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High-temperature stress threatens the growth and yield of crops. Basic helix-loop-helix (bHLH) transcription factors (TFs) have been shown to play important roles in regulating high-temperature resistance in plants. However, the bHLH TFs responsible for high-temperature tolerance in cucumbers have not been identified. We used transcriptome profiling to screen the high temperature-responsive candidate bHLH TFs in cucumber. Here, we found that the expression of 75 CsbHLH genes was altered under high-temperature stress. The expression of the CsSPT gene was induced by high temperatures in TT (Thermotolerant) cucumber plants. However, the Csspt mutant plants obtained by the CRISPR-Cas9 system showed severe thermosensitive symptoms, including wilted leaves with brown margins and reduced root density and cell activity. The Csspt mutant plants also exhibited elevated H2O2 levels and down-regulated photosystem-related genes under normal conditions. Furthermore, there were high relative electrolytic leakage (REC), malondialdehyde (MDA), glutathione (GSH), and superoxide radical (...) levels in the Csspt mutant plants, with decreased Proline content after the high-temperature treatment. Transcriptome analysis showed that the photosystem and chloroplast activities in Csspt mutant plants were extremely disrupted by the high-temperature stress compared with wildtype (WT) plants. Moreover, the plant hormone signal transduction, as well as MAPK and calcium signaling pathways were activated in Csspt mutant plants under high-temperature stress. The HSF and HSP family genes shared the same upregulated expression patterns in Csspt and WT plants under high-temperature conditions. However, most bHLH, NAC, and bZIP family genes were significantly down-regulated by heat in Csspt mutant plants. Thus, these results demonstrated that CsSPT regulated the high-temperature response by recruiting photosynthesis components, signaling pathway molecules, and transcription factors. Our results provide important insights into the heat response mechanism of CsSPT in cucumber and its potential as a target for breeding heat-resistant crops. [ABSTRACT FROM AUTHOR]

Mosaic disease causes a serious epidemic of cucumber plants in Iraq. To investigate causal agents of such symptoms, whole genome and metatrancriptomic sequencing data were collected from pathogenic cucumber leaves. The result shows that Tomato leaf curl Palampur virus DNA-A and B were existed with 2,756 and 2,719 bp sequences that deposited under acc. numbers ON229618 and ON229620 respectively, and the isolate named Babylon1. Further, Squash vein yellowing virus was found with 9,832 bp sequence that deposited under acc. number ON229619, and the isolate called Iraq. Mixed infection reported here for the first time in cucumber in Iraq, highlighting the impact of such infection that threat the cucumber fields. [ABSTRACT FROM AUTHOR]

This study was conducted to compare the effects of NaCl, KCl, MgCl2, MgSO4 and CaCl2 on the anatomical of cotyledon leaves. Five types of salts (NaCl, KCl, MgCl2, MgSO4 and CaCl2) at different concentrations (50, 100, 150 and 200 mM) and deionized water as control are used. A 10 sterilized seeds were placed in Petri dishes containing 5 ml of deionized water or each salinity solution and kept in the growth chamber at 25 ± 1°C. On day 8th, coteyledon leaves were fixed for anatomical study. Results show the response of MTi2 on five different salts is significantly different. The degree histological changes of MTi2 cotyledon leaves increased as the concentration of salts increased. Salts significantly change the structure and arrangement of the upper epidermis cells, mesophyll tissue and lower epidermis cells, also reduce of intracellular space among the mesophyll cells. Results found that no anatomical changes of MTi2 cotyledon leave in any concentration of KCl. [ABSTRACT FROM AUTHOR]

Cucumber, Cucumis sativus L. (2n = 2x = 14), is an important vegetable crop worldwide. It was the first specialty crop with a publicly available draft genome. Its relatively small, diploid genome, short life cycle, and self-compatible mating system offers advantages for genetic studies. In recent years, significant progress has been made in molecular mapping, and identification of genes and QTL responsible for key phenotypic traits, but a systematic review of the work is lacking. Here, we conducted an extensive literature review on mutants, genes and QTL that have been molecularly mapped or characterized in cucumber. We documented 81 simply inherited trait genes or major-effect QTL that have been cloned or fine mapped. For each gene, detailed information was compiled including chromosome locations, allelic variants and associated polymorphisms, predicted functions, and diagnostic markers that could be used for marker-assisted selection in cucumber breeding. We also documented 322 QTL for 42 quantitative traits, including 109 for disease resistances against seven pathogens. By alignment of these QTL on the latest version of cucumber draft genomes, consensus QTL across multiple studies were inferred, which provided insights into heritable correlations among different traits. Through collaborative efforts among public and private cucumber researchers, we identified 130 quantitative traits and developed a set of recommendations for QTL nomenclature in cucumber. This is the first attempt to systematically summarize, analyze and inventory cucumber mutants, cloned or mapped genes and QTL, which should be a useful resource for the cucurbit research community. [ABSTRACT FROM AUTHOR]

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Abstract This study aims to investigate key genes involved in molecular regulatory networks of cucumber sex determination. Genome-wide high-throughput RNA sequencing was performed for young apical buds of gynoecious and weak female cucumber at three growth stages (one-leaf one-bud, three-leaf one-bud, and five-leaf one-bud). Seven comparisons from the same cultivar at three different stages and at the same stage between the two cultivars were analyzed, and the results revealed that compared with differentially expressed genes (DEGs) in weak female cucumber, more genes were upregulated at the one-leaf one-bud stage and downregulated at the three-leaf one-bud stage in gynoecious cucumber. In addition, there were four kinds of gene expression trends (0, 1, 6, and 7), which were significantly enriched in gynoecious cucumber, while only two kinds of gene expression trends (5 and 6) were significantly enriched in weak female cucumber. Together with the data of the Gene Ontology (GO), pathway, gene expression trends and qRT-PCR, nine genes were identified and considered as candidate genes that may be involved in sex differentiation regulation in cucumber. These genes included Cs-MCM6 , Cs-ACT3 , Cs-XRCC4 , Cs-MCM2 , Cs-CDC45 , Cs-Dpri , Cs-H2B , Cs-CDC20 and Cs-CNGC1. Among these genes, five genes (Cs-MCM6 , Cs-MCM2 , Cs-CDC45 , Cs-Dpri , and Cs-CDC20) were involved in the cell cycle pathway, suggesting that the cell cycle pathway may play an important role in sex determination in cucumber. Highlights • RNA-Seq of gynoecious and weak female cucumber at three different growth stages. • The comprehensive analysis of GO, KEGG gene expression trends and qRT-PCR. • Among Nine genes identified as candidates, five involved in the cell cycle pathway. • The analysis of probable connections between the cell cycle genes and ET related genes. • A probable model of sex differentiation regulation network was built. [ABSTRACT FROM AUTHOR]

Melatonin plays an important role in stress tolerance in plants. In this study, exogenous melatonin significantly alleviated the dwarf phenotype and inhibited the decrease of plant fresh weight induced by excess copper (Cu2+). Our results indicated that melatonin alleviated Cu2+ toxicity by improving Cu2+ sequestration, carbon metabolism and ROS (reactive oxygen species) scavenging, rather than by influencing the Cu2+ uptake under excess Cu2+ conditions. Transcriptome analysis showed that melatonin broadly altered gene expression under Cu2+ stress. Melatonin increased the levels of glutathione and phytochelatin to chelate excess Cu2+ and promoted cell wall trapping, thus keeping more Cu2+ in the cell wall and vacuole. Melatonin inhibited ROS production and enhanced antioxidant systems at the transcriptional level and enzyme activities, thus building a line of defense in response to excess Cu2+. The distribution of nutrient elements was recovered by melatonin which was disturbed by Cu2+. In addition, melatonin activated carbon metabolism, especially glycolysis and the pentose phosphate pathway, to generate more ATP, an intermediate for biosynthesis. Taken together, melatonin alleviated Cu2+ toxicity in cucumber via multiple mechanisms. These results will help to resolve the toxic effects of Cu2+ stress on plant growth and development. These results can be used for new strategies to solve problems associated with Cu2+ stress. [ABSTRACT FROM AUTHOR]

Key message: The overexpression of CsBCATs promotes flowering in Arabidopsis by regulating the expression of flowering time genes.Abstract: The branched-chain amino acid transferases (BCATs) play an important role in the metabolism of branched-chain amino acids (BCAAs), such as isoleucine, leucine, and valine. They function in both the synthesis and the degradation of this class of amino acids. We identified and characterized the three BCAT genes in cucumber (Cucumis sativus L.). The tissue-specific expression profiling in cucumber plants revealed that CsBCAT2 and CsBCAT7 were highly expressed in the reproductive tissues, whereas CsBCAT3 expression was highly detected in the vegetative tissues. The subcellular localization patterns of three CsBCATs were observed in the mitochondria. The functional analyses of CsBCATs showed that CsBCAT2 and CsBCAT3 restored the growth of bat1Δ/bat2Δ double knockout yeast (Saccharomyces cerevisiae), and CsBCAT3 and CsBCAT7 with different substrate preferences acted in a reverse reaction. The transgenic approach demonstrated that the overexpression of the three CsBCATs resulted in early flowering phenotypes, which were associated with the upregulation of FLOWERING LOCUS T (FT) and SUPPRESSOR OF OVEREXPRESSION OF CONSTANS1 (SOC1) in a manner in which they were dependent on GIGANTEA (GI)/CONSTANS (CO) and SHORT VEGETATIVE PHASE (SVP)/FLOWERING LOCUS C (FLC) modules. Our results, which are observed in conjunction, suggest that there is an interconnection between BCAT genes that function in BCAA metabolism and the flowering time in plants. [ABSTRACT FROM AUTHOR]

Summary: The fruit epidermal features such as the size of tubercules are important fruit quality traits for cucumber production. But the mechanisms underlying tubercule formation remain elusive. Here, tubercule size locus CsTS1 was identified by map‐based cloning and was found to encode an oleosin protein. Allelic variation was identified in the promoter region of CsTS1, resulting in low expression of CsTS1 in all 22 different small‐warty or nonwarty cucumber lines. High CsTS1 expression levels were closely correlated with increased fruit tubercule size among 44 different cucumber lines. Transgenic complementation and RNAi‐mediated gene silencing of CsTS1 in transgenic cucumber plants demonstrated that CsTS1 positively regulates the development of tubercules. CsTS1 is highly expressed in the peel at fruit tubercule forming and enlargement stage. Auxin content and expression of three auxin signalling pathway genes were altered in the 35S:CsTS1 and CsTS1‐RNAi fruit tubercules, a result that was supported by comparing the cell size of the control and transgenic fruit tubercules. CsTu, a C2H2 zinc finger domain transcription factor that regulates tubercule initiation, binds directly to the CsTS1 promoter and promotes its expression. Taken together, our results reveal a novel mechanism in which the CsTu‐TS1 complex promotes fruit tubercule formation in cucumber. [ABSTRACT FROM AUTHOR]

Summer vegetables production is enormously influenced by elevated temperature above thresh hold level which finally brings about a threat to food security in Indo-Pak region. Genetic variability is a significant tool to address this issue. The current study was intended to screen out heat tolerant cucumber genotypes and assessment of certain heat tolerant and sensitive genotypes for some water related, physiological and biochemical attributes. After one-month emergence of seedlings of twentyfive cucumber genotypes were subjected to elevated temperature (40°C/32°C day/night) for one week. Selection of cucumber genotypes for heat tolerance and sensitive was done based on several morphological, physiological and biochemical attributes. Substantial variation among genotypes was observed according to their capability to tolerate heat stress. Genotypes L3466 and Desi-cucumber (having electrolyte leakage of 50.5 and 46.5%, respectively) were found the most heat tolerant, while Suyo Long and Poinsett were found sensitive to heat stress (having electrolyte leakage of 52.3 and 54.5%, respectively). The significant difference was observed in water-related attributes, antioxidant activities, osmoprotectants and lipid peroxidation in leaves of tolerant (L3466 and Desi-cucumber) and sensitive (Suyo Long and Poinsett) genotypes under heat stress (40°C/32°C) when further analyzed. It was concluded that a few genotypes were more tolerant to elevated temperature (40°C) than others under study. [ABSTRACT FROM AUTHOR]

Gynoecious is an important economic trait of cucumber for determinant of earliness and yield, yet genetic mechanism is not well understood for this trait. The experiment was conducted using F2 mapping population by crossing of PPC-2, a gynoecious and parthenocarpic line with Pusa Uday (monoecious and non-parthenocarpic cultivar). Out of 179 SSR markers screened, 39 markers differentiated the gynoecious and monoecious parents. However, only 17 markers were segregating with F2 mapping population, those were used for genotyping and linkage map analysis and these markers were placed along with F locus on chromosome 6 covering a total distance of 100.4cM. The SSR markers, SSR13251 and UW020605 were found to be closely linked to gynoecious (F) locus at 1.0 and 4.5 cM, respectively. The segregation of F2 population of PPC-2 × Pusa Uday and GPC-1 × Punjab Naveen and test crosses for sex type herein suggested that single dominant gene controlled the gynoecious sex expression in cucumber particularly in gynoecious genotypes PPC-2 and GPC-1. Therefore, the monogenic dominant nature of gynoecious sex identified in the present experiment and SSR markers closely linked to the F locus will be useful in marker-assisted backcross breeding for transfering gynoecious trait into horticulturally desirable varieties. [ABSTRACT FROM AUTHOR]

Highlights • This study provides the first evidence for the Zn-dependent regulation and the direction of Zn transport by the plant Zn-transporting heterodimeric complexes at the secretory pathway. Abstract Heterodimeric complexes formed by members of the cation facilitator (CDF) family catalyse the import of Zn into the secretory pathway of yeast and vertebrate cells. Orthologous proteins AtMTP5 and AtMTP12 from Arabidopsis have also been shown to form a heterodimeric complex at the Golgi compartment of plant cells that possibly transport Zn. In this study we show that cucumber proteins CsMTP5 and CsMTP12 form a functional heterodimer that is involved in the loading of Zn into the ER lumen under low Zn, and not in the detoxification of yeast from Zn excess through vesicle-mediated exocytosis. Using specific antibodies, we demonstrate that CsMTP5 is localized at the Golgi compartment of cucumber cells and is markedly up-regulated upon Zn deficiency. The level of CsMTP5 transcript in cucumber is also significantly elevated in Zn-limiting conditions, whereas the expression of CsMTP12 is independent of the availability of Zn. Therefore we propose that the cucumber heterodimeric complex CsMTP5-CsMTP12 functions to deliver Zn to Zn-dependent proteins of the Golgi compartment and is regulated by zinc at the level of CsMTP5 transcription. [ABSTRACT FROM AUTHOR]

In this study, the effect of spraying mother plants with various levels of putrescine, spermidine, and cycocel (each at 0, 50, 500, and 5000 mg/l) were assessed on the frequency of haploid embryos produced from unfertilized ovaries and subsequent regeneration of derived embryos. Significantly higher haploid embryos were obtained when mother plants were sprayed with putrescine at 500 mg/l (5.2 embryos/fruit), spermidine at 50 mg/l (4.8 embryos/fruit), and cycocel at 50 mg/l (5.2 embryos/fruit) as compared to the control (without spraying, 3.2 embryos/fruit). However, embryogenesis induction was decreased drastically as the concentration of all the three compounds tested was increased and the lowest haploid embryos were observed when 5000 mg/l of spermidine (0.4 embryos/fruit) or cycocel (2.0 embryos/fruit) were applied. Only spermidine at 50 mg/l led to 100% regeneration into fully developed plantlets. The seed setting and size of fruits were also affected by polyamines and cycocel applications. Ploidy analysis using a flow cytometer indicated that all regenerated plantlets contain the gametic chromosome number (n = x = 7) of parental plants and the results of chromosome counting also confirmed the haploid nature of regenerated plantlets. It can be concluded that the induction of haploid embryogenesis from unfertilized ovaries after pollination with irradiated pollen and subsequent conversion of derived embryos into the plantlets could be improved in Cucumis sativus L. by applying appropriate levels of putrescine, spermidine, and cycocel. [ABSTRACT FROM AUTHOR]

Summary: Plants employ tight genetic control to integrate intrinsic growth signals and environmental cues to enable organs to grow to a defined size. Many genes contributing to cell proliferation and/or cell expansion, and consequently organ size control, have been identified, but the regulatory pathways are poorly understood. Here we have characterized a cucumber littleleaf (ll) mutant which exhibits smaller organ sizes but more lateral branches than the wild type. The small organ size in ll was due to a reduction of both cell number and cell size. Quantitative trait locus (QTL) analyses revealed co‐localization of major‐effect QTLs for fruit size, fruit and seed weight, as well as number of lateral branches, with the LL locus indicating pleiotropic effects of the ll mutation. We demonstrate that LL is an ortholog of Arabidopsis STERILE APETALA (SAP) encoding a WD40 repeat domain‐containing protein; the mutant protein differed from the wild type by a single amino acid substitution (W264G) in the second WD40 repeat. W264 was conserved in 34 vascular plant genomes examined. Phylogenetic analysis suggested that LL originated before the emergence of flowering plants but was lost in the grass genome lineage. The function of LL in organ size control was confirmed by its overexpression in transgenic cucumbers and ectopic expression in Arabidopsis. Transcriptome profiling in LL and ll bulks revealed a complex regulatory network for LL‐mediated organ size variation that involves several known organ size regulators and associated pathways. The data support LL as an important player in organ size control and lateral branch development in cucumber. [ABSTRACT FROM AUTHOR]

In cucumber (Cucumis sativus L.), the differentiation and development of female flowers are important processes that directly affect the fruit yield and quality. Sex differentiation is mainly controlled by three ethylene synthase genes, F (CsACS1G), M (CsACS2), and A (CsACS11). Thus, ethylene plays a key role in the sex differentiation in cucumber. The "one-hormone hypothesis" posits that F and M regulate the ethylene levels and initiate female flower development in cucumber. Nonetheless, the precise molecular mechanism of this process remains elusive. To investigate the mechanism by which F and M regulate the sex phenotype, three cucumber near-isogenic lines, namely H34 (FFmmAA, hermaphroditic), G12 (FFMMAA, gynoecious), and M12 (ffMMAA, monoecious), with different F and M loci were generated. The transcriptomic analysis of the apical shoots revealed that the expression of the B-class floral homeotic genes, CsPI (Csa4G358770) and CsAP3 (Csa3G865440), was immensely suppressed in G12 (100% female flowers) but highly expressed in M12 (~90% male flowers). In contrast, CAG2 (Csa1G467100), which is an AG-like C-class floral homeotic gene, was specifically highly expressed in G12. Thus, the initiation of female flowers is likely to be caused by the downregulation of B-class and upregulation of C-class genes by ethylene production in the floral primordium. Additionally, CsERF31, which was highly expressed in G12, showed temporal and spatial expression patterns similar to those of M and responded to the ethylene-related chemical treatments. The biochemical experiments further demonstrated that CsERF31 could directly bind the promoter of M and promote its expression. Thus, CsERF31 responded to the ethylene signal derived from F and mediated the positive feedback regulation of ethylene by activating M expression, which offers an extended "one-hormone hypothesis" of sex differentiation in cucumber. [ABSTRACT FROM AUTHOR]

Key message: A yellow green peel mutant (ygp) in cucumber was caused by a mutation in Csa2G352940 encoding MYB36 transcription factor.Abstract: Peel color is one of the important agronomic traits of cucumber (Cucumis sativus L.). However, studies on the molecular regulation mechanism of peel color in cucumber are few. In this study, a cucumber yellow green peel mutant (ygp) of cucumber mutagenized with ethylmethylsulfone by using a wild type cucumber with dark green peel was identified. Pigment measurements indicated that the chlorophyll content of the ygp mutant was less than that of the wild type. Genetic analysis revealed that the phenotype of the ygp mutant was monogenic recessive inheritance. MutMap and genotyping results demonstrated that Csa2G352940 (CsMYB36), encoding the transcription factor MYB36, was the causal gene of the ygp mutant in cucumber. CsMYB36 was downregulated in the fruit of the ygp mutant. Transcriptome profile analysis of the fruit peel of the ygp mutant identified 92 candidate genes including genes that encode Casparian strip (CsCASP1) and pigment synthesis protein (CsMYC2) involved in peel color development in cucumber. CsMYB36 may regulate yellow green coloration in cucumber by interacting with these genes. Overall, these results showed that CsMYB36 can regulate the yellow green peel coloration in cucumber. [ABSTRACT FROM AUTHOR]

Grafting is a widely used technique, and graft compatibility between the rootstock and scion is a prerequisite for grafting. To date, the underlying causes of graft compatibility/incompatibility remain largely unknown. Here, using cucumber ( Cucumis sativus L.) grafted onto pumpkin ( Cucurbita L.) rootstocks with different degrees of graft compatibility, and both self-grafting and non-grafting as controls, an integrative analysis of mRNA and miRNA expression and regulatory networks was conducted by using RNA-Seq and sRNA-Seq at 25 days after grafting (DAG). A total of 223 differentially expressed genes (DEGs) and 30 differentially expressed miRNAs (DEMs) related to graft compatibility were identified based on their fold change. Using a combination of GO annotations and KEGG pathway data, the functional annotations and pathways of DEGs and DEM targets showed that a number of metabolic, physiological and hormonal responses are involved in graft compatibility in cucumber leaves including metabolic processes (e.g., “carbohydrate metabolic processes”), nutrient transport (e.g., “sugar transport”), signal transduction (e.g., “MAPK cascade”), plant hormone signal transduction (e.g., “abscisic acid-activated signaling pathway”), transcription factors (e.g., MYB, NAC and bHLH), oxidation-reduction processes, and defense responses. The results of our comprehensive analysis suggested that compatible rootstocks might possess a greater ability for cell proliferation and a more efficient carbohydrate metabolism that promotes plant growth. In contrast, incompatible grafts induced multiple defense response-related genes and various transcription factors, likely in response to stress. Additionally, they consumed large amounts of energy, which ultimately restrained the plants normal development. This study advances our understanding of the molecular mechanisms underlying plant graft compatible/incompatible responses and provides numerous mRNA and miRNA candidates for more in-depth studies into the graft compatibility process. [ABSTRACT FROM AUTHOR]

Cucumis anguria is a potential genetic resource for improving crops of the genus Cucumis, owing to its broad-spectrum resistance. However, few cytogenetic studies on C. anguria have been reported because of its small metaphase chromosomes and the scarcity of distinguished chromosomal landmarks. In this study, 14 single-copy genes from cucumber and rDNAs were used as probes for FISH to identify the individual chromosomes of C. anguria. The distinctive signal distribution patterns of the probes allowed us to distinguish each chromosome of C. anguria (A01-A12). Further, detailed chromosome characteristics were obtained through pachytene chromosome FISH. The lengths of pachytene chromosomes varied from 54.80 to 143.41 μm. The proportion of heterochromatin regions varied from 13.56% to 63.86%. Finally, the chromosomal homeologous relationship between C. anguria and cucumber (C1-C7) was analyzed. The results showed that A06 + A09, A03 + A12, A02 + A04, and A01 + A11 were homeologs of C1, C2, C3, and C6, respectively. Furthemore, chromosomes A08, A10, and A05 were homeologs of C4, C5, and C7, respectively. Chromosome identification and homeologous relationship analysis between C. anguria and cucumber lay the foundation for further research of genome structure evolution in species of Cucumis. [ABSTRACT FROM AUTHOR]

Key message: Two round-leaf mutants, rl-1 and rl-2, were identified from EMS-induced mutagenesis. High throughput sequencing and map-based cloning suggested CsPID encoding a Ser/Thr protein kinase as the most possible candidate for rl-1. Rl-2 was allelic to Rl-1.Abstract: Leaf shape is an important plant architecture trait that is affected by plant hormones, especially auxin. In Arabidopsis, PINOID (PID), a regulator for the auxin polar transporter PIN (PIN-FORMED) affects leaf shape formation, but this function of PID in crop plants has not been well studied. From an EMS mutagenesis population, we identified two round-leaf (rl) mutants, C356 and C949. Segregation analysis suggested that both mutations were controlled by single recessive genes, rl-1 and rl-2, respectively. With map-based cloning, we show that CsPID as the candidate gene of rl-1; a non-synonymous SNP in the second exon of CsPID resulted in an amino acid substitution and the round leaf phenotype. As compared in the wild type plant, CsPID had significantly lower expression in the root, leaf and female flowers in C356, which may result in the less developed roots, round leaves and abnormal female flowers, respectively in the rl-1 mutant. Among the three copies of PID genes, CsPID, CsPID2 and CSPID2L (CsPID2-like) in the cucumber genome, CsPID was the only one with significantly differential expression in adult leaves between WT and C356 suggesting CsPID plays a main role in leaf shape formation. The rl-2 mutation in C949 was also cloned, which was due to another SNP in a nearby location of rl-1 in the same CsPID gene. The two round leaf mutants and the work presented herein provide a good foundation for understanding the molecular mechanisms of CsPID in cucumber leaf development. [ABSTRACT FROM AUTHOR]

This experiment was carried out during two seasons; the first season 2016 included the planting of cucumber seeds from different global origins, which symbolized P1 and P2-P10 in a plastic house with (506 m2) area, at Yusufiya – Baghdad to produce hybrids. During Spring season 2017 the genotypes seeds were planted (10 parents and 27 single cross hybrids with codes F1 and F2-F27 and three common commercial control hybrids with codes C1, C2 and C3) according RCBD design with three replicates, The genotype P5 was superior in the branches number per plant (9.67) and number of leaves per plant (220.33) as well as in total yield of experimental unit 18.03 kg, The hybrid F17 (P5×P9) took lowest number of days number until first female flower appearance (34.00 days) and number of days until first harvest (37.67 days), as well as it produce the highest fruit weight 178.747 gm, the most of hybrids had significant heterosis, the hybrid F23 had the highest positive hybrid vigor in number of leaves per plant (73.03%), the hybrids F4, F17 and F19 had negative heterosis in number of days until first female flower appearance, eight hybrids had positive hybrid vigor in weight of fruit but 16 hybrids had heterosis in experimental unit yield and the highest value obtained from F27 67.77%, while in control hybrid vigor, 15 hybrids had the superiority in numbers of branches so the highest value obtained from F3 53.96%, also it had the highest value of control hybrid vigor in number of leaves per plant 93.21%, the hybrid F27 had significant control hybrid vigor in experimental unit yield 66.79%. [ABSTRACT FROM AUTHOR]

Heterotrimeric guanine nucleotide-binding proteins (G proteins) composed of alpha (Gα), beta (Gβ), and gamma (Gγ) subunits are central signal transducers mediating the cellular response to multiple stimuli, such as cold, in eukaryotes. Plant Gg subunits, divided into A, B, and C three structurally distinct types, provide proper cellular localization and functional specificity to the heterotrimer complex. Here, we demonstrate that a type C Gg subunit CsGG3.2 is involved in the regulation of the CBF regulon and plant tolerance to cold stresses in cucumber (Cucumis sativus L.). We showed that CsGG3.2 transcript abundance was positively induced by cold treatments. Transgenic cucumber plants (T1) constitutively over-expressing CsGG3.2 exhibits tolerance to chilling conditions and increased expression of CBF genes and their regulon. Antioxidative enzymes, i.e., superoxide dismutase, catalase, peroxidase, and glutathione reductase activities increased in cold-stressed transgenic plants. The reactive oxygen species, oxygen free radical and H2O2, production, as well as membrane lipid peroxidation (MDA) production decreased in transgenic plants, suggesting a better antioxidant system to cope the oxidative-damages caused by cold stress. These findings provide evidence for a critical role of CsGG3.2 in mediating cold signal transduction in plant cells. [ABSTRACT FROM AUTHOR]

Fruit epidermal features such as the number and size of trichomes or spines are important fruit quality traits in cucumber production. Little is known about the molecular mechanisms underlying fruit spine formation in cucumber. Here, we report functional characterization of the cucumber CsMYB6 gene, which encodes a MIXTA-like MYB transcription factor that plays an important role in regulating fruit trichome development. Spatial-temporal expression analyses revealed high-level expression of CsMYB6 in the epidermis of cucumber ovaries during fruit spine initiation, which was similar to the expression of CsTRY, a homolog of the Arabidopsis TRY gene that also plays a key role in trichome development. Overexpression of CsMYB6 and CsTRY in cucumber and Arabidopsis revealed that CsMYB6 and CsTRY act as negative regulators of trichome initiation in both species, and that CsMYB6 acted upstream of CsTRY in this process. CsMYB6 was found to bind to the three MYB binding sites inside the promoter region of CsTRY, and protein--protein interaction assays suggested that CsTRY also directly interacted with CsMYB6 protein. The results also revealed conserved and divergent roles of CsMYB6 and its Arabidopsis homolog AtMYB106 in trichome development. Collectively, our results reveal a novel mechanism in which the CsMYB6-CsTRY complex negatively regulates fruit trichome formation in cucumber. [ABSTRACT FROM AUTHOR]

Cysteine-rich polycomb-like protein (CPP) transcription factors are a small gene family involved in the regulation of plant growth, development and stress response. Genome-wide identification and characterization of CPP gene family have been carried out in several plant species. However, no comprehensive phylogenetic analysis or expression profiling of CPP genes in Cucumis sativus has been reported. In this study, we characterized the CPP family genes in C. sativus, and 5 CPP candidate genes were found in cucumber genome. CPP proteins from cucumber and other plant species were classified into two groups, which were further divided into five subgroups based on the phylogenetic distribution. Most CPP genes in the same subgroup shared similar gene structures and conserved motifs. Transcriptome data revealed that CsCPP genes were expressed in leaves, ovaries, flowers, stems, roots, and tendril tissues. qRT-PCR expression analysis showed that many CsCPP genes exhibited different expression patterns in cucumber leaves under abiotic stresses including salt, cold, drought, and ABA. These results demonstrate that cucumber CPP gene family may play critical roles in plant development as well as in the responses to environmental stresses. [ABSTRACT FROM AUTHOR]

Two experiments, field and laboratory were conducted to study the allelopathic effect of using dry powder and aqueous extract of leaves, roots and bark of Eucalyptus sp. on seed germination and growth of seedling of snake cucumber Cucumis melo cv. Local. Seven concentrations; 0, 2, 4, 6, 8, 10, and 12g dry powder/Kg soil of leaves, roots or bark were used in the field experiment. For aqueous extract, seven concentrations were also used; 0%, 2%, 4%, 6%, 8%, 10%, and 12% in the laboratory experiment. The two experiments were lay out in CRD design with four replications. Percentage and mean germination time, chlorophyll content, dry weight reduction over control index, response index and radical and plumulelength were measured. Results of the field experiments revealed that the addition of dry powder of leaves, roots and bark ofEucalyptussp. decreased seed germination percent in proportional with the increase of the concentration used. The least germination percent was obtained using Eucalyptus root dry powder at 12g dry powder/Kg soil. Chlorophyll content did not change significantly due to the addition of leaves dry powder, while it was decreased significantly at the higher concentrations of roots and bark dry powder of Eucalyptus. Generally, chlorophyll increased at the lower concentrations of the dry powder. As for dry weight reduction over control parameter, the percent increased as the concentration of the dry powder of Eucalyptus increased. With regard to aqueous extract, it caused significant reduction in seed germination percent with increasing the concentration used, and it also increased the germination time rate. The seed germination percent was 0% at 12% of leaf aqueous extract of Eucalyptus and it was 20% at the same concentration of aqueous extract of roots and bark of Eucalyptus. Generally, the response index became more negative as the aqueous extract concentration increased. For the plumule and radical length, there was a pronounced reduction in length as the concentration of the aqueous extract increased. It can be concluded from these results that dry powder of leaves, roots and bark and their aqueous extract contain inhibitory allelopathic compounds which inhibit the growth of the cucumber seedlings. [ABSTRACT FROM AUTHOR]

Key message: Host resistances in PI 197088 cucumber to downy and powdery mildew pathogens are conferred by 11 (3 with major effect) and 4 (1 major effect) QTL, respectively, and three of which are co-localized.Abstract: The downy mildew (DM) and powdery mildew (PM) are the two most important foliar diseases of cucurbit crops worldwide. The cucumber accession PI 197088 exhibits high-level resistances to both pathogens. Here, we reported QTL mapping results for DM and PM resistances with 148 recombinant inbred lines from a cross between PI 197088 and the susceptible line ‘Coolgreen’. Phenotypic data on responses to natural DM and PM infection were collected in multi-year and multi-location replicated field trials. A high-density genetic map with 2780 single nucleotide polymorphisms (SNPs) from genotyping-by-sequencing and 55 microsatellite markers was developed, which revealed genomic regions with segregation distortion and mis-assemblies in the ‘9930’ cucumber draft genome. QTL analysis identified 11 and 4 QTL for DM and PM resistances accounting for more than 73.5 and 63.0% total phenotypic variance, respectively. Among the 11 DM resistance QTL, dm5.1, dm5.2, and dm5.3 were major-effect contributing QTL, whereas dm1.1, dm2.1, and dm6.2 conferred susceptibility. Of the 4 QTL for PM resistance, pm5.1 was the major-effect QTL explaining 32.4% phenotypic variance and the minor-effect QTL pm6.1 contributed to disease susceptibility. Three PM QTL, pm2.1, pm5.1, and pm6.1, were co-localized with DM QTL dm2.1, dm5.2, and dm6.1, respectively, which was consistent with the observed linkage of PM and DM resistances in PI 197088. The genetic architecture of DM resistance in PI 197088 and another resistant line WI7120 (PI 330628) was compared, and the potential of using PI 197088 in cucumber breeding for downy and powdery mildew resistances is discussed. [ABSTRACT FROM AUTHOR]

Cucumber (Cucumis sativus L.) has a large, paternally transmitted mitochondrial genome. Cucumber plants regenerated from cell cultures occasionally show paternally transmitted mosaic (MSC) phenotypes, characterized by slower growth, chlorotic patterns on the leaves and fruit, lower fertility, and rearrangements in their mitochondrial DNAs (mtDNAs). MSC lines 3, 12, and 16 originated from different cell cultures all established using the highly inbred, wild-type line B. These MSC lines possess different rearrangements and under-represented regions in their mtDNAs. We completed RNA-seq on normalized and non-normalized cDNA libraries from MSC3, MSC12, and MSC16 to study their nuclear gene-expression profiles relative to inbred B. Results from both libraries indicated that gene expression in MSC12 and MSC16 were more similar to each other than MSC3. Forty-one differentially expressed genes (DEGs) were upregulated and one downregulated in the MSC lines relative to B. Gene functional classifications revealed that more than half of these DEGs are associated with stress-response pathways. Consistent with this observation, we detected elevated levels of hydrogen peroxide throughout leaf tissue in all MSC lines compared to wild-type line B. These results demonstrate that independently produced MSC lines with different mitochondrial polymorphisms show unique and shared nuclear responses. This study revealed genes associated with stress response that could become selection targets to develop cucumber cultivars with increased stress tolerance, and further support of cucumber as a model plant to study nuclear-mitochondrial interactions. [ABSTRACT FROM AUTHOR]

Protein Phosphatase 2C (PP2C) is an important phosphatase-like protein in eukaryotic organisms that can negatively regulate protein kinase cascade abscisic acid (ABA) signal system through phosphorylation and carry out vital roles in various cell processes. The previous study indicated that the accumulation of reactive oxygen species (ROS) is a part of mechanism of glucohexaose-induced resistance in cucumber cotyledons, and CsPP2C80s might play a crucial role in processes related to ROS produce and signal transduction. To identify the mechanism of CsPP2C80s involved in glucohexaose and ABA signaling regulating cell redox status, the effects of glucohexaose and ROS inhibitor pretreatment on endogenous ABA content and ABA signaling genes expression levels of cucumber seedlings were analysed. These results suggest that cucumber CsPP2C80s are involved in ROS accumulation and ABA signal transduction pathway induced by glucohexaose, CsPP2C80s play a positive regulatory role in process of ABA combined with ABA receptors (PYLs) to activate SNF1-related protein kinases 2 (SnRK2s) and regulate NADPH oxidase to produce extracellular hydrogen peroxide (H2O2), providing unequivocal molecular evidence of PP2C-mediated ABA response mechanisms functioning in cell redox status induced by glucohexaose. [ABSTRACT FROM AUTHOR]

The sex differentiation of cucumber directly affects cucumber fruit yield, and low night temperature (LT) promotes female flower differentiation. However, studies on the effects of LT on sex differentiation are scarce. To better understand this mechanism, we used transcriptomics to examine the expression patterns of genes related to female flower differentiation in the cucumber cultivar ‘C09-123’ under LT and high night temperature (HT). We identified a total of 1654 differentially expressed genes in response to LT. There were 1147 up-regulated genes and 507 down-regulated genes under LT compared with their expression under HT. Gene ontology (GO) analysis revealed that the differentially expressed genes were mainly involved in cellular process, metabolic process, response to stimulus process and other processes (biological process). Many of these differentially expressed genes (DEGs) were related to glucose metabolism, cysteine and methionine metabolism and the ethylene and auxin signal transduction pathway and were up-regulated under LT, which promotes female differentiation, compared with their expression level under HT. These results suggest that changes in these genes are likely to affect the corresponding metabolism, thus inducing the female flower differentiation of cucumber under LT. Ethylene and auxin play important roles in the induction of female flower differentiation under LT. This study provides valuable resources for further exploring the molecular basis of LT induction of female flower differentiation and for enabling targeted breeding strategies for developing varieties with superior strong female differentiation to achieve yield potential. [ABSTRACT FROM AUTHOR]

Presence of insects in agricultural habitat is affected by the surrounding circumstances such as the complexity and structure of landscape. Landscape structure is often formed as a consequence of the fragmentation of semi-natural habitat, which can negatively affect species richness and abundance of insects. This study was aimed to study the effect of complexity and structure of landscape on the diversity, abundance and traits of flower-visiting insects in cucumber fields. This study was conducted in cucumber fields surrounded by other agricultural crops, shrubs, semi-natural habitat and housing area, in Bogor, Cianjur and Sukabumi regencies, West Java, Indonesia. In a total of 16 agricultural areas, complexity and parameter of landscape especially class area (CA), number of patches (NumP), mean patch size (MPS), total edge (TE), and mean shape index (MSI) of seminatural habitats were measured. Sampling of flower-visiting insects was conducted using scan sampling methods. The result showed that landscape complexity affected species richness (but not abundance and trait) of flower-visiting insects both for mobile and less-mobile insects. Flower-visiting insects also responded differently to landscape structure. Species richness, abundance and variation of body size of mobile insects were affected by structure of semi-natural habitat. [ABSTRACT FROM AUTHOR]

Key message : The cucumber male sterility gene ms - 3 was fine mapped in a 76 kb region harboring an MMD1 -like gene Csa3M006660 that may be responsible for the male sterile in cucumber. Abstract: A cucumber ( Cucumis sativus L.) male sterile mutant ( ms- 3) in an advanced-generation inbred line was identified, and genetic analysis revealed that the male sterility trait was controlled by a recessive nuclear gene, ms- 3, which was stably inherited. Histological studies suggested that the main cause of the male sterility was defective microsporogenesis, resulting in no tetrad or microspores being formed. Bulked segregant analysis (BSA) and genotyping of an F population of 2553 individuals were employed used to fine map ms- 3, which was delimited to a 76 Kb region. In this region, a single non-synonymous SNP was found in the Csa3M006660 gene locus, which was predicted to result in an amino acid change. Quantitative RT-PCR analysis of Csa3M006660 was consistent with the fact that it plays a role in the early development of cucumber pollen. The protein encoded by Csa3M006660 is predicted to be homeodomain (PHD) finger protein, and the high degree of sequence conservation with homologs from a range of plant species further suggested the importance of the ms- 3 non-synonymous mutation. The data presented here provide support for Csa3M006660 as the most likely candidate gene for Ms- 3. [ABSTRACT FROM AUTHOR]

Key message: Using map-based cloning of ts gene, we identified a new sort of gene involved in the initiation of multicellular tender spine in cucumber. Abstract: The cucumber ( Cucumis sativus L.) fruit contains spines on the surface, which is an extremely valuable quality trait affecting the selection of customers. In this study, we elaborated cucumber line NC072 with wild type (WT) hard fruit spines and its spontaneous mutant NC073, possessing tender and soft spines on fruits. The mutant trait was named as tender spines ( ts), which is controlled by a single recessive nuclear gene. We identified the gene ts by map-based cloning with an F segregating population of 721 individuals generated from NC073 and WT line SA419-2. It was located between two markers Indel6239679 and Indel6349344, 109.7 kb physical distance on chromosome 1 containing fifteen putative genes. With sequencing and quantitative reverse transcription-polymerase chain reaction analysis, the Csa1G056960 gene was considered as the most possible candidate gene of ts. In the mutant, Csa1G056960 has a nucleotide change in the 5′ splicing site of the second intron, which causes different splicing to delete the second exon, resulting in a N-terminal deletion in the predicted amino acid sequence. The gene encodes a C-type lectin receptor-like tyrosine-protein kinase which would play an important role in the formation of cucumber fruit. This is firstly reported of a receptor kinase gene regulating the development of multicellular spines/trichomes in plants. The ts allele could accelerate the molecular breeding of cucumber soft spines. [ABSTRACT FROM AUTHOR]

The present study was performed to analyze the genotype x environment (G×E) interaction for fruit yield of 5 genotypes in four environments; Ikom, Calabar, Obubra and Obudu located at different agro-ecological zones of Cross River State. The cucumber genotypes were grown in randomized complete block design in three replicates in 2015 cropping season. The yield data was analyzed using additive main effect and multiplicative interaction (AMMI) and genotype plus genotype by environment (GGE). Additive main effect and multiplicative interaction (AMMI) analysis of variance showed statistically significant effect of genotypes, environments and the genotype x environment interaction (P < 0.01%). The environment explained 59.59%which showed high differences in variety response to different locations tested. Genotype (G) and genotype x environment interaction (G x E) accounted 15.83% and 11.89% respectively. The first interaction principal component axis (IPCA1) was significant (P < 0.01) except the (IPCA 2) and explained 11.50% and 0.36% of the G X E sum of squares respectively. The Additive main effect and multiplicative interaction stability value (ASV) showed that significant difference existed in the G x E component. Based on the stability parameters, it revealed that none of the genotypes were stable for fruit yield, however according to ASV, and GGE Bi-plot graphical representation, Ashley genotype in relative terms was stable. The genotypes Poinsett (48.43 t ha-1),Ashley(47.49 t ha-1) and Marketer (41.66 t ha-1) were considered to have adaptability to favorable environments, while Market More (MM 13.97t ha-1) and Super Marketer (SM 16.66 t ha-1) adapted to unfavorable conditions for fruit yield. Based on AMMI and GGE bi-plot, ASL had the widest adaptation and was considered as the ideal genotype, whereas P.ST showed specific adaptation. The ideal environments were IKOM (66.85 t ha-1) and OBURA (56.93 t ha-1). Through the GGE bi-plot and AMMI analysis, the superior genotypes identified could serve as references for genotype evaluation and inclusion in further testing in other seasons and environments. [ABSTRACT FROM AUTHOR]

Firmness of skin is an important quality of processing cucumbers, which is a feature of the palisade epidermis in these types compared to flat epidermis in fresh cucumbers. This study was conducted to map the Pe (palisade epidermis) and analyse the candidate gene. Populations derived from the cross of two inbred lines, NCG122 with fruit flat epidermis and NCG121 with fruit palisade epidermis, were used to identify the inheritance of palisade epidermis and to map the gene involved in its development. The results showed that the palisade epidermis trait is controlled by a single gene, Pe, that is dominant over flat epidermis. Seven simple sequence repeat ( SSR) and five insertion deletion (Indel) markers were identified to be linked to the Pe gene. It was mapped to cucumber chromosome 5 (Chr.5) between SSR14611 and Indelpe12 with genetic distances of 0.3 cM and 0.2 cM, respectively. The physical distance of the genomic region harbouring the gene was 227.5 kb with 26 predicted candidate genes. The accuracy of marker-assisted selection using the molecular markers, Indelpe12 and SSR14611, was 68% and 88%, respectively. [ABSTRACT FROM AUTHOR]

As the group II LEA (late embryogenesis abundant) proteins, dehydrins (DHNs) play an important role in plant growth and development, as well as in response to abiotic or biotic stress challenges. In this study, a DHN gene named CsLEA11 was identified and characterized from Cucumis sativus. Sequence analysis of CsLEA11 showed that it is a YSK-type DHN protein rich in hydrophilic amino acids. Expression analyses revealed that the transcription of CsLEA11 could be significantly induced by heat and cold stress. The recombinant plasmid was transformed into Escherichia coli BL21 and isopropy-β- d-thiogalactoside (IPTG) was used to induce recombinant E. coli to express CsLEA11 gene. Overexpression of CsLEA11 in E. coli enhanced cell viability and conferred tolerance to heat and cold stress. Furthermore, CsLEA11 protein could protect the activity of lactate dehydrogenase (LDH) under heat stress. Taken together, our data demonstrate that CsLEA11 might function in tolerance of cucumber to heat and cold stress. [ABSTRACT FROM AUTHOR]

The translationally controlled tumor protein (TCTP) is a family of abundant and ubiquitous proteins involved in several important primary functions. Cucumbers harbor two TCTP genes, CsTCTP1 and CsTCTP2; however, their functional roles remain unclear. In this study, we isolated CsTCTP1 and CsTCTP2 (XP-004134215 and XP-004135602, respectively) promoters, full-length cDNA and genomic sequences from Cucumis sativus. Bioinformatics analysis, containing cis-acting elements, structural domains, phylogenetic tree and conserved motifs, suggested the conservation and divergence of CsTCTP1 and CsTCTP2, thus providing knowledge regarding their functions. Expression analysis indicated that CsTCTP1 and CsTCTP2 exhibited tissue-specific expression and were regulated by biotic or abiotic stresses in C. sativus. Furthermore, CsTCTP1 and CsTCTP2 were regulated by ABA and may be associated with the TOR (target of rapamycin) signaling pathway. In a prokaryotic expression analysis, CsTCTP1 and CsTCTP2 showed positive responses to salt and heat stresses and a negative response to drought and HgCl2 stresses. TCTP may exert multiple functions in various cellular processes. [ABSTRACT FROM AUTHOR]

The present investigation was undertaken inF1population of 48 crosses, developed by crossing 16 lines (8 gynoecious) and 3 testers during the year 2011. All the parental lines and theirF1hybrids were evaluated in randomised complete block design for yield and its contributing traits during the year 2012. Experimental results revealed that parental lines LC-1-1, CGN-20953, CGN-19533, Gyne-5, LC-15-5 and testers Japanese Long Green and K-75 were found superior on the basis of mean performance and general combining ability effects. The cross combinations LC-1-1 × K-75 (monoecious), CGN-19533 × K-75 (gynoecious), CGN-20953 × Poinsette (gynoecious), Gyne-5 × K-75 (gynoecious) and LC-3-3 × Poinsette (monoecious) excelled based on per se performance, specific combining ability and heterosis studies. Further, performance of top 10 heterotic hybrids illustrated the presence over dominance effects in all the crosses except in one cross, where no dominance was observed. Gene action studies indicated that non-additive gene action governed all the traits under study, suggesting the importance of heterosis breeding for the development of high yielding stable parthenocarpic gynoecious hybrids in cucumber. [ABSTRACT FROM AUTHOR]

Key message: A novel dwarf cucumber mutant, scp- 2, displays a typical BR biosynthesis-deficient phenotype, which is due to a mutation in CsDET2 for a steroid 5-alpha-reductase. Abstract: Brassinosteroids (BRs) are a group of plant hormones that play important roles in the development of plant architecture, and extreme dwarfism is a typical outcome of BR-deficiency. Most cucumber ( Cucumis sativus L.) varieties have an indeterminate growth habit, and dwarfism may have its value in manipulation of plant architecture and improve production in certain production systems. In this study, we identified a spontaneous dwarf mutant, super compact- 2 ( scp- 2), that also has dark green, wrinkle leaves. Genetic analyses indicated that scp- 2 was different from two previously reported dwarf mutants: compact ( cp) and super compact- 1 ( scp- 1). Map-based cloning revealed that the mutant phenotype was due to two single nucleotide polymorphism and a single-base insertion in the CsDET2 gene that resulted in a missense mutation in a conserved amino acid and thus a truncated protein lacking the conserved catalytic domains in the predicted steroid 5 α-reductase protein. Measurement of endogenous hormone levels indicated a reduced level of brassinolide (BL, a bioactive BR) in scp- 2, and the mutant phenotype could be partially rescued by the application of epibrassinolide (EBR). In addition, scp- 2 mutant seedlings exhibited dark-grown de-etiolation, and defects in cell elongation and vascular development. These data support that scp- 2 is a BR biosynthesis-deficient mutant, and that the CsDET2 gene plays a key role in BR biosynthesis in cucumber. We also described the systemic BR responses and discussed the specific BR-related phenotypes in cucumber plants. [ABSTRACT FROM AUTHOR]

A simple, sensitive and inexpensive method of ion-pair stir bar sorptive extraction (IP-SBSE) combined with high performance liquid chromatography -ultraviolet (HPLC-UV) detection was developed for the simultaneous determination of three acidic phytohormones (salicylic acid (SA), indole-3-acetic acid (IAA), and abscisic acid (ABA)) in vegetables. With the addition of cationic surfactant-cetyltrimethylammonium bromide (CTAB) in sample solutions, ion pair between CTAB and target phytohormones were formed, leading to an improvement of the extraction efficiency for target phytohormones by C 18 silica coated SBSE. The factors affecting the extraction efficiency of three target phytohormones by IP-C 18 coated SBSE were optimized, and the optimal experimental conditions were established. Under the optimal conditions, the limits of detection for SA, IAA and ABA obtained by IP-C 18 -SBSE-HPLC-UV were 2.7, 2.1 and 0.3 μg L −1 , with the relative standard deviations of 6.0%, 5.0% and 8.3%, respectively, and the enrichment factor was 32–49-fold. The developed method was applied to the determination of SA, IAA and ABA in cucumbers and green bean sprouts, and the recoveries of SA, IAA and ABA for the spiked samples were between 72.8% and 109.5%. [ABSTRACT FROM AUTHOR]

Superoxide dismutase (SOD) proteins are widely present in the plant kingdom and play important roles in different biological processes. However, little is known about the SOD genes in cucumber. In this study, night SOD genes were identified from cucumber (Cucumis sativus) using bioinformatics-based methods, including 5 Cu/ZnSODs, 3 FeSODs, and 1 MnSOD. Gene structure and motif analysis indicated that most of the SOD genes have relatively conserved exon/intron arrangement and motif composition. Phylogenetic analyses with SODs from cucumber and several other species revealed that these SOD proteins can be traced back to two ancestral SODs before the divergence of monocot and dicot plants. Many cis-elements related to stress responses and plant hormones were found in the promoter sequence of each CsSOD gene. Gene expression analysis revealed that most of the CsSOD genes are expressed in almost all the tested tissues. qRT-PCR analysis of 8 selected CsSOD genes showed that these genes could respond to heat, cold, osmotic, and salt stresses. Our results provide a basis for further functional research on SOD gene family in cucumber and facilitate their potential applications in the genetic improvement of cucumber. [ABSTRACT FROM AUTHOR]

Key message : This is the first quantitative estimation of spontaneous polyploidy in cucumber and we detected 2.2% polyploids in a greenhouse study. We provide evidence that polyploidization is consistent with endoreduplication and is an on-going process during plant growth. Abstract: Cucumber occasionally produces polyploid plants, which are problematic for growers because these plants produce misshaped fruits with non-viable seeds. In this study, we undertook the first quantitative study to estimate the relative frequency of spontaneous polyploids in cucumber. Seeds of recombinant inbred lines were produced in different environments, plants were grown in the field and greenhouse, and flow cytometry was used to establish ploidies. From 1422 greenhouse-grown plants, the overall relative frequency of spontaneous polyploidy was 2.2%. Plants possessed nuclei of different ploidies in the same leaves (mosaic) and on different parts of the same plant (chimeric). Our results provide evidence of endoreduplication and polysomaty in cucumber, and that it is an on-going and dynamic process. There was a significant effect ( p = 0.018) of seed production environment on the occurrence of polyploid plants. Seed and seedling traits were not accurate predictors of eventual polyploids, and we recommend that cucumber producers rogue plants based on stature and leaf serration to remove potential polyploids. [ABSTRACT FROM AUTHOR]

Key message : QTL analysis revealed 11 QTL underlying flowering time and fruit size variation in the semi-wild Xishuangbanna cucumber, of which, FT6.2 and FS5.2 played the most important roles in determining photoperiod-dependent flowering time and round-fruit shape, respectively. Abstract: Flowering time and fruit size are two important traits in domestication and diversifying selection in cucumber, but their genetic basis is not well understood. Here we reported QTL mapping results on flowering time and fruit size with F and F segregating populations derived from the cross between WI7200, a small fruited, early flowering primitive cultivated cucumber and WI7167, a round-fruited, later flowering semi-wild Xishuangbanna (XIS) cucumber. A linkage map with 267 microsatellite marker loci was developed with 138 F plants. Phenotypic data of male and female flowering time, fruit length and diameter and three other traits (mature fruit weight and number, and seedling hypocotyl length) were collected in multiple environments. Three flowering time QTL, FT1.1, FT5.1 and FT6.2 were identified, in which FT6.2 played the most important role in conferring less photoperiod sensitive early flowering during domestication whereas FT1.1 seemed more influential in regulating flowering time within the cultivated cucumber. Eight consensus fruit size QTL distributed in 7 chromosomes were detected, each of which contributed to both longitudinal and radial growth in cucumber fruit development. Among them, FS5.2 on chromosome 5 exhibited the largest effect on the determination of round fruit shape that was characteristic of the WI7167 XIS cucumber. Possible roles of these flowering time and fruit size QTL in domestication of cucumber and crop evolution of the semi-wild XIS cucumber, as well as the genetic basis of round fruit shape in cucumber are discussed. [ABSTRACT FROM AUTHOR]

Cucumis × hytivus (2n = 4× = 38) is a synthetic allotetraploid obtained from interspecific hybridization between the cucumber (2n = 2× = 14) and its wild relative C. hystrix (2n = 2× = 24). The synthesis of this species built a bridge for cucumber improvement through gene introgression. Allotriploid and introgression lines (ILs) have previously been produced and characterized with respect to morphology, cytology, and molecular markers. However, no clear evidence of how the chromosomal segments of C. hystrix were introgressed and inherited was found owing to the small size of chromosomes. In the present study, cucumber- C. hystrix introgression lines were developed by backcrossing the allotriploid to North China cucumber breeding line 'P01' followed by self-pollination. The introgressed segments of C. hystrix in the ILs were revealed by meiotic pachytene chromosome analysis. Fluorescence in situ hybridization (FISH) was performed on pachytene chromosomes using fosmid clones from cucumber, which confirmed that introgression occurred in the long arm of chromosome 7. Molecular analysis using a set of 53 simple sequence repeats (SSRs) indicated that the chromosomal segments of C. hystrix were introduced into 4 cucumber chromosomes, the short arms of chromosomes 2 and 6, and long arms of chromosomes 3 and 7. The inheritance of alien sequences in the long arm of chromosome 7 was investigated with 21 SSRs in self-pollinated progenies. C. hystrix-specific bands of several SSRs were still present in some individuals, indicating that the introgressed segment was partially preserved. The first unambiguous identification of alien chromosome segments in cucumber ILs using combined molecular cytogenetics could facilitate the determination of effects of wild alleles and promote cucumber improvement. [ABSTRACT FROM AUTHOR]

Cucumber is one of the most important vegetable crops in the world. To establish an efficient genetic transformation system in cucumber, the role of different factors such as pre-cultivation time, acetosyringone concentration, infection time and cocultivation time that can influence the transformation, was evaluated. In addition, Csexpansin 10 (CsEXP10) gene was transformed into the cucumber genome to produce transgenic lines. The results showed that various optimal parameters such as 100 mg L-1 of kanamycin concentration for selection of transformants, 2 d of pre-cultivation time, 100 μmol L-1 of acetosyringone concentration, 15 min of infection time and 2 d of co-cultivation time were obtained using cotyledonary node explants. The rooting frequency observed on Murashige and Skoog (MS) medium supplemented with 0.2 mg L-1 indole acetic acid and 400 mg L-1 cefotaxime was found to be 100.00%. The positive transgenic cucumber lines were identified using PCR analysis and GUS staining assay. It suggests that the genetic transformation system developed using cotyledonary node explants is efficient and successful in cucumber. [ABSTRACT FROM AUTHOR]

Background: Cucumber downy mildew, caused by P. cubensis, is an important leaf disease that can severely affect cucumber production. In recent years, cucumber target spot, caused by C. cassiicola, has been reported in both Asia and Europe and is now considered as a major disease disrupting cucumber production. Single-disease-resistant cucumber varieties have been unable to satisfy production needs. To explore the molecular mechanisms of cucumber resistance to these two diseases, cucumber cultivars D9320 (resistant to downy mildew and target spot) and D0401 (susceptible to downy mildew and target spot) were used as experimental materials in this study. We used transcriptome sequencing technology to identify genes related to disease resistance and verified using transgenic technology. Results: We screened out the cucumber resistance-related gene CsERF004 using transcriptome sequencing technology. Induction by pathogens, salicylic acid (SA), and ethylene (ET) resulted in the up-regulation of CsERF004. Three treatments, namely, inoculation with C. cassiicola alone, inoculation with P. cubensis alone, and simultaneous inoculation with both pathogens, all resulted in the significant and sustained up-regulation of CsERF004 in the resistant cultivar D9320, during the early stage of infection. In the susceptible cultivar D0401, CsERF004 expression was also significantly up-regulated at the later stage of infection but to a lesser extent and for a shorter duration than in the resistant cultivar D9320. The CsERF004 gene encodes a protein localizes to the nucleus. The over-expression of CsERF004 in the susceptible cultivar D0401 resulted in the significant up-regulation of the CsPR1 and CsPR4 genes and increased the levels of SA and ET, which enhanced the resistance of cucumber to downy mildew and target spot. Conclusions: Analyses of the CsERF004 expression pattern in disease-resistant and susceptible cucumber cultivars and transgenic validation indicate that CsERF004 confers resistance to P. cubensis and C. cassiicola. The findings of this study can help to better understanding of mechanisms of response to pathogens and in establishment the genetic basis for the development of cucumber broad-spectrum resistant cultivars. [ABSTRACT FROM AUTHOR]

Nowadays, approximately 5.8% in adult population around the world are suffering by diabetes. It can be caused by an increase in risk factors such as being overweight. Also it has been estimated that the number of patients will be doubled in near future and the demands for insulin hormone will be growing up by 3 to 4 % annually. Therefore, it's necessary to develop new methods for hormone production with high rate of capacity in future. By advanced technology of transgenic DNA, the transgenic plants are introduced as an attractive system for expression and production of many kinds of pharmaceutical proteins. In this study, we investigated transfer of Human Proinsulin Gene into the Cucumber (Cucumissativus L.). Transgenic cucumber could be a great prospect for future source of eatable insulin pharmaceutical drugs to be taken by patients.Agrobacterium tumefaciensstrain LBA4404 carrying proinsulin genes with CaMV 35S promoter was used for the transformation purpose. The transgenic plants were analyzed by PCR, RT-PCR, SDS-PAGE, Dot blot and Electrochemiluminescence techniques. Production of proinsulin in cucumber could be a great prospect in molecular farming of human proinsulin. [ABSTRACT FROM AUTHOR]

Background: Powdery mildew (PM) causing fungi are well-known pathogens, infecting over 10.000 plant species, including the economically important crop cucumber (Cucumis sativus L.). Loss-of-function mutations in clade V MLO genes have previously been shown to lead to recessively inherited broad-spectrum resistance to PM in several species. In cucumber, one clade V MLO homolog (CsaMLO8) was previously identified as being a susceptibility factor to PM. Two other closely related homologs (CsaMLO1 and CsaMLO11) were found, but their function was not yet unravelled. Methods: CsaMLO1 and CsaMLO11 were cloned from cucumber and overexpressed in a tomato mlo mutant. The transcript abundances of all three CsaMLO genes in different cucumber tissues were quantified using qRT-PCR and RNA-seq, with and without inoculation with the cucumber PM fungus Podosphaera xanthii. Allelic variation of CsaMLO1 and CsaMLO11 was screened in silico in sequenced cucumber germplasm. Results: Heterologous overexpression of all three CsaMLO genes in the tomato mlo mutant restored susceptibility to PM caused by Oidium neolycopersici, albeit to a different extent: whereas overexpression of CsaMLO1 or CsaMLO8 completely restored susceptibility, overexpression of CsaMLO11 was only partially able to restore PM susceptibility. Furthermore, it was observed by qRT-PCR and RNA-seq that CsaMLO8 was significantly higher expressed in noninoculated cucumber compared to the other two MLO genes. However, inoculation with P. xanthii led to upregulation of CsaMLO1, but not to upregulation of CsaMLO8 or CsaMLO11. Conclusions: Both CsaMLO1 and CsaMLO11 are functional susceptibility genes, although we conclude that based on the transcript abundance CsaMLO8 is probably the major clade V MLO gene in cucumber regarding providing susceptibility to PM. Potential loss-of-function mutations in CsaMLO1 and CsaMLO11 have not been identified. The generation and analysis of such mutants are interesting subjects for further investigation. [ABSTRACT FROM AUTHOR]

The hypocotyl-derived adventitious root (AR) is an important morphological acclimation to waterlogging stress; however, its genetic basis has not been adequately understood. In the present study, a mixed major gene plus polygene inheritance model was used to analyze AR numbers (ARN) 7 days after waterlogging treatment in six generations (P, P, F, B, B and F), using cucumber waterlogging tolerant line Zaoer-N and sensitive Pepino as parents. The results showed that the genetic model D-4, mixed one negative dominance major gene and additive-dominance polygenes, is the best-fitting genetic model for waterlogging-triggered ARN phenotype. A genetic linkage map spanning 550.8 cM and consisting of 149 simple sequence repeat (SSR) markers segregating into seven linkage groups was constructed. Three QTLs (ARN3.1, ARN5.1, and ARN6.1) distributed on chromosomes 3, 5, and 6 were identified by composite interval mapping. The major-effect QTL, ARN6.1, located between SSR12898 and SSR04751, was the only locus detected in three seasons, with least likelihood (LOD) scores of 8.8, 10.4, and 9.5 and account for 17.6, 24, and 19.8% of the phenotypic variance, respectively. Using five additional single nucleotide polymorphism (SNP) makers, the ARN6.1 was narrowed down to a 0.79 Mb interval franked by SSR12898 and SNP25558853. Illumina RNA-sequencing data generated on hypocotyls of two parents 48 h after waterlogging treatment revealed 15 genes in the 0.79 Mb interval were differentially expressed, including Csa6G503880 encoding a salicylic acid methyl transferase-like protein, Csa6G504590 encoding a cytochrome P450 monooxygenase, and Csa6G505230 encoding a heavy metal-associated protein. Our findings shed light on the genetic architecture underlying adventitious rooting during waterlogging stress in cucumber, and provide a list of potential gene targets for further elucidating waterlogging tolerance in plants. [ABSTRACT FROM AUTHOR]

Gummy stem blight (GSB), a common disease of all major cucurbits, is caused by the fungus Didymella bryoniae. It results in serious losses in fruit production, which in cucumber can be up to 80% or more. Because the severity of the disease varies from season to season and also because of the harm to the environment caused by using pesticides to control the disease, the best method for overcoming GSB in cucumber is to develop more resistant cultivars by molecular breeding. There are no reports on molecular markers for use in breeding GSB resistance and no studies on chromosomal mapping of resistance. In this paper, a set of 160 F recombinant inbred lines (RILs) were derived from the cross between the wild-type GSB-resistant cucumber accession PI 183967 and the cultivated GSB-susceptible accession 931. A total of 2112 pairs of SSR primers were used to study the inheritance of GSB resistance and to detect quantitative trait loci (QTLs) conferring resistance in the cucumber stem. Genetic analysis indicated that resistance to GSB in PI 183967 was quantitative and mainly governed by three pairs of additive epistatic major genes. Five QTLs, gsb- s1.1, gsb- s2.1, gsb- s6.1, gsb- s6.2, and gsb- s6.3, for resistance to GSB in cucumber stems were detected. The loci gsb- s1.1 and gsb- s2.1 with phenotypic variations of 8.7 and 6.7% were mapped to chromosomes (Chr.) 1 and 2, respectively. The loci gsb- s6.1, gsb- s6.2, and gsb- s6.3 were linked on Chr.6. Locus gsb-s6.2 accounted for the highest phenotypic variation of 22.7% and was flanked by markers SSR04083 and SSR02940 with genetic distances of 5.0 and 1.8 cM, respectively. There were 117 candidate genes predicted between SSR04083 and SSR02940, of which 14 were related to disease resistance. [ABSTRACT FROM AUTHOR]

Among cucurbits, cucumber is distinct for its unique sex mechanism and this feature can easily be manipulated for the production of F1 hybrid seeds. Considerable heterosis is manifested in cucumber for various traits. In India, only few studies utilizing Gynoecious lines in heterosis breeding programme have been reported in cucumber. Moreover, the basic information on combining ability in cucumber would aid the breeder in developing improved hybrid cultivars. So keeping this in view the present studies were undertaken to determine the nature and magnitude of genetic variation among parents and F1's, extent of heterosis in F1's and to obtain information regarding general and specific combining ability effects of different economic traits. Twenty-eight non-reciprocal F1 hybrids derived from eight diverse cucumber genotypes including one gynoecious line were evaluated in randomized block design with three replications to study the heterosis and combining ability for yield and yield attributing traits. The analysis of variance indicated significant variability among all the genotypes for all the traits. The mean square due to GCA and SCA were highly significant for all the characters indicating the importance of both additive and non-additive genetic components for the characters under study. The parent 'Summer Kheera' was the best combiner for four characters viz. marketable yield, fruit diameter, fruit length and vine length. On the basis of mean and heterosis over check, the hybrid combination JLG x Summer Kheera and JLG x NCH-1 were best for marketable yield and fruit weight whereas Swarna sheetal x EC-27075 and Pant Kheera-1 x EC-27075 were best for fruit length and diameter. On basis of SCA effects results differ from that of mean and heterosis. On basis of SCA effects Gy-14 x Punjab Naveen and Gy-14 x Pant Kheera-1 were observed best w.r.t yield and yield attributing traits except earliness. The study of inheritance of different characters indicated the predominance of non-additive gene effects for most of the characters. Therefore, the improvement for these characters can be achieved through hybrid development. [ABSTRACT FROM AUTHOR]

Key message : QTL analysis revealed two interacting loci, FS1.2 and FS2.1, underlying round fruit shape in WI7239 cucumber; CsSUN , a homolog of tomato fruit shape gene SUN , was a candidate for FS1.2. Abstract: Fruit size is an important quality and yield trait in cucumber, but its genetic basis remains poorly understood. Here we reported QTL mapping results on fruit size with segregating populations derived from the cross between WI7238 (long fruit) and WI7239 (round fruit) inbred cucumber lines. Phenotypic data of fruit length and diameter were collected at anthesis, immature and mature fruit stages in four environments. Ten major-effect QTL were detected for six traits; synthesis of information from these QTL supported two genes, FS1.2 and FS2.1, underlying fruit size variation in the examined populations. Under the two-gene model, deviation from expected segregation ratio in fruit length and diameter among segregating populations was observed, which could be explained mainly by the interactions between FS1.2 and FS2.1, and segregation distortion in the FS2.1 region. Genome-wide candidate gene search identified CsSUN, a homolog of the tomato fruit shape gene SUN, as the candidate for FS1.2. The round-fruited WI7239 had a 161-bp deletion in the first exon of CsSUN, and its expression in WI7239 was significantly lower than that in WI7238. A marker derived from this deletion was mapped at the peak location of FS1.2 in QTL analysis. Comparative analysis suggested the melon gene CmSUN- 14, a homolog of CsSUN as a candidate of the fl2/fd2/fw2 QTL in melon. This study revealed the unique genetic architecture of round fruit shape in WI7239 cucumber. It also highlights the power of QTL analysis for traits with a simple genetic basis but their expression is complicated by other factors. [ABSTRACT FROM AUTHOR]