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CAMTA are calcium-modulating binding transcription factors that contribute to plant development. We identified 46 CAMTA genes from eight Rosaceae species and divided them into five subgroups based on a phylogenetic tree. Our analysis indicated that CAMTA is a highly conserved family among Rosaceae species, with a conserved DNA-binding domain (CG-1) and a conserved transcription factor immunoglobulin domain (TIG). Following a recent whole-genome duplication event, the genomes of Chinese white pear, European pear, and apple experienced significant expansion, resulting in the number of CAMTA genes being twice that of the other species. Cis-element identification showed that the distribution of the zein metabolism regulation-responsive element was different in the promoters of Chinese white pear (55.56%) and European pear (11.11%) CAMTA gene families. The gene expression results showed that PbrCAMTA1, 2, 6, 7 was highly expressed in pear fruit. Among them, PbrCAMTA2 may have a key influence on fruit softening, as observed in transient transformation experiments. In conclusion, our results provide crucial insights into the evolution of the CAMTA gene family in pear and other Rosaceae species and identify a candidate PbrCAMTA gene, which is involved in the dynamic development of pear fruits.

Glycine-aspartic acid-serine-leucine (GDSL) type lipases/esterases genes play critical roles in plant development and are related to the responses to abiotic and biotic stress. However, little is known about the GDSL family in pear (Pyrus spp.). Studies have shown GDSL-domain proteins play key roles in suberin deposition. Suberin deposition in the fruit epidermis, also called russeting, is an important defect that negatively affects consumer appeal in some fruit species, such as pear, apple and grapevine. Fruit russeting is mainly associated with cuticle microcracking and suberin accumulation in the inner part of the epidermal cell walls. To gain insight into the role of the GDSL gene family in suberin deposition and russet development in pear, we performed a genome-wide characterization of the GDSL family, including their identification, chromosomal localization, phylogenetic relationships, and expression patterns, in different tissues/organs in pear. One hundred and thirteen GDSL-type lipases/esterases genes were identified in the pear genome, and a phylogenetic analysis revealed that GDSL family can be classified into four distinct groups. Thirty GDSL genes were co-expressed with five homolog pear genes of three well-known suberin biosynthesis Arabidopsis genes (AtGPAT5, AtASFT, and AtCYP86B1) in the transcriptional co-expression network during pear fruit development. Among the 30 co-expressed GDSL genes, twelve genes were further analyzed by quantitative Real-time PCR, and the results showed the expression levels of the 12 genes were different between the russet exocarp and green exocarp of sand pear at different fruit development stages. Our study provides a detailed overview of the GDSL gene family and lays the foundation for future functional characterization of GDSL genes in P. bretschneideri.

Hexanal slows down the ripening process in fresh produce by inhibiting the activity of phospholipase D, thereby increasing shelf life. This study focused on comparing the single time exposure and continuous exposure of post-harvest Anjou and Bartlett pears to hexanal by dipping or fumigating them to enhance their shelf life. Continuous exposure of hexanal was achieved by developing a hexanal encapsulated fiber (HEF), which releases hexanal vapor due to the increased humidity (96 ± 2% RH) in the container headspace as a result of respiration. The fruits were stored in cold storage (0 ± 2 °C) as well as at normal room temperature (20 ± 2 °C) and their storage capacity was compared between the treatments. Fruit parameters such as physiological loss of weight (PLW), firmness, and total soluble solids (TSS) showed only minor differences between hexanal treated and untreated fruits. Between the two varieties, Anjou exhibited slightly higher values than Bartlett. However, when the fruits are visually evaluated, the main aspect of consumer preference, HEF-treated fruits had a better appeal in both varieties and in both conditions. Bartlett responded better than Anjou even in cold storage conditions, suggesting that there are varietal differences in their response to hexanal. Both hexanal treatments helped color retention and reduced fungal infection under the storage conditions tested.

The objective of the work was to determine the antioxidant potential in vitro of freeze-dried peel extracts of 20 fruits from the northern region of Peru through five tests (Folin-Ciocalteu, DPPH., ABTS+., FRAP and CUPRAC). According to multivariate statistical analyzes, five groups were found: (i.) peel extracts with the highest values of antioxidant capacity (AC) from custard apple, and star fruit; (ii.) rind extracts with high AC values from quince, sweet granadilla, guava, and black grape; (iii.) husk extracts with middle values of AC from passion fruit, and red mombin; (iv.) shell extracts with low AC values from tangerine, mandarine, and bitter orange; and, (v.) coating extracts with the lowest AC values from pawpaw, red pawpaw, muskmelon, dragon fruit, yellow and red indian figs, pear, apple, and green grape. To conclude, the fruit lyophilized-husk extracts of custard apple, star fruit, quince, sweet granadilla, guava, and black grape obtained the best AC.

The resistant phenotype of pear cultivars includes either complete resistance or tolerance to the attack by the causative agent of fire blight. The effect of ferritin and active iron (Fe2+) concentrations was compared in resistant (Dargazi), tolerant (Harrow Sweet), and susceptible (Bartlett) pear cultivars inoculated with a wild type strain of Erwinia amylovora (Ea273). The examination of necrosis revealed that resistance to the disease manifested itself as a delay in the appearance of symptoms and progression of the disease. Despite a rise in ferritin levels in all cultivars following disease agent inoculation, resistant and tolerant cultivars showed greater ferritin levels than susceptible cultivar. In addition, only resistant and tolerant cultivars displayed a drop in Fe2+ levels. The rate of decrease in Fe2+ content in Dargazi and Harrow sweet cultivars was 28 and 33%, respectively. Hydrogen peroxide (H2O2) and hydroxyl radical (OH•−) accumulation and intensities were considerably distinctive. Furthermore, tolerant and sensitive cultivars started producing OH•− radicals faster than resistant cultivar. According to these findings, different pathways are employed by pear cultivars to respond to the causative agent of fire blight.

Pear has an S-RNase-based gametophytic self-incompatibility (SI) system. Nuclear DNA degradation is a typical feature of incompatible pollen tube death, and is among the many physiological functions of vacuoles. However, the specific changes that occur in vacuoles, as well as the associated regulatory mechanism in pear SI, are currently unclear. Although research in tobacco has shown that, decreased activity of diacylglycerol kinase (DGK) results in the morphological change of pollen tube vacuole, whether DGK regulates the pollen tube vacuole of tree plants and whether it occurs in SI response, is currently unclear. We found DGK activity is essential for pear pollen tube growth, and DGK4 regulates pollen tube vacuole morphology following its high expression and deposition at the tip and shank edge of the pollen tube of pear. Specifically, incompatible S-RNase may induce cytoplasmic acidification of the pollen tube by inhibiting V-ATPase V0 dominant a1 subunit gene expression as early as 30 min after treatment, when the pollen tube is still alive. Cytoplasmic acidification induced by incompatible S-RNase resulting in reduced DGK4 abundance and deposition, leading to morphological change of the vacuole and fragmentation of nuclear DNA, which indicates DGK4 is a key factor in pear SI response. This article is protected by copyright. All rights reserved.

Food security is threatened in Southern Africa, because of unpredictable droughts and higher summer temperatures brought on by climate change and global warming. Durable and hardy plants that grow easily and quickly in such conditions must be adopted to ensure sustainable and reliable food supplies. The young cladodes (nopalitos) from the cactus pear plant, which adapts to hot and dry climates, is an underutilised alternative food source that can serve as a healthy vegetable. It thrives in many environments such as deserts, below sea level, high altitude regions and tropical regions with temperatures above 50°C. Nopalitos are a traditional staple vegetable and have been consumed in Mexico for over 9000 years. However, it is underutilised and unknown as an alternative vegetable in Africa. Research on the physiochemical and nutritional content has been conducted. However, the information on harvesting nopalitos from cultivars available in South Africa for optimal edible quality is not available. Good quality nopalitos are young, thin, bright green, soft, fresh and not too sour or slimy. This paper aims to identify the effect of and the interaction between size, cultivar and harvesting season to obtain optimal eating quality. Data were obtained for two cultivars (Morado and Fusicaulis) at 9 cm, 12 cm, 15 cm, 18 cm, 21 cm and 24 cm, which were harvested in spring (October) and autumn (March) over two years. The quality characteristics were translated into the measurable attributes of morphology (weight, width, diameter, volume and surface area), texture (firmness and compressibility), colour (L*, a*, b*, C*and h°), turgidity (moisture content, mucilage yield and viscosity) and gustatory (percentage titratable acidity, pH and total soluble solids). ANOVA and Principal Component Analyses were performed to determine significant differences and interactions between the length groups, two cultivars and two seasons. The results showed that the size, cultivar and season influenced the edible characteristics. Both cultivars were most tender at 15 cm and presented the best edible qualities in spring. Morado showed better colour, turgidity and gustatory qualities. Morado was thinner, a brighter green colour, less sour and less slimy compared to Fusicaulis nopalitos.

Pears are one of the oldest and the third most important fruit species grown in temperate regions. They are consumed because of their nutritional and health benefits, in fresh form or as various processed products. This article resolves the etiology of the Penicillium-like mold symptoms on pear fruits in Serbia. Samples of pear fruits with blue mold and other Penicillium-like mold symptoms were collected in Serbia from 2016 to 2019, from four storages. The recovered isolates were identified and characterized according to a polyphasic approach. Morphological and physiological analyses were performed on three media and five temperatures, respectively. Four loci (internal transcribed spacer, beta-tubulin, calmodulin, and DNA-dependent RNA polymerase II second largest subunit) were used for sequencing, genetic identification, and phylogenetic analyses. The results of the identification by conventional and molecular methods were in agreement, and they revealed that the obtained isolates belong to five species: Penicillium crustosum, P. expansum, P. italicum, Talaromyces minioluteus, and T. rugulosus. In a pathogenicity test, P. crustosum, P. expansum, T. minioluteus, and T. rugulosus produced decay on artificially inoculated pear fruits, and P. italicum induced tissue response lesions. The results of this study are the first reports of T. minioluteus and T. rugulosus as postharvest pear pathogens. Also, these are the first world records of T. minioluteus, T. rugulosus, and P. italicum on fruits of European pear. Furthermore, this is the first finding of P. crustosum, P. expansum, P. italicum, T. minioluteus, and T. rugulosus on pear fruit in Serbia.

In addition to their use in traditional medicine, cactus pear (Opuntia species) are a source of vegetal nutrients in many countries. The aims of this study were to determine variability in the nutritional value of 42 spineless cactus pear cultivars, identify correlations between nutritional traits, and determine superior cultivars based on cladode nutritional value. Cladodes of 42 spineless cactus pear cultivars grown under the same glasshouse conditions were collected from the Roodeplaat research farm of the Agricultural Research Council, South Africa. The sliced, dried and powdered cladodes were subjected to quantitative analysis of their vitamin C, β-carotene and mineral element contents. Significant variations in nutritional values were observed among the different cultivars. Vitamin C content ranged from 8.95 mg/100 g in cultivar Ofer to 124 mg/100 g in cultivar Malta, whilst β-carotene content ranged from 3.9 mg/100 g in cultivar Murado to 31.4 mg/100 g in cultivar Cross X. Potassium and calcium were the most abundant mineral elements present, whilst iron was found to be the least present among the mineral elements quantified. A significant positive association was established between calcium (Ca), potassium (K) and zinc (Zn) contents. A direct selection for increased concentration of Ca could be a selection criterion for the development of population with an indirect improvement of K and Zn concentrations. The observed variations highlight the need for a careful cultivar selection for population and product development using spineless cactus pear cladodes.

The comparison of the influence of foliar fertilization with four preparations on the growth of ‘Conference’ maiden pear trees growing on MA quince rootstock was conducted in a nursery in a three-year period. The evaluation was conducted on the basis of maidens growth parameters and the state of their leaf minerals content as well as on photosynthetic activity of the maiden trees. The preparations used in the experiment affected the improvement of some growth parameters studied, especially the stem diameter and fresh mass of the maidens. Biopuls Original turned out to be the best preparation as it improved significantly three out of five studied growth parameters. A varied impact of the preparations used on the content of micro and macro-elements in leaves was detected. All tested preparations positively influenced the leaves area index of maiden trees except for Blackjak preparation. Photosynthetic intensity of maiden pear trees nourished through leaves was significantly smaller in comparison with the control. Only plants treated with Biopulus Original were characterized by a higher concentration of CO2 and its level in intercellular space. The aim of the second experiment was to check the influence of the application of Trifender WP preparation with hydrogel on the growth of ‘Champion’ maiden quince trees at the stage of planting the rootstocks into a nursery. A better branching of the rootstocks was obtained after the use of the preparation with hydrogel and the hydrogel alone. The trees in these combinations were also characterized by bigger fresh and dry mass of the leaves. The influence of Trifinder WP applied in connection with hydrogel was the best.

The occurrence of water-soaked brown flesh in pear fruit is closely related to an activated biological Maillard reaction during the latter half of maturation. In this study, samples of immature and mature pear fruits were assessed for the incidence of water-soaked brown flesh (WSBF), sugar content, expression level of sugar metabolism-related genes, and activity of the Maillard and oxidative stress reactions. The occurrence of WSBF disorder was rare in immature fruit, but was pronounced in mature fruit. Glucose content of the flesh was higher in mature fruit with WSBF than in immature fruit without WSBF. Conversely, sucrose content was inversely correlated to glucose content. Higher levels of the neutral invertase gene (PpNIV) were detected in mature fruit compared with immature fruit. Levels of oxidative stress and Maillard reaction products in the flesh of mature fruit were determined. The strongest Maillard and oxidative stress reactions were observed in cells adjacent to the vascular bundle, and these reactions diminished with distance from the vascular bundle. Furthermore, examination of cells near the vascular bundle revealed stronger signal intensity on the phloem side compared to the xylem side. Cellular examination of the phloem side of immature and mature fruits indicated that mature fruit had a stronger signal intensity than immature fruit in both reactions. These results suggest that an increase in the Maillard reaction, attributed to an increased concentration of reducing sugars, during the maturation period may be fundamentally involved in the occurrence of this disorder through oxidative stress.

Recently, Cadophoraluteo-olivacea has been reported as a post-harvest pathogen of side rot of apple (Malusdomestica) in Latvia, and of pear (Pyruscommunis) in Italy and the Netherlands. In 2018 and 2019, in South Tyrol (northern Italy) 11 fungal cultures, identified as C.luteo-olivacea based on ITS (internal transcribed spacer region) sequence data, were obtained from apple fruit displaying post-harvest side rot symptoms. The fruit were sampled in packinghouses representing different apple growing areas of South Tyrol. For a more accurate taxonomic assignment, two additional molecular genetic loci, β-tubulin (TUB2) and translation elongation factor 1α (TEF-1α), of seven isolates were amplified and sequenced. Phylogenetic analysis based on multi-locus DNA sequence data confirmed that isolates from apple fruit with side rot symptoms indeed represented C.luteo-olivacea. A pathogenicity test performed on apple fruit of ‘Golden Delicious’ confirmed the virulence of a representative isolate. So far, C.luteo-olivacea represents a minor post-harvest pathogen of apple but considering the losses that this fungus can cause to other crops, the awareness about this potential apple disease should be raised.

Background. Natural populations of fruit and small fruit plants in Belarus and their specific and varietal composition for a long time attracted the attention of pomologists and breeders. Identification and mobilization of unique local forms and landraces as genetic sources of useful traits as well as monitoring duplicate collections will contribute to their more effective use in breeding practice to develop competitive domestic cultivars of various crops and reveal the adaptability of foreign cultivars to the conditions of Belarus.Methods. The itinerary of the collecting mission passed through 6 regions of the Republic of Belarus (Gomel, Minsk, Mogilev, Vitebsk, Brest, and Grodno) in 2012–2017.Results. As a result, 221 samples of fruit, small fruit and nut plants were collected, including 18 rootstocks of fruit crops. By 2021, 105 unique landraces were tested in the plant introduction and quarantine nursery and planted in the field gene bank, including 28 accessions of apple, 33 of pear, 11 of sour cherry, 5 of sweet cherry, 9 of plum, 8 of apricot, 1 of almond, 2 of hazel, 3 of garden strawberry, 1 of black chokeberry, 1 of viburnum, and 1 of bird cherry. There are plans to use the obtained accessions in breeding practice assources of valuable agronomic traits (high winter hardiness, high yield, resistance to a set of plant pathogens, etc.).

Anthocyanins are common secondary metabolites in plants that impart red coloration to fruits and flowers. The important WRKY transcription factor family plays multifaceted roles in plant growth and development. In this study, we found a WRKY family gene, Pyrus bretschneideri WRKY75, that may be involved in anthocyanin synthesis in pear. Unlike Arabidopsis thaliana WRKY75, PbWRKY75 may be a positive regulator of anthocyanin synthesis. A transient expression assay indicated that PbWRKY75 promoted pear anthocyanin synthesis. The structural genes (PbANS, PbDFR, and PbUFGT) and positive regulators (PbMYB10 and PbMYB10b) of anthocyanin synthesis were significantly upregulated in the fruitlet skins of PbWRKY75-overexpressing "Zaosu" pears. Subsequently, yeast one-hybrid and dual-luciferase assays indicated that PbWRKY75 promoted PbDFR, PbUFGT, and PbMYB10b expression by activating their promoters. These results revealed that PbWRKY75 may promote the expression of both PbMYB10b and anthocyanin late biosynthetic genes (PbDFR and PbUFGT) by activating their promoters, thereby inducing anthocyanin synthesis in pear. This study enhanced our understanding of the mechanism of pear anthocyanin synthesis, which will be beneficial in the improvement of pear peel color.

The current social demand for organic, sustainable, and eco-friendly approaches for farming, while ensuring the health and productivity of crops is increasing rapidly. Biocontrol agents are applied to crops to ensure biological control of plant pathogens. Research on the biological control of white root rot disease caused by a soil-borne pathogen, Rosellinia necatrix, is limited in pears compared to that in apple and avocado. This pathogenic fungus has an extensive host range, and symptoms of this disease include rotting of roots, yellowing and falling of leaves, wilting, and finally tree death. The severity of the disease caused by R. necatrix , makes it the most harmful fungal pathogen infecting the economical fruit tree species, such as pears, and is one of the main limiting factors in pear farming, with devastating effects on plant health and yield. In addition to agronomic and cultural practices, growers use chemical treatments to control the disease. However, rising public concern about environmental pollution and harmful effects of chemicals in humans and animals has facilitated the search for novel and environmentally friendly disease control methods. This review will briefly summarize the current status of biocontrol agents, ecofriendly methods, and possible approaches to control disease in pear orchards.

Pear (Pyrus bretschneideri), one of the most widely planted fruit trees in the world, is infected by pear ring rot disease, which is triggered by Botryosphaeria dothidea. Previous research has shown that exogenous calcium enhanced pear resistance to B. dothidea. To explore the molecular mechanism of calcium in pear pathogen resistance, we searched the differentially expressed genes (DEGs) between calcium and H2O treatment with B. dothidea inoculation in pear by using RNA-seq data. On the basis of the standard of a proportion of calcium/H2O fold change >2, and the false discovery rate (FDR) 2O and calcium treatments under B. dothidea inoculation at 2 days postinoculation (dpi) (D2) and 8 dpi (D8), respectively, indicating that significantly more genes in D2 responded to calcium treatment. Results of the gene annotation showed that DEGs were focused on plant−pathogen interactions, hormone signal transduction, and phenylpropanoid biosynthesis in D2. Moreover, transient silencing of PbrCML30 (pear calmodulin-like proteins 30), which had significantly higher expression in response to calcium than H2O treatments, conferred compromised resistance to B. dothidea. Exogenous calcium treatment slightly alleviated the symptoms of TRV2-PbrCML30 leaves compared with TRV2 leaves under inoculation, supporting its key role in pear resistance to B. dothidea. Overall, the information obtained in this study provides a possible mechanism of calcium in regulating pear resistance to B. dothidea.

Salicylic acid (SA) plays a pivotal role in delaying fruit ripening and senescence. However, little is known about its underlying mechanism of action. In this study, RNA sequencing was conducted to analyze and compare the transcriptome profiles of SA-treated and control pear fruits. We found a total of 159 and 419 genes differentially expressed between the SA-treated and control pear fruits after 12 and 24 h of treatment, respectively. Among these differentially expressed genes (DEGs), 125 genes were continuously differentially expressed at both treatment times, and they were identified as candidate genes that might be associated with SA-regulated fruit ripening and senescence. Bioinformatics analysis results showed that 125 DEGs were mainly associated with plant hormone biosynthesis and metabolism, cell wall metabolism and modification, antioxidant systems, and senescence-associated transcription factors. Additionally, the expression of several candidate DEGs in ripening and senescent pear fruits after SA treatments were further validated by quantitative real-time PCR (qRT-PCR). This study provides valuable information and enhances the understanding of the comprehensive mechanisms of SA-meditated pear fruit ripening and senescence.

Mildew resistance locus O (MLO) is a plant-specific gene family that plays an important role in the growth and development of plants and their interactions with the environment. However, the available information on this gene family in pear is limited. Here, 24 PbrMLO genes were identified and divided into five subfamilies (I, II, III, IV and V). Whole-genome duplication (WGD) and dispersed duplication contributed to the expansion of the PbrMLO family. In addition, gene expression analysis revealed that PbrMLO genes were distributed in various pear tissues, suggesting their diverse functions. We selected PbrMLO23 for further functional analysis. Expression profile analysis by qRT-PCR showed that PbrMLO23 was highly expressed in pollen. Subcellular localization analysis showed that PbrMLO23 was located on the plasma membrane. When the expression level of PbrMLO23 was knocked down by using antisense oligonucleotides, pollen tube lengths increased, indicating that PbrMLO23 plays a functional role in inhibiting pollen tube growth. In summary, these results provide evolutionary insight into PbrMLO and its functional characteristics and lay a foundation for further analysis of the functions of PbrMLO members in pear.

Alternative splicing (AS) plays a crucial role in plant growth, development and response to various environmental changes. However, whether alternative splicing of MADS-box transcription factors contributes to the flower bud dormancy process in fruit trees still remains unknown. In this work, the AS profile of genes in the dormant flower buds of 'Dangshansu' pear tree were examined. A total number of 3661 alternatively spliced genes were identified, and three mRNA isoforms of the dormancy associated MADS box (DAM) gene, PpDAM1, derived by alternative splicing, designated as PpDAM1.1, PpDAM1.2 and PpDAM1.3, were characterized. Bimolecular fluorescence complementation (BiFC) analysis indicated that AS of PpDAM1 didn't affect the nucleus localization and homo-/heterodimerization of PpDAM1.1, PpDAM1.2 and PpDAM1.3 proteins, but disturbed the translocation of PpDAM1.1/PpDAM1.1, PpDAM1.3/PpDAM1.3, PpDAM1.1/PpDAM1.3, and PpDAM1.2/PpDAM1.3 dimers to the nucleus. Constitutive expression of PpDAM1.2, but not PpDAM1.1 and PpDAM1.3, in Arabidopsis retarded the growth and development of transgenic plants. Further comparative expression analyses of PpDAM1.1, PpDAM1.2 and PpDAM1.3 in the flower buds of 'Dangshansu' and a less dormant pear cultivar, 'Cuiguan', exhibited that the expression of all the three isoforms in 'Dangshansu' were significantly higher than in 'Cuiguan', especially PpDAM1.2, which showed a predominantly higher expression than PpDAM1.1 and PpDAM1.3 in both cultivars. Our results suggest that alternative splicing of PpDAM1 could play a crucial role in pear flower bud dormancy process.

In a recent survey of post-harvest rot pathogens in European pear in Southern Oregon, Alternaria spp. were frequently isolated from orchard samples of pear flowers and fruits. Morphological differences were observed within the isolated cultures. A preliminary NCBI BLAST search analysis using sequences of the ATPase locus across 94 isolates of Alternaria spp. obtained from pear fruit rots revealed three major Alternaria sections: sect. Alternata, sect. Infectoriae, and sect. Ulocladioides. Thirteen isolates were selected based on their genetic and morphological diversity across three Alternaria sections and were subjected to multilocus phylogenetic analysis using sequences from plasma membrane ATPase, calmodulin, and Alt a1 loci. Within sect. Alternata, four Alternaria arborescens isolates and one A. destruens isolate were identified; within sections Infectoriae and Ulocladioides, one A. rosae isolate and two A. botrytis isolates were identified, respectively. The remaining five isolates could not be identified based on the available sequences for the three loci used in this study. In addition to the phylogenetic analysis, pathogenicity assays revealed differential responses to these isolates on four pear cultivars: Anjou, Bartlett, Comice, and Bosc. Inoculation of isolates within Alternaria sect. Alternata resulted in fruit lesions across all cultivars, with Bosc pear being significantly susceptible (P < 0.0001). Isolates within Alternaria sect. Ulocladioides caused rots on Anjou and Bosc pears, while isolates within Alternaria sect. Infectoriae developed rots on Bosc pear only. This study suggests that there is differential susceptibility of pear cultivars to Alternaria rots, and the severity of post-harvest rot depends on the type of Alternaria spp. and cultivar predominant in a region.

Aroma, which plays an essential role in food perception and acceptability, depends on various mixture of volatile organic compounds (VOCs). Meanwhile, as a field of metabolomics, VOC analysis is highly important for aroma improvement and discrimination purposes. In this work, VOCs in pear fruits were determined via headspace solid-phase micro-extraction (HS-SPME) combined with gas chromatography–mass spectrometry (GC–MS) to study variations among different cultivars and storage stages. In 12 cultivars of pear fruits, a total of 121 VOCs were quantified, including 40 esters, 32 alcohols, 16 aldehydes, 13 alkenes, 11 ketones, 4 acids, and 5 other compounds. The types and amounts of VOCs in different cultivars varied dramatically, which were in the range of 13–71 and 3.63–55.65 mg/kg FW (fresh weight), respectively. The Dr. Guyot cultivar showed the highest level of VOCs, both in type and amount. After 21 days storage at 4 °C, total concentration of VOCs increased from initial levels of 50.76 to 101.33 mg/kg FW. Storage at 20 °C made a larger contribution to production for VOCs than that at 4 °C, resulting in the maximum content of VOCs (117.96 mg/kg FW) in fruit after 14 days storage at 4 °C plus 7 days at 20 °C. During storage, the content of esters showed a gradual increase, while the content of alcohols and aldehydes decreased. Based on the results presented, related alcohols were recognized as the intermediates of conversion from aldehydes to esters.

Traditional pear cultivars are increasingly in demand by consumers because of their excellent taste, the possibility of use in sustainable food production systems, convenience as raw materials for obtaining products of high nutritional quality, and perceived health benefits. In this study, individual sugars, organic acids, and polyphenols in the fruits of nine traditional and one commercial pear cultivar during two growing seasons were determined by HPLC. A significant influence of cultivars, growing years, and their interaction on the content of analyzed primary and secondary metabolites was determined. The commercial pear cultivar ‘Président Drouard’ and traditional cultivars ‘Dolokrahan’, ‘Budaljača’, and ‘Krakača’ had a lower content of all analyzed sugars. Overall, traditional pear cultivars had higher total polyphenols in the peel and pulp than ‘Président Drouard’, with the exception ‘Takiša’ and ‘Ahmetova’. High polyphenol content detected in ‘Budaljača’, ‘Dolokrahan’, and ‘Krakača’ shows the utilization value of traditional pear germplasm. The obtained data can serve as practical supporting data for the use of traditional pears in the neutraceutical, pharmaceutical, and food industries.

The Multidrug and Toxic Compound Extrusion (MATE) protein belongs to a secondary transporter gene family, which plays a primary role in transporting many kinds of substrates such as organic compounds, secondary metabolites, and phytohormones. MATE protein members exist in both prokaryotes and eukaryotes. However, evolution and comprehensive analysis of the MATE genes has not been performed in Rosaceae species. In the present study, a total of 404 MATEs genes were identified from six Rosaceae genomes (Prunus avium, Pyrus bretschneideri, Prunus persica, Fragaria vesca, Prunus mume, and Malus domestica) and classified into eight main subfamilies (I-VII) based on structural and phylogenetic analysis. Microcollinearity analysis showed that whole-genome duplication events might play a vital role in the expansion of the MATE genes family. The Ka/Ks analysis, chromosomal localization, subcellular localization, and molecular characteristics (length, weight, and pI) were performed using various bioinformatics tools. Furthermore, different subfamilies have different introns-exons structures, cis-acting elements, and conserved motifs analysis, indicating functional divergence in the MATE family. Subsequently, RNA-seq analysis and real-time qRT-PCR were conducted during Chinese pear fruit development. Moreover, PbMATE genes were significantly expressed under hormonal treatments of MeJA (methyl jasmonate), SA (salicylic acid), and ABA (abscisic acid). Overall, our results provide helpful insights into the functions, expansion complexity, and evolutions of the MATE genes in Chinese pear and five Rosaceae species.

Fire blight, caused by the bacterial phytopathogen Erwinia amylovora, is an economically important and mechanistically complex disease that affects apple and pear production in most geographic production hubs worldwide. We compile, assess, and present a genetic outlook on the progression of an E. amylovora infection in the host. We discuss the key aspects of type III secretion–mediated infection and systemic movement, biofilm formation in xylem, and pathogen dispersal via ooze droplets, a concentrated suspension of bacteria and exopolysaccharide components. We present an overall outlook on the genetic elements contributing to E. amylovora pathogenesis, including an exploration of the impact of floral microbiomes on E. amylovora colonization, and summarize the current knowledge of host responses to an incursion and how this response stimulates further infection and systemic spread. We hope to facilitate the identification of new, unexplored areas of research in this pathosystem that can help identify evolutionarily susceptible genetic targets to ultimately aid in the design of sustainable strategies for fire blight disease mitigation.

The hard-end of pear fruit might be a disorder of the environmental abiotic stress, which is mainly caused by the reduced water intake of the fruit resulting from climate drought. To explore the factors that cause fruit hard-end, two rootstocks of Pyrus betulaefolia and P. bretschneideri with different root absorptive capacity of water and nutrients were used as base stock of ‘Whangkeumbae’ (P. pyrifolia) pear fruit. The results showed that the incidence of hard-end fruit in ‘Whangkeumbae’ pear trees using rootstock with lower rate of water absorptive increased, indicating that this physiological disorder was related with water deficiency. PpNAC187 was selected from RNA-Seq carried out on the calyx end of with and without the hard-end symptom of different rootstocks. The transgenic tobacco overexpressing PpNAC187 showed higher tolerance with drought and salt stress, which might suggest that PpNAC187 acts an important role during the hard-end occurring caused by drought or salt stress.

Anthocyanins are important components in the peel of red pears and contribute to the appearance of the fruit. Melatonin application is known to affect anthocyanin biosynthesis, but the effect of preharvest melatonin application on fruit coloration remains largely unknown. The objective of this study was to determine the effects of preharvest melatonin application on pigmentation, phenolic compounds, and the expression of related genes in Nanhong pear (Pyrus ussuriensis). The applications were performed during the pre-color-change period by spraying 50 or 200 µmol L−1 of melatonin on fruits. We found that treatment with melatonin had a significant effect on color development. The concentrations of anthocyanins and flavonols were enhanced by melatonin treatment, whereas hydroxycinnamate and flavanol concentrations were reduced. Quantitative real-time PCR analyses indicated that the transcription levels for most anthocyanin biosynthetic genes and anthocyanin-related transcription factors were induced by melatonin. Melatonin application also stimulated the expression of melatonin biosynthesis-related genes and consequently caused an increase in endogenous melatonin concentration. These results provide insights into melatonin-induced fruit coloration and will facilitate the application of exogenous melatonin in agriculture.

Background The development of ecofriendly tools against plant diseases is an important issue in crop protection. Screening and selection process of bacterial strains antagonists of 2 pathogenic bacterial species that limit very important crops, Erwinia amylovora, the causal agent of the fire blight disease, and Pectobacterium carotovorum, the causal agent of bacterial potato soft rot, were reported. Bacterial colonies were isolated from different ecological niches, where both pathogens were found: rhizosphere of potato tubers and fruits and leaves of pear trees from the northwest region of Algeria. Direct and indirect confrontation tests against strains of E. amylovora and P. carotovorum were performed. Results Results showed a significant antagonistic activity against both phytopathogenic species, using direct confrontation method and supernatants of cultures (pS. plymuthica had a better inhibitory effect than the strains of P. fluorescens against both pathogens. In vivo results on immature pear fruits showed a significant decrease in the progression of the fire blight symptoms, with a variation in the infection index from one antagonistic strain to another between 31.3 and 50%, and slice of potato showed total inhibition of the pathogen (P. carotovorum) by the antagonistic strains of Serratia plymuthica (p Conclusion This study highlighted that the effective bacteria did not show any infection signs towards plant tissue, and considered as a potential strategy to limit the fire blight and soft rot diseases.

Porfiry Afanasyevich Dibrova was one of the first scientists and breeders standing at the origins of scientific pomiculture in the Urals. He was the author of 23 cultivars of apple, six of pear, one of sour cherry, and one of black currant. In the 1940s, he was the leader of collecting missions exploring the local assortment of fruit and berry crops in 50 districts of Sverdlovsk and Molotov (Perm) Provinces, and the Udmurt Republic. P.A. Dibrova was one of the authors of the first standard set of fruit and berry cultivars for the abovementioned areas. He studied regularities in the inheritance of valuable agronomic and biological traits of fruit crops and identified promising sources for apple and pear breeding. He launched the main plant breeding trends in the Middle Urals, now followed by contemporary breeders: the development of highly winter-hardy cultivars of apple and pear with fruiting precocity, stable yields, excellent fruit quality, and improved biochemical composition in fruits.

Monilinia fructicola has been widely reported as the causal agent of brown rot disease on many Rosaceae family fruits worldwide. It has been reported on stone fruits, e.g., peach, plum, cherry, apricot and mume; as well as pome fruits, e.g., apple, pear and hawthorn. Loquat is a member of the Eriobotrya genus in subfamily Maloideae along with apple, pear and hawthorn. So far, loquat has not been reported as the host of any Monilia species. In June 2019, brown rot symptoms were observed on loquat fruits in an orchard in Wuhan, Hubei Province, China. Thirty single spore isolates were obtained and identified as M. fructicola based on morphological characteristics and molecular analysis. This is the first report of loquat brown rot disease caused by Monilia species in the world. Furthermore, upon artificial inoculation, all three Monilia species from peach in China, i.e., M. fructicola, M. mumecola and M. yunnanensis, could cause typical brown rot disease on loquat fruits. At the same time, M. fructicola isolates from loquat showed virulence similar to those isolates from peach when the pathogenicity test was conducted on peach fruits. These results suggested that loquat could be infected by other Monilia species and that isolates from loquat also have potential to damage other Rosaceae family fruits in practice.

Background Browning spot (BS) disorders seriously affect the appearance quality of ‘Huangguan’ pear and cause economic losses. Many studies on BS have mainly focused on physiological and biochemical aspects, and the molecular mechanism remains unclear. Results In the present study, the structural characteristics of ‘Huangguan’ pear with BS were observed via scanning electron microscopy (SEM), the water loss and brown spots were evaluated, and transcriptomic and metabolomics analyses were conducted to reveal the molecular mechanism underlying ‘Huangguan’ pear skin browning disorder. The results showed that the occurrence of BS was accompanied by a decrease in the wax layer and an increase in lignified cells. Genes related to wax biosynthesis were downregulated in BS, resulting in a decrease in the wax layer in BS. Genes related to lignin were upregulated at the transcriptional level, resulting in upregulation of metabolites related to phenylpropanoid biosynthesis. Expression of calcium-related genes were upregulated in BS. Cold-induced genes may represent the key genes that induce the formation of BS. In addition, the results demonstrated that exogenous NaH2PO4·2H2O and ABA treatment could inhibit the incidence of BS during harvest and storage time by increasing wax-related genes and calcium-related genes expression and increasing plant resistance, whereas the transcriptomics results indicated that GA3 may accelerate the incidence and index of BS. Conclusions The results of this study indicate a molecular mechanism that could explain BS formation and elucidate the effects of different treatments on the incidence and molecular regulation of BS.

Expanding the assortment through the development of new highly adaptable cultivars is the main task of pear breeding in the Middle Urals. The most significant agronomic traits are winter hardiness, high fruit yield, and good fruit quality. The zoned pear assortment for the Middle Urals includes six cultivars. Six more cultivars now undergo the State Variety Trials. One of them is the new pear cultivar ‘Tais’ (breeding number DL-33-104), the result of crossing Dyuymovochka × Zhanna d’Ark. Cv. ‘Tais’ has been in variety studies at Sverdlovsk Horticultural Breeding Station (Yekaterinburg) since 2006. The new cultivar is characterized by good winter hardiness and productivity. The average yield at the age of 10–14 years is 9.42 tons per hectare, while the maximum yield is 19.81 t/ha. Fruits are yellow, with a good sweet taste, weighing 94 g. The content of dry matter is 11.9%, sugars 9.0%, and titratable acids 0.4%. According to the results of long-term research, the new pear cultivar ‘Tais’ was submitted to the State Variety Trials in 2017.

Filtration temperature-sensitive H (FtsH) is an ATP-dependent protease family that plays important roles in many aspects of cellular processes and environmental adaption. However, little information is available about the FtsH genes in pear (Pyrus bretschneideri). In this study, 19 PbrFtsH genes were identified and classified into eight groups with several subgroups. The FtsH genes in pear show high sequence and structural conservation in the coding regions, and the majority of the FtsH members were located on the chromosome 3 (three members), chromosome 9 (four members), and chromosome 15 (three members). The WGD/segmenta, dispersed duplication played a major driving force in pear FtsH evolution. A Synteny analysis provided deep insight into the evolutionary relationships of PbrFtsH genes. The subcellular localization of the PbrFtsH genes showed them in the mitochondrion or chloroplast. Expression profiles derived from transcriptome data and RT-qPCR analysis revealed distinct expression patterns of PbrFtsH genes in different fruit developmental stages. These results provided valuable information that extends our understanding of the function, evolution and expression profile of the FtsH family during fruit development in pear, and a foundation for the further functional characterization of PbrFtsH genes, which can be applied to pear crop improvement.

Fire blight is a devastating disease of apple, pear and quince caused by the Gram-negative bacterium Erwinia amylovora. As antibiotics are not allowed against fire blight in Switzerland, optimization of alternative plant protection strategies is required. In this context, fire blight tolerant cultivars become of higher importance to control the disease. A plant protection product efficacy trial against fire blight with the susceptible cultivar ‘Gala Galaxy’ and the tolerant cultivar ‘Ladina’ bred at Agroscope was set up at the Agroscope Steinobstzentrum Breitenhof in 2018. Four different treatment strategies, including an untreated control, were tested on both cultivars after inoculation with Erwinia amylovora. ‘Ladina’ showed less fire blight blossom cluster infection in untreated and treated plants compared to ‘Gala Galaxy’. Blossom cluster infection rates following different plant protection treatments did not differ significantly from each other in ‘Gala Galaxy’ whereas they did in ‘Ladina’.

Scab caused by Venturia nashicola is one of the most serious diseases of Asian pears, and conventional fungicides used to control scab can lose their efficacy when fungicide-resistant strains develop. In contrast, the efficacy of systemic acquired resistance (SAR) inducers, such as acibenzolar-S-methyl (ASM), is regarded as stable because they have complex, orchestrated modes of action. Here, field efficacy and phytotoxicity of ASM on scab were tested during the growing season and after harvest for 3 years. The high efficacy of ASM indicated that it has promise for controlling scab in the field without an unacceptable level of phytotoxicity.

This study aimed at evaluating the use of phytoregulators in vegetative characteristics of ‘Packham’s Triumph’ pear trees in both 2014/2015 and 2015/2016 cycles. The orchard, was implemented in 2011. The following phytoregulators and doses were used: Ethephon and 6-Benzyladenine at 100, 200, 300 and 400 ml L-1. The experiment had a randomized block design with five replicates. Each experimental unit was composed of a plant. Variables under evaluation were leaf area, annual branch length, annual branch diameter, number of buds on the annual branch, internode length, fertility index and trunk cross section areas of the crown cultivar and of the rootstock. Only the following variables exhibited significance: leaf area, annual branch length and number of buds in plants treated with Ethephon in the 2015/2016 cycle. Leaf area was smaller when high concentrations of Ethephon were applied while the least efficient doses for annual branch length and number of buds were 162.66 ml L-1 and 107.30 ml L-1, respectively

Postharvest quality, quantification of betalains, phenolic compounds, and antioxidant activity of peel, pulp, and juice of fruits of three prickly pears (Opuntia ficus-indica L. Mill.) cultivars of Colegio de Postgraduados in México, were measured. The red and orange cultivars showed outstanding features of postharvest quality (size, texture, TSS and pulp and juice content) highest content of betalains and phenolic compounds. Therefore, highest antioxidant activity. In general, the highest content of bioactive compounds was detected in the peel, besides the content in pulp and juice did not show statistically significant differences. Phenolic content is very high in comparison with other fruits. Antioxidant activity was measured by three assays:FRAP, ABTS, and DPPH. Three cultivars showed a high correlation between antioxidant activity and phenolic compounds. The methodologies used in this work are a very useful tool for the quantification of bioactive compounds in O. ficus-indica fruit tissues.

Scab caused by Venturia nashicola is one of the most serious diseases of Asian pears, including Japanese pear (Pyrus pyrifolia var. culta) and Chinese pears (P. bretschneideri and P. ussuriensis). Breeding scab-resistant pear cultivars is essential to minimize fungicide use and development of fungicide resistance. A survey of pathogenic specialization in V. nashicola is needed to ensure durable scab resistance in cultivated pears. V. nashicola race 1, 2, and 3 isolates, each differing in pathogenicity to Japanese pear cultivar Kousui and Asian pear strain Mamenashi 12, have been reported in Japan. In this study, isolates collected from scabbed pears in China and Taiwan were classified as V. nashicola based on conidial size and mating ability. However, various isolates had pathogenicity distinct from races 1, 2, and 3 according to tests on seven differential host genotypes of pear cultivars from Japan (Kousui and strain Mamenashi 12), China (Jingbaili, Yali, Linyuli, and Nanguoli), and Taiwan (Hengshanli). These new races were designated as races 4 to 7. Progenies characteristic of race 3 isolates were produced using a cross between race 1 and race 2 isolates, suggesting the possible role of sexual recombination in the emergence of novel races. Japanese pear cultivar Kinchaku and Chinese P. sinkiangensis ‘Xiangli’ (a Korla fragrant pear grown in China) did not show visible symptoms after inoculation with any of the seven races. Broad scab resistance in Kinchaku and Xiangli makes them a promising genetic resource for resistance breeding programs.

Background Parthenocarpy results in traits attractive to both consumers and breeders, and it overcomes the obstacle of self-incompatibility in the fruit set of horticultural crops, including pear (Pyrus bretshneider). However, there is limited knowledge regarding the genetic and molecular mechanisms that regulate parthenogenesis. Results Here, in a transcriptional comparison between pollination-dependent fruit and GA4-induced parthenocarpy, PbCYP78A6 was identified and proposed as a candidate gene involved in parthenocarpy. PbCYP78A6 is similar to Arabidopsis thaliana CYP78A6 and highly expressed in pear hypanthia. The increased PbCYP78A6 expression, as assessed by RT-qPCR, was induced by pollination and GA4 exposure. The ectopic overexpression of PbCYP78A6 contributed to parthenocarpic fruit production in tomato. The PbCYP78A6 expression coincided with fertilized and parthenocarpic fruitlets development and the expression of fruit development-related genes as assessed by cytological observations and RT-qPCR, respectively. PbCYP78A6 RNA interference and overexpression in pear calli revealed that the gene is an upstream regulator of specific fruit development-related genes in pear. Conclusions Our findings indicate that PbCYP78A6 plays a critical role in fruit formation and provide insights into controlling parthenocarpy.

Cactus pear is an important source of fodder for herbivores, though its production is affected by soil salinity. This work aimed to evaluate the development of cactus pear clones subjected to salt stress as a measure of their salinity tolerance. The experimental design was a randomized block with 6 replications. Twenty genotypes of cactus pear were used from the Active Germplasm Bank, with variability in resistance to carmine cochineal [Dactylopius opuntiae (Cockerell)] as this insect species destroys many stands of cactus on farms. One cladode was planted per pot containing 12 kg of sandy soil. Water with a salinity of 3.6 dS/m was applied at 14-day intervals. The clones were scored at 28-day intervals for degree of damage to cladodes (1‒5) and were harvested when they reached a score of 5, showing 100% damage (chlorosis and dehydration) to the whole plant. The Liso Forrageiro clone took 419 days to reach Score 5, indicating its greater tolerance to salinity. Highest dry matter yields were achieved by Orelha de Elefante Mexicana and Orelha de Elefante Africana clones with 51.5 and 50.8 g/plant, respectively, while Liso Forrageiro yielded only 36.1 g/plant, despite having similar surface area and weight of roots to these 2 clones. Further studies in the field involving these better-performing clones seem warranted to determine how the pot trial results are repeated in the field, especially in areas where carmine cochineal insect is prevalent.

‘Gold Rush’ pear (Pyrus communis L.) is a russet-coloured fruit with soft buttery textured flesh and is gaining wide popularity in Australia and other countries along with other pear cultivars. The fruit are sensitive to ethylene, and exposure even at very low concentrations significantly reduces the storage duration as well as fruit quality during storage. The efficacy of two new ethylene antagonist compounds, namely, 1H-cyclopropabenzene (BC) and 1H-cyclopropa[b]naphthalene (NC), as well as 1-methylcyclopropene (1-MCP) in regulating ethylene production, respiration rates and maintaining the fruit quality of ‘Gold Rush' pear during 150 d and 200 d of controlled atmosphere (CA) storage (2.3 ± 0.5% O2 and 0.4 ± 0.15% CO2 and 0.50 ± 0.71 °C) was investigated. The pear fruit was fumigated with 1 µM BC (0.09 µL L−1) or 1 µM NC (0.14 µL L−1) or 18 µM 1-MCP (1 µL L−1) for 18 h at room temperature and the untreated fruit was considered as the control. Following 150 d and 200 d CA storage, the fruit fumigated with BC and NC exhibited significantly reduced ethylene and respiratory climacteric peak rates and they were lowest in the fruit treated with 1-MCP. The pear fruit fumigated with ethylene antagonists (BC, NC and 1-MCP) exhibited lower physiological loss of weight (PLW) (up to 2.06 times) and higher fruit firmness (up to 1.07 times) throughout the CA storage period, compared to the control fruit. The fruit fumigated with BC and NC had lower levels of SSC, glucose and sorbitol compared to other treatments. There was no significant effect of ethylene antagonist treatments on levels of individual organic acids, total phenols, ascorbic acid and total antioxidant capacity of the fruit pulp. Therefore, new ethylene antagonist compounds, BC and NC, exhibit the potential to act as ethylene antagonists in long-term CA-stored ‘Gold Rush’ pears to retard the fruit ripening process, extend storage life and maintain the fruit quality. The effectiveness of the different concentrations of BC and NC in suppressing ethylene production in different cultivars of pears warrants further investigation.

Plant laccases are copper-containing glycoproteins oxidizing monolignol, which is a key regulator for lignin polymerization and deposition in plant cell walls. In plants, the LAC gene family has been identified and functionally characterized in Arabidopsis, rice, and other plant species. Whereas, no systematic analysis of LAC genes was explored in pear (Pyrus bretschneideri), especially their biological roles in stress responses. In this study, a total of 40 P. bretschneideri LACs (PbLACs) were identified from the pear genome, among which 32 PbLACs members were distributed on 14 chromosomes, and 8 PbLACs were mapped onto scaffold contigs. Subsequently, the chromosome localizations, gene structures, conserved domains, gene duplication were analyzed comprehensively and bioinformatically. Phylogenetic analysis demonstrated that the PbLACs were classified into seven groups. Synteny analysis exhibited that whole-genome duplication (WGD)/segmental duplication was essential for the expansion of PbLAC family. In detail, the 26 PbLACs duplicated gene pairs were taken place at the two WGD events. Further, our results showed that purifying selection presented as the primary force to drive the evolution of PbLACs. Notably, the transcriptomic data were used for exploring the biological roles of PbLACs in response to abiotic stresses (cold, drought, and salt) in pear. We found that the expression of certain PbLACs was significantly induced by drought, cold or salt treatments, suggesting that these PbLACs are potentially key genes for further functional characterization in pear in the future. Taken together, our results not only contribute to an enhanced understanding of the evolutional complexity of PbLAC gene family but also provide a good platform for functional studies of PbLAC genes in response to various abiotic stresses.

Background The plant U-box (PUB) proteins are a family of ubiquitin ligases (E3) enzymes that involved in diverse biological processes, as well as in responses to plant stress response. However, the characteristics and functional divergence of the PUB gene family have not yet been previously studied in the Chinese white pear (Pyrus bretschneideri). Results In the present study, we identified 62 PbrPUBs in Chinese white pear genome. Based on the phylogenetic relationship, 62 PUB genes were clustered into five groups. The results of conserved motif and gene structure analysis supported the classification phylogenetic tree. The PbrPUB genes were unevenly distribution on 17 pear chromosomes, chromosome 15 housed most member of PUB family, with eight PUB genes. Cis-acting element analysis indicated that PUB genes might participate in diverse biological processes, especially in the response to abiotic stresses. Based on RNA-data from ‘Dangshansuli’ at seven tissues, we found that PUB genes exhibited diverse of expression level in seven tissues, and qRT-PCR experiment further supported the reliable of RNA-Seq data. To identify candidate genes associated with resistance, we conducted qRT-PCR experiment the expression level of pear seed plant under four abiotic stresses, including: ABA, dehydration, salt and cold treatment. One candidate PUB gene associated with dehydration stress was selected to conduct further functional experiment. Subcellular localization revealed PbrPUB18 protein was located on cell nucleus. Furthermore, heterologous over-expression of PbrPUB18 in Arabidopsis indicated that the over-expression of PbrPUB18 could enhance resistance in drought treatment. In conclusions, we systematically identified the PUB genes in pear, and provided useful knowledge for functional identification of PUB genes in pear.

Stone cells have been described to substantially influence pear fruit quality, as lignin and cellulose are the main components of stone cells. However, there are limited studies on the relationship between the variation and molecular basis of stone cells, lignin and cellulose content among different pear varieties. Here, to reveal the variation of stone cell content within different cultivated species, we collected 236 germplasms of sand pear (Pyrus pyrifolia) at 50 days after flower blooming (DAFB), the key stage of stone cell formation. In our results, we measured the content of stone cells, lignin and cellulose and found that these contents ranged from 2.82% to 29.00%, 8.84% to 55.30% and 11.52% to 30.55%, respectively. Further analysis showed that the variation coefficient of stone cell, lignin and cellulose content was 39.10%, 28.03% and 16.71%, respectively. Additionally, a significant correlation between stone cell, lignin and cellulose content were detected, and the correlation coefficient between the contents of stone cell and lignin (0.912) was higher than between the contents of stone cell and cellulose (0.796). Moreover, the average lignin content (29.73%) was higher than the average cellulose content (18.03%) in stone cells in pear fruits, indicating that lignin is the main component of stone cell in pears. Finally, on the basic of the transcriptome data, we identified 10 transcription factors belonging to bHLH, ERF, MYB, and NAC transcript families, which might be involved in lignin formation in stone cells. qRT-PCR experiments verified coincident trends between expression of candidate genes and stone cell content. This research laid foundation for future studies on genetic variation of stone cells in pear fruits and provided important gene resources for stone cell regulation.

Iron is an essential trace element for plants; however, low bioactive Fe in soil continuously places plants in an Fe-deficient environment, triggering oxidative damage. To cope with this, plants make a series of alterations to increase Fe acquisition; however, this regulatory network needs further investigation. In this study, we found notably decreased indoleacetic acid (IAA) content in chlorotic pear (Pyrus bretschneideri Rehd.) leaves caused by Fe deficiency. Furthermore, IAA treatment slightly induced regreening by increasing chlorophyll synthesis and Fe2+ accumulation. At that point, we identified PbrSAUR72 as a key negative effector output of auxin signaling and established its close relationship to Fe deficiency. Furthermore, the transient PbrSAUR72 overexpression could form regreening spots with increased IAA and Fe2+ content in chlorotic pear leaves, whereas its transient silencing does the opposite in normal pear leaves. In addition, cytoplasm-localized PbrSAUR72 exhibits root expression preferences and displays high homology to AtSAUR40/72. This promotes salt tolerance in plants, indicating a putative role for PbrSAUR72 in abiotic stress responses. Indeed, transgenic plants of Solanum lycopersicum and Arabidopsis thaliana overexpressing PbrSAUR72 displayed less sensitivity to Fe deficiency, accompanied by substantially elevated expression of Fe-induced genes, such as FER/FIT, HA, and bHLH39/100. These result in higher ferric chelate reductase and root pH acidification activities, thereby hastening Fe absorption in transgenic plants under an Fe-deficient condition. Moreover, the ectopic overexpression of PbrSAUR72 inhibited reactive oxygen species production in response to Fe deficiency. These findings contribute to a new understanding of PbrSAURs and its involvement in Fe deficiency, providing new insights for the further study of the regulatory mechanisms underlying the Fe deficiency response.

(1) Background: Organic food produced in environmentally friendly farming systems has become increasingly popular. (2) Methods: We used a DNA metabarcoding approach to investigate the differences in the microbial community between organic and conventional ‘Huangguan’ pear fruit; and (3) Results: Compared to a conventional orchard, the fruit firmness in the organic orchard had significantly lowered after 30 days of shelf-life storage at 25 °C, and the soluble solids content (SSC), titratable acid (TA), and decay index were higher. There were differences in the microbial diversity between organic and conventional orchards pears. After 30 days of storage, Fusarium and Starmerella became the main epiphytic fungi in organic fruits, while Meyerozyma was dominant in conventional fruits. Gluconobacter, Acetobacter, and Komagataeibacter were dominant epiphytic bacteria on pears from both organic and conventional orchards after a 30-day storage period. Bacteroides, Muribaculaceae, and Nesterenkonia were the main endophytic bacteria throughout storage. There was a negative correlation between fruit firmness and decay index. Moreover, the abundance of Acetobacter and Starmerella were positively correlated with fruit firmness, while Muribaculaceae was negatively correlated, implying that these three microorganisms may be associated with the postharvest decay of organic fruit; (4) Conclusions: The difference in postharvest quality and decay in organic and conventional fruits could potentially be attributed to the variation in the microbial community during storage.

Light-harvesting chlorophyll a/b binding (Lhc) proteins play a key role in the efficiency of the photosynthetic system of plants and participate in the regulation of plant growth, development, and the response to abiotic stress. In this study, 28 PbrLhc genes of the family were identified in the pear Pyrus bretschneideri genome database, which were distributed on 25 of the 27 chromosomes. Phylogenetic relationship analysis demonstrated that PbrLhc proteins could be divided into five subfamilies. Using MEME Suite, PlantRegMap, and Softberry, the conserved motifs, transcription binding sites, and predicated location of all PbrLhc proteins, respectively, were determined. A collinearity relationship using MCScanX software showed that there was a collinearity relationship between different PbrLhc genes. Using the hierarchical clustering method to develop a heat map of gene expression, five genes were found to be down-regulated under irrigation treatment and up-regulated under drought treatment; seven genes were up-regulated under irrigation treatment and down-regulated under drought treatment. Finally, the results of these analyses will provide theoretical basis for future study on the function and differential expression of PbrLhc genes in response to drought stress.

Brown spot is the most important disease for the culture of cactus prickly pear (Nopalea cochenillifera (L) Salm-Dyck; Cactaceae family), and in many countries, Alternaria spp. are commonly associated with the disease. In Brazil, only three species of Alternaria are associated with brown spot: A. alternata, A. tenuissima, and A. longipes. However, other Alternaria spp. may be involved in the etiology of the disease. This study aimed to identify Alternaria species associated with prickly pear brown spot in Northeast Brazil. Cladodes presenting symptoms of brown spot were collected from three counties in the state of Alagoas and three in the state of Pernambuco. Isolation, obtaining monosporic cultures, and pathogenicity tests were performed. For correct taxonomic positioning of the isolates, morphological and molecular analyses were performed using the internal transcribed spacer (ITS) region and the translation elongation factor 1-alpha (tef1), Alternaria major allergen (Alt a1), glyceraldehyde-3-phosphate dehydrogenase (gapdh), and second largest subunit of RNA polymerase (rpb2). Fourteen pathogenic isolates were obtained, and according to the morphological and molecular analyses, three species of Alternaria were identified: A. gossypina, A. jacinthicola, and A. tomato, all belonging to the Alternata section. A. gossypina, A. jacinthicola, and A. tomato are described for the first time in Nopalea cochenillifera worldwide.