Pear Research Articles

Real-time tracking of fish quality using a cellulose filter paper colorimetric indicator incorporated with prickly pear fruit betacyanins

In the present work, a freshness indicator was developed by immobilizing extracted betacyanins from prickly pear fruit (PFB) onto cellulose filter paper to visually determine fish spoilage. Various properties of the prepared indicator, including color stability, moisture uptake, sensivity to hydrogen sulfide (H2S) gas and pH changes, and chemical analysis were studied. The PFB-based indicator exhibited good color stability at various temperatures and times, with no significan color changes observed during storage at 25, 4, and −18 °C for 8 days. The moisture absorption of the indicator based on PFB was lower than that of cellulose paper, which is crucial for colorimetric indicators. Basic nitrogen and sulfur compounds are the main volatile compounds produced during fish spoilage. The results of the present study showed that both total volatile basic nitrogen (TVB-N) and H2S gas produced during fish spoilage contributed to the color changes of betacyanin-based colorimetric indicators. The prepared freshness indicators were pH-sensitive, with significant color changes due to TVB-N and H2S production during fish storage. A significant correlation was observed between fish quality (pH, TVB-N and total viable count) and the visible color changes of the indicators. The color of the designed indicator shifted from dark pink to pale pink/white during fish storage. These prepared freshness indicators were inexpensive, easy to use, and non-toxic, making them suitable for assessing the quality and shelf life of fish fillets.

Exogenous GA3 Enhances Nitrogen Uptake and Metabolism under Low Nitrate Conditions in 'Duli' (Pyrus betulifolia Bunge) Seedlings.

'Duli' (Pyrus betulifolia Bunge) is one of the main rootstocks of pear trees in China. Gibberellin (GA) is a key plant hormone and the roles of GA in nitrate (NO3-) uptake and metabolism in plants remain unclear. In this study, we investigated the effects of exogenous GA3 on the N metabolism of 'Duli' seedlings under NO3- deficiency. The results showed that exogenous GA3 significantly improves 'Duli' growth under NO3- deficiency. On the one hand, GA3 altered the root architecture, increased the content of endogenous hormones (GA3, IAA, and ZR), and enhanced photosynthesis; on the other hand, it enhanced the activities of N-metabolizing enzymes and the accumulation of N, and increased the expression levels of N absorption (PbNRT2) and the metabolism genes (PbNR, PbGILE, PbGS, and PbGOGAT). However, GA3 did not delay the degradation of chlorophyll. Paclobutrazol had the opposite effect on growth. Overall, GA3 can increase NO3- uptake and metabolism and relieve the growth inhibition of 'Duli' seedlings under NO3- deficiency.

Ultrasound-assisted extraction of betalain-rich bioactive compounds of prickly pear fruit: An optimization study

There is currently an increasing interest in obtaining bioactive components and natural pigments by novel extraction technologies. Betalains are plant-derived secondary metabolites with functional characteristics, suitable for use in food products. Conventional (CE) and ultrasound-assisted extraction (UAE) have been studied to extract betalain-rich bioactive compounds from prickly pear fruit (Opuntia ficus-indica L.). Box-Behnken design was used in response surface methodology to predict the optimal conditions for each parameter based on total betalain content (TBC), total phenolic content (TPC), and antioxidant capacity (TAC). In addition, the antimicrobial activity of the extracts at optimal conditions was investigated against Salmonella enteritidis (ATCC 13076), Escherichia coli O157: H7, and Listeria monocytogenes. Results indicated that optimal conditions for CE were achieved at 2.05-h extraction time, 50 °C, 80% ethanol concentration, and a 1/22.60 solid/solvent ratio, while for UAE, optimal conditions were at 30-min extraction time, 49.99 °C, 40% ethanol concentration, and a 1/30 solid/solvent ratio. The predicted and experimental TBC values for CE were 419.449 and 418.829 mg betalain/kg dry matter, respectively, and for UAE, they were 472.883 and 471.818 mg betalain/kg dry matter. The extracts demonstrated antimicrobial activity solely against Salmonella enteritidis (ATCC 13076). UAE proved more efficient, extracting betalain-rich bioactive compounds in 75% less time compared to CE. Therefore, UAE emerges as a promising novel technology for obtaining natural pigments and bioactives from prickly pear.

Cascading Effects of Boron Application Methods on Nutrient Distribution and Metabolite Profiles in Pear Trees

Cascading Effects of Boron Application Methods on Nutrient Distribution and Metabolite Profiles in Pear Trees

First report of postharvest pear bitter rot caused by Colletotrichum acutatum in Italy.

The fungal genus Colletotrichum includes numerous important plant pathogenic species, some of which causes fruit bitter rot as well as leaf lesions (leaf black spot) on major crops, leading to yield losses (Fu et al. 2019; Talhinhas & Baroncelli, 2023). C. acutatum was reported associated with black spot on fallen, immature fruit of pear (Pyrus pyrifolia) in New Zealand (Damm et al. 2012); however, to our knowledge, this species has not been reported in Italy or nowhere else. In 2022, a significant increase of anthracnose symptoms was observed on pears in Emilia-Romagna region, Italy. Symptoms, such as round brown lesions of 1 to 4 cm, appeared on more than 50% of refrigerated stored fruit. These symptoms were undetectable at the end of September 2022 and appeared after a five-month period of storage (February 2023) at 4°C (e-Xtra 1A and B). Fungal isolates were obtained from symptomatic pears after surfaces sterilization with 96% ethanol by culturing necrotic tissue pieces on Potato Dextrose Agar at 25°C in the dark (e-Xtra 1C and D). Cultures were shades of coral color, from opalescent to sunkist coral, with slight aerial mycelium becoming grey and darker with age. When observed from the reverse side, the color was pink and, with age, became coral orange to dark amaranth. Conidia observed with a light microscope appeared hyaline and fusiform, 8 to 16 × 2.5 to 4 μm, with two pointed ends or one rounded end. (e-Xtra 1E) One reference isolate, named L51, was used for molecular characterization. Total genomic DNA was extracted, and the ITS region of rDNA amplified using the universal primers ITS1 and ITS4, then sequenced. The resulting sequences were 100% identical to those of C. acutatum (NR_144794.1: strain CBS 112996 ITS region; from TYPE material). Based on Damm et al. (2012), partial ACT, GAPDH, CHS and TUB2 gene sequences were also amplified and sequenced (GenBank Accession numbers: ITS: OR882016, ACT: OR882013, GAPDH: OR882011, CHS: OR882012, TUB2: OR882010), to characterize the isolates. Additionally, the multilocus phylogenetic analysis carried out with the obtained and reference sequences (Damm et al. 2012) revealed the species of analyzed isolates and confirmed the BLAST results, identifying the strain as C. acutatum (e-Xtra 1F). Koch's postulates were performed on 10 'Kaiser' pears. Surfaces sterilized fruits with 96% ethanol were subjected to wound inoculation with a conidial suspension (106 conidia ml-1) while 10 fruit were used as negative control and inoculated with sterile water. Following an incubation period of 8-14 days at 15-20°C, symptoms around the inoculation site resembled those initially observed, while the negative control showed no symptoms. Fungal colonies re-isolated from the lesions exhibited the same morphological characteristics as the original isolates. To our knowledge, this is the first report of pear bitter rot caused by C. acutatum in Italy and in Europe (Talhinhas & Baroncelli, 2023). Yet, bitter rot had not been recognized as a notable issue in pear cultivation. Nevertheless, given that pears rank as the 8th most cultivated fruit globally and economically very significant for the Emilia Romagna region in Italy the emergence of pear bitter rot caused by Colletotrichum species has the potential to evolve into a significant worldwide problem, warranting further investigation.

Implementation and Evaluation of Attention Aggregation Technique for Pear Disease Detection

In this study, a novel approach integrating multimodal data processing and attention aggregation techniques is proposed for pear tree disease detection. The focus of the research is to enhance the accuracy and efficiency of disease detection by fusing data from diverse sources, including images and environmental sensors. The experimental results demonstrate that the proposed method outperforms in key performance metrics such as precision, recall, accuracy, and F1-Score. Specifically, the model was tested on the Kaggle dataset and compared with existing advanced models such as RetinaNet, EfficientDet, Detection Transformer (DETR), and the You Only Look Once (YOLO) series. The experimental outcomes indicate that the proposed model achieves a precision of 0.93, a recall of 0.90, an accuracy of 0.92, and an F1-Score of 0.91, surpassing those of the comparative models. Additionally, detailed ablation experiments were conducted on the multimodal weighting module and the dynamic regression loss function to verify their specific contributions to the model performance. These experiments not only validated the effectiveness of the proposed method but also demonstrate its potential application in pear tree disease detection. Through this research, an effective technological solution is provided for the agricultural disease detection domain, offering substantial practical value and broad application prospects.

High-Efficiency In Vitro Root Induction in Pear Microshoots (Pyrus spp.).

Extensive research has been conducted on the in vitro mass propagation of pear (Pyrus spp.) trees through vegetative propagation, demonstrating high efficiency in shoot multiplication across various pear species. However, the low in vitro rooting rates remain a significant barrier to the practical application and commercialization of mass propagation. This study aims to determine the favorable conditions for inducing root formation in the in vitro microshoots of Pyrus genotypes. The base of the microshoots was exposed to a high concentration (2 mg L-1) of auxins (a combination of IBA and NAA) for initial root induction at the moment when callus formation begins. The microshoots were then transferred to an R1 medium (1/2 MS with 30 g L-1 sucrose without PGRs) to promote root development. This method successfully induced rooting in three European pear varieties, one Asian pear variety, and a European-Asian hybrid, resulting in rooting rates of 66.7%, 87.2%, and 100% for the European pear (P. communis), 60% for the Asian pear (P. pyrifolia), and 83.3% for the hybrid pear (P. pyrifolia × P. communis) with an average of 25 days. In contrast, the control group (MS medium) exhibited rooting rates of 0-13.3% after 60 days of culture. These findings will enhance in vitro root induction for various pear varieties and support the mass propagation and acclimatization of pear. The in vitro root induction method developed in this study has the potential for global commercial application in pear cultivation.

Exploring Recycled Polyethylene Terephthalate (PET) Based Cushioning Design to Reduce Bruise Damage in Pears

Post-harvest activities, which include sorting, loading, unloading, and transporting, are potential factors that cause mechanical damage and bruises to fresh produce. This would directly impact fruit shelf-life and, therefore, cause economic losses. This study developed a finite element (FE) model for pear fruit where a steel impactor drop-based test was utilized. The FE model was validated by evaluating it as the experimental model in order to identify bruises of the pear fruit. Therefore, to minimize bruises on the pear fruit, a recycled polyethylene terephthalate (PET) spring-based design was proposed in order to serve as a cushioning design for pear fruits. Design of experiments and response surface methodology were performed in order to minimize the fruit bruise susceptibility response subject to different spring design parameters. The results revealed that reduced spring pitch and increased coil thickness would significantly minimize bruises of pear fruit. The recycled PET proposed design proved its efficiency in reducing FE pear fruit model bruises by about 50%. This study provides insights on assessing bruise susceptibility using finite element analysis and reusing plastic for fresh produce packaging, thus reducing loops in supply chains and achieving a circular economy.

Effects of exogenous GA, IAA, ABA and ethylene on pear (Pyrus pyrifolia) fruit during different development stages

Effects of exogenous GA, IAA, ABA and ethylene on pear (Pyrus pyrifolia) fruit during different development stages

Elucidating the role of prickly pear fruits (Opuntia littoralis) in mitigation of cadmium toxicity in Nile tilapia: impacts on haemato-biochemical and immunological responses

Elucidating the role of prickly pear fruits (Opuntia littoralis) in mitigation of cadmium toxicity in Nile tilapia: impacts on haemato-biochemical and immunological responses

An ‘activator-repressor’ loop controls the anthocyanin biosynthesis in red-skinned pear

The color of red-skinned pear (Pyrus spp.) is primarily attributed to accumulation of anthocyanins, which provide nutritional benefits for human health and are closely associated with the commercial value of fruits. Here, we reported the functional characterization of a R2R3-MYB repressor PyMYB107, which forms an ‘activator-repressor’ loop to control anthocyanin accumulation in the red-skinned pear. PyMYB107 overexpression inhibited anthocyanin biosynthesis in both pear calli and fruits, while virus-induced gene silencing of PyMYB107 increased anthocyanin accumulation in pear fruits. Furthermore, ectopic expression of PyMYB107 decreased anthocyanin accumulation in tomato, strawberry and tobacco. PyMYB107 can competitively bind to PybHLH3 with PyMYB10/MYB114, thereby suppressing the transcriptional activation of key anthocyanin biosynthesis genes, PyANS and PyUFGT. Site-directed mutagenesis showed that mutations within the R3 domain and EAR motif of PyMYB107 eliminated its repressive activity. Additionally, PyMYB107 exhibited a comparable expression pattern to PyMYB10/MYB114 and was transcriptionally activated by them. Our finding advanced comprehension of the repression mechanism underlying anthocyanin accumulation, providing valuable molecular insights into improving quality of pear fruits.

PbbHLH137 interacts with PbGIF1 to regulate pear fruit development by promoting cell expansion to increase fruit size.

The regulation of fruit development is a complex process and a core issue in the fruit tree industry. To investigate the role of PbGIF1 in pear fruit development, we identified a transcription factor PbbHLH137 that regulates pear (Pyrus bretschneideri) fruit development by screening a yeast library constructed from fruit cDNA. Yeast two-hybrid (Y2H), bimolecular fluorescence complementation (BiFC), and split luciferase complementation (split-LUC) assays were performed to confirm the PbbHLH137-PbGIF1 interaction. By tracing the complete fruit development process, we found that PbbHLH137 expression was closely related to fruit size and highly involved at the late pear fruit development stage. Transgenic experiments showed that heterologous expression of PbbHLH137 or PbGIF1 promoted fruit enlargement. PbbHLH137 promoted mainly the expansion of fruit cell volume, whereas PbGIF1 mainly increased the number of cells. Further LUC experiments demonstrated that PbGIF1 promoted the transcriptional activation ability of PbbHLH137. Our work identified PbbHLH137 as a transcription factor that regulates fruit development, and showed that PbGIF1 played an ongoing role during fruit development, making it a candidate gene for genetic improvement of pear fruit development.

A novel, intelligent and computer-assisted electrochemical sensor for extraction and simultaneous determination of patulin and citrinin in apple and pear fruit samples

In this work, a novel electrochemical sensor was fabricated for simultaneous determination of patulin (PT) and citrinin (CT) in apple and pear fruit samples. A glassy carbon electrode (GCE) was modified with graphene-multiwalled carbon nanotubes-ionic liquid (Gr-MWCNTs-IL) which was used as a platform to electrochemical synthesis of molecularly imprinted polymers (MIPs) by using PT and CT as templates, maleic acid as a functional monomer, and ethylene glycol dimethacrylate as a cross linker with the aim of preconcentration and simultaneous determination of the PT and CT. Experimental variables affecting fabrication of the structure of the sensor and hydrodynamic differential pulse voltammetric (HDPV) response of the sensor were optimized by a small central composite design and desirability function. After optimization, the HDPV responses of the sensor were calibrated by multivariate calibration methods in the ranges of 0.5–13 fM and 1.5–18 fM for PT and CT, respectively, with the help of PLS-1, RBF-PLS, rPLS, LS-SVM, and RBF-ANN with the aim of selecting the best algorithm to assist the sensor. Our results confirmed the best performance was observed from RBF-ANN which was used for the analysis of apple and pear fruit samples. Limit of detections of the sensor assisted by RBF-ANN for determination of PT and CT were 0.08 and 0.61 fM, respectively. Several commercial brands were analyzed by the use of sensor assisted by RBF-ANN and HPLC-UV, and the results confirmed performance of the sensor was admirable and comparable with the reference method with lower cost, faster response, and easier procedure which made it to be a reliable alternative method for simultaneous determination of PT and CT in real matrices.

Emergence Characteristics of Fire Blight from 2019 to 2023 in Korea

Erwinia amylovora is a gram-negative plant pathogen that causes fire blight in apple and pear trees, resulting in significant damage worldwide. In this study, we monitored the emergence of fire blight from 2019 to 2023 to determine the emergence patterns and the factors affecting the outbreak of the disease. As a result of the 5-year survey on the emergence of fire blight, a total of 2,029 cases have emerged, mostly in apple trees of 1,378 cases (67.9%) followed by 645 cases (31.8%) in pear trees, and from quince, hawthorn, and mountain ash trees. Fire blight appeared in specific areas of Gyeonggi, Chungnam, Gangwon, and Chungbuk provinces in 2019, but spread to Andong and Yesan in 2021, Muju and Bonghwa in 2023. In 2020 and 2021, there were 744 and 618 cases of fire blight outbreaks, respectively, compared to other years (188–245 cases/year). Notably, 914 of these cases were observed in apple trees from May to July, with 667 cases reported in Chungju and Jecheon. The incidence of fire blight was positively correlated with the daily maximum temperatures and rainy days in January and February, as well as the rainy days in May and June. The average age of the diseased pear trees was 25 years, higher than the 10-year average age of the apple trees. This study provides fundamental information to understand the status and factors affecting the fire blight emergence in Korea. Prevention measures should be established through continuous analysis of the status of fire blight.

Changes of Sensitivity to Streptomycin in Erwinia amylovora Isolated from 2019 to 2023 in Korea

Erwinia amylovora, a causal pathogen of fire blight, has been continuously inducing damage to the apple and pear trees in South Korea since 2015. Farmers apply antibiotics during blooming season to prevent the fire blight. However, continuous use of antibiotics can induce the emergence of resistant bacteria, which consequently reduces control efficacy. In this study, we assessed the minimal inhibitory concentration (MIC) of streptomycin, using a total of 361 E. amylovora isolates that were collected from the six provinces of South Korea from 2019 to 2023. As a result, the MIC of streptomycin ranged from 0.5 to 4 µg/ml and the strA-strB genes were not identified from the isolates. The MIC was higher in the isolates from Gyeonggi-do, Gangwon-do, and Chungcheongbuk-do compared to those from other three provinces. These results may bring broad attention to the use of streptomycin and aid in developing a management protocol for the occurrence of fire blight in South Korea.

Interconnected pyrolysis and activation with in-situ H3PO4 activation of biochar from pear wood chips in a pilot scale dual fluidized bed

Interconnected pyrolysis and activation is a novel technology for combustible gas and biochar production in dual fluidized bed (DFB). The study proposed one-step and two-step methods for pyrolysis and activation of biomass in a pilot scale DFB with capacity of 100 kg/h. Physical and chemical activation occurred simultaneously in DFB system by phosphoric acid (H3PO4) impregnation pretreatment of pear wood chips, and flowing hot flue gas and steam. Stable operating parameters were observed for both methods. The one-step method was superior to the two-step method in terms of the pyrolysis gas quality, biochar pore distribution, micro- and meso-pores structures of biochar, while one-step method reduced the biochar yields. As an activation agent, H3PO4 increased the yields of biochar and pyrolysis gas, promoted formation of micropores and enriched the surface functional groups of biochar with increasing ratio of H3PO4. H3PO4 to biomass ratio of 1:5 reached the maximum biochar yield of 42.3 wt% and highest iodine adsorption value of 648.5 mg/g, increasing by 70.6 % and 90.3 % compared to the biochar without H3PO4 pretreatment, respectively. This DFB system facilitated the diversified use of fluidized beds and the co-production of biochar and product gas with energy saving and CO2 emission reduction.

α-Lipoic acid treatment regulates enzymatic browning and nutritional quality of fresh-cut pear fruit by affecting phenolic and carbohydrate metabolism

Fresh-cut pear fruit is greatly impacted by enzymatic browning, and maintaining quality remains a challenge. This study examined the impact of exogenous α-lipoic acid (α-LA) treatment on enzymatic browning and nutritional quality of fresh-cut pears. Results revealed that 0.5 g/L α-LA treatment effectively maintained color and firmness, and inhibited the increase in microbial number. The α-LA treatment also reduced MDA and H2O2 contents, decreased PPO activity, and enhanced SOD, CAT, and PAL activities. The α-LA treatment notably upregulated phenolic metabolism-related gene expression, including PbPAL, Pb4CL, PbC4H, PbCHI and PbCHS, and then increasing total phenols and flavonoids contents. Furthermore, it also influenced carbohydrate metabolism-related gene expression, including PbSS, PbSPS, PbAI and PbNI, maintaining a high level of sucrose content. These findings indicated that α-LA treatment showed promise in reducing browning and enhancing fresh-cut pears quality, offering a potential postharvest method to prolong the lifespan and maintain nutritional quality.

Object–Environment Fusion of Visual System for Automatic Pear Picking

A visual system is a key tool for automatic fruit harvesting. It faces the challenges of varied occlusion and illumination in the field, resulting in difficulties in fruit recognition and picking. At present, there are many studies that lack a comprehensive analysis of the impact of the environment on harvesting. This study proposes an object–environment fusion visual system. It comprises modules for object perception, environment perception, and picking pose estimation. The object perception module aims to identify and locate pears. The environment perception module is deployed to analyze the three-dimensional (3D) information of objects and obstacles. Finally, the picking pose estimation module fuses the information of the objects and environment to calculate the collision-free picking position and orientation. Additionally, specific implementations are employed for each module. It compares three networks to identify pears for object perception. Voxel-based representation is used to simplify point clouds for environmental perception. A sampler and evaluator are applied for picking pose estimation. The S1 and S2 datasets were acquired in a laboratory pear tree model and the orchard of Zhejiang Academy of Agricultural Sciences, respectively, to evaluate the proposed method. In the S2 dataset, the success rate for picking pose estimation reached 87.11% within the distance range of 30∼50 cm. All of the results demonstrate that the proposed method can be applied to visual perception for automatic pear harvesting.

ECOLOGY OF THE NILGIRI LARGE BURROWING SPIDER HAPLOCLASTUS NILGIRINUS POCOCK, 1899 (ARANEAE, THERAPHOSIDAE) OF NILGIRIS, INDIA

The Nilgiri large burrowing spider, Haploclastus nilgirinus Pocock, 1899, an endemic tarantula in the Nilgiris Region of India, is critical for conservation yet poorly understood in terms of its ecology and habitat. This study addresses this gap by examining the nesting habits, tree-hole dynamics, and prey diversity of the species in Coonoor, The Nilgiris, specifically within tea plantations and fruit orchards. Observations focused on seven pear trees serving as nesting sites, with detailed measurements of nesting holes, including outer and inner circumference, depth, trunk base, ground-based height (gbh), and height from the ground. Data were collected over four consecutive months, both morning and evening. Insect diversity in the orchard was also assessed through counts and diversity indices, revealing variability among trees. The seventh tree had the highest spider population, with 13 spiders in 10 nests. Insect orders such as Blattodea, Orthoptera, Diptera, Hemiptera, and Lepidoptera were most prevalent around the seventh tree’s nests. Across all trees, a total of 25 spiders in 21 nests were documented, with variations in hole size and other tree measurements. This research provides crucial insights into the nesting habits, tree-hole dynamics, and prey diversity of this species, informing conservation efforts for this vulnerable species. As H. nilgirinus faces threats from habitat destruction, climate change, and illegal trade, understanding its ecological needs is vital for developing effective conservation strategies and sustaining ecosystem health.

Calcium lactate treatment modulated fatty acid metabolism to attenuate senescence in ‘Jinfeng’ pear fruit during storage

Fatty acid metabolism not only affects cell membrane functionality but also correlates with the fruit quality and postharvest senescence. This study aims to assess the influence of calcium lactate immersion on lipid metabolism and senescence in ‘Jinfeng’ pear fruit during room temperature storage. The results demonstrated that calcium lactate effectively suppressed malondialdehyde content, respiratory rate, mass loss, and ethylene release, as well as phospholipase D (PLD), hydroperoxide lyase (HPL), lipoxygenase (LOX), lipase (LPS), alcohol acyltransferase (AAT), and alcohol dehydrogenase (ADH) activities in ‘Jinfeng’ pears. Additionally, calcium lactate resulted in an up-regulation of the gene expression levels associated with fatty acid biosynthesis, including PcACC, PcFabG, PcFabI, PcFabZ, PcKASII, PcACP, and PcFAD. Furthermore, there was an increase in the expression of genes involved in fatty acid elongation, such as PcKCS4, PcKCS6, PcKCS7, PcKCS10, PcLACS2, PcLACS4, PcLACS8, and PcCER. Conversely, it caused a down-regulation of the gene expression levels associated with fatty acid degradation, including PcLOX, PcAAT, PcADH, PcPLD, PcACD, PcECH, and PcACOX3. Simultaneously, calcium lactate treatment diminished the content of palmitic acid, while elevating the contents of linolenic acid, linoleic acid, and oleic acid. In summary, postharvest calcium lactate-immersed can efficaciously retard senescence of ‘Jinfeng’ pear fruit through regulating fatty acid lipid metabolism.