Pear Industry Research Articles

Isolation and Identification of Pear Ring Rot Fungus and Resistance Evaluation of Different Pear Varieties

Botryosphaeria dothidea is a significant plant pathogen responsible for causing ulcers, wilt, and fruit decay across a wide range of host plants. One notable fungal disease attributed to B. dothidea is pear tree ring rot, which currently ranks among the most severe diseases affecting pear trees in China. This pathogen primarily targets branches and fruits, occasionally impacting leaves as well, leading to tree weakening, fruit rot, and leaf drop. The annual repercussions of this disease severely affect both the yield and quality of pear fruits, thereby impeding the healthy development of the pear industry. Recent studies have indicated that other species within the B. dothidea complex can also induce pear ring rot; however, specific physiological strains of B. dothidea remain unreported. Consequently, this study collected tissues from pear trees infected with ring rot from orchards located in Liaoning, Hebei, Shandong, and other regions throughout China. Through morphological characterization combined with pathogenicity assessments and DNA sequence comparisons involving partial internal transcribed spacer (ITS), translation elongation factor (TEF), and β-tubulin (TUB) genes, 21 strains belonging to the Botryosphaeria spp. were identified. These 21 strains served as research subjects for inoculating dormant annual branches from 30 germplasm resources of pear trees in vitro. The results demonstrated that all tested strains could induce lesions on the branches which were characterized by dark brown spots. Furthermore, inoculation experiments involving these 21 strains were conducted to evaluate the resistance levels of various pear varieties against ring rot disease. The resistance was assessed by inoculating different isolates onto distinct pear varieties; this approach established the criteria for evaluating resistance while minimizing identification errors stemming from the variable responses exhibited by certain varieties towards individual strains. Ultimately, this study aims to provide a theoretical foundation for effective prevention and treatment strategies against pear ring rot.

Intraguild Predation or Spatial Separation? The efficacy and Interactions of Two Natural Enemy Species for the Biological Control of Pear Psyllid (Cacopsylla pyri)

AbstractPear psyllid (Cacopsylla pyri) is a persistent pest to the pear industry; with an estimated cost of £5 million per annum in the UK alone. This phloem feeding insect is resistant to a large proportion of approved pesticides, necessitating the use of alternative control strategies. Many pear growers practice integrated pest management (IPM) of pear psyllid, focusing on maximizing natural enemy populations, whilst minimizing the use of agrochemical sprays. The anthocorid Anthocoris nemoralis and the European earwig Forficula auricularia are particularly effective at controlling pear psyllid populations during the summer months. Despite the effectiveness of both natural enemies, there is a lack of understanding on whether both species should be promoted together or separately, due to the risk of intraguild predation (IGP) or interference competition. Furthermore, abiotic factors including temperature may influence both behaviors, altering activity level and niche overlap. Although IGP and interference competition have been documented between multiple species of natural enemies neither have been studied between these two specific predators. Using microcosm experiments, olfactometer assays and survival analyses this study demonstrated whether A. nemoralis and F. auricularia can be used in synchrony to control pear psyllid. Results indicated that IGP is present; F. auricularia will consume A. nemoralis when predators are not spatially separate and in absence of psyllid prey. There was no evidence for interference competition, although both predators consumed more prey at higher temperatures. This confirms that pear growers can encourage both predators for the control of pear psyllid without losing predation efficacy.

Re-designing a yield-improving strategy of pear orchards in the Yangtze River Basin, China.

Pear yield is a primary source of income for smallholder farmers in China, yet significant yield disparities exist among different smallholders. Systematic analyses of limiting factors and the feasibility of solutions at the smallholder level are limited. This study employs a novel DEED (Describe, Explain, Explore, and Design) research cycle centered on smallholders to formulate yield-improving strategies. A comprehensive survey of 173 smallholders in the Yangtze River pear district, encompassing Zhejiang province, Jiangxi province, and Shanghai city, was conducted to delineate the current yield status. The boundary line analysis model was applied to elucidate the contributions of various yield-limiting factors. Findings reveal an average yield ranging from 16.7 to 19.3 t ha-1, with a potential highest yield of 37.5 t ha-1. Fertilizer nitrogen (N) was identified as the most pervasive yield-limiting factor, constituting 62.7% of the average limitation at the regional level and 37.7% at the individual smallholder level, surpassing other yield-related factors in all three regions. Subsequently, a 2-year field optimization experiment was conducted to explore the potential for yield improvement through adjustments in N fertilizer rates. Compared with traditional farmer management (FM), the N fertilizer optimization treatment (OPT) resulted in a 38.1% and 22.5% increase in yield for 2022 and 2023, respectively. These results identify N fertilizer application rate as the most important yield-limiting factor and verify the feasibility of optimizing N fertilizer management practices for improving pear yield. This study integrates farmer surveys, boundary line models, and field experiments to provide valuable insights into addressing yield disparities among smallholders in the pear industry. © 2024 Society of Chemical Industry.

The Fungal Diversity and Potential Pathogens Associated with Postharvest Fruit Rot of 'Huangguan' Pear (Pyrus bretschneideri) in Hebei Province, China.

Postharvest fruit rot caused by pathogens is a serious problem in the pear industry. This study investigated the fungal diversity and main pathogens and identified a new pathogen in the stored 'Huangguan' pear (Pyrus bretschneideri Rehd.), the dominant pear variety in northern China. We sampled 20 refrigeration houses from five main producing regions in Hebei Province and used Illumina sequencing technology to detect the fungal composition. Alternaria (56.3%) was the most abundant fungus, followed by Penicillium (9.2%) and Monilinia (6.2%). We also isolated and identified nine strains of Alternaria and four strains of Penicillium. Moreover, we observed a new postharvest fruit disease in 'Huangguan' pear caused by Stemphylium eturmiunum, which was confirmed by phylogenetic analysis by combining the sequences of three conserved genes, including internal transcribed spacer, gapdh, and calmodulin. This study marks the first documentation of S. eturmiunum causing fruit rot in 'Huangguan' pears, offering valuable insights for identifying and controlling this newly identified postharvest disease.

Uncovering the mechanisms underlying pear leaf apoplast protein-mediated resistance against Colletotrichum fructicola through transcriptome and proteome profiling

Pear anthracnose, caused by the fungus Colletotrichum fructicola, is a devastating disease for the pear industry. The apoplast, an extracellular compartment outside the plasma membrane, plays a crucial role in water and nutrient transport, as well as plant-microbe interactions. This study aimed to uncover the molecular mechanism of pear leaf apoplastic protein-mediated resistance to C. fructicola. Apoplast fluid was isolated using the vacuum infiltration method, and defence-related apoplastic proteins were identified through protein mass spectrometry and transcriptome sequencing. We found 213 apoplastic proteins in the leaf apoplast fluid during early C. fructicola infection, with the majority (74.64%) being enzymes, including glycosidases, proteases, and oxidoreductases. Gene Ontology analysis revealed their involvement in defence response, enzyme inhibition, carbohydrate metabolism, and phenylpropanoid biosynthesis. Transcriptome analysis showed the infection induced expression of certain apoplast proteins, potentially contributing to pear leaf resistance. Notably, the expression of PbrGlu1, an endo-β-1,3-glucanase from the glycoside hydrolase 17 family, was significantly higher in infected leaves. Silencing of the PbrGlu1 gene increased pear leaf susceptibility to C. fructicola, leading to more severe symptoms and higher reactive oxygen species content. Overall, our study provides insights into the apoplast space interaction between pear leaves and C. fructicola, identifies a key gene in infected pears, and offers a foundation and new strategy for understanding the molecular mechanisms underlying pear anthracnose and breeding disease-resistant pears.

Assay for transposase accessible-chromatin with high throughput sequencing (ATAC-seq) analysis the molecular responses of postharvest pear during Penicillium expansum infection

Blue mold decay caused by Penicillium expansum is a global destructive postharvest disease, which has brought huge economic losses to the pear industry. Transcription factors play an important role in pear anti-infection defense, and it has been observed that they have multiple functions. However, the roles of numerous TFs in the defense of pear against P. expansum have not been adequately explored. In this study, ATAC-seq was used to screen the TFs of pear against P. expansum, thereby understanding the chromatin-mediated gene regulation in the defense of pear against infection. The peak of differential expression enriched 9 transcription factors (AGL27, AT5G02460, AT2G28810, AT5G66940, AT3G46070 and OBP1, TCP3, BPC1 and TCP17). The up-regulated genes in our study were implicated in the MAPK signaling pathway-plant, plant hormone signal transduction pathway, plant-pathogen interaction pathway, glutathione metabolism pathway, phenylpropanoid biosynthesis, flavonoid biosynthesis pathway and carotenoid biosynthesis pathway were identified. Especially the transcription factors TGA, gene SAUR and CYCD3 in plant hormone signal transduction pathway and NCED, CYP707A in carotenoid biosynthesis pathway were differentially regulated. RT-qPCR analysis of twelve randomly selected differentially expressed peak-related genes confirmed the accuracy of ATAC-seq analysis of P. expansum infected pear.

Functional Analysis of PbbZIP11 Transcription Factor in Response to Cold Stress in Arabidopsis and Pear.

Cold stress is a prominent abiotic factor that adversely affects the growth and yield of pears, consequently restricting the cultivation range and resulting in substantial economic losses for the pear industry. Basic region-leucine zipper (bZIP) transcription factors are widely involved in multiple physiological and biochemical activities of plants, particularly in response to cold stress. In this study, the responsiveness of PbbZIP11 in pear to cold stress was investigated, and its role was explored by using pear callus and Arabidopsis thaliana. The findings revealed that overexpression of PbbZIP11 enhanced the tolerance of pear callus and Arabidopsis thaliana to cold stress. The antioxidant enzyme activities of transgenic plants were enhanced and the expression of C-repeat binding transcription factor (CBF) genes was increased as compared to wild-type plants. To better understand the biological function of PbbZIP11, mRNAs were isolated from overexpressed and wild-type Arabidopsis thaliana after cold stress for whole-genome sequencing. The results showed that the expression of some CBF downstream target genes changed after exposure to cold stress. The results suggested that the PbbZIP11 gene could participate in cold-stress signaling through the CBF-dependent pathway, which provides a theoretical basis for the PbbZIP11-mediated response to cold stress and for the genetic breeding of pear varieties with low-temperature tolerance.

Consumers’ Preferences for Novel and Traditional Pear Cultivars: Evidence from Sensory Evaluation and Willingness-to-pay Elicitation

A significant challenge faced by the US Pacific Northwest pear industry is the limited availability of diverse pear cultivars beyond conventional selections. This scant availability of new pear options that align with consumers’ consistent quality preferences falls short of their expectations and jeopardizes potential demand growth, which poses a threat to the industry’s long-term economic viability. We use a combined approach of sensory evaluation and contingent valuation to uncover preferences and willingness to pay (WTP) for specific pear cultivars, encompassing both novel and traditional types. The outcomes reveal that the key determinants driving WTP are taste and texture attributes. Particularly for early-season pears, a greater liking score for flavor, firmness, and juiciness corresponds to an elevated WTP. For late-season pears, the range of quality attributes expands to encompass overall appearance and sweetness, in addition to the aforementioned factors. Participants who use social media to access information about pears exhibit a heightened WTP. These findings provide valuable insights for the industry to consider revitalizing existing pear orchards through the incorporation of alternatives to conventional pear cultivars.

Specific functions of single pistil S-RNases in S-gene homozygous Pyrus germplasm

Gametophytic self-incompatibility (SI) is regulated by S-allele recognition; that is, pollen in a style with the same S-genotype will undergo programmed cell death and stop growing so that it is unable to complete double fertilization, ultimately resulting in the SI response. S-RNase is the female determinant of SI in pear (Pyrus). In the Pyrus genome, there are two different S-RNase alleles at the S-locus, which generate two different S-RNase products in the pistil. The extracted S-glycoprotein is actually a protein complex. In this study, artificial self-pollination was conducted at the bud stage to overcome SI in ‘Huanghua’ (S1S2) pear. Seven plants homozygous for S1-RNase and four homozygous for S2-RNase were selected from the selfed progeny of ‘Huanghua’ by S-gene molecular identification biotechnology. We investigated the function of single S-RNases isolated from the pistils of S-gene homozygous Pyrus germplasm. The pollen of ‘Huanghua’ could smoothly pass through the style of the S-gene homozygous germplasm and complete fertilization. S-RNases were extracted from flower styles of different genotypes and used to treat different types of pollen. The S-RNase from ‘Huanghua’ completely inhibited the growth of S1S2, S1S1, and S2S2 pollen, while the S-RNase from homozygous germplasm allowed some S1S2 pollen and different single genotypes of pollen to continue growing. These results further validate the core events of SI including cytoskeleton depolymerization and programmed cell death. By iTRAQ-based proteomic analysis of style proteins, a total of 13 S-RNase-related proteins were identified. In summary, we have created reliable S-RNase gene homozygous germplasm, which will play a crucial role in further research on SI in pear and in the development of the pear industry.

Molecular characteristics and hypovirulence of different RNA viruses in Alternaria spp. strains, the pathogenic agent of pear black spot disease in China

Pear black spot (Alternaria spp.) disease widespread in most pear production regions in China, causes early defoliation, which leads to the decline of fruit quality and heavily restricts the healthy development of the pear industry. Presently, no efficient way was found to biocontrol pear black spot disease. The mycovirus-mediated hypovirulent strain is regarded as an important measure of biocontrol of the fungal disease. Therefore, it is particularly urgent to excavate mycoviral resources with hypovirulence in Alternaria spp. strains. This study obtained partial or complete genomes of 14 mycoviruses from 83 Alternaria spp. strains from Wuhan city of China by high throughput sequencing, including 3 double-stranded (ds) RNA and 11 positive single-stranded (+ss) types, which were grouped into 8 distinct lineages, belonging to Chrysoviridae (isolate of AaCV1), Curvulaviridae (one virus), Partitiviridae (one virus), Mitoviridae (three viruses), Botourmiaviridae (five viruses), Deltaflexiviridae (one virus), Fusariviridae (one virus) and Togaviridae (one virus). The multiple mycoviral coinfections were common and prevalent, accounting for 78 % (65/83), with each strain harboring different numbers of mycoviruses, ranging from two to seven in Alternaria spp. Furthermore, the effects of the mycoviruses on the host were analyzed to screen the viruses-inducing hypovirulent strains. The derivative isolates from hypovirulent HB-145 with different mycoviruses were obtained by vertical transmission. It revealed that the mycoviruses have different effects on the virulence of derivative isolates from HB-145. In conclusion, these findings provide important molecular information for the classification, origin, and genetic variety of mycoviruses, and candidate materials for the exploitation of mycoviruses as biocontrol agents.

Applications of 1-methylcyclopropene concentrations and timing in relation to sunlight-related core browning in ‘Bartlett’ pears after extending regular-air storage

Core browning (CB) is a crucial physiological disorder that occurs in ‘Bartlett’ pears after excessive storage. Furthermore, environmental factors such as sunlight exposure cause serious related disorders during storage. 1-methylcyclopropene (1-MCP) positively delays the development of disorders, but results in poor eating quality at retail. Therefore, the primary purpose of this study was to evaluate whether sunlight exposure impacts the development of CB in ‘Bartlett’ pears and to develop optimal postharvest 1-MCP strategies for the pear industry to extend the fruit’s lifespan and deliver desirable eating quality to consumers that prefer melting texture. Over the course of a three-year evaluation, sunlight-exposed (SE) pears consistently displayed a higher CB index than the control and non-exposed (NE) pears after 150 d of regular-air (RA) storage at − 1.1 ± 0.5 °C plus 5 d at 20 ± 0.5 °C. The rapid development of CB was facilitated by decreases in ethylene production rate (EPR), peel chlorophyll content (PCC), and titratable acidity associated with increases in malondialdehyde and soluble o-quinones. Applying 0.15 and 0.3 μL L−1 1-MCP after 15 d of harvest completely protected the fruit from CB for up to 150 d of RA storage. However, these treated pears did not ripen. Lowering the 1-MCP concentration to 0.075 μL L−1 and postponing treatment to 60 d after harvest could control the CB index in the 1.53–2.33 range with a normal ripening process. For SE pears, the use of 0.15 μL L−1 1-MCP applied after 60 d of harvest reduced the CB index to 1.63 without impairing ripening capacity. It was difficult for the pear industry to monitor the EPR of 1-MCP-treated pears over the entire storage period. However, when the PCC of the treated pears fell to 0.4–0.5 IAD after 5 d of ripening, these pears could recover their ethylene generation capacity and softening behavior. Overall, the 0.15–0.075 μL L−1 1-MCP applied after 60 d of harvest provided great benefits in delaying CB development, improving storability, and retaining ripening capacity in SE ‘Bartlett’ pears following the prolonged RA storage.

High-Quality Genome Resource of Nothophoma quercina Causing Brown Spot Disease in Pears

Brown spot, a serious disease caused by Nothophoma quercina, results in small, brown, round-to-oval lesions on the leaves and is a major concern in the pear industry. We previously reported a new pathogenic strain NqHH of Nothophoma quercina, which was isolated from ‘Huanghua’ pear ( Pyrus pyrifolia Nakai, cultivar Huanghua) leaves. However, genome information regarding this pathogen is limited. Herein, we detected the genome-wide sequence of the NqHH strain using the Illumina NovaSeq 6000 and PacBio Sequel Ⅱ systems. The genome of NqHH was estimated to be 35.3 Mb with an N50 length of 1.37 Mb, encoding for 11,659 predicted protein-coding genes. This genome sequence provides valuable information for the selection of pathogenic effectors and comparative genomics of brown spot disease in pears. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license .

Exploring the efficacy of carvacrol as a biocontrol agent against pear Valsa canker

Valsa canker, a fungal disease caused by Valsa pyri, poses a significant threat to the pear industry. Currently, chemical control serves as the primary method to control valsa canker. However, the emergence of resistance can pose a challenge to its effectiveness. Biopesticides are a relatively new option for disease control, but there is limited research on their effects on pear Valsa canker. To determine the effectiveness of different biopesticides, we selected 10 common biopesticides to test their inhibition efficacy and impacts on mycelial growth rate and conidial germination. Results showed that carvacrol had very good antifungal activity; therefore its inhibition mechanisms were further investigated. Electron microscopy and transcriptome data analysis were utilized to examine how carvacrol impeded V. pyri by inducing mycelium deformation, wrinkling, and rupture. Carvacrol also affected plant hormones, thus improving plant resistance to the disease. This study lays the groundwork for the utilization of 10 distinct biopesticides to control V. pyri while elucidating how carvacrol harms the pathogen and prompts the plant defense control mechanism.

Study on the Fragrant Pear-Picking Sequences Based on the Multiple Weighting Method

The production of the Korla fragrant pear is significant, but the optimal harvesting time is short; therefore, the reasonable use of mechanical arms for harvesting is conducive to promoting the sustainable development of the fragrant pear industry. The efficiency of a robot arm when picking fragrant pears is not only determined by the successful extraction of fragrant pears in a complex environment, but the picking sequence of fragrant pears also directly affects the efficiency of the robot arm. In order to simulate an orchard-picking scenario, this paper built three fragrant pear tree models indoors. The number of fragrant pears on the fragrant pear trees was 5, 10, and 20. Three sets of experiments were designed for comparison with real-world conditions. The main steps were as follows: calibrate the three-dimensional coordinates of each fragrant pear on the fragrant pear trees; determine the end position of the robotic arm at each picking point; find the inverse solution for each group; transform the solutions into matrix form using the rated power of each joint as the weight, and identify the minimum value, which is the angle of each joint in the robotic arm when picking the fragrant pear; use the intelligent socket to find the average energy consumption and average time consumed for picking each group of fragrant pears; and determine the loss ratio of the robotic arm based on the amount of rotation in each joint during picking. The experimental results show that the multiple weighting method reduced the energy consumption by 10.627%, 16.072%, and 24.417%, and the time consumption by 11.988%, 14.428%, and 22.561%, respectively, relative to the hybrid ant colony–particle swarm optimization algorithm, which proves the rationality of the fragrant pear picking order delineated using the multiple weighting method.

Detection of Internal Browning Disorder in ‘Greensis’ Pears Using a Portable Non-Destructive Instrument

Internal browning caused by prolonged cold storage poses a significant challenge to the visual appearance and flavor of Asian pears, which are economically valuable and a primary fruit exported from Korea. To address this issue, we established a cost-effective portable non-destructive piece of testing instrument using visible and near-infrared spectroscopy, focusing on the detection and discrimination of internal browning in ‘Greensis’ pears. Our investigation underscores the challenge of visually confirming browning, necessitating alternative methods for accurate assessment. Through comprehensive analysis involving three to four segments of 32 ‘Greensis’ pears, a robust calibration equation was derived. By employing partial least square regression on the absorption spectra within a 650–950 nm range, we developed a predictive model for detecting and quantifying browning. Through principal component analysis, normal pears were distinctly segregated from those exhibiting browning symptoms (discrimination accuracy of 95%). Furthermore, we established that pears with a browning index of 25 ± 2.0 are highly susceptible to browning following extended cold storage. Consequently, our proposed portable non-destructive instrument serves as a pivotal tool for farmers and fruit distributors, enabling efficient and precise selection of high-quality pears in an instance. Overall, our study introduces a practical solution to a pressing issue in the Asian pear industry.

Isolation and characterization of three bacteriophages infecting Erwinia amylovora and their potential as biological control agent

BackgroundFire Blight, incited by Erwinia amylovora, is one of the most damaging pear and apple diseases in the world. Fire blight was introduced to Egypt in the 1960 and threatens the Egypt’s costs for pear industry. Currently, Phage therapy is considered to be secured biological method for controlling plant bacterial diseases. This investigation aimed to isolate and identify molecularly for bacteria causing fire bright disease. As well as isolation and identification bacteriophages via spot and plaque assay techniques from pear fire blight lesions and soil. On the other hand, bacteriophages were identified based on plaque morphology, virion morphology, physical characters, profile of DNA restriction and protein.ResultsPathogenicity test revealed that healthy seedlings and pear fruits were responsive to fire blight E. amylovora. Considering the relatively wide host range and greatest protein and genetic variability, using restriction enzyme pattern, the three diversity phage isolates named, EAP1, EAP2 and EAP3 showed a lack of diversity out of five were fatherly characterized. The phages confirmed the close relation of EAP1, EAP2 to Siphoviridae (hexagonal head and long flexible non-contractile tail) and EAP3 to Myoviridae (icosahedral head and contractile tail). The phages retained higher lytic competence of 90.4; 92.68 and 95.25% for EAP1, EAP2 and EAP3, respectively. The phages were stable at strong alkaline (pH 10) 2% salt solution conditions and UV spectra. While EAP3 phage revealed the hexagonal head and very short tail that belongs to Myoviridae family. Bacteriophages were characterized by digestion of the phage DNA with three restriction endonucleases and were placed into three groups based on the patterns. Bacteriophages were 9 used for reducing bacterial infection populations and severity on pear. In a bioassay, the biocontrol of E. amylovora was evaluated using disks of immature pear fruit. On the pear disk surface, bacterial exudate was considerably suppressed by all phage isolates. According to measurements of the bacterial population still present on the disk surface, phage therapy could reduce it by up to 97%. Bacteriophages reduced pear fire blight disease severity on pear fruit trails.ConclusionThe results indicated that bacteriophage isolates may demonstrate variable reactivity against E. amylovora. Bacteriophages reduced pear fire blight disease severity on pear fruit trials. The results indicated that bacteriophage isolates may demonstrate variable reactivity against E. amylovora.

Physiological disorders, textural property, and cell wall metabolism of ‘Gem’ pears (Pyrus communis L.) affected by oxygen regimes and harvest maturity under controlled atmosphere storage

The primary purpose of this study was to develop optimal controlled atmosphere (CA) strategies for the pear industry to utilize ‘Gem’ pears. The influences of two O2 regimes (1.0% O2 and 2.2% O2 [commercial practice concentration] with ∼0.05% CO2) on decay, physiological disorders (i.e. internal breakdown, superficial scald, and black speck), storage and eating quality attributes, cell wall components, and cell wall-modifying enzymes were evaluated at two harvest maturities (H1; 48.01 N; H2; 42.19 N) of ‘Gem’ pears. Earlier harvested pears (H1) stored under regular-air (RA) conditions had lower rates of superficial scald and internal breakdown relative to later harvested pears (H2), especially in extended storage (8–10 months). However, storage and eating quality for air-stored H1 and H2 fruit deteriorated after 6 months. CA regimes extended ‘Gem’ storage longevity from 8 to 10 months, with 1.0% O2 resulting in lower incidences of superficial scald and internal breakdown disorders and higher peel chlorophyll content and titratable acidity by delaying the peak of ethylene production rate (EPR) compared to 2.2% O2. Notably, the rates of black speck in H1 and H2 fruit were controlled at below 5% in both O2 regimes. Furthermore, 1.0 and 2.2% O2 stored H1 and H2 pears ripened and developed a melting texture with full flavor and juiciness during 6–8 months of storage. Additionally, the water-soluble (WSP), cyclohexanetrans-1,2-diaminetetra-soluble (CSP), and Na2CO3-soluble polyuronides (SSP) combined with pectin methylesterase (PME), α-arabinofuranosidase (α-ARF), and β-galactosidase (β-GAL) contributed to fruit softening and desirable eating quality in ‘Gem’ pears. In conclusion, 2.2% O2 with ∼0.05% CO2 improved the fruit quality of ‘Gem’ pears harvested at 48.01 N, while the quality of fruit harvested at 42.19 N or below could be improved by the application of 1.0% O2.

Jasmonic acid negatively regulates branch growth in pear.

The quality of seedlings is an important factor for development of the pear industry. A strong seedling with few branches and suitable internodes is ideal material as a rootstock for grafting and breeding. Several branching mutants of pear rootstocks were identified previously. In the present study, 'QAU-D03' (Pyrus communis L.) and it's mutants were used to explore the mechanism that affects branch formation by conducting phenotypic trait assessment, hormone content analysis, and transcriptome analysis. The mutant plant (MP) showed fewer branches, shorter 1-year-old shoots, and longer petiole length, compared to original plants (OP), i.e., wild type. Endogenous hormone analysis revealed that auxin, cytokinin, and jasmonic acid contents in the stem tips of MP were significantly higher than those of the original plants. In particular, the jasmonic acid content of the MP was 1.8 times higher than that of the original plants. Transcriptome analysis revealed that PcCOI1, which is a transcriptional regulatory gene downstream of the jasmonic acid signaling pathway, was expressed more highly in the MP than in the original plants, whereas the expression levels of PcJAZ and PcMYC were reduced in the MP compared with that of the original plants. In response to treatment with exogenous methyl jasmonate, the original plants phenotype was consistent with that of the MP in developing less branches. These results indicate that jasmonic acid negatively regulates branch growth of pear trees and that jasmonic acid downstream regulatory genes play a crucial role in regulating branching.

Comparative growth, hydraulic conductivity, and sap flow responses of seedlings of two pyrus species to drought stress

Drought is one of the major abiotic stresses limiting the advancement of the pear industry in the arid and semiarid regions of China. Currently, the production of pear seedlings mainly depends on the grafting propagation of rootstocks from Pyrus betulaefolia Bunge and Pyrus calleryana Decne. However, limited information is available on the drought stress potential of these rootstocks. Here, we conducted pot experiments with controlled watering conditions on both rootstocks' seedlings and compared their growth, plant hydraulic conductivity, and stem sap flow velocity. Both rootstocks' seedlings were challenged with three drought regimes i.e. light (LD), moderate (MD), and heavy (HD) drought stress. The results indicated that P. betulaefolia performed better in growth than P. calleryana under the same drought regimes. Under LD, MD, and HD the relative growth of the new shoots, leaf-specific canopy hydraulic conductivity, leaf, stem, and root hydraulic conductivity, and stem sap flow velocity of P. betulaefolia exhibited reduction as compared to control (CK). Similar reduction trends were noted for P. calleryana, with slight variations in the case of stem-specific canopy hydraulic conductivity.

Non-destructive quality assessment method for Korla fragrant pears based on electrical properties and adaptive neural-fuzzy inference system

This study aimed to achieve the rapid and non-destructive quality assessment of Korla fragrant pears, thereby maximising the value of damaged pears and improving the market supply–demand balance. The electrical characteristics of damaged Korla fragrant pears were measured using a fruit electrical property detector and the trends in the quality of the fragrant pears within their shelf life were analysed. The quality of damaged Korla fragrant pears was predicted by using an adaptive neural-fuzzy inference system (ANFIS). Electrical properties were used as inputs to the system and quality was the output of the system. A total of eight functional models with different degrees of membership were constructed and the optimal one was selected. The results demonstrated that the equivalent parallel capacitance (Cp) of the damaged Korla fragrant pears increased gradually throughout their shelf life, while equivalent parallel resistance (Rp) and complex impedance (Z) decreased. Additionally, the green–red difference (a*) increased gradually, while hardness and soluble solid content (SSC) decreased continuously. Based on the combination of electrical properties and the ANFIS, gbellmf was the optimal model to determine the SSC of the damaged Korla fragrant pears (R2 = 0.9123) and gaussmf was the optimal model to determine the hardness and a* of the damaged Korla fragrant pears (R2 = 0.9112 and 0.8853, respectively). It was concluded that the combined use of electrical properties and the ANFIS method enabled the successful quality assessment of fragrant pears. This approach was conducive to facilitating the optimisation and updating of non-destructive quality assessment technologies for fragrant pears, promoting quality and efficiency improvement in the fragrant pear industry.