ELONGATED HYPOTCOTYL5 and SPINE BASE SIZE1 together mediate light-regulated spine expansion in cucumber.

Plant trichome development is influenced by diverse developmental and environmental signals, but the molecular mechanisms involved are not well understood in most plant species. Fruit spines (trichomes) are an important trait in cucumber (Cucumis sativus L.), as they affect both fruit smoothness and commercial quality. Spine Base Size1 (CsSBS1) has been identified as essential for regulating fruit spine size in cucumber. Here, we discovered that CsSBS1 controls a season-dependent phenotype of spine base size in wild-type plants. Decreased light intensity led to reduced expression of CsSBS1 and smaller spine base size in wild-type plants, but not in the mutants with CsSBS1 deletion. Additionally, knockout of CsSBS1 resulted in smaller fruit spine base size and eliminated the light-induced expansion of spines. Overexpression of CsSBS1 increased spine base size and rescued the decrease in spine base size under low light conditions. Further analysis revealed that ELONGATED HYPOTCOTYL5 (HY5), a major transcription factor involved in light signaling pathways, directly binds to the promoter of CsSBS1 and activates its expression. Knockout of CsHY5 led to smaller fruit spine base size and abolished the light-induced expansion of spines. Taken together, our study findings have clarified a CsHY5-CsSBS1 regulatory module that mediates light-regulated spine expansion in cucumber. This finding offers a strategy for cucumber breeders to develop fruit with stable appearance quality under changing light conditions.

Natural allelic variation in the EamA-like transporter, CmSN, is associated with fruit skin netting in melon.

KEY MESSAGE: A SNP mutation in CmSN, encoding an EamA-like transporter, is responsible for fruit skin netting in melon. In maturing melon (Cucumis melo L.), the rind becomes reticulated or netted, a unique characteristic that dramatically changes the appearance of the fruit. However, little is known about the molecular basis of fruit skin netting formation in this important cucurbit crop. Here, we conducted map-based cloning of a skin netting (CmSN) locus using segregating populations derived from the cross between the smooth-fruit line H906 and the netted-fruit line H581. The results showed that CmSN was controlled by a single dominant gene and was primarily positioned on melon chromosome 2, within a physical interval of ~ 351 kb. Further fine mapping in a large F2 population narrowed this region to a 71-kb region harboring 5 genes. MELO3C010288, which encodes a protein in the EamA-like transporter family, is the best possible candidate gene for the netted phenotype. Two nonsynonymous single nucleotide polymorphisms (SNPs) were identified in the third and sixth exons of the CmSN gene and co-segregated with the skin netting (SN) phenotype among the genetic population. A genome-wide association study (GWAS) determined that CmSN is probably a domestication gene under selective pressure during the subspecies C. melo subsp. melo differentiation. The SNP in the third exon of CmSN (the leading SNP in GWAS) revealed a bi-allelic diversity in natural accessions with SN traits. Our results lay a foundation for deciphering the molecular mechanism underlying the formation of fruit skin netting in melon, as well as provide a strategy for genetic improvement of netted fruit using a marker-assisted selection approach.

Melon yellow-green plant (Cmygp) encodes a Golden2-like transcription factor regulating chlorophyll synthesis and chloroplast development.

KEY MESSAGE: A SNP mutation in CmYGP gene encoding Golden2-like transcription factor is responsible for melon yellow-green plant trait. Chlorophylls are essential and beneficial substances for both plant and human health. Identifying the regulatory network of chlorophyll is necessary to improve the nutritional quality of fruits. At least six etiolation genes have been identified in different melon varieties, but none of them have been cloned, and the molecular mechanisms underlying chlorophyll synthesis and chloroplast development in melon remain unclear. Here, the NSL73046, a yellow-green plant (Cmygp) mutant, enabled the map-based cloning of the first etiolation gene in melon. CmYGP encodes a Golden2-like transcription factor. Spatiotemporal expression analyses confirmed the high CmYGP expression in all green tissues, particularly in young leaves and fruit peels. Virus-induced gene silencing and the development of near-isogenic line by marker-assisted selection further confirmed that downregulation of CmYGP can reduce chloroplast number and chlorophyll content, thereby resulting in yellow-green leaves and fruits in melon, and overexpression of CmYGP in tomatoes also led to dark-green leaves and fruits. RNA-seq analysis revealed that CmYGP greatly affected the expression of key genes associated with chloroplast development. Taken together, these findings demonstrated that CmYGP regulate chlorophyll synthesis and chloroplast development thus affect fruit development in melon. This study also offers a new strategy to enhance fruit quality in melon.

Chromosomal fragment deletion in APRR2-repeated locus modulates the dark stem color in Cucurbita pepo.

KEY MESSAGE: Cp4.1LG15g03420 (CpDsc-1), which encodes a two-component response regulator-like protein (APRR2) in the nucleus, influences dark green stem formation in Cucurbita pepo by regulating the chlorophyll content. Stem color is an important agronomic trait in zucchini (Cucurbita pepo) for robust seeding and high yield. However, the gene controlling the stem color has not been characterized. In this study, we identified a single locus accounting for the dark green stem color of C. pepo (CpDsc-1). Genetic analysis of this trait in segregated populations derived from two parental lines (line 296 with dark green stems and line 274 with light green stems) revealed that stem color was controlled by a single dominant gene (dark green vs. light green). In bulked segregant analysis, CpDsc-1 was mapped to a 2.09-Mb interval on chromosome 15. This region was further narrowed to 65.2 kb using linkage analysis of the F2 population. Sequencing analysis revealed a 14 kb deletion between Cp4.1LG15g03420 and Cp4.1LG15g03360; these two genes both encoded a two-component response regulator-like protein (APRR2). The incomplete structures of the two APRR2 genes and abnormal chloroplasts in line 274 might be the main cause of the light green phenotype. Gene expression pattern analysis showed that only Cp4.1LG15g03420 was upregulated in line 296. Subcellular localization analysis indicated that Cp4.1LG15g03420 was a nuclear gene. Furthermore, a co-dominant marker, G4563 (93% accuracy rate), and a co-segregation marker, Fra3, were established in 111 diverse germplasms; both of these markers were tightly linked with the color trait. This study provided insights into chlorophyll regulation mechanisms and revealed the markers valuable for marker-assisted selection in future zucchini breeding.

miR-122-5p Inhibits the Proliferation, Invasion and Growth of Bile Duct Carcinoma Cells by Targeting ALDOA.

BACKGROUND/AIMS: Bile duct cancer, although not among the most common tumors, still accounts for more and more worldwide deaths each year. By attempting to verify an overexpression of ALDOA in cholangiocarcinoma tissues and cells and explore the underlying molecular mechanism regulated by miR-122-5p, this study was designed to provide a potential molecular target in bile duct cancer treatment. METHODS: Western blot and immunohistochemistry were performed to detect the ALDOA protein level in duct carcinoma tissues. The transfection efficiency was confirmed by western blot and/or RT-qPCR assay. The proliferation of bile duct carcinoma cells was determined by MTT and colony formation assay. The invasion ability of bile duct carcinoma cells was evaluated with Transwell invasion assay. Flow cytometry detected cell apoptosis of bile duct carcinoma cells. The miRNAs which modulate ALDOA were filtrated from bioinformatics software and clinical specimens. The target relationship was confirmed by dual luciferase reporter assay. Furthermore, a xenograft model was completed to verify the impact of miRNA on inhibition growth of bile duct carcinoma cells. RESULTS: ALDOA was found up-regulated in bile duct carcinoma tissues and cells. Knockdown of ALDOA promoted the apoptosis of cells and inhibited the proliferation and invasion of bile duct carcinoma cells. Bioinformatics and clinical specimens indicated the negative correlation and targeted regulation between miR-122-5p and ALDOA. By down-regulating ALDOA, overexpression of miR-122-5p appeared to promote cell apoptosis and significantly inhibit cell proliferation, invasion in vitro and suppress the tumor growth in vivo. CONCLUSION: miR-122-5p inhibited proliferation and invasion of bile duct carcinoma cells and promoted cell apoptosis by targeting ALDOA expression.

GLABROUS (CmGL) encodes a HD-ZIP IV transcription factor playing roles in multicellular trichome initiation in melon.

KEY MESSAGE: Map-based cloning identified CmGL that encodes a HD-ZIP type IV transcription factor that controls multicellular trichome initiation in melon. Trichomes are small hairs covering the aerial parts of plants that originate from the epidermal cells, which can protect plants against the damage by insects and pathogens. The regulatory pathway of unicellular trichomes has been well studied in the model plant Arabidopsis. Little is known about the genetic control and regulation of trichome development in melon (Cucumis melo L.) which has multicellular trichomes. In this study, we identified a melon mutant, cmgl, which showed completely glabrous on all aerial organs. A bulked segregant analysis was conducted to identify polymorphic markers for linkage analysis in a population with 256 F2 plants, which allowed to locate the cmgl locus in melon chromosome VIII. Next-generation sequencing-aided marker discovery and fine mapping in a large population with 1536 F2 plants narrowed the candidate gene region to 12 kb that harbored only one candidate gene for cmgl, which encoded a class IV homeodomain-associated leucine zipper transcription factor. Four SNPs in the coding region of the CmGL gene were identified between the two parental lines; a single base substitution from C to A resulted in a premature termination codon and a truncated protein in the cmgl. The SNP was converted into a dCAPS marker, which showed co-segregation in the F2 population and 564 melon accessions. Result of this study will be helpful for better understanding of genetic control of trichome development in melon and marker-assisted selection in developing new cultivars.

Time-dependent expression of PEDF and VEGF in blood serum and retina of rats with oxygen-induced retinopathy.

The effects of the balance changes of pigment epithelium growth factor (PEDF) and vascular endothelial growth factor (VEGF) in whole-body and retinal tissue on rats with oxygen-induced retinopathy were investigated. Forty-eight neonatal SD rats at the age of 7 days were randomly divided into 4 groups. The neonatal rats in experimental groups were exposed to 75% to 80% oxygen for 5 days and then to normal air, and those in control groups were kept feeding in normal air. At the age of 17 and 22 days, all the neonatal rats received retina angiography with FITC-dextran and the pathological changes of retinal vessels and perfusion were observed. HE staining of the tissue section and the number counting of endothelial cells extending beyond the inner limiting membrane were performed to evaluate the endothelial proliferation. Immunohistochemistry was applied to detect the expression of PEDF and VEGF in retinal tissue, and ELISA to detect their expression in serum. A hypoxic-ischemic proliferation of retina and more endothelial cells extending beyond the inner limiting membrane were found in the neonatal rats in both experimental groups of 17-day old and 22-day old as compared with those in control group with the difference being statistically significant (P<0.01). VEGF staining of the rats in the 17-day old experimental group was significantly stronger, with an increasing positive rate, than that of the rats in the 17-day old control group (P<0.01). PEDF staining of the rats of 22 days old was weaker than that of the rats of 17 days old in the experimental groups (P<0.01). There was no significant difference in serum VEGF concentration among all groups (P>0.05). The serum PEDF concentration in the rats of 17 days old in experimental group was decreased significantly as compared with that in the rats of 17 days old in control group (P<0.01), and in experimental groups, the serum PEDF concentration of the rats of 22 days old was increased as compared with that of the rats of 17 days old (P<0.01). In conclusion, the obviously decreased serum PEDF concentration and the abnormal enhanced expression of VEGF density in local retinal tissue broke down the balance of PEDF/VEGF in whole-body or local tissues, which might play an important role in retinal vascular proliferation.

Genetic variants at 13q12.12 are associated with high myopia in the Han Chinese population.

High myopia, which is extremely prevalent in the Chinese population, is one of the leading causes of blindness in the world. Genetic factors play a critical role in the development of the condition. To identify the genetic variants associated with high myopia in the Han Chinese, we conducted a genome-wide association study (GWAS) of 493,947 SNPs in 1088 individuals (419 cases and 669 controls) from a Han Chinese cohort and followed up on signals that were associated with p < 1.0 × 10(-4) in three independent cohorts (combined, 2803 cases and 5642 controls). We identified a significant association between high myopia and a variant at 13q12.12 (rs9318086, combined p = 1.91 × 10(-16), heterozygous odds ratio = 1.32, and homozygous odds ratio = 1.64). Furthermore, five additional SNPs (rs9510902, rs3794338, rs1886970, rs7325450, and rs7331047) in the same linkage disequilibrium (LD) block with rs9318086 also proved to be significantly associated with high myopia in the Han Chinese population; p values ranged from 5.46 × 10(-11) to 6.16 × 10(-16). This associated locus contains three genes-MIPEP, C1QTNF9B-AS1, and C1QTNF9B. MIPEP and C1QTNF9B were found to be expressed in the retina and retinal pigment epithelium (RPE) and are more likely than C1QTNF9B-AS1 to be associated with high myopia given the evidence of retinal signaling that controls eye growth. Our results suggest that the variants at 13q12.12 are associated with high myopia.

Microsatellite analysis of genetic relationships between wild and cultivated melons in Northwest and Central China.

The genetic relationships between the wild and cultivated melon accessions from Northwest and Central China were dissected using 22 microsatellite markers. A total of 153 alleles, a high level of expected heterozygosity (0.669), and a low observed heterozygosity (0.156) were detected in the total panel. Differences on the allelic composition and heterozygosity levels were found between the two accession types and the wild accessions revealed a higher level of genetic diversity. The UPGMA analysis of the total panel showed that (a) most wild accessions from Northwest China were clustered independently from the cultivated accessions, and (b) the wild and cultivated accessions from Central China presented a high genetic closeness and showed a divergence from those of Northwest China. Similar positioning of the most accessions was observed with the principal coordinate analysis and STRUCTURE analysis. Pairwise FST and Nei's genetic distance quantified the genetic differentiation among the different accession types and further verified our findings. We concluded that the wild melons from Northwest China have a distinctive genetic background and could be the true wild forms, while the wild melons from Central China showed a close relationship to the local cultivars and could be a return from the cultivated melons in the same region. Our results offer an insight into the genetic resources of the main melon producing regions in China, which is essential for maximizing utilization of the traits of interest in wild melons.

Lung squamous cell carcinoma metastasizing to the nasopharynx following bronchoscopy intervention therapies: a case report.

Metastatic carcinoma to the nasopharynx is extremely rare, and few cases have been reported in the literature. In the present report, we describe the case of a patient with a mass in the nasopharynx found by bronchoscopy. Our patient was a 61-year-old man receiving multiple bronchoscopy intervention therapies for advanced lung squamous cell carcinoma (SCC), which was histopathologically confirmed. The SCC metastasized to the nasopharynx following the bronchoscopy intervention therapies. The lesion was considered metastatic from lung cancer on the basis of clinical and histological clues. The exact mechanism of lung cancer metastasis to the nasopharynx in this case remains unclear because either implantation or hematogenous and lymphatic spread is possible. A thorough head and neck examination should be undertaken during bronchoscopic evaluation, especially in patients receiving bronchoscopy intervention therapies. The early detection of a silent nasopharyngeal metastasis is important to choosing from among the multiple treatment options available.

Exome sequencing identifies ZNF644 mutations in high myopia.

Myopia is the most common ocular disorder worldwide, and high myopia in particular is one of the leading causes of blindness. Genetic factors play a critical role in the development of myopia, especially high myopia. Recently, the exome sequencing approach has been successfully used for the disease gene identification of Mendelian disorders. Here we show a successful application of exome sequencing to identify a gene for an autosomal dominant disorder, and we have identified a gene potentially responsible for high myopia in a monogenic form. We captured exomes of two affected individuals from a Han Chinese family with high myopia and performed sequencing analysis by a second-generation sequencer with a mean coverage of 30× and sufficient depth to call variants at ∼97% of each targeted exome. The shared genetic variants of these two affected individuals in the family being studied were filtered against the 1000 Genomes Project and the dbSNP131 database. A mutation A672G in zinc finger protein 644 isoform 1 (ZNF644) was identified as being related to the phenotype of this family. After we performed sequencing analysis of the exons in the ZNF644 gene in 300 sporadic cases of high myopia, we identified an additional five mutations (I587V, R680G, C699Y, 3'UTR+12 C>G, and 3'UTR+592 G>A) in 11 different patients. All these mutations were absent in 600 normal controls. The ZNF644 gene was expressed in human retinal and retinal pigment epithelium (RPE). Given that ZNF644 is predicted to be a transcription factor that may regulate genes involved in eye development, mutation may cause the axial elongation of eyeball found in high myopia patients. Our results suggest that ZNF644 might be a causal gene for high myopia in a monogenic form.

Genome-wide identification of the melon (Cucumis melo L.) response regulator gene family and functional analysis of CmRR6 and CmPRR3 in response to cold stress.

The response regulator (RR) gene family play crucial roles in cytokinin signal transduction, plant development, and resistance to abiotic stress. However, there are no reports on the identification and functional characterization of RR genes in melon. In this study, a total of 18 CmRRs were identified and classified into type A, type B, and clock PRRs, based on phylogenetic analysis. Most of the CmRRs displayed tissue-specific expression patterns, and some were induced by cold stress according to two RNA-seq datasets. The expression patterns of CmRR2/6/11/15 and CmPRR2/3 under cold treatment were confirmed by qRT-PCR. Subcellular localization assays indicated that CmRR6 and CmPRR3 were primarily localized in the nucleus and chloroplast. Furthermore, when either CmRR6 or CmPRR3 were silenced using tobacco ringspot virus (TRSV), the cold tolerance of the virus-induced gene silencing (VIGS) melon plants were significantly enhanced, as evidenced by measurements of chlorophyll fluorescence, ion leakage, reactive oxygen, proline, and malondialdehyde levels. Additionally, the expression levels of CmCBF1, CmCBF2, and CmCBF3 were significantly increased in CmRR6-silenced and CmPRR3-silenced plants under cold treatment. Our findings suggest that CmRRs contribute to cold stress responses and provide new insights for further pursuing the molecular mechanisms underlying CmRRs-mediated cold tolerance in melon.

Altered cortical thickness and structural covariance networks in chronic low back pain.

BACKGROUND: Despite regional brain structural changes having been reported in patients with chronic low back pain (CLBP), the topological properties of structural covariance networks (SCNs), which refer to the organization of the SCNs, remain unclear. This study applied graph theoretical analysis to explore the alterations of the topological properties of SCNs, aiming to comprehend the integration and separation of SCNs in patients with CLBP. METHODS: A total of 38 patients with CLBP and 38 healthy controls (HCs), balanced for age and sex, were scanned using three-dimensional T1-weighted magnetic resonance imaging. The cortical thickness was extracted from 68 brain regions, according to the Desikan-Killiany atlas, and used to reconstruct the SCNs. Subsequently, graph theoretical analysis was employed to evaluate the alterations of the topological properties in the SCNs of patients with CLBP. RESULTS: In comparison to HCs, patients with CLBP had less cortical thickness in the left superior frontal cortex. Additionally, the cortical thickness of the left superior frontal cortex was negatively correlated with the Visual Analogue Scale scores of patients with CLBP. Furthermore, patients with CLBP, relative to HCs, exhibited lower global efficiency and small-worldness, as well as a longer characteristic path length. This indicates a decline in the brain's capacity to transmit and process information, potentially impacting the processing of pain signals in patients with CLBP and contributing to the development of CLBP. In contrast, there were no significant differences in the clustering coefficient, local efficiency, nodal efficiency, nodal betweenness centrality, or nodal degree between the two groups. CONCLUSIONS: From the regional cortical thickness to the complex brain network level, our study demonstrated changes in the cortical thickness and topological properties of the SCNs in patients with CLBP, thus aiding in a better understanding of the pathophysiological mechanisms of CLBP.

Altered volume of the amygdala subregions in patients with chronic low back pain.

Background: Neuroimaging studies have suggested a pivotal role for the amygdala involvement in chronic low back pain (CLBP). However, the relationship between the amygdala subregions and CLBP has not yet been delineated. This study aimed to analyze whether the amygdala subregions were linked to the development of CLBP. Methods: A total of 45 patients with CLBP and 45 healthy controls (HCs) were included in this study. All subjects were asked to complete a three-dimensional T1-weighted magnetic resonance imaging (3D-T1 MRI) scan. FreeSurfer 7.3.2 was applied to preprocess the structural MRI images and segment the amygdala into nine subregions. Afterwards, comparisons were made between the two groups in terms of the volumes of the amygdala subregions. Correlation analysis is utilized to examine the relationship between the amygdala subregion and the scale scores, as well as the pain duration in patients with CLBP. Additionally, logistic regression was used to explore the risk of the amygdala and its subregions for CLBP. Results: In comparison to HCs, patients with CLBP exhibited a significant enlargement of the left central nucleus (Ce) and left cortical nucleus (Co). Furthermore, the increased volume of the left Ce was associated with a higher risk of CLBP. Conclusion: Our study suggests that the left Ce and left Co may be involved in the pathophysiological processes of CLBP. Moreover, the volume of the left Ce may be a biomarker for detecting the risk of CLBP.

Algorithm of automatic identification of diabetic retinopathy foci based on ultra-widefield scanning laser ophthalmoscopy.

AIM: To propose an algorithm for automatic detection of diabetic retinopathy (DR) lesions based on ultra-widefield scanning laser ophthalmoscopy (SLO). METHODS: The algorithm utilized the FasterRCNN (Faster Regions with CNN features)+ResNet50 (Residua Network 50)+FPN (Feature Pyramid Networks) method for detecting hemorrhagic spots, cotton wool spots, exudates, and microaneurysms in DR ultra-widefield SLO. Subimage segmentation combined with a deeper residual network FasterRCNN+ResNet50 was employed for feature extraction to enhance intelligent learning rate. Feature fusion was carried out by the feature pyramid network FPN, which significantly improved lesion detection rates in SLO fundus images. RESULTS: By analyzing 1076 ultra-widefield SLO images provided by our hospital, with a resolution of 2600×2048 dpi, the accuracy rates for hemorrhagic spots, cotton wool spots, exudates, and microaneurysms were found to be 87.23%, 83.57%, 86.75%, and 54.94%, respectively. CONCLUSION: The proposed algorithm demonstrates intelligent detection of DR lesions in ultra-widefield SLO, providing significant advantages over traditional fundus color imaging intelligent diagnosis algorithms.

Evaluation of MMP2 as a candidate gene for high myopia.

PURPOSE: Matrix metalloproteinase 2 (MMP2) has been shown to be expressed in the human sclera, and is increased in the sclera of the eye with myopia induced by form deprivation in chicks when compared with the control eye. The purpose of this study was to examine the relationship between high myopia and MMP2 in a mainland Han Chinese population. METHODS: Four hundred unrelated patients with high myopia and 400 normal controls in a mainland Han Chinese population were studied. All the subjects were genotyped for 20 tag single nucleotide polymorphisms (SNPs) in MMP2 with the dye terminator-based SNaPshot method. The distribution of the genotypes in the cases and controls was compared with a χ(2) test. Screening for mutations in the coding regions and the adjacent intronic regions of MMP2 was performed in 200 patients with high myopia and 200 normal controls by direct sequencing. RESULTS: None of the 20 tested SNPs showed significant association with high myopia in this study. Seven variations were detected upon sequencing of the coding regions and the adjacent intronic regions of MMP2 in 200 subjects with high myopia and 200 normal controls. One novel variation, c.1287G>A (p.K429K), was detected in 79 of the 200 patients with high myopia (65 heterozygous and 14 homozygous) and in 84 of the 200 controls (67 heterozygous and 17 homozygous). The c.1810G>A mutation (p. Arg500His) was detected in three of the 200 patients with high myopia but not in the controls. The five other variations, known as polymorphisms, were detected in the case and control groups. CONCLUSIONS: We found no evidence that MMP2 is responsible for high myopia in these Han Chinese subjects and hence is unlikely to be important in the genetic predisposition to high myopia. Our results imply that MMP2 may not play a major role in high myopia in the Han Chinese population.

Gastric and duodenal squamous cell carcinoma: metastatic or primary?

Either metastatic or primary squamous cell carcinoma in the gastrointestinal tract is extremely rare, with very few cases reported in the literature. In this paper, we report a case in which the patient presented with dysphagia during the course of radiotherapy for recurrent lung cancer in a mediastinal lymph node. Although the dysphagia mimicked radiation esophagitis, the ultimate cause proved to be gastric and duodenal metastases from primary lung squamous cell carcinoma. Taking into account the value of identification of metastatic or primary SCC in the stomach and duodenum on the prognosis and treatment options, it is imperative that the correct diagnosis be established. This report is followed by a discussion of the differential diagnosis between metastatic and primary squamous cell carcinoma in the stomach and duodenum.

Identification of candidate genes that regulate the trade-off between seedling cold tolerance and fruit quality in melon (Cucumis melo L.).

Trade-offs between survival and growth are widely observed in plants. Melon is an annual, trailing herb that produces economically valuable fruits that are traditionally cultivated in early spring in China. Melon seedlings are sensitive to low temperatures, and thus usually suffer from cold stress during the early growth period. However, little is known about the mechanism behind the trade-offs between seedling cold tolerance and fruit quality in melon. In this study, a total of 31 primary metabolites were detected from the mature fruits of eight melon lines that differ with respect to seedling cold tolerance; these included 12 amino acids, 10 organic acids, and 9 soluble sugars. Our results showed that concentrations of most of the primary metabolites in the cold-resistant melons were generally lower than in the cold-sensitive melons; the greatest difference in metabolite levels was observed between the cold-resistant line H581 and the moderately cold-resistant line HH09. The metabolite and transcriptome data for these two lines were then subjected to weighted correlation network analysis, resulting in the identification of five key candidate genes underlying the balancing between seedling cold tolerance and fruit quality. Among these genes, CmEAF7 might play multiple roles in regulating chloroplast development, photosynthesis, and the ABA pathway. Furthermore, multi-method functional analysis showed that CmEAF7 can certainly improve both seedling cold tolerance and fruit quality in melon. Our study identified an agriculturally important gene, CmEAF7, and provides a new insight into breeding methods to develop melon cultivars with seedling cold tolerance and high fruit quality.

A heat shock protein gene, CsHsp45.9, involved in the response to diverse stresses in cucumber.

Heat shock proteins (Hsps) are a family of highly conserved proteins present in all organisms. They mediate a range of cytoprotective functions as molecular chaperones and are recently reported to regulate the immune response. Using suppression subtractive hybridization, we isolated and characterized a cucumber cDNA, designated CsHsp45.9, which encodes a putative heat shock protein of 45.9 kDa protein, containing three conserved DnaJ domains belonging to the Type I Hsp40 family. Real-time quantitative RT-PCR analysis revealed that CsHsp45.9 was significantly induced in cucumber leaves inoculated with downy mildew (Pseudoperonospora cubensis) in this incompatible interaction. Gene expression was also strongly up-regulated by various abiotic stresses. CsHsp45.9 was mainly expressed in flowers with a flower-specific, stamen- and pistil-predominant expression pattern. This suggests that CsHsp45.9 harbors broad-spectrum responses to both biotic and abiotic stresses and may play a role in downy mildew resistance in cucumber.