Unraveling a Small Secreted Peptide SUBPEP3 That Positively Regulates Salt-Stress Tolerance in Pyrus betulifolia.

Small secreted peptides (SSPs) play important roles in regulating plants' growth and development in response to external stimulus, but the genes and functions of SSPs in many species are still unknown. Therefore, it is particularly significant to characterize and annotate SSP genes in plant genomes. As a widely used stock of pears, Pyrus betulifolia has strong resistance to biotic and abiotic stresses. In this study, we analyzed the SSPs genes in the genome of P. betulifolia according to their characteristics and homology. A total of 1195 SSP genes were identified, and most of them are signaling molecules. Among these, we identified a new SSP, subtilase peptide 3 (SUBPEP3), which derived from the PA region of preSUBPEP3, increasing the expression level under salt stress. Both adding synthetic peptide SUBPEP3 to the culture medium of pears and the overexpression of SUBPEP3 in tobacco can improve the salt tolerance of plants. In summary, we annotated the SSP genes in the P. betulifolia genome and identified a small secreted peptide SUBPEP3 that regulates the salt tolerance of P. betulifolia, which provides an important theoretical basis for further revealing the function of SSPs.

Comparative physiological and transcriptomic analysis reveals an improved biological control efficacy of Sporidiobolus pararoseus Y16 enhanced with ascorbic acid against the oxidative stress tolerance caused by Penicillium expansum in pears.

Sporidiobolus pararoseus Y16, a species of significant ecological importance, has distinctive physiological and biological regulatory systems that aid in its survival and environmental adaptation. The goal of this investigation was to understand the complex interactions between physiological and molecular mechanisms in pear fruits as induced by S. pararoseus Y16. The study investigated the use of S. pararoseus Y16 and ascorbic acid (VC) in combination in controlling blue mold decay in pears via physiological and transcriptomic approach. The study results showed that treatment of S. pararoseus Y16 with 150 µg/mL VC reduced pears blue mold disease incidence from 43% to 11%. Furthermore, the combination of S. pararoseus Y16 and VC significantly inhibited mycelia growth and spore germination of Penicillium expansum in the pear's wounds. The pre-treatment did not impair post-harvest qualities of pear fruit but increased antioxidant enzyme activity specifically polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT) activities as well as phenylalanine ammonia-lyase (PAL) enzyme activity. The transcriptome analysis further uncovered 395 differentially expressed genes (DEGs) and pathways involved in defense mechanisms and disease resistance. Notable pathways of the DEGs include plant-pathogen interaction, tyrosine metabolism, and hormone signal transduction pathways. The integrative approach with both physiological and transcriptomic tools to investigate postharvest pathology in pear fruits with clarification on how S. pararoseus Y16 enhanced with VC, improved gene expression for disease defense, and create alternative controls strategies for managing postharvest diseases.

Genome-wide identification of GA2ox genes family and analysis of PbrGA2ox1-mediated enhanced chlorophyll accumulation by promoting chloroplast development in pear.

BACKGROUND: Chlorophyll (Chl) is an agronomic trait associated with photosynthesis and yield. Gibberellin 2-oxidases (GA2oxs) have previously been shown to be involved in Chl accumulation. However, whether and how the PbrGA2ox proteins (PbrGA2oxs) mediate Chl accumulation in pear (Pyrus spp.) is scarce. RESULTS: Here, we aimed to elucidate the role of the pear GA2ox gene family in Chl accumulation and the related underlying mechanisms. We isolated 13 PbrGA2ox genes (PbrGA2oxs) from the pear database and identified PbrGA2ox1 as a potential regulator of Chl accumulation. We found that transiently overexpressing PbrGA2ox1 in chlorotic pear leaves led to Chl accumulation, and PbrGA2ox1 silencing in normal pear leaves led to Chl degradation, as evident by the regreening and chlorosis phenomenon, respectively. Meanwhile, PbrGA2ox1-overexpressing (OE) tobacco plants discernably exhibited Chl built-up, as evidenced by significantly higher Pn and Fv/Fm. In addition, RNA sequencing (RNA-seq), physiological and biochemical investigations revealed an increase in abscisic acid (ABA), methyl jasmonate (MeJA), and salicylic acid (SA) concentrations and signaling pathways; a marked elevation in reducing and soluble sugar contents; and a marginal decline in the starch and sucrose levels in OE plants. Interestingly, PbrGA2ox1 overexpression did not prominently affect Chl synthesis. However, it indeed facilitated chloroplast development by increasing chloroplast number per cell and compacting the thylakoid granum stacks. These findings might jointly contribute to Chl accumulation in OE plants. CONCLUSION: Overall, our results suggested that GA2oxs accelerate Chl accumulation by stimulating chloroplast development and proved the potential of PbrGA2ox1 as a candidate gene for genetically breeding biofortified pear plants with a higher yield.

Sucrose, cell wall, and polyamine metabolisms involve in preserving postharvest quality of 'Zaosu' pear fruit by L-glutamate treatment.

'Zaosu' pear fruit is prone to yellowing of the surface and softening of the flesh after harvest. This work was performed to assess the influences of L-glutamate treatment on the quality of 'Zaosu' pears and elucidate the underlying mechanisms involved. Results demonstrated that L-glutamate immersion reduced ethylene release, respiratory intensity, weight loss, brightness (L*), redness (a*), yellowness (b*), and total coloration difference (ΔE); enhanced ascorbic acid, soluble solids, and soluble sugar contents; maintained chlorophyll content and flesh firmness of pears. L-glutamate also restrained the activities of neutral invertase and acid invertase, while enhancing sucrose phosphate synthetase and sucrose synthase activities to facilitate sucrose accumulation. The transcriptions of PbSGR1, PbSGR2, PbCHL, PbPPH, PbRCCR, and PbNYC were suppressed by L-glutamate, resulting in a deceleration of chlorophyll degradation. L-glutamate concurrently suppressed the transcription levels and enzymatic activities of polygalacturonases, pectin methylesterases, cellulase, and ß-glucosidase. It restrained polygalacturonic acid trans-eliminase and pectin methyl-trans-eliminase activities as well as inhibited the transcription levels of PbPL and Pbß-gal. Moreover, the gene transcriptions and enzymatic activities of arginine decarboxylase, ornithine decarboxylase, S-adenosine methionine decarboxylase, glutamate decarboxylase, γ-aminobutyric acid transaminase, glutamine synthetase along with the PbSPDS transcription was promoted by L-glutamate. L-glutamate also resulted in the down-regulation of PbPAO, PbDAO, PbSSADH, PbGDH, and PbGOGAT transcription levels, while enhancing γ-aminobutyric acid, glutamate, and pyruvate acid contents in pears. These findings suggest that L-glutamate immersion can effectively maintain the storage quality of 'Zaosu' pears via modulating key enzyme activities and gene transcriptions involved in sucrose, chlorophyll, cell wall, and polyamine metabolism.

A novel fluorescent probe with a large Stokes shift for colorimetric and selective detection of cysteine in water, milk, cucumber, pear and tomato.

Cysteine is an important amino acid that is related to human health and food safety. How to effectively detect Cys in food has received widespread attention. Compared with other methods, fluorescent probes have the advantages of simple operation, high sensitivity, and good selectivity. Therefore, a selective fluorescence probe 2 for Cys in food was designed and synthesized. Probe 2 employed the acrylate group as a thiol-recognition site for Cys, which endowed probe 2 with better selectivity for Cys over Hcy and GSH. The recognition pathway underwent Michael addition, intramolecular cyclization, and concomitant release of the piperideine-based fluorophore, along with a chromogenic change from yellow to orange. This pathway was supported by 1H NMR analysis and DFT calculations. In addition, probe 2 displays a linear response to Cys concentrations (0-30 µM), low detection limit (0.89 µM), and large Stokes shift (125 nm). Overall, probe 2 showed great application potential for the quantitative determination of Cys in water, milk, cucumber, pear and tomato.

Identification and expression analysis of ATP-binding cassette (ABC) transporters revealed its role in regulating stress response in pear (Pyrus bretchneideri).

BACKGROUND: ATP-binding cassette (ABC) transporter proteins constitute a plant gene superfamily crucial for growth, development, and responses to environmental stresses. Despite their identification in various plants like maize, rice, and Arabidopsis, little is known about the information on ABC transporters in pear. To investigate the functions of ABC transporters in pear development and abiotic stress response, we conducted an extensive analysis of ABC gene family in the pear genome. RESULTS: In this study, 177 ABC transporter genes were successfully identified in the pear genome, classified into seven subfamilies: 8 ABCAs, 40 ABCBs, 24 ABCCs, 8 ABCDs, 9 ABCEs, 8 ABCFs, and 80 ABCGs. Ten motifs were common among all ABC transporter proteins, while distinct motif structures were observed for each subfamily. Distribution analysis revealed 85 PbrABC transporter genes across 17 chromosomes, driven primarily by WGD and dispersed duplication. Cis-regulatory element analysis of PbrABC promoters indicated associations with phytohormones and stress responses. Tissue-specific expression profiles demonstrated varied expression levels across tissues, suggesting diverse functions in development. Furthermore, several PbrABC genes responded to abiotic stresses, with 82 genes sensitive to salt stress, including 40 upregulated and 23 downregulated genes. Additionally, 91 genes were responsive to drought stress, with 22 upregulated and 36 downregulated genes. These findings highlight the pivotal role of PbrABC genes in abiotic stress responses. CONCLUSION: This study provides evolutionary insights into PbrABC transporter genes, establishing a foundation for future research on their functions in pear. The identified motifs, distribution patterns, and stress-responsive expressions contribute to understanding the regulatory mechanisms of ABC transporters in pear. The observed tissue-specific expression profiles suggest diverse roles in developmental processes. Notably, the significant responses to salt and drought stress emphasize the importance of PbrABC genes in mediating adaptive responses. Overall, our study advances the understanding of PbrABC transporter genes in pear, opening avenues for further investigations in plant molecular biology and stress physiology.

Biocontrol activity and potential mechanism of volatile organic compounds from Aspergillus niger strain La2 against pear Valsa canker.

BACKGROUND: Valsa canker caused by Valsa pyri is one of the most destructive diseases of pear, leading to severe yield and economic losses. Volatile organic compounds (VOCs) from endophytes have important roles in the regulation of plant disease. In this study, we investigated the biocontrol activity of the endophytic fungus Aspergillus niger strain La2 and its antagonistic VOCs against pear Valsa canker. RESULTS: Strain La2 exhibited an obvious inhibitory effect against V. pyri. A colonization assay suggested that strain La2 could complete its life cycle on pear twigs. The symptoms of pear Valsa canker were weakened on detached pear twigs after treatment with strain La2. In addition, VOCs from strain La2 also significantly suppressed mycelial growth in V. pyri. Based on the results of headspace solid-phase microextraction/gas chromatography-mass spectrometry analysis, six possible VOCs produced by strain La2 were detected, of which 2,4-di-tert-butylphenol and 4-methyl-1-pentanol were the main antagonistic VOCs in terms of their effect on pear Valsa canker in vitro and in vivo. Further results showed that 4-methyl-1-pentanol could destroy the V. pyri hyphal structure and cell membrane integrity. Importantly, the activities of pear defense-related enzymes (polyphenol oxidase, phenylalanine ammonia lyase and superoxide dismutase) were enhanced after 4-methyl-1-pentanol treatment in pear twigs, suggesting that 4-methyl-1-pentanol might induce a plant disease resistance response. CONCLUSION: Aspergillus niger strain La2 and its VOCs 2,4-di-tert-butylphenol and 4-methyl-1-pentanol have potential as novel biocontrol agents of pear Valsa canker. © 2024 Society of Chemical Industry.

Enhancing productivity, modifying biochemical parameters, and regulating the phenylpropanoid pathway in 'Le-Conte' pears through optimal protocatechuic acid treatments.

BACKGROUND: This study aimed to investigate the impact of protocatechuic acid (PRC) treatments on the productivity and fruit quality of 'Le-Conte' pears, with a specific focus on productivity, stone cells content, and antioxidant activity. The research spanned over three consecutive cultivating seasons, with the first season serving as a preliminary study to determine the optimal PRC concentrations and the most effective number of spray applications. During the initial season, response surface methodology (RSM) was employed to optimize PRC concentration and application frequency. PRC was evaluated at concentrations ranging from 50 to 400 ppm, with treatment frequencies of either once or twice. Considering the optimal conditions obtained from RSM results, PRC treatments at 200 ppm and 300 ppm were applied twice, and their respective effects were studied in comparison to the control in the following seasons. RESULTS: RSM results indicated that PRC at 200 and 300 ppm, applied twice, once during full bloom and again three weeks later, yielded the most significant effects. Subsequent studies revealed that PRC treatments had a substantial impact on various aspects of fruit production and quality. Applying 300 ppm PRC once during full bloom and again three weeks later resulted in higher fruit set percentages, lower fruit abscission, and enhanced fruit yield compared to untreated trees. Additionally, the 200 ppm PRC treatment maintained physicochemical characteristics such as fruit color, increased total soluble solids (TSS), and total sugar, and maintained higher ascorbic acid content and antioxidant capacity in the fruits while reducing stone cells content and lignin. Notably, enzyme activities related to phenylpropanoid metabolism and stone cells, including phenylalanine ammonia-lyase (PAL), cinnamate-4-hydroxylase (C4H), 4-Coumarate-CoA Ligase (4CL), cinnamyl alcohol dehydrogenase (CAD), and cinnamoyl-CoA reductase (CCR), as well as peroxidase, polyphenol oxidase, and laccase, were significantly regulated by PRC treatments. CONCLUSION: Overall, this study suggests that PRC treatments are suitable for enhancing pear yield and quality, with PRC at 200 ppm being the more recommended option over 300 ppm. This approach serves as an effective strategy for achieving a balance between enhancing the productivity and fruit quality of 'Le-Conte' pears.

Improved Dosimetry with Daily Online Adaptive Radiotherapy for Cervical Cancer: Waltzing the Pear.

AIMS: Standard of care radiotherapy for locally advanced cervical cancer includes large margins to ensure the uterocervix remains within the treatment fields over the course of treatment. Daily online cone-beam adaptive radiotherapy corrects for interfractional changes by adjusting the plan to match the target position during each treatment session, thus allowing for significantly reduced clinical target volume (CTV) to planning target volume (PTV) margins. We hypothesise that reduced margins from daily online adaptive radiotherapy will reduce organ at risk dose without compromising target coverage. MATERIALS AND METHODS: Ten patients with cervical cancer (stage IIB-IIIC2) were treated with definitive chemoradiation using daily online cone-beam adaptive radiotherapy in 25-27 fractions. Initial and all adapted treatment plans were generated with CTV to PTV margins versus standard of care image-guided radiotherapy (IGRT) plans as follows: cervix/uterus/gross tumour volume (0.5 versus 1.5 cm), parametria/vagina (0.5 versus 1.0 cm) and nodal chains and gross nodes (0.5 versus 0.5 cm). IGRT plans were created and copied to synthetic computed tomography scans and contours generated from each daily adapted fraction. The dosimetry of each clinically treated online adapted fraction was compared with emulated IGRT plans. Statistical significance was defined as P < 0.05. RESULTS: Daily online cone-beam adaptive radiotherapy significantly improves bowel bag dosimetry compared with IGRT, with a reduction in V40 by an average of 91.3 cm3 [V40 (-6.2%) and V45 (-6.1%)]. The daily adapted plans showed significant improvements in bladder and rectum [V40 (-25.2% and -36.0%) and V30 (-9.7% and -17.1%), respectively]. Additionally, bone marrow had a significantly reduced dose [V10 (-2.7%) and V20 (-3.3%)]. Daily online cone-beam adaptive radiotherapy improved uterocervix CTV coverage and reduced hotspots compared with IGRT [D95% (+1.6%) and Dmax (-0.9%)]. CONCLUSIONS: Reduced CTV to PTV margins achievable with daily online adaptive radiotherapy improves organ at risk dosimetry and target coverage when compared with standard of care IGRT for locally advanced cervical cancer. The clinical impact of improved dosimetry is currently undergoing investigation.

Techno-functional properties of active film based on guar gum-propolis and its application for "Nanguo" pears preservation.

Guar gum (GG) composite films, incorporating the ethanolic extract of propolis (EEP), were prepared and subjected to a comprehensive investigation of their functional characteristics. The addition of EEP resulted in a discernible enhancement in the opacity, moisture barrier capacity, and elongation at break. Incorporating EEP led to a noteworthy increase in the total phenolic and total flavonoid content of the films, resulting in superior antioxidant capacity upon GG-EEP films. Remarkably, the addition of 5 % EEP yielded noteworthy outcomes, manifesting in a DPPH radical scavenging rate of 47.60 % and the ABTS radical scavenging rate of 94.87 %, as well as FRAP and cupric reducing power of 331.98 mmol FeSO4-7H2O kg-1 and 56.95 µg TE mg-1, respectively. In addition, GG-EEP films demonstrated antifungal effect against Penicillium expansum and Aspergillus niger, along with a sustained antibacterial effect against Escherichia coli and Staphylococcus aureus. GG-EEP films had superior inhibitory ability against Gram-positive bacteria than Gram-negative bacteria. Crucially, GG-EEP composite films played a pivotal role in reducing both lesion diameter and depth, concurrently mitigating weight loss and firmness decline during the storage period of "Nanguo" pears. Therefore, GG-EEP composite films have the considerable potential to serve as advanced and effective active packaging materials for food preservation.

Transcription factor PbNAC71 regulates xylem and vessel development to control plant height.

Dwarfism is an important agronomic trait in fruit breeding programs. However, the germplasm resources required to generate dwarf pear (Pyrus spp.) varieties are limited. Moreover, the mechanisms underlying dwarfism remain unclear. In this study, "Yunnan" quince (Cydonia oblonga Mill.) had a dwarfing effect on "Zaosu" pear. Additionally, the dwarfism-related NAC transcription factor gene PbNAC71 was isolated from pear trees comprising "Zaosu" (scion) grafted onto "Yunnan" quince (rootstock). Transgenic Nicotiana benthamiana and pear OHF-333 (Pyrus communis) plants overexpressing PbNAC71 exhibited dwarfism, with a substantially smaller xylem and vessel area relative to the wild-type controls. Yeast one-hybrid, dual-luciferase, chromatin immunoprecipitation-qPCR, and electrophoretic mobility shift assays indicated that PbNAC71 downregulates PbWalls are thin 1 expression by binding to NAC-binding elements in its promoter. Yeast two-hybrid assays showed that PbNAC71 interacts with the E3 ubiquitin ligase PbRING finger protein 217 (PbRNF217). Furthermore, PbRNF217 promotes the ubiquitin-mediated degradation of PbNAC71 by the 26S proteasome, thereby regulating plant height as well as xylem and vessel development. Our findings reveal a mechanism underlying pear dwarfism and expand our understanding of the molecular basis of dwarfism in woody plants.

Genome-wide identification of the Pyrus R2R3-MYB gene family and PhMYB62 regulation analysis in Pyrus hopeiensis flowers at low temperature.

The R2R3-MYB gene family play an important role in plant growth, development and stress responses. In this study, a total of 122 PcoR2R3-MYB genes were identified and grouped into 26 clades in pear. And these PcoMYBs were unevenly distributed among 17 chromosomes. The sequence characteristics, conversed motifs, exon/intron structures, classification, duplication events and cis-acting elements were also investigated. The gene duplication events showed that segmental duplication may play key roles in expansion of the PcoMYB gene family. Pyrus hopeiensis, which is a valuable wild resource, has strong cold resistance. An integrative analyses of miRNA and mRNA showed that PhMYB62 was involved in regulating low-temperature stress in P. hopeiensis flower organs. Subcellular localization analysis showed that PhMYB62 protein was specifically localized to the nucleus. The result of DAP-seq showed that PhMYB62 responded to low-temperature stress in P. hopeiensis by regulating TFs, which were associated with plant stress resistance, and POD, GAUT12, AUX28 and CHS genes. Subsequently, yeast one-hybrid verified that PhMYB62 could bind and activate the promoter of POD gene. The current study would provide a comprehensive information for further functional research on the stress-responsive R2R3-MYB gene candidates in pear, and may help to identify the genes associated with cold resistance for the cultivation of cold-resistant pear varieties.

PbBPC4 involved in a xylem-deficient dwarf phenotype in pear by directly regulating the expression of PbXND1.

Dwarfing is an important agronomic trait in fruit breeding. At present, dwarf cultivars or dwarfing rootstocks are used for high-density planting. Although some dwarf rootstocks have been used in the cultivation of pear (Pyrus bretschneideri Rehd), the breeding of dwarf pear rootstocks or cultivars is still sorely lacking. A previous study reported that PbXND1 results in a xylem-dwarf phenotype in pear trees. However, the regulatory mechanism upstream of PbXND1 is unclear. In this study, we identified PbBPC4 as an upstream regulatory factor of PbXND1 in yeast one-hybrid assays. In ß-glucuronidase staining and dual-luciferase assays, PbBPC4 enhanced the activity of the PbXND1 promoter. Tobacco plants overexpressing PbBPC4 showed decreased plant height because of a reduced xylem size. Similar changes in the xylem was observed in transgenic pear roots; those overexpressing PbBPC4 showed reduced xylem size, and those with silencing PbBPC4 expression showed increased xylem size, greater density of xylem vessels, and a larger proportion of the xylem out of the total cross-section area. Expression analyses showed that PbBPC4 increases the transcription of PbXND1, leading to reduced transcript levels of genes involved in the positive regulation of xylem development, ultimately resulting in a xylem-deficient dwarf phenotype. Taken together, our results reveal the mechanism by which PbBPC4 participates in the regulation of xylem development via directly altering the expression of PbXND1, thus leading to the dwarf phenotype in pear. These findings have reference value for the breeding of dwarf pear trees.

BdCV1-Encoded P3 Silencing Suppressor Identification and Its Roles in Botryosphaeria dothidea, Causing Pear Ring Rot Disease.

Pear ring rot disease is an important branch disease, caused by Botryosphaeria dothidea. With the discovery of fungal viruses, the use of their attenuated properties for biological control provides a new strategy for the biological control of fungal disease. RNA silencing is a major antiviral defense mechanism in plants, insects, and fungi. Viruses encode and utilize RNA silencing suppressors to suppress host defenses. Previous studies revealed that Botryosphaeria dothidea chrysovirus 1 (BdCV1) exhibited weak pathogenicity and could activate host gene silencing by infecting B. dothidea. The aim of our study was to investigate whether BdCV1 can encode a silencing suppressor and what effect it has on the host. In this study, the capability of silencing inhibitory activity of four BdCV1-encoded proteins was analyzed, and the P3 protein was identified as a BdCV1 RNA silencing suppressor in the exotic host Nicotiana benthamiana line 16c. In addition, we demonstrated that P3 could inhibit local silencing, block systemic RNA silencing, and induce the necrosis reaction of tobacco leaves. Furthermore, overexpression of P3 could slow down the growth rate and reduce the pathogenicity of B. dothidea, and to some extent affect the expression level of RNA silencing components and virus-derived siRNAs (vsiRNAs). Combined with transcriptomic analysis, P3 had an effect on the gene expression and biological process of B. dothidea. The obtained results provide new theoretical information for further study of interaction between BdCV1 P3 as a potential silencing suppressor and B. dothidea.

Anti-Diabetic Potential of Polyphenol-Rich Fruits from the Maleae Tribe-A Review of In Vitro and In Vivo Animal and Human Trials.

The Maleae tribe consists of over one thousand species, including many well-known polyphenol-containing fruit crops with wide-ranging biological properties, e.g., apples (Malus), chokeberries (Aronia), pears (Pyrus), quinces (Cydonia, Chaenomeles), saskatoon (Amelanchier), loquats (Eriobotrya), medlars (Mespilus), rowans (Sorbus), and hawthorns (Crataegus). Considering the current interest in the concept of functional foods and the still-insufficient methods of diabetes management, the anti-diabetic potential of fruits has been studied intensively, including those of the Maleae tribe. This paper is the first comprehensive overview of this selected topic, covering articles published from 2000 to 2023 (131 articles in total). The first part of this review focuses on the potential mechanisms of action of fruits investigated so far (46 species), including their effects on tissue-specific glucose transport and the expression or activity of proteins in the insulin signalling pathway. The second part covers the phytocompounds responsible for particular fruits' activity-primarily polyphenols (e.g., flavonols, dihydrochalcones, proanthocyanidins, anthocyanins, phenolic acids), but also polysaccharides, triterpenes, and their additive and synergistic effects. In summary, fruits from the Maleae tribe seem promising as functional foods and anti-diabetic agents; however, their prospects for more expansive pro-health application require further research, especially more profound in vivo trials.

Development of a novel, sustainable, cellulose-based food packaging material and its application for pears.

This study aimed to develop a cellulose-based active food packaging material using paper, a biodegradable, sustainable, recyclable, renewable, and relatively low-cost material. For electrospray coating, fulvic acid (FA), which has antioxidant and antimicrobial properties, and sericin (S) were used as an active agent and a carrier medium, respectively. Solutions prepared at various concentrations and ratios of FA and S were analyzed, the properties of the active packaging material were examined, and the effect on the quality of pears was studied. The optimum conditions of electrospraying for minimum droplet size and maximum antibacterial effect were 0.8 g/mL concentration of solutions, 1:1 FA:S ratio, 20 kV voltage, 0.75 mL/h flow rate, and 23 cm collector-needle tip distance. FA had static, lethal, and inhibitory effects on Pseudomonas syringae and P. digitatum, the common pathogenic microorganisms on pears. The antioxidant activity of FA was higher than that of S (872.96 mM vs. 239.36 mM). At the end of the 90-day storage period, pears stored in the active packaging material at 7 °C and 90% RH showed better preserved color and texture, matured later, had a lower antimicrobial load, and were more appreciated in sensory evaluation than other samples.

Effects of vacuum microwave combined with freeze-drying on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices.

The effects of freeze-drying (FD), vacuum microwave drying after freeze-drying (FD-VMD), and freeze-drying after vacuum microwave drying (VMD-FD) on the physicochemical properties, phenolic compounds, and antioxidant capacity of pear fruit slices were investigated. The results showed that FD samples had the highest crispness value (116.30 N·sec) and the lowest volume shrinkage ratio value (5.48%). Compared to FD, the VMD-FD and FD-VMD methods could save drying time without affecting the color of dried samples. FD-VMD samples had the lowest rehydration capacity and maintained a homogeneous porous structure, while the VMD-FD samples had obvious collapse. Compared to VMD-FD samples, FD-VMD samples had higher contents of ascorbic acid (20.91 mg/100 g), total phenolic (7.62 mg/g), total anthocyanin (0.21 mg/g), and gallic acid (1.21 µg/g). Moreover, FD-VMD samples showed the highest antioxidant capacity as evaluated by the 2,2-diphenyl-1-(2,4,6-trinitrophenyl) hydrazyl scavenging activity, 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) scavenging capacity, and H2 O2 content. Compared with FD and VMD-FD, FD-VMD was most effective in maintaining better quality and shortening drying time of pear fruit slices. These findings suggested that FD-VMD might be a promising drying technique in the fruits and vegetable processing industries.

PbrWRKY70 increases pear (Pyrus bretschneideri Rehd) black spot disease tolerance by negatively regulating ethylene synthesis via PbrERF1B-2.

Various pear plant cultivars exhibit diverse abilities to resist pear black spot disease (BSD), while the precise molecular mechanisms of resistance against pear BSD remain unclear. This study proposed a profound expression of a WRKY gene, namely PbrWRKY70, derived from Pyrus bretschneideri Rehd, within a BSD-resistant pear cultivar. Comparative analysis against the wild-type revealed that the overexpression of PbrWRKY70 engendered augmented BSD resistance of transgenic Arabidopsis thaliana and pear calli. Notably, the transgenic plants exhibited higher activities of superoxide dismutase and peroxidase, along with an elevated capacity to counteract superoxide anions via increased anti-O2-. Additionally, these plants displayed diminished lesion diameter, as well as reduced levels of hydrogen peroxide, malondialdehyde and 1-aminocyclopropane-1-carboxylic acid (ACC) contents. We subsequently demonstrated that PbrWRKY70 selectively bound to the promoter region of ethylene-responsive transcription factor 1B-2 (PbrERF1B-2), a potential negative regulator of ACC, thereby downregulating the expression of ACC synthase gene (PbrACS3). Consequently, we confirmed that PbrWRKY70 could enhance pear resistance against BSD by reducing ethylene production via modulation of the PbrERF1B-2-PbrACS3 pathway. This study established the pivotal relationship among PbrWRKY70, ethylene synthesis and pear BSD resistance, fostering the development of novel BSD-resistant cultivars. Furthermore, this breakthrough holds the potential to enhance pear fruit yield and optimize storage and processing during the later stages of fruit maturation.

Pandora cacopsyllae Eilenberg, Keller & Humber (Entomophthorales: Entomophthoraceae), a new species infecting pear psyllid Cacopsylla pyri L. (Hemiptera: Psyllidae).

The new species Pandora cacopsyllae Eilenberg, Keller & Humber (Entomophthorales) is described. The fungus was found on infected pear psyllids Cacopsylla pyri (Hemiptera: Psyllidae) in a pear orchard in Zealand, Denmark. Morphological structures (conidia, rhizoids, cystidia) were described on the designated type host C. pyri. In addition, conidia from an in vitro culture were described. Pandora cacopsyllae differs from other Pandora species by a) C. pyri is the natural host; b) conidia are different from other Pandora species infecting Psylloidea; c) ITS differs from other Pandora species infecting Hemiptera. The fungus has a high potential for future use in biological control of Cacopsylla pest species as well as other psyllids.

The PcMYB44-mediated miR397-PcLACs module regulates defence-induced lignification in pear resistance to fungal disease.

Diseases caused by Alternaria alternata and Botryosphaeria dothidea diminish pear yield and quality, and restrict the pear agricultural industry. Lignification is a conserved mechanism for plant resistance against pathogen invasion. The regulatory mechanisms underlying defence-induced lignification in pear in response to fungal pathogen infection remain unknown. In this study, analysis of lignification level and lignin content in pear revealed that A. alternata and B. dothidea induced lignification, and transcriptomics showed that lignin biosynthesis was affected. To explore whether laccases (LACs) mediated by miR397 regulate lignification in pear, we investigated the role of PcmiR397 in repressing the expression of PcLACs using 5'-RNA ligase-mediated-RACE and co-transformation in tobacco. Opposite expression patterns for PcmiR397 and PcLAC target genes were observed in pear in response to pathogens. Transient transformation in pear demonstrated that silencing PcmiR397 and overexpressing a single PcLAC enhanced resistance to pathogens via lignin synthesis. To further reveal the mechanism underpinning the PcMIR397 response of pear to pathogens, the PcMIR397 promoter was analysed, and pMIR397-1039 was found to be inhibited by pathogen infection. The transcription factor PcMYB44 was up-regulated, and it bound to the PcMIR397 promoter and inhibited transcription following pathogen infection. The results demonstrate the role of PcmiR397-PcLACs in broad-spectrum resistance to fungal disease, and the potential role of PcMYB44 involved in the miR397-PcLAC module in regulating defence-induced lignification. The findings provide valuable candidate gene resources and guidance for molecular breeding to improve resistance to fungal disease in pear.