Asian Pear Research Articles

Review of fruit cork spot disorder of Asian pear (Pyrus spp.).

Cork spot disorder has affected the fruit of Asian pear since the 1990s and has become serious in recent years with increasingly affected cultivars and areas. The commodity value of affected fruit is greatly decreased, resulting in severe economic losses. Cork spot disorder of pear fruit is a physiological disorder, and the factors responsible are relatively complex. Research on the cause of cork spot disorder is still at an early stage and, thus, further investigations are needed to elucidate the underlying mechanism of the disorder. In this review, current knowledge of the factors associated with the incidence of cork spot disorder in Asian pear fruit is summarized, including fruit growth and development, fruit nutrient status, and environmental factors. Potential preventive measures and priorities for future research are outlined.

Genetic mapping of the pear scab resistance gene Vnlf using a pseudo-BC3 population derived from Japanese pear cultivars and European pear ‘La France’

Pear scab disease caused by Venturia nashicola is one of the most serious diseases of Asian pears. To facilitate the breeding of scab-resistant cultivars, we mapped and developed markers for a resistance gene from the European pear (Pyrus communis) cultivar ‘La France’. By using a pseudo-backcross strategy to introduce genes from ‘La France’ into Japanese pear (P. pyrifolia) cultivars, we developed a mapping population from a cross between Japanese pear ‘Akiakari’ and interspecific hybrid progeny line 537–14. The individuals in the mapping population were evaluated for resistance by inoculation testing in 2020 and 2021. The segregation ratio of resistant to susceptible individuals was 1:1, indicating that resistance is inherited as a single dominant gene, which we named Vnlf. A genetic linkage map was constructed using single-nucleotide polymorphism (SNP) and simple sequence repeat (SSR) markers. On the basis of the genetic map of 537–14, we narrowed down the putative region carrying Vnlf to 959 kb on chromosome 2 between SNPs Chr2_20220913 and Chr2_21180341. To facilitate marker-assisted selection in Japanese pear breeding programs, we developed SSRs closely linked to Vnlf, one of which (LFA02a09) showed complete linkage to the resistance phenotype in an inoculation test of 175 individuals. These linked markers will enable introgression of Vnlf into breeding materials without the need for inoculation tests and will facilitate pyramiding Vnlf with other scab resistance loci.

Expectorant Effects of Immature Asian Pear Extract on PM2.5-Induced Subacute Pulmonary Injury in Mice

This study investigated the expectorant effects of immature Asian pear extract (IAP; Pyrus pyrifolia Nakai) on subacute pulmonary injuries in Balb/c mice induced by particulate matter with a diameter of approximately 2.5 μm (PM2.5). IAP was administered at three doses, namely, 400, 200, and 100 mg/kg. The body weight and weight gain changes, lung weights, lung and body surface gross inspections, tracheal secretions, and substance P and ACh content in lung tissue homogenate were observed one day after the tenth IAP administration. The mRNA expression of the genes related to mucus production and lung histopathology was compared with that of the negative and positive controls. Favorable pulmonary protective effects on PM2.5-induced subacute pulmonary injuries, mucus overproduction, and respiratory acidosis were observed in groups treated with IAP at all three doses, possibly through potent anti-inflammatory and mucolytic expectorant activities mediated by the increase in the content of lung substances P and ACh and the downregulation of lung MUC5AC and MUC5B mRNA expression in a dose-dependent manner. The results of this study show that an appropriate oral administration of IAP has sufficient pulmonary protective effects and can be used as a candidate for the development of functional food ingredients.

Use of novel postharvest Aloe vera gel coating for suppression of ripening changes in Asian pears during long‐term cold storage

SummaryThe impact of Aloe vera gel (AVG) coatings (0%, 25%, 50% and 75%) was evaluated on the ripening‐related quality parameters in ‘Patharnakh’ pear fruit during long‐term cold storage (0 ± 1 °C and 90–95% RH). Results showed that AVG coating extended the storage life of fruit by minimising mass loss, decay index, respiration rate, polyphenol oxidase activity, softening enzyme activities like pectin methylesterase (PME) polygalacturonase (PG) and cellulase and maintaining the preliminary sensory quality (SQ), firmness, soluble solid content (SSC), total phenols, titratable acidity (TA) over the control. Among all AVG treatments, 75% AVG treatment was found most promising for suppressing mass long, lowering respiration rate and preserved overall fruit quality up to 60 days of cold storage in ‘Patharnakh’ pear fruit. Hence, AVG proved as an alternative to non‐edible coatings for extending the pear's marketable span and cutting down the adverse effects of health and environmental hazards.

Identification and genetic mapping of novel resistance gene, Rvn4, for pear scab in Chinese pear

Pear scab, caused by Venturia nashicola, is one of the most harmful diseases of pears, especially of Japanese and Chinese pears. The breeding of new cultivars resistant to pear scab has long been an aim of the Asian pear breeding programs. Although loci for pear scab disease resistance have been identified in Japanese and European pears, information on the genes controlling scab resistance in Chinese pears is limited. Genetic control of scab resistance in Chinese pear is reported to involve a single dominant gene. Here, we reaffirmed the scab resistance in the Chinese pear ‘Hong Li’ controls a single dominant gene and identified the exact location of a scab resistance gene, Rvn4. We first mapped Rvn4 at the top of linkage group (LG) 7 and then used public genome sequences to develop novel simple sequence repeat (SSR) markers to enrich the target region. Using these novel SSRs and the previously published SSR markers, we constructed a LG 7 of ‘Hong Li’ with an average marker density of 1.4 cM per marker. The novel SSR marker Pbr.chr07.20 had a significant linkage to Rvn4, with a genetic distance of 1.3 cM. The identification of the precise locus of Rvn4 in Chinese pear, together with previous studies in Japanese and European pear, will enhance our understanding of the mechanisms of pear scab resistance. DNA markers linked to the novel gene may also allow efficient selection of scab-resistant seedlings in pear breeding programs and the pyramiding of multiple resistance genes.

Interspecificity of Scab Fungus Isolated from Wild Syrian Pear (Pyrus syriaca)

Scab on pear is caused by two pathogens, Venturia pyrina on European pear and V. nashicola on Asian pear. Five races of V. pyrina and seven races of V. nashicola have been reported thus far and pathological specialization occurs in both species. Among them, the five race isolates of V. pyrina were previously found from wild Syrian pear. In this study, mating and morphological characteristics of Venturia isolates from Syrian pear were compared with those of isolates from European and Japanese pear cultivated in Japan. The results from mating experiments showed that Syrian pear isolates were compatible with European pear isolates of V. pyrina to produce ascospores but were sterile with V. nashicola isolates in culture. Interestingly, however, the size and shape of conidia collected from naturally infected leaves of Syrian pear resembled those of V. nashicola. This finding may open the way to study coevolution between pear hosts and Venturia spp. in the future.

Physiochemical Changes of European Pear cv. Conference and Asian Pear cv. Yali during Cold Storage

This study evaluated the physiochemical changes of one commercial European pear variety ‘Conference’ and one Asian pear variety ‘Yali’ during 60 days of storage at 1 °C. Content of organic acids, ethylene and formation of CO2 were determined using HPLC/UV-VIS and GC/FID and TCD detectors, respectively. This study presents an evaluation of the influence of the above-mentioned factors and long-term storage on quality parameters, including the antioxidant capacity of an important European and Asian pear cultivar. There was a significant effect of temperature on respiration rate in both varieties. Development of the respiration intensity had a similar course in European and Asian pears. The high values of CO2 production at the beginning of storage for the variety ‘Conference’ (14.08 mg·kg−1·h−1) and ‘Yali’ (23.37 mg·kg−1·h−1) were followed by a sharp decline of 80% and 83% at later stages of storage at 1 °C, respectively. Ethylene formation in fruit increased with storage time and was the highest after 60 days in cold storage, especially in ‘Yali’ (7.14 µL·kg−1·h−1). The results show the relation between ethylene formation and ripening-related fruit parameters. The ‘Yali’ variety showed negligible changes in soluble solids content and flesh firmness during storage ranging from 0.35 to 0.60 MPa. The most represented sugar determined enzymatically was fructose and malic acid was the dominant organic acid in pear fruit. Antioxidant activity determined using the FRAP and DPPH methods did not change significantly during 60 days of storage.

First Report of Canker Caused by Pectobacterium actinidiae on Asian Pear Trees (Pyrus pyrifolia) in South Korea.

In July 2020, pear trees (Pyrus pyrifolia cv. Niitaka) with cankers displaying dark-red bacterial ooze on the trunk and branches were found in two pear orchards located in Naju, Jeollanam-do, South Korea (34°57'50″ N, 126°43'52″ E and 34°56'14″ N, 126°33'42″ E). The incidence was 1.5% (3 out of 200 trees) and 0.83% (1 out of 120 trees), respectively. The symptoms were similar to those of the bleeding canker caused by Dickeya fangzhongdai (Choi et al. 2021), which is typically observed in October. The bacterial ooze was suspended in sterile water and streaked in Luria-Bertani (LB) medium to isolate single bacterial colonies. Two isolates (PRI-B16 and PRI-B17) from representative diseased trees were selected for investigation. Physiological and biochemical characteristics of the isolates analyzed using the BIOLOG GEN III MicroPlate™ system (Biolog, Hayward, CA, USA) were similar to the characteristics of Pectobacterium actinidiae (Portier et al. 2019). These isolates were positively utilized stachyose, L-galactonic acid-g-lactone, guanidine hydrochloride and weakly utilized (-)-D-arabitol (Portier et al. 2019). Bacterial genomic DNA was extracted from cell cultured in 5 ml LB at 28C for 2 days using G-spin DNA extraction kit (iNtRON Biotechnology, Korea) according to the manufacturer's protocol. PCR amplification was amplified as Portier et al. (2019). The generated their sequences of the small subunit ribosomal RNA (16S rRNA) using primers 27f and 1492r (Heuer et al. 1997) (Genebank accession numbers: ON951863 and ON951864) were 99.86% and 99.76% identical, respectively, to that of P. actinidiae isolate SCPJ-1 (KY307837.1) by a BLAST search against gene bank databases. The dnaX (Genebank accession nos: ON960281 and ON960282), leuS (Genebank accession nos: ON960283 and ON960284), and recA (Genebank accession nos: ON960285 and ON960286) genes of these isolates were also amplified and sequenced by previously described Stawiak et al. (2009) for dnaX and leuS, and Waleron et al. (2002) for recA. A neighbor-joining phylogenetic analysis based on the concatenated dnaX, leuS, and recA sequences placed the two isolates in a clade containing previously identified P. actinidiae isolates. A pathogenicity test was conducted using two-year-old pear (P. pyrifolia cv. Nittaka) trees grown in a greenhouse. Wounded and unwounded pear tree branches were inoculated with 10 µL of the bacterial suspension (108 CFU/ml) or sterile water as a control. The inoculated plants were maintained at 30°C without light for 2 days under 85-90% humidity. At 7 days post-inoculation, bacterial ooze was observed on the branches inoculated with a bacterial suspension, whereas branches subjected to unwounded inoculation and water inoculation exhibited no symptoms. This assay was performed three times. We reisolated two colonies from each sample showing typical bleeding symptoms and confirmed their identity by sequencing the dnaX locus. Pectobacterium actinidiae has been reported to cause canker in pear trees in Brazil (Araujo et al. 2021) as well as kiwifruit in South Korea (Koh et al. 2012). This is the first report of P. actinidiae causing canker on pear trees in South Korea and is, therefore, pathologically significant.

A Review of Storage Temperature Recommendations for Apples and Pears.

An exploration of the range of expert opinions on the optimum storage temperature for apples and pears in RA (refrigerated air), CA (controlled atmosphere), and DCA (dynamic controlled atmosphere) is provided, based on the accumulated postharvest data from the last 20 years. Apple cultivars have been divided into two storage temperature groups (0 to 1 °C and >1 °C), based on chilling sensitivity. Increasingly, gradual cooling, rather than rapid cooling, is recommended for apple cultivars, especially for chilling-sensitive cultivars. European pear cultivars are held at storage temperatures close to or just below 0 °C since they are not chilling-sensitive, and most cultivars require a cold temperature to induce ethylene production and ripening, especially if picked early for long-term storage. Asian pears apparently have higher temperature requirements in CA, compared with European pears. The temperature recommendations for RA and CA storage differ in some apple and European pear cultivars. In such cases, the CA recommendation is, on average, approximately 0.9 °C higher for apple cultivars and approximately 0.5 °C higher for pear cultivars, compared with RA. Research evidence suggests that some apple and pear cultivars can be stored at higher temperatures in DCA than in CA, and if the ethylene inhibitor, 1-methylcyclopropene (1-MCP), is applied in CA and/or DCA, leading to possible energy savings and quality benefits. A cool growing season may increase postharvest disorders, depending on cultivar and region. The store or packinghouse manager may choose to mitigate potential postharvest problems by maintaining the storage temperature at or above the temperature listed here and/or using stepwise (gradual) cooling. The storage temperature can affect the humidity and vapour pressure deficit (driving force) in the storage room. Altering the vapour pressure deficit controls the water loss in stored fruit, which can affect various quality parameters and the occurrence of several storage disorders.

Comparison of the shoot and blossom susceptibility of European and Asian pear cultivars to fire blight across different conditions

The susceptibility of 14 pear cultivars to the bacterium Erwinia amylovora, the causal agent of fire blight disease, was evaluated using three different methods of in vivo inoculation – the leaf inoculation method on detached shoots of pear cultivars in a climate chamber, and the terminal shoot and blossom inoculation methods on potted trees of the same pear cultivars in a net house. The results of the artificial inoculations of the European and Asian pear cultivars were compared using the susceptibility score scale, as well as the ANOVA and post hoc methods. The differences among the pear cultivar susceptibility increased during the evaluation periods in the given year, but there were no significant differences between the annual evaluation in 2020 and 2021. The results of the pear cultivar susceptibility after inoculation of the detached shoots differed significantly from the results of the terminal shoot and blossom inoculation. The detached shoot susceptibility under pathogen-favourable conditions in the climate chamber was lower than the terminal shoot and blossom susceptibility in the net house for most pear cultivars. In both years, the highest values of the terminal shoot and blossom susceptibility were coincidently calculated for the Ananaska českĂĄ European old cultivar and the Nijissejkii Asian cultivar.

Pest categorisation of Xylella taiwanensis.

The EFSA Plant Health Panelperformed a pest categorisation of Xylella taiwanensis, a Gram-negative bacterium belonging to the Xanthomonadaceae. The pathogen is a well-defined taxonomic entity, and it is the causal agent of the pear leaf scorch. X. taiwanensis is present in subtropical and temperate areas of the island of Taiwan, where it affects low chilling pear cultivars of the species Pyrus pyrifolia (Asian pear). No other plant species are reported to be affected by the pathogen. The pathogen is not known to be present in the EU territory and it is not included in the Commission Implementing Regulation (EU) 2019/2072. The main pathway for the entry of the pathogen into the EU territory is host plants for planting (except seeds); another possible pathway might be represented by putative insect vectors, though their identity remains unknown. The cultivated area of P. pyrifolia in the EU territory is very limited. Conversely, the genetically related P. communis is widely cultivated in most EU Member States and there is no information so far on the susceptibility of its several cultivars. Should the pest establish in the EU, economic impact is expected, provided that suitable insect vectors are present and P. communis is as susceptible to infection as P. pyrifolia. Phytosanitary measures are available to prevent the introduction and spread of the pathogen into the EU, since plants for planting from Taiwan is a closed pathway; nonetheless, putative vectors, if confirmed and identified, may represent an additional risk of the pathogen's introduction and spread. The lack of knowledge on whether X. taiwanensis can infect P. communis, the identity and presence of suitable vectors in the EU lead to key uncertainties on entry, establishment, spread and impact. X. taiwanensis satisfies the criteria that are within the remit of EFSA to assess for this species to be regarded as a potential Union quarantine pest.

Physicochemical, antioxidative and sensory properties of pre-treated sliced pear cultivar during frozen storage

Pear is a typical fruit of temperate zones with high nutritive values and organoleptic properties, but when this fresh fruit being harvested, it will undergo chemical changes which can cause spoilage and product deterioration. Freezing could be as a preservative method to maintain quality attributes (colour, texture) of fresh produce that change over time. The purpose of this study is to determine ascorbic acid content and antioxidant activity of frozen fruit treated with osmotic solution. Pears were pre-treated with blanching, osmotic and both blanching and osmotic solution prior to freezing. Two varieties of pear fruit which are Asian pear and Packham pear were analyzed for physicochemical (colour and texture), antioxidative properties (ascorbic acid content, antioxidant activity and total phenolic content) and sensory acceptability. The pears were subjected to different pre-treatments prior to freezing such as blanching and osmotic solution during storage. The results showed that colour attributes of frozen pears were significantly affected by treatment which in contrast to texture properties of frozen pears during storage. Ascorbic acid content of frozen Packham pear was recorded the highest (6.38 ± 0.96 mg/100 g) after treated in osmotic solution compared to frozen Asian pear, the highest (4.62 ± 1.15 mg/100 g) was found in blanching treatment prior to storage, both tested after day 1 of storage. When treated in blanching treatment, the antioxidant activity of frozen Packham pear using DPPH assay exhibited (84.61 ± 0.69 %) contains high scavenging activity on day 1, while for Asian pear (67.63 ± 2.37 %) in blanching treatment on day 3. Using seven-point hedonic scale, sensory acceptability shows that frozen Asian pear treated in osmotic solution was highly rated among consumers with overall acceptance of 5.80 ± 0.85. Thus, combination of pre-treatment which were osmotic and blanching and freezing helps to retain the quality of frozen pears during period of storage.

Species-Specific Detection and Quantification of Erwinia pyrifoliae in Plants by a Direct SYBR Green Quantitative Real-Time PCR Assay

The present study describes a SYBR Green real-time quantitative (q) PCR assay to detect Erwinia pyrifoliae in plants. E. pyrifoliae, first described in South Korea, is a phytopathogenic bacterial species in the genus Erwinia. In particular, specific detection, quantitation, and identification of E. pyrifoliae is still challenging, as symptoms resulting from its colonization of Asian pear blossoms are very similar to those caused by E. amylovora. E. pyrifoliae has biochemical, phenotypic, and genetic properties similar to those of E. amylovora. Moreover, other Erwinia species, including E. tasmaniensis and E. billingiae, are also detected by currently available molecular methods and with traditional methods as well. Therefore, in this study, previously published genome sequences of the genera Erwinia and Pantoea were compared to exploit species-specific genes for use as improved qPCR targets to detect E. pyrifoliae. In silico analyses of the selected gene and designed primer sequences, in conjunction with bio-SYBR Green real-time qPCR, confirmed the robustness of this newly developed assay. Consequently, the bio-SYBR Green real-time qPCR-based protocols developed here can be used for rapid and specific detection of E. pyrifoliae. They will potentially simplify and facilitate diagnosis and monitoring of this pathogen and guide plant disease management. [Formula: see text] Copyright © 2022 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Fire blight resistance, irrigation and conducive wet weather improve Erwinia amylovora winter survival in cankers.

Erwinia amylovora causes fire blight, a disease responsible for enormous economic losses in the pome fruit-producing areas where it is present. Despite the abundant research on fire blight, information about E. amylovora population dynamics and survival in fire blight cankers and the plant defense responses to this pathogen in the infected bark are limited. In our study, we obtained fire blight cankers in apple, pear, and Asian pear cultivars showing differing resistance to the disease by shoot inoculation with E. amylovora. We collected cankers from irrigated and non-irrigated trees every 3 months in two independent field experiments and analyzed samples by viability digital PCR. We also assessed the expression of pathogenicity-related (PR) genes in the bark of selected apple and Asian pear cultivars. A logistic regression analysis revealed the impact of environmental and host factors on E. amylovora detection rates in cankers. The chances of detecting live E. amylovora cells in cankers increased significantly in those collected from irrigated trees, in July, and/or during an experiment performed in a year with an expected average rainfall when compared to samples from non-irrigated trees, collected in January, and/or during an experiment performed under environmental conditions dominated by drought. We found a positive correlation between the pathogen detection rates in cankers and the host resistance to fire blight that might be explained by lower E. amylovora survival rates in more damaged tissues of susceptible hosts. The genes PR-1, PR-2, PR-5, and PR-8 were induced in the bark surrounding apple and Asian pear fire blight cankers. Our study, involving the analysis of more than 800 canker samples, provides new knowledge about the fire blight disease cycle and lays the foundation for improved fire blight management and eradication strategies in pome fruit orchards.

An identical-by-descent segment harbors a 12-bp insertion determining fruit softening during domestication and speciation in Pyrus

BackgroundAlthough the wild relatives of pear originated in southwest China, this fruit crop was independently domesticated and improved in Asia and Europe, and there are major phenotypic differences (e.g., maturity and fruit firmness) between Asian and European pears. ResultsIn this study, we examined the genomes of 113 diverse pear accessions using an identity-by-descent (IBD) approach to investigate how historical gene flow has shaped fruit firmness traits in Asian and European pears. We found a 3-Mbp IBD-enriched region (IBD-ER) that has undergone “convergent domestication” in both the Asian and European pear lineages, and a genome-wide association study (GWAS) of fruit firmness phenotypes strongly implicated the TRANSLOCON AT THE INNER CHLOROPLAST ENVELOPE55 (TIC55) locus within this 3-Mbp IBD-ER. Furthermore, we identified a tandem duplication that includes a 12-bp insertion located in the first exon of TIC55 that is uniquely present in Asian pears, and expression analysis showed that the pear TIC55 gene is highly expressed in Asian pear, while it is weakly or not expressed in European pear; this could contribute to the differences in fruit firmness between Asian and European pear fruits.ConclusionsOur findings provide insights into how pear fruit softening has been impacted during domestication, and we identified candidate genes associated with fruit softening that can contribute to the breeding and improvement of pear and other fruit crops.

EFICIÊNCIA DE ATRATIVOS ALIMENTARES NA CAPTURA E NO MONITORAMENTO DE MOSCA-DAS-FRUTAS SUL-AMERICANA EM POMAR DE PEREIRA ASIÁTICA

ABSTRACT The South American fruit fly, Anastrepha fraterculus (Diptera: Tephritidae) is the most important insect pest in pear tree crops in Southern Brazil. Several studies pointed to the controversial efficacy of some food lures used for capture and monitoring this species in various fruit species. This study aimed to evaluate the efficacy of food lures available in the Brazilian market in capturing and monitoring A. fraterculus in relation to grape juice. The experiment was conducted during the 2014/2015 and 2015/2016 crop seasons in an Asian pear (Pyrus spp.) orchard located in Caçador, State of Santa Catarina, Brazil. The food lures evaluated were CeraTrap®, BioAnastrepha®, Torula®, Isca Mosca®, BioFruit®, and grape juice (a standard food lure in Southern Brazil). For each attractant substance, population fluctuations of A. fraterculus were recorded as well as the average number of female and male specimens captured, the FTD (fly/trap/day) rate of capture, the number of control indications, and mean weekly evaporation. The first A. fraterculus adults were captured in November, and in both crop seasons the population peak was found in January. CeraTrap® was more effective in capturing females and males and indicated a higher number of control indications compared to the other food lures. Grape juice presented lower effectiveness compared to CeraTrap®, including the evaporation parameter. It was concluded that CeraTrap® is the most effective food attractant in capturing adults of A. fraterculus and more accurate in detecting its population levels in Asian pear orchards, therefore, it is recommended rather than the usual grape juice.

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

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

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.

Improvement of Sourdough and Bread Qualities by Fermented Water of Asian Pears and Assam Tea Leaves with Co-Cultures of Lactiplantibacillus plantarum and Saccharomyces cerevisiae.

Qualities of sourdough and sourdough bread using fermented water from Asian pears and Assam tea leaves with Lactiplantibacillus plantarum 299v and Saccharomyces cerevisiae TISTR 5059 as starter cultures were evaluated. Changes in the growth of lactic acid bacteria and yeast, pH, sourdough height, total phenolic contents (TPCs) and antioxidant activities detected by ORAC, FRAP and DPPH radical scavenging assays were monitored during sourdough production. Mature sourdough was achieved within 4 h after 18 h retard fermentation and used for bread production. The bread was then analyzed to determine chemical and physical properties, nutritional compositions, TPCs, antioxidant activities and sensory properties as well as shelf-life stability. Results showed that fermented water significantly promoted the growth of yeast and increased TPCs and antioxidant activities of sourdough. Compared to common sourdough bread, fermented water sourdough bread resulted in 10% lower sugar and 12% higher dietary fiber with improved consumer acceptability; TPCs and antioxidant activities also increased by 2–3 times. The fermented water sourdough bread maintained microbial quality within the standard range, with adequate TPCs after storage at room temperature for 7 days. Fermented water from Asian pears and Assam tea leaves with L. plantarum 299v and S. cerevisiae TISTR 5059 as starter cultures improved dough fermentation and bread quality.