PGIPs) of pear during the interactions with V. nashicola leading to susceptibility or resistance. PGIP protein was detected from immature fruit of Kousui and Kinchaku. It showed a molecular mass of 42 kDa that shifted to 35 kDa after chemical deglycosylation. The gene pgip was amplified by PCR using genomic DNA and/or cDNA from young leaves of Kousui, Kinchaku, and European pear cvs. Flemish Beauty, ‘Bartlett’, and an Asian wild pear strain ‘Mamenashi 12’, then sequenced after sub-cloning. Some conserved variations were identified in the sequence indicating that gene family also exists in pgip of Japanese pear and confirmed by Southern blot analysis. The expression of PGIP was studied in scab-inoculated leaves of the susceptible Kousui and the resistant Kinchaku and Flemish Beauty. pgip Gene and its encoding protein were highly and rapidly activated in these resistant plants. In addition, PGIP extracts derived from Kinchaku and Flemish Beauty partially inhibited the activity of polygalacturonase (PG) from V. nashicola suggesting a possible role of PGIP in limiting fungal growth frequently observed in these resistant cultivars.

Infection Behavior ofVenturia nashicola, the Cause of Scab on Asian Pears

ABSTRACT The infection of Japanese pear by Venturia nashicola, the cause of scab on Asian pears (Japanese pear, Pyrus pylifolia var. culta; Chinese pear, P. ussuriensis), was examined using light and electron microscopy to determine the mechanism of resistance in pears. Early stages of infection were similar on the susceptible cv. Kosui, the resistant cv. Kinchaku, and the nonhost European pear (P. communis) cv. Flemish Beauty. V. nashicola penetrated only the cuticle layer on pear leaves and formed subcuticular hyphae on all three cultivars. Hyphae were localized in the pectin layer of pear leaves and never penetrated into the cytoplasm of epidermal cells. This restriction of fungal growth suggested that pectinases released by infection hyphae or subcuticular hyphae may be important in infection. Subcuticular hyphae were modified ultrastructurally in the pectin layer of resistant pear cultivars accompanied by fungal cell death. In contrast, fungal cells appeared intact in susceptible pear cultivars, suggesting the existence of resistance mechanisms.

TRAINING AND ROOTSTOCK STUDIES WITH PEAR CULTIVARS ON QUINCE SIZE-CONTROLLING CLONES.

In 1987, a study consisting of 3 training systems (TS) [Supported modified leader (S), Free Palmette (P) and Mini-Tatura (MT)] with Anjou (A), Bartlett (B) and Flemish Beauty (FB) on Quince A & C and Provonce C134, in a high and ultradensity planting, was initiated on a fine sandy loam soil. Blossoms were counted and removed during 1988 to 1990 seasons. Palmette TS increased bloom efficiency (BE) but did not affect the number of florets/cluster. Quince C produced higher BE than either QA or C134. Bartlett had the highest BE followed by A & FB. Anjou exhibited more florets/cluster than either B or FB. Rootstock or TS did not influence this variable.Irrespective of rootstock and training, the largest trees were FB followed by A & B. Quince C produced trees smaller than QA & C134. Mini-Tatura reduced tree size significantly compared to S & P. The cumulative yield for 1991 & 92 (5th and 6th leaves) was 85 tonnes/ha for MT compared to 35 & 37 for S and P respectively. Quince clones had no effect on yield, but A was significantly less productive than B or FB. Cultivar, rootstock or training did not affect mean fruit weight during 1992. Bartlett had higher number of pears/tree compared to A & FB. Palmette training system produced more pears per tree in comparison to S and MT.

落葉果樹の冬芽の液体窒素中での凍結保存

A long-term preservation of germplasm of fruit trees is becoming important. This study was designed to develop a routine method for long-term preservation of hardy deciduous fruit buds in liquid nitrogen. Dormant shoots of apple (Akane, Red Gold, Jonathan, Fuji, Starking Delicious, Golden Delicious), pear and Japanese pear (Chojuro, Hokusei, Mishirazu, Bartlett, Flemish Beauty), currant (London Market), raspberry (Latham), blueberry (Harbert), gooseberry (Oregon Champion) were collected in early January and were subjected to an artificial hardening regime which consisted of holding samples at -5°C for 14 days, -10°C for 3 days to induce maximum hardiness. After hardening the twigs enclosed in polyethylene bags were cooled at 5°C increments each day to -30°C, and then to -70°C in 10°C increment at two hours intervals. Twigs frozen to selected test temperatures were thawed in air at 0°C. Twigs prefrozen to -40°C or -50°C were immersed in liquid nitrogen for 2 hours, and were then rewarmed slowly in air at 0°C. In the twigs of apple (Akane, Red Gold, Jonathan, Fuji, Starking Delicious, Golden Delicious), pear (Mishirazu, Hokusei, Flemish Beauty) currant (London Market), gooseberry (Oregon Champion), little or no injury were observed in the leaf buds and cortex, when immersed in liquid nitrogen after prefreezing to -40° or -50°C. Thus, this prefreezing method is applicable to the longterm cryopreservation of leaf buds of these hardy deciduous fruit trees in liquid nitrogen.

SEASONAL CHANGES IN THE EPIPHYTIC POPULATION OF ERWINIA AMYLOVORA ON APPLE AND PEAR

Erwinia amylovora (Burr.) Winsl. et al., the pathogen causing fireblight, was readily isolated from symptomless leaves in blocks of Lodi apple (Malus sylvestris Mill.), Bartlett pear (Pyrus communis L.) and a multicultivar pear block. The frequency of positive assays appeared to be related to the incidence of fireblight symptoms. However, the percent positive samples was highly variable, making prediction of blight outbreaks difficult. The bacterial population was highest from mid-July to the end of August. Before and after this period numbers of E. amylovora were relatively low. The pathogen was isolated from apparently healthy dormant buds of Lodi apple and Flemish Beauty pear.

Studies on pear scab

The authors have carried out taxonomic investigations of the causal fungus of Japanese pear scab for several years. The results are summarized in this paper as follows.1. The overwintered spots of Japanese pear scab on the twigs are somewhat sunken and show distinct cracks surrounding the lesions, while those of European pears are more or less swollen, producing the stroma under the periderm in the spots.2. The stroma of Japanese pear fungus develop well and conidiophores abundantly grow in cluster, causing dark sooty appearance of the spots. Conidia are 7∼23×5.0∼7.5μ in size, smaller than those of European pear fungus.3. The perithecia of Japanese pear fungus are depressed conic globoid in shape and 50.0∼150.0μ in height, while those of European pear fungus are globoid and 77.5∼200.0μ in height, much taller than the former.4. The ascospores of Japanese pear fungus are unequally 2-celled and measure 10.0∼15.0× 3.8∼6.3μ. They are smaller than those of the European pear fungus, especialy the lower cells are much shorter than those of the latter.5. According to the inoculation experiments, Japanese pear fungus showed distinct pathogenicity to the leading varieties of Japanese pear, but was unable to attack the European pear varieties such as Flemish Beauty and Bartlett. On the other hand the European pear fungus infected only Flemish Beauty but no Japanese varieties.6. Based on the data reported in the present as well as the previous papers (23) by the authors, the causal fungus of Japanese pear scab is considered to be a distinct species from European pear scab fungus, Venturia pirina Aderhold. The authors propose the name Venturia nashicola to the present fungus.“Nashi”represents pear in Japanese. The diagnosis of the fungus is as follows.Venturia nashicola n. sp.Perithecia gregarious or scattered under the epidermis of the affected leaves, depressed conic globoid, the wall dark colored, membranous, hard, and consist of two or three layers of brownish cells, 50∼150μ in height and 53∼138μ in diameter; ostiole very long.Asci hyaline, clavate or long ovate, 35∼60×5∼10μ; eight-spored. Ascospores hyaline or light brown, two celled, shoesole-shaped, 10∼15×3.8∼6.3μ.Conidia dark brown, long oval or fusiform, 7.5∼22.5×5.0∼7.5μ, and 14.4×6.0μ on the average. Conidiophores clustered, erect, and simple, 10∼20μ in length. Conidia borne singly on the warty tips of conidiophores.Habitat: On the leaves, twigs, and fruits of Pirus serotina Rehder and Pirus ussuriensis var. sinensis Kikuchi, producing scabby spots.Locality: Throughout Japan