Bud dormancy is a critical developmental process that allows perennial plants to survive unfavorable environmental conditions. Pear is one of the most important deciduous fruit trees in the world, ...but the mechanisms regulating bud dormancy in this species are unknown. Because genomic information for pear is currently unavailable, transcriptome and digital gene expression data for this species would be valuable resources to better understand the molecular and biological mechanisms regulating its bud dormancy.
We performed de novo transcriptome assembly and digital gene expression (DGE) profiling analyses of 'Suli' pear (Pyrus pyrifolia white pear group) using the Illumina RNA-seq system. RNA-Seq generated approximately 100 M high-quality reads that were assembled into 69,393 unigenes (mean length = 853 bp), including 14,531 clusters and 34,194 singletons. A total of 51,448 (74.1%) unigenes were annotated using public protein databases with a cut-off E-value above 10-5. We mainly compared gene expression levels at four time-points during bud dormancy. Between Nov. 15 and Dec. 15, Dec. 15 and Jan. 15, and Jan. 15 and Feb. 15, 1,978, 1,024, and 3,468 genes were differentially expressed, respectively. Hierarchical clustering analysis arranged 190 significantly differentially-expressed genes into seven groups. Seven genes were randomly selected to confirm their expression levels using quantitative real-time PCR.
The new transcriptomes offer comprehensive sequence and DGE profiling data for a dynamic view of transcriptomic variation during bud dormancy in pear. These data provided a basis for future studies of metabolism during bud dormancy in non-model but economically-important perennial species.
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DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, SIK, UILJ, UKNU, UL, UM, UPUK
To understand the soil nutrient status of pear orchards in Beijing, we investigated their fertilization situation, including the fertilizer type, amount, and period. Furthermore, soil samples were ...collected at a depth of 0 to 40 cm to determine the contents of soil nitrogen, phosphorus, and potassium. The status of nutrient profits and losses was analyzed. The results showed that 50% of the pear orchards received organic fertilizer as a single nutrient source, and 35.7% of the pear orchards received a combined application of organic fertilizer and chemical fertilizer. Most pear orchards received organic fertilizer in autumn, but the application of chemical fertilizer occurred mainly before germination and during fruit expansion. The average nutrient input to the investigated pear orchards was 569.6 kg/ha for N, 855.0 kg/ha for P 2 O 5 , and 448.1 kg/ha for K 2 O, and the corresponding proportion of organic fertilizer was 76.9%, 88.0%, and 85.8%, respectively. However, the pear orchards had surpluses of nitrogen, phosphorus, and potassium, with average surplus amounts as high as 445.5, 794.3, and 321.4 kg/ha, respectively. Among all pear orchards surveyed, 93.33% faced environmental risks and 37.04% faced leaching risks. The average content of soil phosphorus was 2.23 times its critical value, and 64.29% of the studied pear orchards exceeded the critical value. Most pear orchards had surplus potassium, with 26.92% exceeding 500 kg/ha. This study provides a basis for soil improvement, high-quality production of fruits, and efficient utilization of pear orchards in Beijing.
In August 2020, anthracnose-like symptoms was observed on pear fruit (Pyrus pyrifolia P. communis) cultivated at 0.2 ha by the National Institute of Horticultural and Herbal Science Pear Research ...Institute at the Rural Development Administration (Naju, Jeonnam Province in Korea). Symptoms were observed only on fruit (112 days after full bloom (DAFB)), and disease incidences was at least 90%. Initial black specks developed into larger brown or black lesions on fruit after 3 days. Later, sunken lesions with orange conidial masses were observed. Finally, infected fruit dropped prematurely. To isolate and identify the pathogen, small pieces (5 5 mm) from the margin of lesions on fruit were surface sterilized by immersing in 70% ethanol for 1 minute, washed three times with sterile water, dried, and placed on water agar amended with 100 ppm streptomycin, then incubated in the dark at 25°C. Hyphae emerging from the three independent tissues were subcultured on Potato Dextrose Agar (PDA), resulting in three independent isolates (CP-1, CP-2, CP-3) after single spore isolation. Colonies were pale gray on PDA, but the colony edges were white. Conidia were transparent, cylindrical with rounded ends, and 13.8 to 20.1 μm 4.8 to 6.2 μm (avg. 18.3 μm 5.4 μm, n = 100) in size. Appressoria were dark brown, globose or subcylindrical, and 6.3 to 9.5 μm 5.2 to 6.9 μm in size (8.1 6.1 μm, n = 100). The morphological characteristics were similar to the descriptions of C. gloeosporioides species complex (Weir et al. 2012). Sequences of ITS (MT921589-91), GAPDH (MT921987-89), CAL (MT921990-92), ACT (MT921993-95), CHS-1 (MT921996-98), TUB2 (921999-01), and ApMAT (MT922002-04) sequences from CP-1, CP-2, and CP-3 matched with C. fruiticola strain BRIP 62871 (100%; MK298285), HXQT-2 (100%; MN52588), HXQT-2 (100%; MN52839), HXQT-2 (99.65; MN525801), ICKP18B4 (99.34%; LC494275), HB5 (100%; MH985245), and GQHZJ23 (100%; MN338294), respectively. Concatenated gene sequences were used for a phylogenetic analysis based on the maximum likelihood method. The reference gene accessions and other information are presented in Weir et al. (2012). The analysis placed the isolates within a clade comprising C. fructicola. Pathogenicity of CP-1 was tested using 120 healthy pear fruits. The fruit surfaces were sterilized with 70% ethyl alcohol for 2 min and washed twice with sterilized water. Three 120 DAFB fruits were inoculated with 10 l of a conidial suspension (1×106 conidia/ml) with and without wounding. Another three control fruits were inoculated with sterile distilled with and without wounding. The inoculated fruit were placed in a plastic box to maintain high humidity and incubated in the dark at 25°C. Symptoms were observed on both wounded fruits after 3 days post inoculation (dpi) and 5 dpi on the unwounded fruits. No symptoms were observed in the control on both the wounded fruits. Pathogenicity tests was performed in duplicate. The pathogen was re-isolated from symptomatic tissues (100%) on treatments on both the wounded and unwounded fruits, but not control. The identity of the both re-isolated pathogen from the wounded and unwounded fruits was confirmed via analysis of seven genes and morphological characteristics, thus fulfilling Koch's postulates. Although C. fructicola has been reported on apples and peaches in Korea (Kim et al. 2018; Lee et al. 2020), this is the first report of anthracnose caused by C. fructicola on pear fruit in Korea, highlighting the need for systematically investigating the diversity and incidence of pear anthracnose in Korea. This study will contribute to the development of control strategies for anthracnose disease on pear fruit in Korea.
Summary
Red fruits are popular and widely accepted by consumers because of an enhanced appearance and enriched anthocyanins. The molecular mechanism of anthocyanin regulation in red‐skinned pear ...(Pyrus) has been studied, and the genes encoding the biosynthetic steps and several transcription factors (TFs) have been characterized. In this study, a candidate R2R3 MYB TF, PyMYB114, was identified by linkage to the quantitative trait loci (QTL) for red skin color on linkage group 5 in a population of Chinese pear (Pyrus bretschneideri). The function of PyMYB114 was verified by transient transformation in tobacco (Nicotinana tabacum) leaves and strawberry (Fragaria) and pear fruits, resulting in the biosynthesis of anthocyanin. Suppression of PyMYB114 could inhibit anthocyanin biosynthesis in red‐skinned pears. The ERF/AP2 TF PyERF3 was found to interact with PyMYB114 and its partner PybHLH3 to co‐regulate anthocyanin biosynthesis, as shown by a dual luciferase reporter system and a yeast two‐hybrid assay. In addition, the transcript abundance of PyMYB114 and PyMYB10 were correlated, and co‐transformation of these two genes into tobacco and strawberry led to enhanced anthocyanin biosynthesis. This interaction network provides insight into the coloration of fruits and the interaction of different TFs to regulate anthocyanin biosynthesis.
Significance Statement
Red‐colored fruits are popular and widely accepted because of an enhanced appearance and enriched anthocyanins. However, the molecular mechanisms underlying the coloration of red‐skinned pears are inconsistent between different genetic backgrounds. PyMYB114 was identified by QTL mapping, and its function in interacting with PyERF3 and PybHLH3 to co‐regulate anthocyanin biosynthesis of pear was revealed. An interaction of PyMYB114 and PyMYB10 leading to enhanced anthocyanin biosynthesis was verified in tobacco and strawberry.
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BFBNIB, FZAB, GIS, IJS, KILJ, NLZOH, NUK, OILJ, SBCE, SBMB, UL, UM, UPUK
•Intracellular Ca2+ responses to pear scab infection in two cultivars were analyzed.•Mechanisms underpinning scab-induced intracellular Ca2+ changes were elaborated.•Six Ca2+ sensor genes participate ...in pear scab resistance in the resistant cultivar.
In this study, we investigated the role of Ca2+ signaling in pear (Pyrus. bretschneideri Rehd) in response to pear scab (Venturia nashicola Tanak et Yamamota) infection. We analyzed the responses of intracellular Ca2+ and expression changes of Ca2+ sensor-related genes in two pear cultivars of differing resistance (the resistant ‘Huangguan’ and the susceptible ‘Xuehua’) following V. nashicola infection by using fluorescence microscopy, microplate spectrophotometry, and real-time quantitative PCR assays. Over a 60 min treatment period, V. nashicola induced elevated Ca2+ fluorescence in cell protoplasts (loaded with Fluo-3 AM) from fruit callus cultures of both pear cultivars, but the Ca2+ change patterns differed. Both LaCl3 (a plasma membrane Ca2+ channel inhibitor) and EGTA (an extracellular Ca2+ chelator) inhibited Ca2+cyt in both cultivars, while BAPTA-AM (an intracellular Ca2+ chelator) showed no inhibitory effect. The relative expression levels of PbCaM1, PbCaM5, PbCBL1, PbCIPK2, PbCPK1, and PbCPK2 in ‘Huangguan’ pear were significantly upregulated following infection and peaked at 72 post-infection hour. PbCPK1 and PbCPK2 underwent the most intense expression changes of these six genes tested. In ‘Xuehua’ pear, only PbCBL1 and PbCIPK2 were significantly upregulated following infection, while the remaining genes were downregulated to varying degrees. In conclusion, V. nashicola infection induced Ca2+ signaling in pear cells, and changes in Ca2+cyt were mainly due to extracellular Ca2+ influx. In ‘Huangguan’ pear, all tested genes related to Ca2+ sensors responded to V. nashicola infection, and might participate in resistance to the scab pathogen.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
‘Korla’ fragrant pear ( Pyrus sinkiangensis T.T. Yu) variety has shown severe coarse skin in recent years. The intrinsic quality of its coarse fruit shows an increase in the number of stone cells and ...poor taste. In this study, stone cells and the cell wall of coarse pear (CP) and normal pear (NP) during various development stages were compared using paraffin-sectioning and transmission electron microscopy (TEM), and the relationships between lignin-related genes and stone cell formation and cell wall thickening were also analyzed. Our results show that giant stone cells are formed and distributed in the core of pear, whereas many of these crack 60 days after flowering (DAF). The period of stone cell fragmentation occurs later in CP fruits than in NP fruits. Parenchyma cell wall development in CP and NP fruits varies from 120 DAF to maturity. The parenchyma cell wall of CP fruits thickens, whereas that of NP fruits is thinner during the same period. The expression pattern of five genes ( Pp4CL1-l , PpHCT-l , Pp4CL2-l , PpPOD4 , and PpPOD25 ) coincides with changes in stone cell content in the pulp. Correlation analysis demonstrates a significant correlation between stone cell content and the expression level of the five genes ( ρ < 0.05). In addition, the expression of those five genes and PpCCR1 genes in CP fruits significantly increases during maturation and is highly correlated with the thickness of the parenchyma cell wall. The aim of this work is to provide insights into the mechanism of stone cell and parenchyma cell wall development in pear fruits and identify important candidate genes to regulate the quality of fruit texture using bioengineering methods.
•Spraying 0.4% ZnSO4 caused fertilizer burns on all-age leaves and unbagged fruitlets.•ZnEDTA can be safely used at a higher spraying rate of 1.5%.•1.5% ZnEDTA is an effective approach to produce ...high-level Zn-fortified pears.•Contents of other mineral elements in zinc-fortified pear were not reduced.
The increases in the Zn-biofortification level are currently limited to the spraying rates, as the widely-used ZnSO4 fertilizer applications at high spraying rates cause leaf and fruitlet burn, along with yield losses. To address this, in our investigation, the effects of inorganic Zn sources and chelated Zn sources at normal to excess concentrations on foliage health, photosynthetic performance, yield, and mineral concentration changes in pear fruits were compared to establish how to maximize the Zn concentration without fertilizer burn. The 2020 field results showed that the chelated Zn sources (ZnEDTA, ZnGly and ZnGlc) caused less foliar burn than inorganic Zn sources (ZnNO3 and ZnSO4). The safety threshold concentration of ZnEDTA was 1.5%, which was substantially higher than that of the other sources (0.4%). The results of the nationwide broad-spectrum tests on eight pear cultivars at three locations in 2021 confirmed that spraying 1.5% ZnEDTA is an effective approach to produce high-level Zn-fortified pears, without compromising agronomic performance. Our study not only provides new insights into chelated fertilizers but will also help to promote producing of Zn-fortified pears.
The model diagram of spraying ZnEDTA and ZnSO4 on Zn biofortification, leaf burn, and yield losses. Display omitted
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Changes in membrane integrity and permeability are related to pericarp browning.•PLD and LOX activities and PuPLD and PuLOX expression increased in pericarp browning.•Pericarp browning severity ...during shelf life is related to duration of cold storage.•Membrane damage due to expression of PuPLD and PuLOX caused pericarp browning.
Cold storage is the primary postharvest technology used to maintain fruit quality and is generally employed to prolong the storage life of ‘Nanguo’ pears (Pyrus ussuriensis Maxim). However, pericarp browning gradually appeared when ‘Nanguo’ pears were kept at 20°C after storage for 120 and 180d at 0°C. In this study, changes in the browning substrate and activity of key enzyme, membrane permeability, and the extent of membrane lipid peroxidation were investigated. Changes in the activity and gene expression of enzymes involved in the membrane lipid metabolism pathway were also studied. Significantly higher polyphenol oxidase (PPO) activity and lower total phenolic content were observed in fruit when browning occurred. Fruit kept for 180d in cold storage showed a significant increase in membrane permeability and malondialdehyde (MDA) content compared to fruit stored for 60 and 120d. This increase occurred late in cold storage and was maintained during subsequent shelf life. The activity of lipoxygenase (LOX) was remarkably increased and levels of PuPLD and PuLOX transcripts were markedly up-regulated during cold storage. During shelf life after cold storage, when pericarp browning occurred, the activities of phospholipase D (PLD) and LOX were significantly higher and expressions of PuPLD and PuLOX were significantly increased. These results indicated that the severity of pericarp browning during shelf life is related to the duration of cold storage. Pericarp browning resulted from membrane damage, possibly due to expression of PuPLD and PuLOX.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
•Pathogenesis of pear infected by A. alternata was monitored by HSI.•HSI was successfully used for early identification of pear black spot disease.•Spectral angle mapper was used to identify and ...segment the fruit infected area.•SVM model had better classification accuracy for early detection of disease.
Pathogenetic process monitoring and early detection of black spot disease caused by Alternaria alternata on pear fruit is still difficult, as it causes only minor changes in the appearance of the infected area during the early stages of infection. In this study, the potential of hyperspectral imaging (HSI) for monitoring the pathogenetic process and early detection of the disease on pear fruit was evaluated. Fresh Korla pears were inoculated with Alternaria alternata and hyperspectral images were acquired from infected and control samples. Spectral angle mapping was performed to segment the infected area from sound tissue, and to monitor the pathogenetic process of the disease. Support vector machine (SVM), k-nearest neighbor, and partial least squares discriminant analysis models were developed and evaluated for their ability to detect early onset of the disease. Results concluded that the SVM model with an overall accuracy of 97.5% was most suitable for the proposed HSI technique. This study is the first reported attempt to use HSI to monitor the pathogenetic process and detect the early symptom of the disease in pear fruit.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
•Hyperspectral imaging technology was used to detect bruise damage in Shingo pear.•NIR range of 950–1650nm was effective for detecting bruise underneath pear skin.•Optimal waveband ratio for ...detecting pear bruises was determined based on F-value.•The best threshold waveband ratio detected bruises with accuracy of 92%.•Hyperspectral NIR imaging could be a potential detection method for fruit bruises.
Bruise damage on pears is one of the most crucial internal quality factors, which needs to be detected in postharvest quality sorting processes. Near-infrared imaging techniques (NIR) have effective potentials for identifying and detecting bruises since bruises result in the rupture of internal cell walls due to defects on agricultural materials. In this study, a novel NIR technique, hyperspectral imaging with beyond NIR range of 950–1650nm, was investigated for detecting bruise damages underneath the pear skin, which has never been examined in the past. A classification algorithm based on F-value was applied for analysis of image to find the optimal waveband ratio for the discrimination of bruises against sound surface. The result demonstrated that the best threshold waveband ratio detected bruises with the accuracy of 92%, illustrating that the hyperspectral infra-red imaging technique with the region beyond NIR could be a potential detection method for pear bruises.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK
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