Japanese Pear Research Articles

Changing surface wax compositions and related gene expression in three cultivars of Chinese pear fruits during cold storage.

The surface wax of fruit has a significant effect on abiotic stress and fruit quality. In this study, the composition of the waxes found on fruit surfaces and the related gene expression of three different pear cultivars (Xuehua, Yali, and Yuluxiang) were investigated during cold storage. The results showed that 35 wax compositions were found on the surfaces of the three pear cultivars, mainly including C29 alkane, three fatty acids, two esters, three aldehydes, three fatty alcohols, and three triterpenoids. The largest amount of C29 alkane, three fatty acids and two esters were found in Yuluxiang (YLX) on day 90, while aldehydes with carbons of C30 and C32 were the highest in Yali (YL). Xuehua (XH) showed the largest amount of C22 fatty alcohol on day 180 compared to YLX and YL. Larger amounts of triterpenoids were found in XH and YL when compared to YLX. The expression levels of fifteen wax related genes (LACS1, KCS2, KCS6, FDH, KCS20, GL8, CER10, CER60, LTPG1, LTP4, ABCG12, CER1L, CAC3, CAC3L, and DGAT1L) reached their peak at day 45 in YLX, compared to XH and YL, their expression levels in YLX were higher to different degrees. These results suggest that the different expression patterns of wax-related genes may be closely related to the difference in wax compositions of the surface wax of three pear cultivars.

Transcriptome changes associated with boron applications in fruits of watercore-susceptible pear cultivar

Watercore is a common physiological disorder in pear and is closely related to the excessive accumulation of sorbitol and sucrose. Our previous research found that the incidence of watercore in 'Akibae' (Pyrus pyrifolia cv. Akibae) fruit significantly decreased after boron application (BA). Moreover, the foliar spray of boric acid also significantly improved fruit quality. However, the mechanisms underlying the pear fruit response to BA was still limited. A comprehensive transcriptome analysis of BA treatment 'Akibae' pear fruit was performed in this study. Transcriptome results revealed a total of 3146 up-regulated and 1145 down-regulated differentially expressed genes (DEGs) between control and treated fruits of 'Akibae' pear. BA significantly induced the expression of sorbitol metabolism and sucrose metabolism genes. In addition, BA also increased the expression of starch degradation, fatty acid synthesis, IAA (indole-3-acetic acid) degradation, and GA (gibberellin acid) synthesis genes and inhibited the expression of ethylene synthesis genes. These findings suggested that BA probably alleviates 'Akibae' watercore occurrence and improves fruit quality by regulating the decrease in sorbitol and sucrose, the increase in fatty acids and the balance of plant hormones. Our results provide further information for understanding the molecular mechanism of the effect of BA on pear fruit.

SNP-based high-density linkage map construction and QTL mapping of black spot disease resistance in Chinese sand pear.

Black spot disease (PBS) caused by Alternaria alternata is an economic disease of pear (Pyrus pyrifolia Nakai). Developing cultivars with durable PBS resistance traits is an important research objective for improving pear germplasm. The Deshengxiang is a popular pear variety in China and resistant to PBS. This study aimed to detect quantitative trait loci (QTL) associated with PBS resistance trait in pear and determine closely linked molecular markers by specific locus amplified fragment sequencing (SLAF-seq). F1 population resulting from a cross between "Deshengxiang" (female) and "Guiguan," a susceptible (male) variety, was developed and evaluated in 2016 and 2017. SLAF technology was used to discover SNPs in the F1 individuals and subsequently a high-density genetic linkage map for PBS resistance was constructed which contained 17,604 SNP markers. Based on the linkage map, the markers were distributed into 17 linkage groups, spanning 1548.48cM, with a mean marker distance of 0.09cM, representing the densest genetic map of the genus Pyrus. QTL analysis of PBS resistance identified a locus strongly related to PBS resistance at 77.68 ~ 112.99cM on linkage group 15, which was further narrowed down to 93.79 ~ 112.99cM. Two markers, Marker94293 and Marker94206, located at 97.47 and 102.93cM, were closely associated with PBS resistance, with a Δ (SNP index) value of 0.46. Co-localization of QTL interval, bioinformatics analysis, and functional annotation revealed PBS putative candidate genes. Overall, the high-density pear linkage map is a suitable reference for mapping PBS resistance trait, QTL, and genes identified in this study contribute information that could be useful for PBS improvement in pear.

PpZAT5 suppresses the expression of a B-box gene PpBBX18 to inhibit anthocyanin biosynthesis in the fruit peel of red pear.

BBX (B-box) proteins play a vital role in light-induced anthocyanin biosynthesis. PpBBX18 was an indispensable regulator for the induction of anthocyanin biosynthesis in the peel of red pear fruit (Pyrus pyrifolia Nakai.). However, the upstream regulation of BBX genes has not been well characterized. In this study, PpZAT5, a cysteine2/histidine2-type transcription factor, was discovered as the upstream negative regulator of PpBBX18. The results showed that PpZAT5 functions as a transcriptional repressor and directly binds to the CAAT motif of PpBBX18 and inhibits its expression. PpZAT5 expression was inhibited by light, which is converse to the expression pattern of anthocyanin-related structural genes. In addition, less anthocyanin accumulated in the PpZAT5-overexpressing pear calli than in the wild-type pear calli; on the contrary, more anthocyanin accumulated in PpZAT5-RNAi pear calli. Moreover, the crucial genes involved in light-induced anthocyanin biosynthesis were markedly down-regulated in the transcriptome of PpZAT5 overexpression pear calli compared to wild-type. In conclusion, our study indicates that PpBBX18 is negatively regulated by a C2H2-type transcriptional repressor, PpZAT5, which reduces anthocyanin content in pear. The present results demonstrate an upstream molecular mechanism of PpBBX18 and provide insights into light-induced anthocyanin biosynthesis.

Crop Load Management in Nashi Pear—A Review

Most nashi cultivars require heavy thinning, and this has traditionally been performed by the time and labour-intensive practice of hand thinning. Crop load management is a key cost driver for nashi production, but there are limited cost-effective options available for nashi growers compared to other pome fruit, especially apples and, to a lesser extent, European pears. There is, however, potential to adapt some of the thinning tools and techniques used in apples and European pears to reduce the labour requirements and high cost of thinning in nashi, thus improving industry profitability. Several chemical thinning agents have potential for nashi, and an understanding of the optimal application rates, times and weather conditions for each chemical, as well as the conditions/factors that impact the tree carbon balance, will improve the predictability of chemical thinning. However, it is difficult to target specific flowers/fruitlets within a cluster with chemicals, and the flowers that produce the preferred fruit shape and size are in the middle of the flower cluster. Mechanical thinning during the flowering period with either Darwin or BAUM-style string thinners has potential, particularly as these devices can be used as early as flower emergence. As for chemical thinning, the issue of non-selectivity needs to be addressed; however, the development of mechatronic systems should overcome most problems that occur with the currently available mechanical thinners. Shading at critical times is an avenue that could be explored further to ascertain the critical stage when developing fruit are susceptible to enable the determination of the optimal timing and duration of shading. Targeted pruning and bud thinning during the dormant winter period to reduce the floral bud numbers is a valuable option for the precise placement of fruit in optimal positions and to set up the required number of clusters. This review highlighted several tools/techniques that, with further work, can be incorporated into a systematic approach to crop load management in nashi while reducing the risk and cost.

Early defoliation induces auxin redistribution, promoting paradormancy release in pear buds.

Paradormancy of fruit trees occurs in summer and autumn when signals from adjacent organs stimulate buds to develop slowly. This stage has received less attention that the other stages of dormancy, and the underlying mechanism remains uncharacterized. Early defoliation in late summer and early autumn is usually followed by out-of-season blooming in pear (Pyrus spp.), which substantially decreases the number of buds the following spring and negatively affects fruit production. This early bud flush is an example of paradormancy release. Here, we determined that flower bud auxin content is stable after defoliation; however, polar distribution of the pear (Pyrus pyrifolia) PIN-FORMED auxin efflux carrier 1b (PpyPIN1b) implied that auxin tends to be exported from buds. Transcriptome analysis of floral buds after artificial defoliation revealed changes in auxin metabolism, transport, and signal transduction pathways. Exogenous application of a high concentration of the auxin analog 1-naphthaleneacetic acid (300 mg/L) suppressed PpyPIN1b expression and its protein accumulation in the cell membrane, likely leading to decreased auxin efflux from buds, which hindered flower bud sprouting. Furthermore, carbohydrates and additional hormones also influenced out-of-season flowering. Our results indicate that defoliation-induced auxin efflux from buds accelerates bud paradormancy release. This differs from release of apical-dominance-related lateral bud paradormancy after the apex is removed. Our findings and proposed model further elucidate the mechanism underlying paradormancy and will help researchers to develop methods for inhibiting early defoliation-induced out-of-season bud sprouting.

1-Methylcyclopropene Maintains Firmness and Peel Color and Reduces Decay Area of Artificially Wounded Fruits in Mature Japanese Pear (Pyrus pyrifolia Nakai ‘Shizukisui’)

Abstract Recently, there has been an increasing need to prolong the quality of matured fruits to promote the distribution of fresh fruits to consumers and processing facilities. Studies have shown that 1-methylcyclopropene (1-MCP), an inhibitor of ethylene, can maintain the firmness and quality of several fruits for a long duration. Therefore, the aim of this study was to examine the effect of 1-MCP treatment on the firmness, rind color, and decay rate of the Japanese pear ‘Shizukisui’. Results showed that 1-MCP treatment alone and 1-MCP treatment after precooling significantly maintained the firmness of mature fruits compared with untreated fruits. However, the presence or absence of ethylene addition did not significantly affect fruit firmness; moreover, 1-MCP treatment after precooling tended to reduce moisture loss in immature fruits. Regarding the peel color of the fruits, 1-MCP treatment alone and 1-MCP after precooling treatment increased the L*, b*, and C* values of mature fruits but reduced the values in immature fruits. Compared with the control group, the 1-MCP treatment caused a decrease in the decay area of wounded ‘Shizukisui’ and ‘Kosui’ fruits and decreased the decay rate of wounded ‘Kosui’. Overall, this study showed that 1-MCP treatment maintained the firmness and peel color of Japanese pear and reduced its decay rate.

Antioxidant and Hypoglycemic Activity of Sequentially Extracted Fractions from Pingguoli Pear Fermentation Broth and Identification of Bioactive Compounds.

Pear fruits have been reported to contain abundant bioactive compounds and exhibit antidiabetic activity. In this study, Pingguoli pear (Pyrus pyrifolia cv.‘Pingguoli’) fermentation broth was sequentially extracted by five solvents with increasing polarity (petroleum ether, chloroform, ethyl acetate, n-butanol, and water) to evaluate its antioxidant and hypothermic activities, and then the main compounds of the fraction with the highest activity were assessed, which might be responsible for such activities. The results showed that the ethyl acetate fraction (EAF) exhibited the highest antioxidant activity according to DPPH (IC50 = 0.238 mg/mL), ABTS (IC50 = 0.293 mg/mL), and FRAP (IC50 = 0.193 mg/mL) assays. The in vitro hypoglycemic activity assay showed that EAF exhibited the strongest inhibitory effect, with IC50 values of 0.34 and 0.95 mg/mL for α-amylase and α-glucosidase, respectively. The glucose consumption in HepG2 cells treated with EAF was significantly increased to 252%, compare with control group. Liquid chromatography–mass spectrometry analysis implied that the main compounds, 3′-C-glucosylisoliquiritigenin, robustside D, caffeic acid, and chlorogenic acid may be potential candidates for the antioxidant and hypoglycemic activities of the EAF. This study suggested that EAF of Pingguoli pear fermentation broth could be utilized for development of potential functional food and antidiabetic agents.

Microbiota modulation and anti-obesity effects of fermented Pyrus ussuriensis Maxim extract against high-fat diet-induced obesity in rats

Pyrus ussuriensis Maxim (Korean pear) has been used for hundreds of years as a traditional herbal medicine due to its strong phytochemical profile and pharmacological efficacy. In this study, we evaluated the anti-obesity potential of Pyrus ussuriensis Maxim extracts (PUE) and investigated the underlying mechanisms using a combination of in vitro, in vivo, and microbiota regulation approaches. In an adipogenesis assay, the fermented (F)PUE and non-fermented (NF)PUE significantly reduced the differentiation of 3T3-L1 preadipocyte in a dose-dependent manner with an IC50 of 85.33 and 96.67 µg/mL, respectively. In a high-fat diet (HFD)-induced obese rat model (n = 8 animals/group), oral administration of FPUE additionally reduced the total body weight gain significantly. No difference in food intake was observed, however, between the control-chow diet, FPUE, and NFPUE-treated HFD rats. Adipose tissue mass and systemic insulin resistance were markedly reduced in FPUE-treated HFD rats, in a dose-dependent manner. Treatment with FPUE also greatly improved obesity-related biomarkers, including total cholesterol, leptin, active ghrelin, Total GIP, adiponectin, and proinflammatory cytokines. Moreover, FPUE significantly suppressed HFD-induced adipogenic genes expression, while increasing fatty acid oxidation-related genes expression. Additionally, FPUE treatment attenuated the HFD-induced Firmicutes proportion within the intestinal microbiota by regulating key metabolic pathways, thus enhancing microbial population diversity (e.g., increasing Bacteroides, Bifidobacterium, Prevotella, Eubacterium, and Clostridium). Together, these results reveal a strong anti-obesity potential of FPUE through adipogenesis, lipid metabolism, weight reduction, and microbiota regulation, raising the possibility of developing FPUE as a novel therapeutic agent to control obesity and obesity-associated metabolic disorders.

ROS-mediated Lignin Biosynthesis is Associated with Cell Wall Expansion in Asian Pear (Pyrus pyrifolia Nakai) During Fruit Development and Ripening

ROS-mediated Lignin Biosynthesis is Associated with Cell Wall Expansion in Asian Pear (Pyrus pyrifolia Nakai) During Fruit Development and Ripening

Plant Growth Inhibitory Activity and the Response of Different Rootstocks to Soil Sickness Syndrome in Japanese Pear Tree

Soil sickness syndrome in Japanese pear (Pyrus pyrifolia (Burm.f.) Nakai) affects the growth of the tree and decreases fruit yield. This study investigated the growth-inhibitory activity in Japanese pear (Pyrus pyrifolia (Burm.f.) Nakai) using the rhizosphere soil assay method to elucidate the characteristics of growth-inhibitory substances in Japanese pears. As a result, the root bark had the highest growth inhibitory activity during the growing season of the Japanese pear. For comparative analysis, the growth-inhibitory activities of Japanese apricots (Prunus mume Sieb. Et Zucc.) and figs (Ficus carica L.) were also investigated. Similar to the Japanese pear, the root bark of Japanese apricots and figs had a higher inhibition rate than the root pith. Like Japanese apricots and figs, it was inferred that the growth inhibitory substances accumulate in the bark of the Japanese pear. Furthermore, soil sickness syndrome in Japanese pear saplings did not occur when a fragment of Japanese pear shoots or thick roots was mixed with non-pear soil (soil with no history of Japanese pear cultivation). Based on these findings, it is considered that the condition of soil sickness in Japanese pear is caused by the accumulation of phenolic compounds such as arbutin, which is accumulated in the bark of the tree, secreted from the roots, and subsequently builds up in the soil. Additionally, the degree of occurrence of soil sickness syndrome depending on the rootstock was clarified. It was observed that the rate of growth inhibition was significantly higher in Pyrus betulifolia (Birchleaf pear) than in Pyrus pyrifolia (Japanese pear). Even when Japanese pear trees were planted in soils with no history of Japanese pear cultivation, the initial growth of P. betulifolia was 1.4 times that of P. pyrifolia. It is suggested that P. betulifolia is weak against soil sickness, but is excellent at initial growth itself. Our findings are important because P. pyrifolia is used for cultivation, in combination with other mitigation measures, such as soil dressing in replanted fields.

Comparison studies on sucrose metabolism and phenolic content during fruit growth and maturation in pear cultivars

Abstract ‘Patharnakh’ (Pyrus pyrifolia Burm.) (PN), a hard pear and ‘Punjab Beauty’ (Pyrus communis L. × Pyrus pyrifolia Burm.) (PB), a soft pear are dominant low-chill pear cultivars of subtropics of India. Present investigation reports the changes in sugar metabolism and related enzymatic activities in fruits of ‘PN’ and ‘PB’ cultivars harvested at different developmental stages from 45 to 150 days after fruit set. Total soluble sugars, fructose, and sucrose contents were higher in ‘PB’ as compared to ‘PN’ during fruit growth and maturation stages. Total phenols and flavanols increased initially and then showed a decreasing trend towards maturity. Sucrose synthase (SS) and sucrose phosphate synthase (SPS) activities strongly correlated to sucrose content in ‘PN’ but SPS was weakly related in ‘PB’ fruits. Acid and neutral invertases showed a negative correlation with sucrose content in ‘PN’, and a reverse trend in ‘PB’ cultivar was observed. It is concluded that SS and SPS are crucial for sucrose accumulation in ‘PN’, but invertase enzymes are also important for sucrose accumulation in ‘PB’ fruits.

Involvement of long non-coding RNAs in pear fruit senescence under high- and low-temperature conditions

Pear fruit senescence under high- and low-temperature conditions has been reported to be mediated by microRNAs. Long non-coding RNAs (lncRNAs), which can function as competing endogenous RNAs that interact with microRNAs, may also be involved in temperature-affected fruit senescence. Based on the transcriptome and microRNA sequencings, in this study, 3 330 lncRNAs were isolated from Pyrus pyrifolia fruit. Of these lncRNAs, 2 060 and 537 were responsive to high- and low-temperature conditions, respectively. Of these differentially expressed lncRNAs, 82 and 24 correlated to the mRNAs involved in fruit senescence under high- and low-temperature conditions, respectively. Moreover, three lncRNAs were predicted to be competing endogenous RNAs (ceRNAs) that interact with the microRNAs involved in fruit senescence, while one and two ceRNAs were involved in fruit senescence under high- and low-temperature conditions, respectively. A dual-luciferase assay showed that the interaction of an lncRNA with a microRNA disrupts the action of the microRNA on the expression of its target mRNA(s). Furthermore, four alternative splicing-derived lncRNAs interacted with miR172i homologies (Novel_88 and Novel_69) to relieve the repressed expression of their target and produce an miR172i precursor. Correlation analysis of microRNA expression suggested that Novel_69 is likely involved in the cleavage of the pre-miR172i hairpin to generate mature miR172i. Taken together, lncRNAs are involved in pear fruit senescence under high- or low-temperature conditions through ceRNAs and the production of microRNA.

Diversity in Acidity between Core and Pulp of Asian Pear Fruit Is Mainly Regulated by the Collaborative Activity of PH8.1 and DIC2 Genes during Fruit Development

The pear (Pyrus pyrifolia) is an important accessory fruit in which the pear core is tarter than the pear pulp. However, the reason for the acidic core and diversity in the taste of the same fruit is not clear. In this study, we observed that the citrate contents were three times higher in the core than in the pulp, while the malate content decreased along with fruit development and was significantly lower in the core than in the pulp at 110 days after flowering. Overall transcript levels for citrate-malate synthesis-related genes increased more in the pear core than the pulp at early fruit development, while degradation-related genes activity was nearly similar or non-significant between the core and pulp during fruit development. The lesser malate accumulation in the pear core compared to the pulp at 110 DAF was possibly due to the reduced activity of tDT2 gene. Regarding citrate accumulation, we identified five important p-type H+-ATPase genes in pear and found that the relative expression level of the PH8.1 gene was four-fold higher in the core than in the pulp during fruit development. Moreover, the expression level of di-carboxylate carrier gene 2 (DIC2) was constantly and significantly higher in the core than in the pulp. In addition, correlation analysis signified that the transcript levels of the two genes PH8.1 and DIC2 positively and significantly correlated with the citrate contents. These results suggested that the increased and collaborative activity of PH8.1 and DIC2 played a key role in the higher citrate accumulation in the core than the pulp, thus, with the help of molecular breeding tools, the citrate contents can be optimized in pear fruit for divers and improved fruit flavoring.

Evaluation of the early defoliation trait and identification of resistance genes through a comprehensive transcriptome analysis in pears

Early defoliation, which usually occurs during summer in pear trees, is gradually becoming a major problem that poses a serious threat to the pear industry in southern China. However, there is no system for evaluating the responses of different cultivars to early defoliation, and our knowledge of the potential molecular regulation of the genes underlying this phenomenon is still limited. In this study, we conducted field investigations of 155 pear accessions to assess their resistance or susceptibility to early defoliation. A total of 126 accessions were found to be susceptible to early defoliation, and only 29 accessions were resistant. Among them, 19 resistant accessions belong to the sand pear species (Pyrus pyrifolia). To identify the resistance genes related to early defoliation, the healthy and diseased samples of two sand pear accessions, namely, the resistant early defoliation accession ‘Whasan’ and the susceptible early defoliation accession ‘Cuiguan’, were used to perform RNA sequencing. Compared with ‘Cuiguan’, a total of 444 genes were uniquely differentially expressed in ‘Whasan’. Combined with GO and KEGG enrichment analyses, we found that early defoliation was closely related to the stress response. Furthermore, a weighted gene co-expression network analysis revealed a high correlation of WRKY and ethylene responsive factor (ERF) transcription factors with early defoliation resistance. This study provides useful resistant germplasm resources and new insights into potentially essential genes that respond to early defoliation in pears, which may facilitate a better understanding of the resistance mechanism and molecular breeding of resistant pear cultivars.

QTL analysis and development of HRM markers associated with fruit shape in interspecific pears (Pyrus pyrifolia × P. bretschneideri)

Fruit shape is one of the important quantitative traits in pear (Pyrus spp.) breeding program, thus genetic study related to fruit shape could be beneficial to pear breeding. Quantitative trait loci (QTL) analysis was carried out using ‘Whangkeumbae’ (P. pyrifolia, round) × ‘Yali’ (P. bretschneideri, pyriform) and high-resolution melting (HRM) markers were developed. The genetic linkage map of ‘Whangkeumbae’ × ‘Yali’ was constructed using single nucleotide polymorphisms (SNPs) derived from Axiom Pear 70 K Genotyping Array and simple sequence repeats. The integrated genetic linkage map of ‘Whangkeumbae’ × ‘Yali’ showed ~ 90% of genome coverage, a total genetic distance of 998.2 cM, and a marker density of 1.6 cM. F1 progenies of ‘Whangkeumbae’ × ‘Yali’ showed normal distribution of fruit length (L), diameter (D), and L/D ratio. Three QTLs located in linkage group (LG) 6, 7, and 12 were identified with LOD thresholds of 2.8–3.0. Six HRM markers were developed using array-SNPs anchored in the QTLs and predicted fruit shape with 28.6–65.3% accuracy. Notably, accuracy was increased by ~ 90% using an HRM marker combination consisting of CBp06sn02, CBp07sn01, and CBp12sn03. These results could provide a better understanding of the genetic mechanism of fruit shape development and reducing pear breeding period.

Composite coating of chitosan with salicylic acid retards pear fruit softening under cold and supermarket storage

Fruit softening is enzyme mediated degradation process determined by the action of cell wall modifying enzymes. Present study evaluated the combined effects of chitosan (CH) and salicylic acid (SA) coatings in modulation of fruit softening enzymes in Punjab Beauty pear (Pyrus pyrifolia × Pyrus communis) fruit stored under cold (0–1 °C and 90–95 % RH) and supermarket (20–22 °C and 80–85 % RH) conditions. Composite CH + SA coatings reduced mass loss and retained fruit firmness throughout the 67 and 20 days storage period. In addition, CH + SA prevented membrane damage by suppressing the electrolyte leakage and malondialdehyde (MDA) accumulation as compared to CH or SA alone. CH 2.0 % + SA 2.0 mM coating efficiently delayed the cell wall degrading enzymatic activities including pectin methylesterase (PME), polygalacturonase (PG) and cellulase associated with fruit softening up to 60 and 15 days storage period in cold and supermarket conditions, respectively.

An assessment of the genetic diversity of pear (Pyrus L.) germplasm resources based on the fruit phenotypic traits

Germplasm resources are an important basis for genetic breeding and analysis of complex traits, and research on genetic diversity is conducive to the exploration and creation of new types of germplasm. In this study, the distribution frequency, coefficient of variation, Shannon–Wiener index, and variance and cluster analyses were used to analyze the diversity and trait differences of 39 fruit phenotypic traits from 570 pear accessions, which included 456 pear accessions from 11 species and 114 interspecific hybrid cultivars that had been stored in the National Germplasm Repository of Apple and Pear (Xingcheng, China). The comprehensive evaluation indices were screened by correlation, principal component and regression analyses. A total of 132 variant types were detected in 28 categorical traits of pear germplasm fruit, which indicate a rich diversity. The diversity indices in decreasing order were: fruit shape (1.949), attitude of calyx (1.908), flesh texture type (1.700), persistency of calyx (1.681), russet location (1.658), relief of area around eye basin (1.644), flavor (1.610) and ground color (1.592). The coefficient of variation of titratable acidity in the 11 numerical traits of pear germplasm fruit was as high as 128.43%, which could more effectively reflect the differences between pear accessions. The phenotypic differentiation coefficient Vst (66.4%) among the five cultivated pear species, including Pyrus bretschneideri (White Pear), P. pyrifolia (Sand Pear), P. ussuriensis (Ussurian Pear), P. sinkiangensis (Xinjiang Pear), and P. communis (European Pear), was higher than the within population phenotypic differentiation coefficient Vst (33.6%). The variation among populations was the main source of variation in pear fruit traits. A hierarchical cluster analysis divided the 389 accessions of six cultivated pear species, including P. pashia (Himalayan Pear), into six categories. There were certain characteristics within the populations, and the differences between populations were not completely clustered by region. For example, Sand Pear cultivars from Japan and the Korean Peninsula clustered together with those from China. Most of the White Pear cultivars clustered with the Sand Pear, and a few clustered with the Ussurian Pear cultivars. The Ussurian Pear and European Pear cultivars clustered separately. The Xinjiang Pear and Himalayan Pear did not cluster together, and neither did the cultivars. Seventeen traits, three describing fruit weight and edible rate (fruit diameter, fruit length and fruit core size), five describing outer quality and morphological characteristics (over color, amount of russeting, dot obviousness, fruit shape, and stalk length), and nine describing inner quality (flesh color, juiciness of flesh, aroma, flavor, flesh texture, flesh texture type, soluble solid contents, titratable acidity, and eating quality) were selected from the 39 traits by principal component and stepwise regression analyses. These 17 traits could reflect 99.3% of the total variation and can be used as a comprehensive evaluation index for pear germplasm resources.

Bacteriocin Harvested from the Synbiotic Culture of Selected Lactic Acid Bacteria with Various Vegetables, Cereals, Fruits, Medicinal and Tuber Plants: Inhibition of Vibrio parahaemolyticus

Abstract The present study was to investigate and identify the antimicrobial lactic acid bacteria against some gastrointestinal pathogens, to compare the activity between their synbiotic culture and bacteria culture alone, and to characterize the bacteriocins produced by the synbiotic culture of these isolates. Among 600 isolates of selected lactic acid bacteria, three isolates of Lactocaseibacillus paracasei subsp. paracasei, two of Latilactobacillus curvatus subsp. curvatus, and one of Lactiplantibacillus plantarum exhibited the antibacterial activities against four standard reference bacteria, and twelve clinical strains of food-poisoning bacteria especially Vibrio parahaemolyticus. The synbiotic culture of L. paracasei 9/5, L. curvatus 87/6 and L. plantarum 89/4 which are cultured with sweet corn, grand red bean, papaya, star fruit, nashi pear, and black ginger exhibited significant inhibitions to V. parahaemolyticus. Bacteriocin which was harvested from the synbiotic culture of L. curvatus 87/6 and nashi pear demonstrated the strongest activity to the tested bacteria. After partial purification, ultrafiltration, and ion exchange column chromatography, this bacteriocin was anionic with 40-80 kDa and pI at 4-5. Its antimicrobial activities significantly decreased at pH > 8.0, with trypsin and pepsin digestions as well as after heating at > 100°C. Analyzed with SDS-PAGE, the suspected bacteriocin band was detected in the increased intensity, lower intensity, and was not detected after harvested from the synbiotic culture, the bacterial culture alone, and only plant powder extract, respectively. It was concluded that the synbiotic culture of L. curvatus with some prebiotics could induce potent antimicrobial bacteriocin production. Keywords: Lactic acid bacteria, Prebiotics, Synbiotic, Bacteriocin, Vibrio parahaemolyticus

Isolation, Screening, and Characterization of Fungal Isolates with Pectinolytic Activity from Decaying Fruits

Filamentous fungi are potential source of pectinolytic enzyme production used in fruit processing industry can be isolated from decaying fruits as substrates. Thus, this study was conducted to isolate, screen, characterize pectinase-producing fungi from decaying fruits and assess their pectinolytic activity. Decaying fruits samples were collected from fruit stands of Iloilo City Terminal Market. Pectinolytic fungi were grown and screened for pectinolytic activity using pectinolytic activity plate assay based on the decolorization coefficient value. Results showed three genera of fungi isolated from various decaying fruits which include Aspergillus (9 isolates), Rhizopus (1 isolate), and Mucor (1 isolate). Aspergillus spp. was the most dominant fungal isolate obtained from decaying fruits of ampalaya (Momordica charantia), pear (Pyrus pyrifolia), pineapple (Ananas comosus), tomato (Lycopersicon esculentum), lemon (Citrus limon), melon (Cucumis melo), calamansi (Citrus microcarpa), and mango (Mangifera indica). The Aspergillus spp. showed significant pectinolytic activity among the fungi effectively screened based on the decolorization coefficient value obtained. Thus, common fungi with pectinolytic activities are mitosporic genera isolated from decaying fruits that can be applied in agro-biotechnological industry.