Comprehensive analysis of KCS gene family in pear reveals the involvement of PbrKCSs in cuticular wax and suberin synthesis and pear fruit skin formation.

Cuticular wax, cutin and suberin polyesters covering the surface of some fleshy fruit are tightly associated with skin color and appearance. ß-Ketoacyl-CoA synthase (KCS) is a rate-limiting enzyme participating in the synthesis of very-long-chain fatty acids (VLCFAs), the essential precursors of cuticular waxes and aliphatic monomers of suberin. However, information on the KCS gene family in pear genome and the specific members involved in pear fruit skin formation remain unclear. In the present study, we performed an investigation of the composition and amount of cuticular waxes, cutin and aliphatic suberin in skins of four sand pear varieties with distinct colors (russet, semi-russet, and green) and demonstrated that the metabolic shifts of cuticular waxes and suberin leading to the significant differences of sand pear skin color. A genome-wide identification of KCS genes from the pear genome was conducted and 35 KCS coding genes were characterized and analyzed. Expression profile analysis revealed that the KCS genes had diverse expression patterns among different pear skins and the transcript abundance of PbrKCS15, PbrKCS19, PbrKCS24, and PbrKCS28 were consistent with the accumulation of cuticular waxes and suberin in fruit skin respectively. Subcellular localization analysis demonstrated that PbrKCS15, PbrKCS19, PbrKCS24 and PbrKCS28 located on the endoplasmic reticulum (ER). Further, transient over-expression of PbrKCS15, PbrKCS19, and PbrKCS24 in pear fruit skins significantly increased cuticular wax accumulation, whereas PbrKCS28 notably induced suberin deposition. In conclusion, pear fruit skin color and appearance are controlled in a coordinated way by the deposition of the cuticular waxes and suberin. PbrKCS15, PbrKCS19, and PbrKCS24 are involved in cuticular wax biosynthesis, and PbrKCS28 is involved in suberin biosynthesis, which play essential roles in pear fruit skin formation. Moreover, this work provides a foundation for further understanding the functions of KCS genes in pear.

PpyMYB144 transcriptionally regulates pear fruit skin russeting by activating the cytochrome P450 gene PpyCYP86B1.

MAIN CONCLUSION: PpyMYB144 directly activates the promoter of PpyCYP86B1, promotes the synthesis of α, ω-diacids, and involves in pear fruit skin russeting. Russeting is an economically important surface disorder in pear (Pyrus pyrifolia) fruit. Previous research has demonstrated that suberin is the pivotal chemical component contributing to pear fruit skin russeting, and fruit bagging treatment effectively reduces the amount of suberin of fruits, and thereby reduces the russeting phenotype. However, the mechanisms of pear fruit skin russeting remain largely unclear, particularly the transcriptional regulation. Here, we dissected suberin concentration and composition of pear fruits along fruit development and confirmed that α, ω-diacids are the predominant constituents in russeted pear fruit skins. Two cytochrome P450 monooxygenase (CYP) family genes (PpyCYP86A1 and PpyCYP86B1) and nine MYB genes were isolated from pear fruit. Expressions of PpyCYP86A1, PpyCYP86B1, and five MYB genes (PpyMYB34, PpyMYB138, PpyMYB138-like, PpyMYB139, and PpyMYB144) were up-regulated during fruit russeting and showed significant correlations with the changes of α, ω-diacids. In addition, dual-luciferase assays indicated that PpyMYB144 could trans-activate the promoter of PpyCYP86B1, and the activation was abolished by motif mutagenesis of AC element on the PpyCYP86B1 promoter. Further, Agrobacterium-mediated transient expression of PpyCYP86B1 and PpyMYB144 in pear fruits induced the deposition of aliphatic suberin. Thus, PpyMYB144 is a novel direct activator of PpyCYP86B1 and contributes to pear fruit skin russeting.

Transcriptome changes associated with boron applications in fruits of watercore-susceptible pear cultivar.

BACKGROUND: Watercore is a common physiological disorder in pear and is closely related to the excessive accumulation of sorbitol and sucrose. Our previous research found that the incidence of watercore in 'Akibae' (Pyrus pyrifolia cv. Akibae) fruit significantly decreased after boron application (BA). Moreover, the foliar spray of boric acid also significantly improved fruit quality. However, the mechanisms underlying the pear fruit response to BA was still limited. METHODS AND RESULTS: A comprehensive transcriptome analysis of BA treatment 'Akibae' pear fruit was performed in this study. Transcriptome results revealed a total of 3146 up-regulated and 1145 down-regulated differentially expressed genes (DEGs) between control and treated fruits of 'Akibae' pear. BA significantly induced the expression of sorbitol metabolism and sucrose metabolism genes. In addition, BA also increased the expression of starch degradation, fatty acid synthesis, IAA (indole-3-acetic acid) degradation, and GA (gibberellin acid) synthesis genes and inhibited the expression of ethylene synthesis genes. CONCLUSIONS: These findings suggested that BA probably alleviates 'Akibae' watercore occurrence and improves fruit quality by regulating the decrease in sorbitol and sucrose, the increase in fatty acids and the balance of plant hormones. Our results provide further information for understanding the molecular mechanism of the effect of BA on pear fruit.

Transcriptome and Metabolite Conjoint Analysis Reveals the Seed Dormancy Release Process in Callery Pear.

Seed dormancy transition is a vital developmental process for seedling propagation and agricultural production. The process is precisely regulated by diverse endogenous genetic factors and environmental cues. Callery pear (Pyrus calleryana Decne) is an important rootstock species that requires cold stratification to break seed dormancy, but the mechanisms underlying pear seed dormancy release are not yet fully understood. Here, we analyzed the transcriptome profiles at three different stages of cold stratification in callery pear seeds using RNA sequencing combined with phytohormone and sugar content measurements. Significant alterations in hormone contents and carbohydrate metabolism were observed and reflected the dormancy status of the seeds. The expressions of genes related to plant hormone metabolism and signaling transduction, including indole-3-acetic acid (IAA) biosynthesis (ASAs, TSA, NITs, YUC, and AAO) genes as well as several abscisic acid (ABA) and gibberellic acid (GA) catabolism and signaling transduction genes (CYP707As, GA2ox, and DELLAs), were consistent with endogenous hormone changes. We further found that several genes involved in cytokinin (CTK), ethylene (ETH), brassionolide (BR), and jasmonic acid (JA) metabolism and signaling transduction were differentially expressed and integrated in pear seed dormancy release. In accordance with changes in starch and soluble sugar contents, the genes associated with starch and sucrose metabolism were significantly up-regulated during seed dormancy release progression. Furthermore, the expression levels of genes involved in lipid metabolism pathways were also up-regulated. Finally, 447 transcription factor (TF) genes (including ERF, bHLH, bZIP, NAC, WRKY, and MYB genes) were observed to be differentially expressed during seed cold stratification and might relate to pear seed dormancy release. Our results suggest that the mechanism underlying pear seed dormancy release is a complex, transcriptionally regulated process involving hormones, sugars, lipids, and TFs.

Magnetism manipulated by ferroelectric polarization and epitaxial strain in a La0.75Sr0.25MnO3/BaTiO3 system.

Exploring the manipulation of magnetism in perovskite oxides is scientifically interesting and of great technical importance in next-generation magnetic memory. Dual control of magnetism in superlattices through epitaxial strain and ferroelectric polarization may induce rich physical properties. In this work, we demonstrated a strong magnetoelectric coupling that appears in an La0.75Sr0.25MnO3/BaTiO3 superlattice. Reversible transitions in ferromagnetism, ferrimagnetism and anti-ferromagnetism, with strong magnetoelectric coupling, are achieved by precisely controlling the magnitude and spin-direction of the magnetic moments of Mn. Half-metallicity is demonstrated in the MnO2 layers, accompanied by the spin polarization of the superlattice varying from 100% to 0%. We realize the coexistence of ferroelectric polarization and metallicity, i.e., "ferroelectric metal". The variation in strain and re-orientation of polarization lead to a change in interfacial Ti-O and Mn-O bond lengths, and hence a hybridization state, determining the magnetism of our system. The purpose-designed LSMO/BTO superlattice with intrinsic magnetoelectric coupling is a particularly interesting model system that can provide guidance for the development of spintronic devices.

Transcriptome and Metabolome Analyses Provide Insights into the Watercore Disorder on "Akibae" Pear Fruit.

Watercore is a physiological disorder that commonly occurs in sand pear cultivars. The typical symptom of watercore tissue is transparency, and it is often accompanied by browning, breakdown and a bitter taste during fruit ripening. To better understand the molecular mechanisms of watercore affecting fruit quality, this study performed transcriptome and metabolome analyses on watercore pulp from "Akibae" fruit 125 days after flowering. The present study found that the "Akibae" pear watercore pulp contained higher sorbitol and sucrose than healthy fruit. Moreover, the structure of the cell wall was destroyed, and the content of pectin, cellulose and hemicellulose was significantly decreased. In addition, the content of ethanol and acetaldehyde was significantly increased, and the content of polyphenol was significantly decreased. Watercore induced up-regulated expression levels of sorbitol synthesis-related (sorbitol-6-phosphate dehydrogenase, S6PDH) and sucrose synthesis-related genes (sucrose synthesis, SS), whereas it inhibited the expression of sorbitol decomposition-related genes (sorbitol dehydrogenase, SDH) and sorbitol transport genes (sorbitol transporter, SOT). Watercore also strongly induced increased expression levels of cell wall-degrading enzymes (polygalactosidase, PG; ellulase, CX; pectin methylesterase, PME), as well as ethanol synthesis-related (alcohol dehydrogenase, ADH), acetaldehyde synthesis-related (pyruvate decarboxylase, PDC) and polyphenol decomposition-related genes (polyphenol oxidase, PPO). Moreover, the genes that are involved in ethylene (1-aminocyclopropane- 1-carboxylate oxidase, ACO; 1-aminocyclopropane- 1-carboxylate synthase, ACS) and abscisic acid (short-chain alcohol dehydrogenase, SDR; aldehyde oxidase, AAO) synthesis were significantly up-regulated. In addition, the bitter tasting amino acids, alkaloids and polyphenols were significantly increased in watercore tissue. Above all, these findings suggested that the metabolic disorder of sorbitol and sucrose can lead to an increase in plant hormones (abscisic acid and ethylene) and anaerobic respiration, resulting in aggravated fruit rot and the formation of bitter substances.

Turnover of diacylglycerol kinase 4 by cytoplasmic acidification induces vacuole morphological change and nuclear DNA degradation in the early stage of pear self-incompatibility response.

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 that 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 domain 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 results in reduced DGK4 abundance and deposition, leading to morphological change of the vacuole and fragmentation of nuclear DNA, which indicates that DGK4 is a key factor in pear SI response.

P68 RNA helicase promotes invasion of glioma cells through negatively regulating DUSP5.

Gliomas are the most common central nervous system tumors. They show malignant characteristics indicating rapid proliferation and a high invasive capacity and are associated with a poor prognosis. In our previous study, p68 was overexpressed in glioma cells and correlated with both the degree of glioma differentiation and poor overall survival. Downregulating p68 significantly suppressed proliferation in glioma cells. Moreover, we found that the p68 gene promoted glioma cell growth by activating the nuclear factor-κB signaling pathway by a downstream molecular mechanism that remains incompletely understood. In this study, we found that dual specificity phosphatase 5 (DUSP5) is a downstream target of p68, using microarray analysis, and that p68 negatively regulates DUSP5. Upregulating DUSP5 in stably expressing cell lines (U87 and LN-229) suppressed proliferation, invasion, and migration in glioma cells in vitro, consistent with the downregulation of p68. Furthermore, upregulating DUSP5 inhibited ERK phosphorylation, whereas downregulating DUSP5 rescued the level of ERK phosphorylation, indicating that DUSP5 might negatively regulate ERK signaling. Additionally, we show that DUSP5 levels were lower in high-grade glioma than in low-grade glioma. These results suggest that the p68-induced negative regulation of DUSP5 promoted invasion by glioma cells and mediated the activation of the ERK signaling pathway.

Organic-Inorganic Hybrid Heterometallic Halides with Low-Dimensional Structures and Red Photoluminescence Emissions.

In recent years, although low-dimensional hybrid lead halides have received great attention due to the fascinating photoluminescent (PL) properties, the research is still on the early stage and only limited phases have been explored and characterized. Here, by introducing heterometals as mixed structural compositions and optical activity centers, we prepared a series of low-dimensional hybrid heterometallic halides, namely as, [(Me)-DABCO]2Cu2PbI6, [(Me)2-DABCO]2M5Pb2I13 (M = Cu and Ag) and [(Me)2-DABCO]Ag2PbBr6 (Me = methyl group, DABCO = 1,4-diazabicyclo[2.2.2]octane). These hybrid halides feature a low-dimensional 0D [Cu2PbI6]2- cluster, a 1D [M5Pb2I13]4- chain, and a 2D [Ag2PbBr6]2- layer, respectively, on the basis of corner-, edge- and face-sharing connecting of [MX4] tetrahedrons, [PbX5] quadrangular pyramids, and [PbX6] octahedrons. Under the photoexcitation, these hybrid heterometallic halides exhibit deep-red luminescent emissions from 711 to 801 nm with the largest Stocks shift of 395 nm. The temperature-dependent PL emissions, PL lifetime, and theoretical calculations are also investigated to probe into the intrinsic nature of photoluminescent emissions. This work affords new types of hybrid halides by introducing different metal centers to probe into the structural evolution and photoluminescent properties.

Electron localization in niobium doped CaMnO3 due to the energy difference of electronic states of Mn and Nb.

The electron localization in Nb-doped CaMnO3 is analyzed in terms of the space and energy distribution of electronic states employing first-principles calculations. The energy difference of Mn 3d states and Nb 4d states makes NbO6 octahedra impede electrical conduction, so the random distribution of Nb in lattices leads to the localization of electrons near the bottom of the conduction bands. Therefore, although more carriers are introduced when Nb-doping content increases, both the electrical conductivity and absolute thermopower decrease in Nb heavy doped CaMnO3. The calculated transport properties agree well with the experimental data, supporting the analysis of localization.

Novel Three-Dimensional Semiconducting Materials Based on Hybrid d10 Transition Metal Halogenides as Visible Light-Driven Photocatalysts.

The development of new visible light-driven photocatalysts based on semiconducting materials remains a greatly interesting and challenging task for the purpose of solving the energy crisis and environmental issues. By using photosensitive [(Me)2-2,2'-bipy]2+ (1,1'-dimethyl-2,2'-bipyridinium) cation as template, we synthesized one new type of inorganic-organic hybrid cuprous and silver halogenides of [(Me)2-2,2'-bipy]M8X10 (M = Cu, Ag, X = Br, I). The compounds feature a three-dimensional anionic [M8X10]2- network composed of a one-dimensional [M8X12] chain based on MX4 tetrahedral units. The photosensitization of organic cationic templates results in narrow band gaps of hybrid compounds (1.66-2.06 eV), which feature stable visible light-driven photodegradation activities for organic pollutants. A detailed study of the photocatalytic mechanism, including the photoelectric response, photoluminescence spectra, and theoretical calculations, shows that the organic cationic template effectively inhibits the recombination of photoinduced electron-hole pairs leading to excellent photocatalytic activities and photochemical stabilities.

PpyLTP36 and PpyLTP39 are involved in the transmembrane transport of cuticular wax and are associated with the occurrence of pear fruit russeting.

Non-specific lipid-transfer proteins (nsLTPs) are a group of small, cysteine-rich proteins that are involved in the transport of cuticular wax and other lipid compounds. Accumulating evidence suggests that dynamic changes in cuticular waxes are strongly associated with fruit russeting, an undesirable visual quality that negatively affects consumer appeal in pears. Currently, the regulatory role of nsLTPs in cuticular wax deposition and pear fruit skin russeting remains unclear. Here, we characterized the variations of cuticular waxes in non-treated (russeted) and preharvest bagging treated (non-russeted) pear fruits throughout fruit development and confirmed that the contents of cuticular waxes were significantly negatively correlated with the occurrence of pear fruit russeting. Based on RNA-Sequencing (RNA-Seq) and quantitative real-time PCR (qRT-PCR) analyses, two nsLTP genes (PpyLTP36 and PpyLTP39) were identified, which exhibited high expression levels in non-russeted pear fruit skins and were significantly repressed during fruit skin russeting. Subcellular localization analysis demonstrated that PpyLTP36 and PpyLTP39 were localized to the plasma membrane (PM). Further, transient Virus-Induced Gene Silencing (VIGS) analyses of PpyLTP36 and PpyLTP39 in pear fruits significantly reduced cuticular wax deposition. In conclusion, PpyLTP36 and PpyLTP39 are involved in the transmembrane transport of cuticular wax and are associated with pear fruit skin russeting.

Integrated physiological analyses, transcriptome, and DNA methylation reveal superiority of pear stigma-style complex development regulation.

Styles and stigmas are crucial components of the fertilization process that allows a pear tree to bear fruit. The information regarding the development mechanism of pear style and stigma is still unclear. Our results demonstrated that IAA, ABA, and BR are significantly increased at 1 DBF, while JA is decreased at 5 DBF. The fructose and starch contents significantly increased at 1 DBF when the style with stigma was ready for pollination. Transcriptome and DNA methylation analysis showed 8087 DEGs and 3771 DMRs were enriched in plant hormones biosynthesis, carbohydrate biosynthesis and metabolism, and TFs in 1 DBF as compared with 7 DBF. The CHH methylation type of DMRs accounts for 84.75%. Most DMRs of CHH upregulated in 1 DBF vs. 7 DBF. This study found for the first time that transcription factor ERFs and DNA methylation are involved in regulating the growth and development of fruit plant style and stigma.

S genotyping in Japanese plum and sweet cherry by allele-specific hybridization using streptavidin-coated magnetic beads.

KEY MESSAGE: We report a rapid and reliable method for S genotyping of Rosaceae fruit trees, which would to be useful for successful planting of cross-compatible cultivars in orchards. Japanese plum (Prunus salicina) and sweet cherry (Prunus avium), belonging to the family Rosaceae, possess gametophytic self-incompatibility controlled by a single polymorphic locus containing at least two linked genes, S-RNase and SFB (S-haplotype-specific F-box gene). For successful planting of cross-compatible cultivars of Rosaceae fruit trees in commercial orchards, it is necessary to obtain information on S genotypes of cultivars. Recently, a method of dot-blot analysis utilizing allele-specific oligonucleotides having sequences of SFB-HVa region has been developed for identification of S haplotypes in Japanese plum and sweet cherry. However, dot-blot hybridization requires considerable time and skill for analysis even of a small number of plant samples. Thus, a quick and efficient method for S genotyping was developed in this study. In this method, instead of a nylon membrane used for dot-blot hybridization, streptavidin-coated magnetic beads are used to immobilize PCR products, which are hybridized with allele-specific oligonucleotide probes. Our improved method allowed us to identify 10 S haplotypes (S-a, S-b, S-c, S-d, S-e, S-f, S-h, S-k, S-7 and S-10) of 13 Japanese plum cultivars and 10 S haplotypes (S-1, S-2, S-3, S-4, S-4', S-5, S-6, S-7, S-9 and S-16) of 13 sweet cherry cultivars utilizing SFB or S-RNase gene polymorphism. This method would be suitable for identification of S genotypes of a small number of plant samples.

Transcriptome Analysis in Pyrus betulaefolia Roots in Response to Short-Term Boron Deficiency.

Boron (B) deficiency stress is frequently observed in pear orchards and causes a considerable loss of productivity and fruit quality. Pyrus betulaefolia is one of the most important rootstocks that has been widely used in pear production. The present study confirmed that the boron form of different tissues showed various changes, and the free boron content was significantly decreased under the short-term B deficiency condition. Moreover, the ABA and JA content also significantly accumulated in the root after short-term B deficiency treatment. A comprehensive transcriptome analysis of 24 h B deficiency treatment P. betulaefolia root was performed in this study. Transcriptome results revealed a total of 1230 up-regulated and 642 down-regulated differentially expressed genes (DEGs), respectively. B deficiency significantly increased the expression of the key aquaporin gene NIP5-1. In addition, B deficiency also increased the expression of ABA (ZEP and NCED) and JA (LOX, AOS and OPR) synthesis genes. Several MYB, WRKY, bHLH and ERF transcription factors were induced by B deficiency stress, which may relate to the regulation of B uptake and plant hormone synthesis. Overall, these findings suggested that P. betulaefolia root had adaptive responses to short-term B deficiency stress by improved boron absorption ability and hormone (JA and ABA) synthesis. The transcriptome analysis provided further information for understanding the mechanism of the pear rootstock responses to B deficiency stress.

S-RNase disrupts tip-localized reactive oxygen species and induces nuclear DNA degradation in incompatible pollen tubes of Pyrus pyrifolia.

Pear (Pyrus pyrifolia L.) has an S-RNase-based gametophytic self-incompatibility (SI) mechanism, and S-RNase has also been implicated in the rejection of self-pollen and genetically identical pollen. However, RNA degradation might be only the beginning of the SI response, not the end. Recent in vitro studies suggest that S-RNase triggers mitochondrial alteration and DNA degradation in the incompatible pollen tube of Pyrus pyrifolia, and it seems that a relationship exists between self S-RNase, actin depolymerization and DNA degradation. To further uncover the SI response in pear, the relationship between self S-RNase and tip-localized reactive oxygen species (ROS) was evaluated. Our results show that S-RNase specifically disrupted tip-localized ROS of incompatible pollen tubes via arrest of ROS formation in mitochondria and cell walls. The mitochondrial ROS disruption was related to mitochondrial alteration, whereas cell wall ROS disruption was related to a decrease in NADPH. Tip-localized ROS disruption not only decreased the Ca(2+) current and depolymerized the actin cytoskeleton, but it also induced nuclear DNA degradation. These results indicate that tip-localized ROS disruption occurs in Pyrus pyrifolia SI. Importantly, we demonstrated nuclear DNA degradation in the incompatible pollen tube after pollination in vivo. This result validates our in vitro system in vivo.

Phosphatidylinositol transfer protein-alpha in netrin-1-induced PLC signalling and neurite outgrowth.

Neurite extension is essential for wiring the nervous system during development. Although several factors are known to regulate neurite outgrowth, the underlying mechanisms remain unclear. Here, we provide evidence for a role of phosphatidylinositol transfer protein-alpha (PlTPalpha) in neurite extension in response to netrin-1, an extracellular guidance cue. PlTPalpha interacts with the netrin receptor DCC (deleted in colorectal cancer) and neogenin. Netrin-1 stimulates PlTPalpha binding to DCC and to phosphatidylinositol (5) phosphate [Pl(5)P], increases its lipid-transfer activity and elevates hydrolysis of phosphatidylinositol bisphosphate (PlP2). In addition, the stimulated PIP2 hydrolysis requires PlTPalpha. Furthermore, cortical explants of PlTPalpha mutant mice are defective in extending neurites in response to netrin-1. Commissural neurons from chicken embryos expressing a dominant-negative PlTPalpha mutant show reduced axon outgrowth. Morpholino-mediated knockdown of PlTPalpha expression in zebrafish embryos leads to dose-dependent defects in motor-neuron axons and reduced numbers of spinal-cord neurons. Taken together, these results identify a crucial role for PlTPalpha in netrin-1-induced neurite outgrowth, revealing a signalling mechanism for DCC/neogenin and PlTPalpha regulation.

Watercore Pear Fruit Respiration Changed and Accumulated γ-Aminobutyric Acid (GABA) in Response to Inner Hypoxia Stress.

Watercore is a physiological disorder which often occurs on the pear fruit and the excessive accumulation of sorbitol in fruit intercellular space is considered to be an important cause of watercore. Our previous studies found that the metabolic disorder of sugars may lead to hypoxia stress and disturb respiration, resulting in aggravated fruit rot and the formation of bitter substances. However, the further changes of respiration and the fruit response mechanism are not well understood. A comprehensive transcriptome analysis of 'Akibae' pear watercore fruit was performed in this study. The transcriptome results revealed the hypoxia stress significantly induced the expression of several key enzymes in the TCA cycle and may lead to the accumulation of succinic acid in watercore fruit. The glycolytic pathway was also significantly enhanced in watercore fruit. Moreover, the γ-aminobutyric acid (GABA) synthesis related genes, glutamate decarboxylase (GAD) genes and polyamine oxidase (PAO) genes, which associated with the GABA shunt and the polyamine degradation pathway were significantly upregulated. In addition, the PpGAD1 transcript level increased significantly along with the increase of GAD activity and GABA content in the watercore fruit. Above all, these findings suggested that the hypoxic response was marked by a significant increase of the hypoxia-inducible metabolites succinic acid and GABA and that PpGAD1 may play a key role in response to watercore by controlling the GABA synthesis.

A sorbitol transporter gene plays specific role in the occurrence of watercore by modulating the level of intercellular sorbitol in pear.

Watercore is a physiological disorder which often occurs on the fruits of pear and closely related to the influence of environment factors, such as high temperature. The excessive accumulation of sorbitol in fruit intercellular space is considered to be an important cause of watercore. Sorbitol transporter (SOT) is the key translocation protein of sorbitol and our previous study found the PpSOT3 expression was significantly decreased in high temperature induced-watercore pear fruit by transcriptome method. How PpSOT3 regulates the occurrence of watercore in pear remains unclear. The present study found that PpSOT3 had different expression pattern in watercore-susceptible (Akibae and Hosui) and watercore-resistant (Aikansui) pear cultivars of young fruit and mature fruit. Moreover, the accumulation of intercellular sorbitol in watercore fruit was significantly higher than that in healthy fruit, and the expression of PpSOT3 was significantly inhibited. After the treatment of sugar transport inhibitor (para-chloromercuribenzenesulphonic acid, PCMBS), the fruit pulp occurred water-soaking and the expression of PpSOT3 and the intercellular sorbitol content was significantly decreased and increased, respectively. Subcellular localization showed that PpSOT3 was located in plasma membrane. Both transient overexpression and RNAi assays suggested PpSOT3 had the function of sorbitol uptake. Taken together, these results demonstrate that PpSOT3 was a PCMBS-sensitive sorbitol transporter and played an important role in the occurrence of watercore by modulating the level of intercellular sorbitol content.

Correlation Between the Number of Fiberoptic Bronchoscopies and Nosocomial Infection/Colonization of Carbapenem-Resistant Enterobacteriaceae.

Objective: The present study aims to explore the effects of different numbers of fiberoptic bronchoscopic examinations on the nosocomial infection/colonization of carbapenem-resistant Enterobacteriaceae (CRE). Methods: The data of 129 patients admitted to the intensive care unit of a grade 3A hospital were retrospectively analyzed, and CRE nosocomial infection/colonization situations in patients with fiberoptic bronchoscope application times of 1, 2, 3, and ≥4 were statistically analyzed. Results: The incidence of nosocomial infection/colonization of CRE increased significantly when the number of fiberoptic bronchoscopic examinations was ≥3. Conclusion: Nosocomial infection/colonization of CRE is highly correlated with an increased number of fiberoptic bronchoscopic examinations.