Pyrus Serotina Rehd Research Articles

Growth characteristics, yield, and fruit quality of the Asian pear genotypes (Pyrus serotina Rehd.) in climatic conditions of Isfahan- Iran

Growth characteristics, yield, and fruit quality of the Asian pear genotypes (Pyrus serotina Rehd.) in climatic conditions of Isfahan- Iran

Genetic Relationship of Iranian Pear Genotypes with European and Asian Pears as Revealed by Random Amplified Polymorphic DNA Markers

ABSTRACTGenetic variation within specific fruit tree germplasms is an important tool in fruit tree breeding programs. In the present work, the genetic relationship of 31 European and Iranian (Pyrus communis L.) and Asian (Pyrus serotina Rehd) genotypes of pear were studied using 19 randomly amplified polymorphic DNA (RAPD) primers. Fifteen out of the 19 primers used in this study amplified 3373 clear and reproducible bands associated with 150 loci and many of them were polymorphic. The dendrogram resulting from the unweighted pair-group method of arithmetic cluster analysis separated the cultivars into eight groups. The correlation coefficient between the cophenetic matrix and the similarity matrix was 0.82 (r = 0.82). There was a significant difference between populations and most studied genotypes clustered closely together based on their geographic origin and Iranian pears placed between two groups of pears. Results showed the suitability of RAPD analysis in genetic diversity study of pear.

Evaluation of susceptibility of pear and plum cultivars to winter frost

ABSTRACT The damage to pear and plum buds was investigated in Mashhad, after a period of unusually warm weather for a few days in March 2013 followed by a sudden drop in temperature to -12°C. Frost damages of vegetative and reproductive buds and spur-part below the buds of pear and plum cultivars were investigated based on visual observations. The following pear (Pyrus communis L.) cultivars were investigated: William’s, Bell de june, Ida, Spadona, Koshia, Domkaj, Dare Gazi, Mohamad Ali, Boheme, Shekari, Ghodumi and one Asian pear (Pyrus serotina Rehd.). Japanese plum (P. salicina L.) included ’Shiro’, ’Shams’, ’Computi’ and European plum (Prunus domestica L.) included ’Stanley’, ‘Early Santa Rosa’, ’Late Santa Rosa’, ’Shablon’ and ’Black Diamond’. Electrical conductivity (EC) and proline content were measured in reproductive buds. It was discovered that visual damages were different between cultivars, as the vegetative pear bud of ‘Ghodumi’ suffered the most damage and all parts of ‘Late Santa Rosa’ were the most susceptible in plum cultivars. On the other hand, ‘Computi’ had the most resistant reproductive bud and no damage was observed in the other parts. The EC and proline content of ‘Dare Gazi’ were the highest despite the fact that high proline content did not show high resistance, which was related to the phenological stage of ‘Dare Gazi’.

α-Farnesene and antioxidative enzyme systems in Asian pear ( Pyrus serotina Rehd.) fruit

The effects of 1-methylcyclopropene (1-MCP) on ripening, superficial scald and concentrations of α-farnesene, conjugated trienols (CTols) and antioxidant enzyme activity of ‘KS 6’ Asian pear ( Pyrus serotina Rehd.) were studied. 1-MCP treated (2 μL L −1) or untreated control fruit were stored at 1 °C and 90–95% RH for up to 120 days. 1-MCP treated fruit were firmer than untreated fruit. Application of 1-MCP delayed skin color change. Scald appeared after shorter storage duration and was reduced, but not entirely controlled, with 1-MCP. Accumulation of α-farnesene and oxidation were slower in skin of 1-MCP treated fruit compared with controls. Catalase and peroxidase activities in untreated fruit either increased while activities decreased in 1-MCP treated fruit. Superoxide dismutase activity remained stable. The treatment of Asian pears with 1-MCP followed by cold storage maintained textural characteristics with less scald incidence.

PREVENTION OF ENZYMATIC BROWNING OF ASIAN PEAR (PYRUS SEROTINA REHD.) BY SOME ANTI-BROWNING AGENTS

Mature fruit of the 'KS 13 ' Asian pear (Pyrus serotina Rehd.) cultivar were harvested from eight-year-old trees grown on European pear seedling rootstocks at Tarbiat Modares University (TMU) research orchard. Water extracts of onion and garlic bulbs were prepared and their effects on polyphenol oxidase activity and browning of Asian pear fruit juice were investigated. The polyphenol oxidase (PPO) of Asian pear was inhibited by onion and garlic extracts, and the inhibitory effect of these extracts on PPO was increased after heating them. The extracts' inhibitory effect increased with increasing heating temperature and time. In addition, results indicated that the inhibitory effect of garlic extract was greater than that of onion extract. The browning of Asian pear juice was retarded by addition of both fresh and heated onion and garlic extracts. The extracts inhibited the PPO activity non-competitively. Therefore, the inhibitory effect of these extracts against juice browning seems to be due to their impact on PPO activity.

Hot water treatment of Japanese pear trees is effective against white root rot caused by Rosellinia necatrix Prillieux

Hot water was dripped into the rhizosphere of Japanese pear trees (Pyrus serotina Rehd. grafted on P. betulifolia Bunge.) infested with the white root rot fungus Rosellinia necatrix Prillieux, to destroy the fungus. Isolates of R. necatrix from diseased roots of Japanese pear were vulnerable to water at temperatures above 35°C, and the fungus was eradicated from the colonized substrate when water at 35°C was provided for 3 days. The time required to eradicate R. necatrix decreased exponentially with increasing temperature. Japanese pear trees tolerated a temperature of 45°C without reduction in vigor. Field experiments demonstrated the practical use of hot water drip irrigation (HWD). HWD at 50°C completely destroyed white root rot mycelia on diseased roots, and many rootlets grew after the treatment. HWD at this temperature caused no injury to the trees. HWD of diseased orchard trees was assessed in Takamori and Iida in southern Nagano, Japan. The fungus recurred in two of four trees 28 months after treatment in Takamori and in two of ten trees 16 months after treatment in Iida. The new mycelia emerged on thick roots deep within the soil. Although there is a possibility of recurrence, HWD treatment is a practical control measure for white root rot.

Influence of endogenous and exogenous RNases on the variation of pollen cytosolic-free Ca2+ in Pyrus serotina Rehd

The objective of this study was to examine whether S-RNase plays a specific role in the pre-germinated Pyrus pollen. Effects of exogenous RNase and endogenous S-RNase on concentration of cytosolic-free calcium ([Ca2+]i) variation of pre-germinated Pyrus pollen were studied. [Ca2+]i variation caused by different RNases were complex. In 1 h after being cultured, exogenous RNase, RNase T1 and RNase A, and endogenous incompatible ‘Hohsui’ RNase promoted the [Ca2+]i of ‘Hohsui’ pollen. Acid proteins of ‘Hohsui’ had no remarkable influence on the [Ca2+]i of self-pollen. Endogenous compatible ‘Kohsui’ RNase reduced the [Ca2+]i of ‘Hohsui’ pollen, but compatible ‘Hohsui’ RNase can stimulate the [Ca2+]i of ‘Kohsui’ pollen. RNase T1, RNase A and incompatible ‘Kohsui’ S-RNase can also make ‘Kohsui’ pollen [Ca2+]i increase. Different from ‘Hohsui’ pollen, acid proteins of ‘Hohsui’ pull down the ‘Kohsui’ pollen [Ca2+]i remarkably. Conclusion can be made that during the prophase of pollen germination, endogenous S-RNase has no specific effect on pollen [Ca2+]i changes.

Effect of leaf position and age on anatomical structure, photosynthesis, stomatal conductance and transpiration of Asian pear

The effects of leaf position and leaf age on gas exchange, transpiration, stomatal resistance, and anatomical structure of seven-year-old trees of Asian pear cv. Huanghua and Jingshiu II (Pyrus serotina Rehd. cv. culta rehd.) were examined under field conditions. Individual leaves were monitored from unfolding to maturation, and detailed measurements were made on leaves at various node positions and leaf ages. The anatomical structure varied according to the node position of the leaf, with palisade thickness increasing and the thickness of spongy mesophyll decreasing from the base to the apex of the branch. Intercellular space fraction of leaves decreased from the apex to the base of a shoot. ”Huanghua” leaves took 20 days for full expansion while ”Jingshiu II” required 25 days. Net photosynthesis (Pn) and stomatal conductance (Gs) of both genotypes increased with leaf age, particularly in the early stage. Pn reached a maximum value when the leaf was completely expanded. Leaves at different developmental stages from the apical position to the base performed differently. The transpiration rate and the vapor pressure deficit of older leaves on the base of the branch were higher than those of the younger leaves at the apex of the branch. Leaves at node 3 to 16 had higher saturation vapor pressure and transpiration rates. Both the apical and basal leaves had higher stomatal resistance and lower net photosynthesis than leaves in an intermediate position.

DEVELOPMENT OF AN H-SHAPED TRAINING SYSTEM FOR JAPANESE PEAR

An H-shaped training system, which is expected to improve work efficiency, has been established for Japanese pear (Pyrus serotina Rehd.). According to the method devised by Ishida, the primary and secondary scaffold branches were trained vertically for three years to facilitate vigorous shoot growth. Length of the secondary scaffold branches was about 2.5 m in the third dormant season, which was equivalent to 60% of the length of the mature tree. The canopy area of a seven-year-old tree was 10.7 m2, which was significantly smaller than that of the standard system, but not significantly different from trees trained to the straight line system. The yield per tree was not significantly different among training systems during the experiment period except in the first bearing year. The soluble solids concentration was the same as that of the other systems tested. Flesh firmness was significantly different among training systems, but the order varied depending on the year.

Relationships between fruit set, pollen-tube growth, and S-RNase concentration in the self-incompatible Japanese pear

Fruit set after self-pollination varied from 0.6 to 15.2% and the growth rate of self pollen-tubes in the style also varied from 0 to 39% among the Japanese pear cultivars ( Pyrus serotina Rehd.); the former data were calculated using the results reported by several workers at different locations during several years, and the latter were our experimental results using a stylar culture technique in vitro. Cultivar differences in fruit set matched well with differences in the tube growth ( r=0.852 **, n=12) ( **; significant at 1% level by t-test). Concentration of the sum of two S-RNases in the style was cultivar-dependent, and it showed a negative relation to fruit set ( r=−0.764 *, n=7) ( *; significant at 5% level) or pollen-tube growth ( r=−0.888 **, n=18). The correlation coefficients between the pollen-tube growth and S 1-, S 2-, S 3-, S 4-, or S 5-RNase concentration were; −0.714 ( n=5), −0.242 ( n=6), −0.560 ( n=4), −0.701 * ( n=9), or −0.948 ( n=4), respectively. Cultivar differences in the expression of self-incompatibility may, thus, be present in the Japanese pear and regulated, at least in part, by the concentration of S-RNase differentially produced in the style of each cultivar.

Selective inhibition of the growth of incompatible pollen tubes by S-protein in the Japanese pear

The S-allele-associated proteins (S-proteins) in the styles of the Japanese pear (Pyrus serotina Rehd. var. culta Rehd.) were purified by cation exchange chromatography. Their inhibitory action on the growth of incompatible pollen tubes (pollen tubes bearing the same S- allele as in the style from which the S-proteins were prepared) was characterized in vitro. Germination and tube growth of self-pollen (pollen from the same cultivar from which the S-proteins were prepared) decreased dose-dependently when the S-protein was added to the medium. Tube length was reduced to 10% that of compatible pollen tubes (pollen tubes bearing the S-allele different from that in the style from which the S-proteins were prepared) at 1.5 µg µl1. S-proteins from Shinsui (S 4 S 5 ) also inhibited growth of cross-incompatible Kosui (S 4 S 5 ) pollen tubes, but not of compatible Chojuro (S 2 S 3 ) pollen tubes. After inactivation of RNase of the S- protein, the inhibitory action of the S-protein disappeared. These results indicate that the S-protein acts directly to inhibit growth of incompatible pollen tubes in Japanese pear styles, and that the RNase activity of the protein is essential for the biological function. However, small amounts of proteins that co-migrated with the S-protein may also play some roles in the inhibition. This is the first report on the selective inhibitory action of S-proteins in Rosaceae.

Lupeol esters from the twig bark of Japanese pear (Pyrus serotina Rehd.) cv. Shinko.

Five new lupeol esters, lup-20(29)-ene-3beta-yl eicosanoate, docosanoate, tetracosanoate, hexacosanoate and octacosanoate, were isolated as a mixture from the twig bark of Japanese pear (Pyrus serotina Rehd.) cv. Shinko, together with lupeol and epifriedelinol. Their structures were determined by spectral analyses including 2D-NMR experiments.

Sugars and organic acids contents of European Pyrus comminus L. and Asian Pyrus serotina r Rehd. pear cultivars

The content of sugars (glucose, fructose, sucrose, sorbitol) and organic acids (citric, malic, fumaric, tartaric) was analysed with HPLC (High Performance Liquid Chromatography) in pear fruits of 18 European (Pyrus communis L.) and 4 Asian (Pyrus serotina Rehd.) cultivars. The cultivars differed in the content of different sugars and organic acids. Fructose varied in the European pear cultivars from 23.7 g kg &1 in cv. ‚Conference™ to 66.1 g kg &1 in cv. ‚Clapp Favorite™ and in the Asian cultivars from 27.9 g kg &1 in cv. ‚Shinseiki™ to 45.7 g kg &1 in cv. ‚Koshui™. Sorbitol varied in the European pear cultivars from 12.5 g kg &1 in cv. ‚Conference™ to 24.9 g kg &1 in cv. ‚Beurré Bosc™ and in the Asian cultivars from 5.0 g kg &1 in cv ‚Shinseiki™ to 19.0 g kg &1 in cv. ‚Kumoi™. The Asian pear cultivars contained more total sugars than the European ones. The early cultivars of pears contained more than 1.0 g kg &1 of citric acid and the late ones less than 1.0 g kg &1 . The cvs. ‚Williams Bon Chrétien™, ‚Early Morettini™, ‚Princess Mariane™, ‚Koshui™ and ‚Hoshui™ contained more citric than malic acid. In the cvs. ‚Concorde™, ‚Conference™ and ‚Beurré Alexandre Lucas™ no citric acid was traced. The content of tartaric acid was traced only in cv. ‚Hardy™.

Comparison of an S-protein expression between self-compatible and -incompatible Japanese pear cultivars

An S4-allele-associated protein (S4-protein) was identified by both isoelectricfocusing (IEF) polyacrylamide-gel electrophoresis and N-terminal amino-acid sequences in self-incompatible Nijisseiki (self-in- compatibility genotype=S2S4) and self-compatible Osa-Nijisseiki (S2S4SM, SM=stylar-part mutant) styles of the Japanese pear, Pyrus serotina Rehd. var. culta Rehd. Expression of the protein in the cultivars was compared during flower bud development and at post-transcriptional levels.

Antioxidative Activities of Young Fruit Extracts of Japanese Pear and Satsuma Mandarin

The alcohol extract prepared from young fruits of Japanese pear (Pyrus serotina Rehd. var. culta). The crude extract had strong antioxidative activity for linoleic acid oxidation. The extract contained polyphenols such as chlorogenic acid analogues (Chl) and catechin analogues (Cat). Chl and Cat comprised about 28% and 15% of the polyphenol (PP) contents of the young fruit (590 mg/ 100g fresh weight), respectively. Total PP, Chl and Cat contents were markedly decreased during the fruit development. Linoleic acid oxidation was inhibited 70% and 90% by 5mM Chlogenic acid and Catechin, respectively. Another PP reagents, such as catechol, resorcinol, and hydroquinon also had the antioxidative activity. Above results indicated that PPs, such as Chi and Cat, were the principal constituents of the natural antioxdant of the young fruit extract. The young fruit extract showed the antioxidative activity for about two month. The extract of the young Satsuma mandarin (Citrus unshiu Mar.) fruit, containning a large amount of polyphenols, also showed the antioxidative activity for linoleic acid oxidation. These results suggested that the young fruit extracts were able to employ as a natural antioxidant for fatty foods.

花柱培養法によるニホンナシの自家および交配不和合反応の品種間差の解析

Varietal differences of pollen tube growth among self-, cross-incompatible and cross-compatible pollinations were investigated by semi vitro assay using detached styles in Japanese pear (Pyrus serotina Rehd. var. culta Rehd.) cultivars. Among the 52 self-compatible and -incompatible cultivars, the pollen tubes grew in considerably different ways. The percentages of styles with protruding pollen tubes from the basal cut end ranged from 0 to 47. Pollen tubes of 'Shinsetsu', Nihonyamanashi, self-compatible 'Osa-Nijisseiki', and self-compatible strains obtained from 'Osa-Nijisseiki' grew well, and those of 'Okusankitsu', 'Yasato', 'Kikusui', 'Nijisseiki', and 'Kisui' did intermediately, whereas pollen tubes of 'Shinsui', 'Chojuro', 'Kimizukawase', 'Hohsui', 'Kohsui', and 'Kohzo' grew poorly. Similar tendencies were observed when the number of pollen tubes protruding from the basal cut end among cultivars was counted. Generally, pollen tubes of cultivars derived from 'Nijisseiki' grew better than did those of 'Kohsui' and 'Shinsui', indicating that the rate of pollen tube elongation of cultivars is a heritable character. In cross-incompatible and -compatible pollination combinations, the pollen tubes grew quite differently, depending on the parental combinations. The percentages of styles with protruding pollen tubes from the cut end ranged from 0 to 40 in cross-incompatible combinations, and from 26 to 97 in cross-compatible ones. By using excised styles shortened to 1/2 or 1/3 of the original length, the percentage of styles with protruding pollen tubes from the cut end improved. The growth of self-and cross-incompatible pollen tubes became much better so that the promotion patterns were classified as follows : 1) tube elongation becomes better as the style is shortened ; 2) tube elongation becomes better but there are no differences between 1/2 and 1/3 reduction in style length ; 3) pollen tube elongation becomes better only in the 1/3 style length, and 4) no change was found. These differences indicate that the inhibition of pollen tube growth occurs in different parts of the style among respective cultivars.

Recovery of Declined Pear Tree Vitality through Grafting with Scions from a Vigorous Cultivar

Taiwan, located in subtropic regions, naturally is not an ideal region for temperate-zone fruit trees' production due to the supra-optimum temperature, heavy rainfall, and higher relative humidity in summer and insufficient chilling in winter. Higher relative humidity and temperature in summer and autumn months cause excessive vegetative growth, resulting in poor flowerbud initiation and formation. Typhoon invasions result in the severe damage of twigs as well as the loss of quality and yield of fruits. In order to overcome these natural barriers, Hengshan (Pyrus serotina Rehd.) pear has been selected as a major cultivar for lowlands in Taiwan. It has low-chilling requirement and higher temperature tolerance. Branches of Hengshan are pulled and tied to a horizontal wire net to adapt to the environmental status. This trellis system enhances flowerbud initiation through the retardation of vegetative growth. It also induces numerous water shoots. Scions from high-chilling cultivars grown at a high altitude on mountains are grafted onto water shoots of Hengshan pear trees. The system has been successful in the production of both high-chilling pears in June and the Hengshan pears in August, and has made production of both pears an important industry in Taiwan. Heavy load and trellis systems, however, result in hastening the senescence of Hengshan trees. Vitality of trees could be restored by grafting scions from a vigorous cultivar, P. koehnei, onto the terminal position of the branches. The practice resulted in several advantages including: 1) uniform growth of branches, 2) redistribution of water shoots, 3) inducing formation of calluses on old damaged trunks, 4) quick recovery of mealybug-damaged branches, 5) rejuvenation of branches, and 6) termination of dormancy.

Style-specific and developmentally regulated accumulation of a glycosylated thaumatin/PR5-like protein in Japanese pear (Pyrus serotina Rehd.).

The stylar proteins of Japanese pear (Pyrus serotina Rehd.) were analyzed by two-dimensional gel electrophoresis, and a 32-kDa protein with an isoelectric point of 4.8 was found to be a major component in the style. The 32-kDa protein was a soluble glycoprotein which reacted with concanavalin A. The 32-kDa protein specifically accumulated in the style in a developmentally regulated manner, but was not detected in the other floral organs and leaves. An oligonucleotide representing the N-terminal amino acid sequence of the 32-kDa protein was used to amplify a cDNA fragment by polymerase chain reaction (PCR). The generated PCR product was used to screen a style cDNA library. The selected cDNA clone encoded 244 amino acid residues containing the N-terminal sequence of the 32-kDa protein. The N-terminus of the protein was preceded by putative signal peptide of 22 amino acid residues. The 32-kDa protein showed significant homology with the thaumatin/PR5-like proteins, and was named PsTL1 (Pyrus serotina thaumatin-like protein 1). The possible biological role of PsTL1 in the styles is discussed.

Polyuronides Changes in Japanese and Chinese Pear Fruits during Ripening on the Tree.

Changes in contents and molecular distribution of polyuronides were determined on Japanese pear 'Chojuro' (Pyrus serotina Rehd. var. culta) and Chinese pear 'Yali'(P. ussuriensis Maxim. var. sinensis Kikuchi) fruits. The ratios of water-soluble (F1) fraction to total polyuronides increased and that of acid-soluble (F4) fraction decreased as firmness decreased with ripening in both cultivars. However, 'Chojuro' contained polyuronides of predominantly lower molecular weight than did 'Yali' in the F4 fraction.

Comparison of the Quality of the Japanese Pear 'Nijisseiki'(Pyrus serotina Rehd. var. culta) grown in Japan and California (USA)

Comparison of the Quality of the Japanese Pear 'Nijisseiki'(Pyrus serotina Rehd. var. culta) grown in Japan and California (USA)