Cucumber Fruit Development Research Articles

Genetic and molecular regulation of fruit development in cucumber.

Fruit development can be generally classified into a set of biologically sequential stages including fruit initiation, growth, and ripening. Cucumber, a globally important vegetable crop, displays two important features during fruit development: parthenocarpy at fruit initiation and prematurity at harvest for consumption. Therefore, fruit growth plays essential role for cucumber yield and quality formation, and has become the research hot spot in cucumber fruit development. Here, we describe recent advances in molecular mechanisms underlying fruit growth in cucumber, include key players and regulatory networks controlling fruit length variation, fruit neck elongation, and locule development. We also provide insights into future directions for scientific research and breeding strategies in cucumber.

Cell wall invertase 3 plays critical roles in providing sugars during pollination and fertilization in cucumber.

In plants, pollen-pistil interactions during pollination and fertilization mediate pollen hydration and germination, pollen tube growth, and seed set and development. Cell wall invertases (CWINs) help provide the carbohydrates for pollen development; however, their roles in pollination and fertilization have not been well established. In cucumber (Cucumis sativus), CsCWIN3 showed the highest expression in flowers, and we further examined CsCWIN3 for functions during pollination to seed set. Both CsCWIN3 transcript and CsCWIN3 protein exhibited similar expression patterns in the sepals, petals, stamen filaments, anther tapetum, and pollen of male flowers, as well as in the stigma, style, transmitting tract, and ovule funiculus of female flowers. Notably, repression of CsCWIN3 in cucumber did not affect the formation of parthenocarpic fruit but resulted in an arrested growth of stigma integuments in female flowers and a partially delayed dehiscence of anthers with decreased pollen viability in male flowers. Consequently, the pollen tube grew poorly in the gynoecia after pollination. In addition, CsCWIN3-RNA interference plants also showed affected seed development. Considering that sugar transporters could function in cucumber fecundity, we highlight the role of CsCWIN3 and a potential close collaboration between CWIN and sugar transporters in these processes. Overall, we used molecular and physiological analyses to determine the CsCWIN3-mediated metabolism during pollen formation, pollen tube growth, and plant fecundity. CsCWIN3 has essential roles from pollination and fertilization to seed set but not parthenocarpic fruit development in cucumber.

Mapping and identification of CsSF4, a gene encoding a UDP-N-acetyl glucosamine-peptide N-acetylglucosaminyltransferase required for fruit elongation in cucumber (Cucumis sativus L.).

The short fruit length phenotype in sf4 is caused by a SNP in Csa1G665390, which encodes an O-linked N-acetylglucosamine (GlcNAc) transferase in cucumber. Cucumber fruit is an excellent resource for studying fruit morphology due to its fast growth rate and naturally abundant morphological variations. The regulatory mechanisms underlying plant organ size and shape are important and fundamental biological questions. In this study, a short-fruit length mutant, sf4, was identified from an ethyl methanesulfonate (EMS) mutagenesis population derived from the North China-type cucumber inbred line WD1. Genetic analysis indicated that the short fruit length phenotype of sf4 was controlled by a recessive nuclear gene. The SF4 locus was located in a 116.7-kb genomic region between the SNP markers GCSNP75 and GCSNP82 on chromosome 1. Genomic and cDNA sequences analysis indicated that a single G to A transition at the last nucleotide of Csa1G665390 intron 21 in sf4 changed the splice site from GT-AG to GT-AA, resulting in a 42-bp deletion in exon 22. Csa1G665390 is presumed to be a candidate gene, CsSF4 that encodes an O-linked N-acetylglucosamine (GlcNAc) transferase (OGT). CsSF4 was highly expressed in the leaves and male flowers of wild-type cucumbers. Transcriptome analysis indicated that sf4 had alterations in expression of many genes involved in hormone response pathways, cell cycle regulation, DNA replication, and cell division, suggesting that cell proliferation-associated gene networks regulate fruit development in cucumber. Identification of CsSF4 will contribute to elucidating the function of OGT in cell proliferation and to understanding fruit elongation mechanisms in cucumber.

Morphological and Genetic Diversity of Cucumber (Cucumis sativus L.) Fruit Development.

Cucumber (Cucumis sativus L.) fruits, which are eaten at an immature stage of development, can vary extensively in morphological features such as size, shape, waxiness, spines, warts, and flesh thickness. Different types of cucumbers that vary in these morphological traits are preferred throughout the world. Numerous studies in recent years have added greatly to our understanding of cucumber fruit development and have identified a variety of genetic factors leading to extensive diversity. Candidate genes influencing floral organ establishment, cell division and cell cycle regulation, hormone biosynthesis and response, sugar transport, trichome development, and cutin, wax, and pigment biosynthesis have all been identified as factors influencing cucumber fruit morphology. The identified genes demonstrate complex interplay between structural genes, transcription factors, and hormone signaling. Identification of genetic factors controlling these traits will facilitate breeding for desired characteristics to increase productivity, improve shipping, handling, and storage traits, and enhance consumer-desired qualities. The following review examines our current understanding of developmental and genetic factors driving diversity of cucumber fruit morphology.

Mining the Roles of Cucumber DUF966 Genes in Fruit Development and Stress Response.

DUF966 genes are widely found in monocotyledons, dicotyledons, mosses, and other species. Current evidence strongly suggests that they are involved in growth regulation and stress tolerance in crops. However, their functions in cucumbers remain unexplored. Here, cucumber CsDUF966 was systemically identified and characterized using bioinformatics. Eight CsDUF966 genes were identified in the cucumber genome. These were phylogenetically separated into three groups. All CsDUF966 proteins were hydrophilic and localized to the nucleus. Moreover, three acidic and five basic proteins were identified. Evolutionary analysis of DUF966 between cucumber and 33 other Cucurbitaceae species/cultivars revealed that most CsDUF966 genes were conserved, whereas CsDUF966_4.c and CsDUF966_7.c were positively selected among the five cucumber cultivars. Expression profiling analysis showed that CsDUF966 had variable expression patterns, and that miRNA164, miRNA166, and Csa-novel-35 were involved in the post-transcriptional regulation of CsDUF966_4.c and CsDUF966_7.c. The expression of CsDUF966_4.c and CsDUF966_7.c, which were under strong neofunctionalization selection, was strictly regulated in fruit and tissues, including seeds, pericarps, peels, and spines, suggesting that these genes are fruit growth regulators and were strongly selected during the cucumber breeding program. In conclusion, the results reveal the roles of CsDUF966s in regulating cucumber fruit development and lay the foundation for further functional studies.

Alkaline α-galactosidase 2 (CsAGA2) plays a pivotal role in mediating source-sink communication in cucumber.

Sugars are necessary for plant growth and fruit development. Cucumber (Cucumis sativus L.) transports sugars, mainly raffinose family oligosaccharides (RFOs), in the vascular bundle. As the dominant sugars in cucumber fruit, glucose and fructose are derived from sucrose, which is the product of RFO hydrolysis by α-galactosidase (α-Gal). Here, we characterized the cucumber alkaline α-galactosidase 2 (CsAGA2) gene and found that CsAGA2 has undergone human selection during cucumber domestication. Further experiments showed that the expression of CsAGA2 increases gradually during fruit development, especially in fruit vasculature. In CsAGA2-RNA interference (RNAi) lines, fruit growth was delayed because of lower hexose production in the peduncle and fruit main vascular bundle (MVB). In contrast, CsAGA2-overexpressing (OE) plants displayed bigger fruits. Functional enrichment analysis of transcriptional data indicated that genes related to sugar metabolism, cell wall metabolism, and hormone signaling were significantly downregulated in the peduncle and fruit MVBs of CsAGA2-RNAi plants. Moreover, downregulation of CsAGA2 also caused negative feedback regulation on source leaves, which was shown by reduced photosynthetic efficiency, fewer plasmodesmata at the surface between mesophyll cell and intermediary cell (IC) or between IC and sieve element, and downregulated gene expression and enzyme activities related to phloem loading, as well as decreased sugar production and exportation from leaves and petioles. The opposite trend was observed in CsAGA2-OE lines. Overall, we conclude that CsAGA2 is essential for cucumber fruit set and development through mediation of sugar communication between sink strength and source activity.

Genome-Wide Identification of YABBY Gene Family in Cucurbitaceae and Expression Analysis in Cucumber (Cucumis sativus L.).

YABBY transcription factors play important roles in plant growth and development. However, little is known about YABBY genes in Cucurbitaceae. Here, we identified 59 YABBY genes from eight cucurbit species, including cucumber (C. sativus L.), melon (C. melon L.), watermelon (C. lanatus), wax gourd (B. hispida), pumpkin (C. maxima), zucchini (C. pepo L.), silver-seed gourd (C. argyrosperma), and bottle gourd (L. siceraria). The 59 YABBY genes were clustered into five subfamilies wherein the gene structures and motifs are conserved, suggesting similar functions within each subfamily. Different YABBY gene numbers in eight cucurbit species indicated that gene loss or duplication events exist in an evolutionary process across Cucurbitaceae. The cis-acting elements analysis implied that the YABBYs may be involved in plant development, and phytohormone, stress, and light responses. Importantly, YABBY genes exhibited organ-specific patterns in expression in cucumber. Furthermore, a gene CsaV3_6G038650 was constitutively expressed at higher levels at different fruit development stages and might play a crucial role in cucumber fruit development. Collectively, our work will provide a better understanding for further function identifications of YABBY genes in Cucurbitaceae.

Involvement of auxin in growth and stress response of cucumber

Cucumber (<italic>Cucumis sativus</italic> L.), an important vegetable, popular worldwide for its crispy texture and special flavor. Plant hormones such as auxin stands out for its dominating function in morpho- and organogenic processes, formation of organs as well as regulation of tropic responses. These developmental processes are entirely or partially dependent on auxin biosynthesis, transport, and signal transduction. In cucumber, auxin not only fine-tunes its morphogenesis but also response to environmental stress. The role of auxin in regulating different organs (root, hypocotyl, shoot, leaf, tendril, flower, and fruit) development in cucumber was reviewed in the present paper. Moreover, the role of auxin in cucumber response to biotic stresses (powdery mildew, downy mildew, and nematode infections) and abiotic stresses (heat, iron, waterlogging, cold, salinity, drought, and heavy metal stresses) was discussed. Finally, we pointed out the blind spots and future research thoughts to extend our understanding of this myriad molecule in cucumber growth and stress biology.

Alternative splicing during fruit development among fleshy fruits

BackgroundAlternative splicing (AS) is an important mechanism of posttranscriptional modification and dynamically regulates multiple physiological processes in plants, including fruit ripening. However, little is known about alternative splicing during fruit development in fleshy fruits.ResultsWe studied the alternative splicing at the immature and ripe stages during fruit development in cucumber, melon, papaya and peach. We found that 14.96–17.48% of multiexon genes exhibited alternative splicing. Intron retention was not always the most frequent event, indicating that the alternative splicing pattern during different developmental process differs. Alternative splicing was significantly more prevalent at the ripe stage than at the immature stage in cucumber and melon, while the opposite trend was shown in papaya and peach, implying that developmental stages adopt different alternative splicing strategies for their specific functions. Some genes involved in fruit ripening underwent stage-specific alternative splicing, indicating that alternative splicing regulates fruits ripening. Conserved alternative splicing events did not appear to be stage-specific. Clustering fruit developmental stages across the four species based on alternative splicing profiles resulted in species-specific clustering, suggesting that diversification of alternative splicing contributes to lineage-specific evolution in fleshy fruits.ConclusionsWe obtained high quality transcriptomes and alternative splicing events during fruit development across the four species. Dynamics and nonconserved alternative splicing were discovered. The candidate stage-specific AS genes involved in fruit ripening will provide valuable insight into the roles of alternative splicing during the developmental processes of fleshy fruits.

Transcriptome profiling reveals key genes related to astringency during cucumber fruit development.

The goal of this study was to provide quantitative data on the catechin contents and underlying molecular regulatory mechanisms in cucumber during fruit development. The dynamic changes in the total catechin contents and RNA-seq-based transcriptome profiling of the flesh and peel of the cucumber cultivar 'YanBai', which is strongly astringent, were examined at three key developmental stages 3, 6 and 9days post-pollination. The total catechin content decreased as cucumber fruit developed and was significantly lower in the flesh than in the peel. In total, 5092 and 4004 genes were found to be differently expressed in the peel and flesh, respectively. Based on a functional annotation, eight structural genes encode enzymes involved in the catechin biosynthesis pathway. Three genes encoding 4-coumarate-CoA ligases, two genes encoding chalcone isomerases, two genes encoding dihydroflavonol-4-reductase and one gene each encoding a phenylalanine ammonia-lyase, flavanone 3-hydroxylase and cinnamate 4-hydroxylase were identified as affecting the catechin content of cucumber. The transcriptome data also revealed the significance of transcription factors, including WD40-repeat proteins, MYB and bHLH, in regulating catechin biosynthesis. These findings help increase our understanding of the molecular mechanisms controlling catechin biosynthesis and astringency development in cucumber fruit.

Changes in catechin contents and expression of catechin biosynthesis-associated genes during early cucumber fruit development

Cucumber (Cucumis sativus L.), a biologically, agriculturally, and economically important vegetable crop consumed worldwide. Catechins (Cs) are the main astringent substances that affect the oral sensory quality of cucumber fruit, and they exhibit potential human health benefits in the amelioration of chronic diseases. However, little is known about the primary components of Cs or their regulatory mechanisms in cucumber. In this study, dynamic changes in C levels and the expression patterns of C-related genes in the peel and flesh of cucumber inbred line ‘YB’, which is strongly astringent during the early fruit development period, were examined. Only three types of Cs, gallocatechin, C and epigallocatechin gallate, were detectable in cucumber fruit, and their contents decreased with fruit development. Gallocatechin was the major C and was present in significantly greater concentrations in peel than in flesh. The expression profiles of 38 genes related to C biosynthesis were investigated by qRT-PCR. We hypothesized that CsPAL3, CsPAL5, CsC4H1, Cs4CL2, CsCHS2, CsCHI2, CsDFR2, CsF3H3, and CsANS are the important C biosynthesis regulators in cucumber fruit. The isolation of genes encoding biosynthetic enzymes provides important molecular resources for further genetic manipulations of C biosynthesis in cucumber.

Relationship between key environmental factors and profiling of volatile compounds during cucumber fruit development under protected cultivation

To provide precision management of cucumber under protected cultivation, the relationships between environmental factors and daily increment of aroma in two lines were analyzed during development, using Pearson correlation and stepwise regression. Irrespective of the line tested, the daily increment of volatile compounds and C6 aldehydes were positively correlated with average daily light intensity (X1), while the daily increment of C9 aldehydes was negatively correlated with average daily relative humidity (X4) and average daytime relative humidity (X7). X1 was considered as the most significant environmental factor which affected the daily increment of volatile compounds in both lines, X7 was the environmental factor which affected the daily increment of C9 aldehydes most in No.14-1, and X1 and X4 were the factors which affected the daily increment of C6 aldehydes and C9 aldehydes most in No.26. A range of environmental factors was forecast for the maximal daily increment of volatile compounds.

Effects of 2,4-Dichlorophenoxyacetic Acid on Cucumber Fruit Development and Metabolism.

The auxin-like compound 2,4-dichlorophenoxyacetic acid (2,4-D) has been widely used as a plant growth regulator in cucumber fruit production; however, its influence on fruit development and metabolism has not been evaluated. In this study, the phenotype of cucumber fruits in both 2,4-D treatment and non-treatment control groups were recorded, and the metabolome of different segments of cucumber fruit at various sampling time points were profiled by a standardized non-targeted metabolomics method based on UPLC-qTOF-MS. The application of 2,4-D increased the early growth rate of the fruit length but had no significant effect on the final fruit length, and produced cucumber fruits with fresh flowers at the top. The 2,4-D treatment also affected the cucumber fruit metabolome, causing significant changes in the stylar end at 4 days after flowering (DAF). The significantly changed metabolites were mainly involved in methionine metabolism, the citric acid cycle and flavonoid metabolism pathways. At the harvest stage, 2,4–D treatment significantly decreased the levels of flavonoids and cinnamic acid derivatives while increased the levels of some of the amino acids. In summary, exogenous application of 2,4-D can greatly alter the phenotype and metabolism of cucumber fruit. These findings will assist in exploring the mechanisms of how 2,4-D treatment changes the fruit phenotype and evaluating the influence of 2,4-D treatment on the nutritional qualities of cucumber fruit.

Identification of Conserved and Diverse Metabolic Shift of the Stylar, Intermediate and Peduncular Segments of Cucumber Fruit during Development.

Cucumber (Cucumis sativus L.) is one of the most important vegetables and contains a high content of nutritionally beneficial metabolites. However, little is known about the metabolic variations among different parts of cucumber fruit and their kinetics during growth. In this study, the dynamic metabolic profiles in the stylar end, the intermediate segment and the peduncular end of cucumber fruit during the development were investigated by employing a non-targeted metabolomics approach, where 238 metabolites were identified. Statistical analyses revealed that both development time and tissue type influenced metabolic changes, while development time seemed to exert more effects than tissue type on the cucumber fruit metabolome. The levels of the most of the detected metabolites decreased gradually, while those of some amino acids, carbohydrates and flavonoids increased across development. The metabolomes of the stylar end and the intermediate segment were similar, although all three parts of the cucumber fruit were separated from each other in orthogonal partial least squares projection to latent structures-discriminant analysis (OPLS-DA) plots. Metabolites association analysis revealed that sn-1 and sn-2 lysophospholipids are synthesized via independent pathways in cucumber fruit. In sum, this study demonstrated both conserved and diverse metabolic kinetics of three parts of cucumber fruit, which will facilitate further study of the regulation of cucumber fruit development as well as their potential applications in nutritious quality improvement of cucumber fruit.

Proteomic insight into fruit set of cucumber (Cucumis sativus L.) suggests the cues of hormone-independent parthenocarpy

BackgroundParthenocarpy is an excellent agronomic trait that enables crops to set fruit in the absence of pollination and fertilization, and therefore to produce seedless fruit. Although parthenocarpy is widely recognized as a hormone-dependent process, hormone-insensitive parthenocarpy can also be observed in cucumber; however, its mechanism is poorly understood. To improve the global understanding of parthenocarpy and address the hormone-insensitive parthenocarpy shown in cucumber, we conducted a physiological and proteomic analysis of differently developed fruits.ResultsPhysiological analysis indicated that the natural hormone-insensitive parthenocarpy of ‘EC1’ has broad hormone-inhibitor resistance, and the endogenous hormones in the natural parthenocarpy (NP) fruits were stable and relatively lower than those of the non-parthenocarpic cultivar ‘8419 s-1.’ Based on the iTRAQ technique, 683 fruit developmental proteins were identified from NP, cytokinin-induced parthenocarpic (CP), pollinated and unpollinated fruits. Gene Ontology (GO) analysis showed that proteins detected from both set and aborted fruits were involved in similar biological processes, such as cell growth, the cell cycle, cell death and communication. Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis revealed that ‘protein synthesis’ was the major biological process that differed between fruit set and fruit abortion. Clustering analysis revealed that different protein expression patterns were involved in CP and NP fruits. Forty-one parthenocarpy-specialized DEPs (differentially expressed proteins) were screened and divided into two distinctive groups: NP-specialized proteins and CP-specialized proteins. Furthermore, qRT-PCR and western blot analysis indicated that NP-specialized proteins showed hormone- or hormone-inhibitor insensitive expression patterns in both ovaries and seedlings.ConclusionsIn this study, the global molecular regulation of fruit development in cucumber was revealed at the protein level. Physiological and proteomic comparisons indicated the presence of hormone-independent parthenocarpy and suppression of fruit abortion in cucumber. The proteomic analysis suggested that hormone-independent parthenocarpy is regulated by hormone-insensitive proteins such as the NP-specialized proteins. Moreover, the regulation of fruit abortion suppression may be closely related to protein synthesis pathways.

QTL mapping of domestication and diversifying selection related traits in round-fruited semi-wild Xishuangbanna cucumber (Cucumis sativus L. var. xishuangbannanesis)

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. 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 F2 and F2:3 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 F2 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.

午後高温・夕方急速降温管理が促成栽培キュウリの生育に及ぼす影響

午後高温・夕方急速降温管理が促成栽培キュウリの生育に及ぼす影響

Identification of the subgenomic promoter of the coat protein gene of cucumber fruit mottle mosaic virus and development of a heterologous expression vector.

Heterologous gene expression using plant virus vectors enables research on host-virus interactions and the production of useful proteins, but the host range of plant viruses limits the practical applications of such vectors. Here, we aimed to develop a viral vector based on cucumber fruit mottle mosaic virus (CFMMV), a member of the genus Tobamovirus, whose members infect cucurbits. The subgenomic promoter (SGP) in the coat protein (CP) gene, which was used to drive heterologous expression, was mapped by analyzing deletion mutants from a CaMV 35S promoter-driven infectious CFMMV clone. The region from nucleotides (nt) -55 to +160 relative to the start codon of the open reading frame (ORF) of CP was found to be a fully active promoter, and the region from nt -55 to +100 was identified as the active core promoter. Based on these SGPs, we constructed a cloning site in the CFMMV vector and successfully expressed enhanced green fluorescent protein (EGFP) in Nicotiana benthamiana and watermelon (Citrullus lanatus). Co-inoculation with the P19 suppressor increased EGFP expression and viral replication by blocking degradation of the viral genome. Our CFMMV vector will be useful as an expression vector in cucurbits.

Expression patterns of genes encoding plasma membrane aquaporins during fruit development in cucumber (Cucumis sativus L.)

Aquaporins are membrane channels precisely regulating water movement through cell membranes in most living organisms. Despite the advances in the physiology of fruit development, their participation during fruit development in cucumber still barely understood. In this paper, the expressions of 12 genes encoding plasma membrane intrinsic proteins (PIPs) were analyzed during cucumber fruit development in our work. Based on the homology search with known PIPs from rice, Arabidopsis and strawberry, 12 cucumber PIP genes subfamily members were identified. Cellular localization assays indicated that CsPIPs were localized in the plasma membrane. The qRT-PCR analysis of CsPIPs showed that 12 CsPIPs were differentially expressed during fruit development. These results suggest that 12 genes encoding plasma membrane intrinsic proteins (CsPIPs) play very important roles in cucumber life cycle and the data generated will be helpful in understanding their precise roles during fruit development in cucumber.

QTL mapping in multiple populations and development stages reveals dynamic quantitative trait loci for fruit size in cucumbers of different market classes

QTL analysis in multi-development stages with different QTL models identified 12 consensus QTLs underlying fruit elongation and radial growth presenting a dynamic view of genetic control of cucumber fruit development. Fruit size is an important quality trait in cucumber (Cucumis sativus L.) of different market classes. However, the genetic and molecular basis of fruit size variations in cucumber is not well understood. In this study, we conducted QTL mapping of fruit size in cucumber using F2, F2-derived F3 families and recombinant inbred lines (RILs) from a cross between two inbred lines Gy14 (North American picking cucumber) and 9930 (North China fresh market cucumber). Phenotypic data of fruit length and diameter were collected at three development stages (anthesis, immature and mature fruits) in six environments over 4years. QTL analysis was performed with three QTL models including composite interval mapping (CIM), Bayesian interval mapping (BIM), and multiple QTL mapping (MQM). Twenty-nine consistent and distinct QTLs were detected for nine traits from multiple mapping populations and QTL models. Synthesis of information from available fruit size QTLs allowed establishment of 12 consensus QTLs underlying fruit elongation and radial growth, which presented a dynamic view of genetic control of cucumber fruit development. Results from this study highlighted the benefits of QTL analysis with multiple QTL models and different mapping populations in improving the power of QTL detection. Discussion was presented in the context of domestication and diversifying selection of fruit length and diameter, marker-assisted selection of fruit size, as well as identification of candidate genes for fruit size QTLs in cucumber.