Melon Accessions Research Articles

Multi-component resistance responses of melon to zucchini yellow mosaic virus.

A major resistance gene of the melon accession PI414723 to zucchini yellow mosaic virus (ZYMV) is located at the Zym-1 locus on chromosome 2, but the underlying defense mechanisms are poorly understood. The physiological responses and expression of selected genes at Zym-1 were assessed in PI414723 and in the susceptible genotype Védrantais. Viral titers and the expression of genes related to systemic acquired resistance (SAR) were evaluated in inoculated (Inoc) and non-inoculated (Non-Inoc) portions of the cotyledons at 3, 7 and 10 days after inoculation (dai) and in apical leaves at 10 dai. ZYMV was detected in both portions of the cotyledons but not in the apical leaves of PI414723 plants. Also, ZYMV was recovered in a susceptible zucchini only from Inoc portions at 3 dai. By contrast, in Védrantais ZYMV was detected and recovered from all tissues at high concentrations. Starchy local lesions and accumulation of transcripts of the SAR marker genes PR1 and PR4 were also detected in the resistant genotype. Plus, transcripts of one candidate resistance gene analog previously located at Zym-1 and of two melon homologs of restricted tobacco etch virus movement 2 (RTM2) genes located close to Zym-1, accumulated only in PI414723. It is proposed that resistance results from the combined action of the R gene, involved in restricting ZYMV replication after a supposed recognition event and of the RTM genes which impact viral systemic movement to distal apical tissues.

The dominant white color trait of the melon fruit rind is associated with epicuticular wax accumulation.

Microscopic analyses and chemical profiling demonstrate that the white rind phenotype in melon fruit is associated with the accumulation of n-alkanes, fatty alcohols, aldehydes and wax esters. Serving as an indicator of quality, the rind (or external) color of fruit directly affects consumer choice. A fruit's color is influenced by factors such as the levels of pigments and deposited epicuticular waxes. The latter produces a white-grayish coating often referred to as "wax bloom". Previous reports have suggested that some melon (Cucumis melo L.) accessions may produce wax blooms, where a dominant white rind color trait was genetically mapped to a major locus on chromosome 7 and suggested to be inherited as a single gene named Wi. We here provide the first direct evidence of the contribution of epicuticular waxes to the dominant white rind trait in melon fruit. Our light and electron microscopy and gas chromatography-mass spectrometry (GC-MS) comparative analysis of melon accessions with white or green rinds reveals that the rind of melon fruit is rich in epicuticular waxes. These waxes are composed of various biochemical classes, including fatty acids, fatty alcohols, aldehydes, fatty amides, n-alkanes, tocopherols, triterpenoids, and wax esters. We show that the dominant white rind phenotype in melon fruit is associated with increased accumulation of n-alkanes, fatty alcohols, aldehydes and wax esters, which are linked with the deposition of crystal-like wax platelets on their surfaces. Together, this study broadens the understanding of natural variation in an important quality trait of melon fruit and promotes the future identification of the causative gene for the dominant white rind trait.

Genetic Diversity and Response of Melon Accessions toMonosporascus cannonballus

ABSTRACTMelon holds significant economic importance for Brazilian agribusiness. It exhibits high polymorphism and genetic variability, yet knowledge regarding its genetic diversity and response to root diseases remains limited. Therefore, this study aimed to assess the genetic diversity and response of melon plant accessions to Monosporascus cannonballus. Two trials were conducted involving 29 melon accessions and a commercial hybrid of the yellow melon plant, Natal RZ. In the first trial, the accessions and the commercial hybrid were grown in the field under a randomised complete block design with three replications. They were evaluated for fruit‐related descriptors: number of fruits per plant (NFP), average fruit weight, shape index, pulp thickness, pulp firmness (PF) and total soluble solids (TSS). Standardised Euclidean distances were calculated on the basis of the results, and the accessions were grouped using the UPGMA method. In the second trial, the melon plant accessions and commercial hybrid were cultivated in a greenhouse under a completely randomised design with 12 replications. For inoculation, wheat grains infested with M. cannonballus isolate CMM‐2429 were used. Evaluations were conducted 60 days after transplanting, assessing the incidence and severity of the disease, and biometric variables. The study revealed genetic variability among the evaluated accessions for fruit descriptors and response to M. cannonballus. Most divergent accessions were A16, A53, NZR, A28, A51 and A44, with divergence primarily observed in NFP, PF and TSS. Promising accessions for breeding programmes aimed at resistance to M. cannonballus included A01, A04, A25, A27 (moderately resistant) and A26 (highly resistant to the pathogen).

Genetic Dissection of ToLCNDV Resistance in Resistant Sources of Cucumis melo.

Tomato leaf curl New Delhi virus (ToLCNDV) is a begomovirus causing significant melon (Cucumis melo) crop losses globally. This study aims to map the ToLCNDV resistance in the PI 414723 melon accession, previously identified and characterized through phenotypic studies, thereby exploring shared genomic regions with the established resistant source WM-7. In the present study, WM-7 and PI 414723 were crossed with the susceptible accessions 'Rochet' and 'Blanco' respectively, to generate F1 hybrids. These hybrids were self-pollinated to generate the populations for mapping the ToLCNDV resistance region and designing markers for marker-assisted selection. Disease evaluation included visual symptom scoring, viral-load quantification and tissue printing. Genotyping-by-sequencing and SNP markers were used for quantitative trait loci (QTL) mapping. For genetic analysis, qPCR and bulked segregant RNA-seq (BSR-seq) were performed. Gene expression was assessed using RNA-seq, and qRT-PCR was used for confirmation. The research narrows the candidate region for resistance in WM-7 and identifies overlapping QTLs on chromosome 11 in PI 414723, found in the region of the DNA primase large subunit. BSR-seq and expression analyses highlight potential regulatory roles of chromosome 2 in conferring resistance. Differential expression was confirmed for six genes in the candidate region on chromosome 2. This study confirms the existence of common resistance genes in PI 414723 and WM-7.

Diversity and abundance of insects associated with two accessions of golden melon (Cucumis melo L.)

This study aims to give fundamental details regarding the diversity and abundance of insects associated with two accessions of Golden melon (Cucumis melo L). There were 1,058 (1,058) different specimens gathered. These insects belong to 7 different Orders (Coleoptera, Lepidoptera, Orthoptera, Diptera, Dictyoptera, Hemiptera, and Hymenoptera) and 22 different (Acrididae, Alydidae, Apidae, Braconidae, Calliphoridae, Chrysomelidae, Coccinellidae, Erotylidae, Formicdae, Gryllidae, Mantidae, Muscidae, Pentatomidae, Pieridae, Reduviidae, Sacrophidae, Scarabaiedae, Scutelleridae, Tachinidae, Tenebrionidae, Tettigonidae and Vespidae). Majority of the insect predators belong to the Formicidae family. Golden melon beds were sampled for insects every 10 weeks from the second week after sowing. Every week, sampling was carried out between 7:00 and 9:00 in the morning using a sweep net, a pitfall, and handpicking. As a result, this knowledge will aid in understanding the various insect pests that affect golden melon (Cucumis melo) systems

Effect of nitrogen, potassium, and iron nutrition on growth and physiological characteristics of local melon accession of Shahdad

Effect of nitrogen, potassium, and iron nutrition on growth and physiological characteristics of local melon accession of Shahdad

A deletion in FLS2 and its expansion after domestication caused global dissemination of melon cultivars defective in flagellin recognition.

FLAGELLIN SENSING 2 (FLS2) encodes a pattern recognition receptor that perceives bacterial flagellin. While putative FLS2 orthologs are broadly conserved in plants, their functional characterization remains limited. Here, we report the identification of orthologs in cucumber (Cucumis sativus) and melon (C. melo), named CsFLS2 and CmFLS2, respectively. Homology searching identified CsFLS2, and virus-induced gene silencing (VIGS) demonstrated that CsFLS2 is required for flg22-triggered ROS generation. Interestingly, genome re-sequencing of melon cv. Lennon and subsequent genomic PCR revealed that Lennon has two CmFLS2 haplotypes, haplotype I encoding full-length CmFLS2 and haplotype II encoding a truncated form. We show that VIGS-mediated knockdown of CmFLS2 haplotype I resulted in a significant reduction in both flg22-triggered ROS generation and immunity to a bacterial pathogen in melon cv. Lennon. Remarkably, genomic PCR of CmFLS2 revealed that 68% of tested commercial melon cultivars possess only CmFLS2 haplotype II: these cultivars thus lack functional CmFLS2. To explore evolutionary aspects of CmFLS2 haplotype II occurrence, we genotyped the CmFLS2 locus in 142 melon accessions by genomic PCR and analyzed 437 released sequences. The results suggest that CmFLS2 haplotype II is derived from C. melo subsp. melo. Furthermore, we suggest that the proportion of CmFLS2 haplotype II increased among the improved melo group compared with the primitive melo group. Collectively, these findings suggest that the deleted FLS2 locus generated in the primitive melo subspecies expanded after domestication, resulting in the spread of commercial melon cultivars defective in flagellin recognition, which is critical for bacterial immunity.

A wild melon reference genome provides novel insights into the domestication of a key gene responsible for melon fruit acidity.

A wild melon reference genome elucidates the genomic basis of fruit acidity domestication. Structural variants (SVs) have been reported to impose major effects on agronomic traits, representing a significant contributor to crop domestication. However, the landscape of SVs between wild and cultivated melons is elusive and how SVs have contributed to melon domestication remains largely unexplored. Here, we report a 379-Mb chromosome-scale genome of a wild progenitor melon accession "P84", with a contig N50 of 14.9Mb. Genome comparison identifies 10,589 SVs between P84 and four cultivated melons with 6937 not characterized in previously analysis of 25 melon genome sequences. Furthermore, the population-scale genotyping of these SVs was determined in 1175 accessions, and 18 GWAS signals including fruit acidity, fruit length, fruit weight, fruit color and sex determination were detected. Based on these genotyped SVs, we identified 3317 highly diverged SVs between wild and cultivated melons, which could be the potential SVs associated with domestication-related traits. Furthermore, we identify novel SVs affecting fruit acidity and proposed the diverged evolutionary trajectories of CmPH, a key regulator of melon fruit acidity, during domestication and selection of different populations. These results will offer valuable resources for genomic studies and genetic improvement in melon.

Bulked Segregant Analysis by Sequencing-Based Genetic Mapping of the Green Spotted Fruit Rind Regulating Locus in Wild Melon XNM020 Reveals Four Possible Candidate Genes

Fruit rind patterns are vital commercial quality traits in melon, in which the spotted or striped fruit rinds contribute to the commercial value of melon and can directly affect the choice of consumers. Although the spotted or non-spotted fruit rind pattern was studied in several cultivated melon accessions, the inheritance and regulating locus of this trait in wild melons are still unknown. Therefore, in this study, the inheritance and regulating loci of the green spotted fruit rind in a wild melon accession XNM020 were explored with F2 segregating populations derived from crossing between XNM020 and a cultivated melon XNM125. Segregating ratios of phenotypic data indicated that the green spotted fruit rind in XNM020 has a monogenic dominant inheritance. BSA-Seq showed that two potential genomic regions on chromosomes 4 (from 0.00 to 2.97 Mb) and 5 (from 0.00 to 2.34 Mb) regulate the formation of the green spotted fruit rind in wild melon XNM020. According to the annotations of polymorphic SNPs (single-nucleotide polymorphisms) and small InDels (insertions and deletions) in target genomic regions and the predicted gene functions, four genes MELO3C003316, MELO3C003375, MELO3C003388, and MELO3C014660 regulating chloroplast development or chlorophyll biosynthesis may be the best candidate genes. The results of this study enriched the inheritances of spotted fruit rinds in melon and also provided target genomic regions for marker-assisted selection breeding of melon focusing on fruit rinds.

Complete genome assembly provides a high-quality skeleton for pan-NLRome construction in melon.

Melon (Cucumis melo L.), being under intensive domestication and selective breeding, displays an abundant phenotypic diversity. Wild germplasm with tolerance to stress represents an untapped genetic resource for discovery of disease-resistance genes. To comprehensively characterize resistance genes in melon, we generate a telomere-to-telomere (T2T) and gap-free genome of wild melon accession PI511890 (C. melo var. chito) with a total length of 375.0 Mb and a contig N50 of 31.24 Mb. The complete genome allows us to dissect genome architecture and identify resistance gene analogs. We construct a pan-NLRome using seven melon genomes, which include 208 variable and 18 core nucleotide-binding leucine-rich repeat receptors (NLRs). Multiple disease-related transcriptome analyses indicate that most up-regulated NLRs induced by pathogens are shell or cloud NLRs. The T2T gap-free assembly and the pan-NLRome not only serve as essential resources for genomic studies and molecular breeding of melon but also provide insights into the genome architecture and NLR diversity.

Integrated full-length transcriptome and metabolome analysis reveals the defence response of melon to gummy stem blight.

Gummy stem blight (GSB), a widespread disease causing great loss to cucurbit production, has become a major threat to melon cultivation. However, the melon-GSB interaction remains largely unknown. Here, full-length transcriptome and widely targeted metabolome were used to investigate the defence responses of resistant (PI511089) and susceptible (Payzawat) melon accessions to GSB pathogen infection at 24 h. The biosynthesis of secondary metabolites and MAPK signalling pathway were specifically enriched for differentially expressed genes in PI511890, while carbohydrate metabolism and amino acid metabolism were specifically enriched in Payzawat. More than 1000 novel genes were identified and MAPK signalling pathway was specifically enriched for them in PI511890. There were 11 793 alternative splicing events involving in the defence response to GSB. Totally, 910 metabolites were identified in Payzawat and PI511890, and flavonoids were the dominant metabolites. Integrated full-length transcriptome and metabolome analysis showed eriodictyol and oxalic acid were the potential marker metabolites for GSB resistance in melon. Moreover, posttranscription regulation was widely involved in the defence response of melon to GSB pathogen infection. These results not only improve our understanding on the interaction between melon and GSB, but also facilitate the genetic improvement of melon with GSB resistance.

Heterosis and combining ability analysis for fruit traits in melon (Cucumis melo L.) involving male sterile and snapmelon lines

Ten melon accessions including eight resistant lines involving one snapmelon line (Cucumismelo var. momordica) and two susceptible lines with one genetic male sterile line were crossed to generate 45 F1?s through half-diallel design. These genotypes were evaluated for yield, quality and disease resistance traits in randomized block design with three replication. Pooled ANOVA for experimental design revealed significant mean squares due to environments except for ?-carotene and TSS of juice and, treatment ? environment except for fruit shape index and TSS of juice. The GCA estimates showed that parents Punjab Sunehri was a good combiner for seed cavity area (-8.80), flesh thickness (0.12), rind thickness (0.42), firmness (0.61), dry matter (1.02) and ? carotene (0.80) while SM-2012-12 for fruit yield (4.74), number of fruits vine-1(3.43), average fruit weight (0.06) and fusarium wilt incidence (-0.51) whereas, KP4HM-15 was good for average fruit weight (0.01), days tofirst fruit ripening (-2.31), TSS (1.21), pH (0.13), titrable acidity (-3.13), ascorbic acid content (5.89) and ?-carotene (0.06). The heterobeltosis ranged from -87.2 to 927.08% for the yield and quality traits whereas for fusarium wilt incidence has -100 to 69.23%.The study offers an opportunity for transferring fusarium wilt incidence into superior horticultural genotype. Hybrids KP4HM-15 ? Kajri Sel. 1, Kajri Sel.1 ? MM-202 and MM-314 ? KP4HM-15 were identified as promising on the basis of phenotypic performance, SCA effects and resistance to fusarium wilt disease. These hybrids can be evaluated further at multilocation to assess their suitability for commercial release.

Post-harvest quality of melon accessions subjected to salinity.

The objective was to evaluate the behavior of melon genotypes (Cucumis melo L.) in the physical, chemical and biochemical quality of melon fruits as a function of electrical conductivity irrigation water levels (ECw). The experimental design adopted was randomized blocks in a 5 x 3 factorial scheme with five replications. The first factor was represented by five salinity levels (0.5, 1.5, 3.0, 4.5, and 6.0 dS m-1) and the second factor by accessions A35, and A24, and the hybrid Sancho. The physical, chemical and biochemical variables showed a reduction in production, with smaller fruits, with less weight, smaller cavity, with increased pulp thickness for Sancho. Vitamin C and yellow flavonoids increased indicating antioxidant power against ROS. The genotypes showed similar post-harvest behavior, however, the hybrid Sancho stood out over the others, possibly because it is an improved material. Accession A24 presented physiological and biochemical responses that classify it as intolerant.

A highly diversified NLR cluster in melon contains homologs that confer powdery mildew and aphid resistance.

Podosphaera xanthii is the main causal agent of powdery mildew (PM) on Cucurbitaceae. In Cucumis melo, the Pm-w resistance gene, which confers resistance to P. xanthii, is located on chromosome 5 in a cluster of nucleotide-binding leucine-rich repeat receptors (NLRs). We used positional cloning and transgenesis, to isolate the Pm-wWMR 29 gene encoding a coiled-coil NLR (CC-NLR). Pm-wWMR 29 conferred high level of resistance to race 1 of PM and intermediate level of resistance to race 3 of PM. Pm-wWMR 29 turned out to be a homolog of the Aphis gossypii resistance gene Vat-1PI 161375. We confirmed that Pm-wWMR 29 did not confer resistance to aphids, while Vat-1PI 161375 did not confer resistance to PM. We showed that both homologs were included in a highly diversified cluster of NLRs, the Vat cluster. Specific Vat-1PI 161375 and Pm-wWMR 29 markers were present in 10% to 13% of 678 accessions representative of wild and cultivated melon types worldwide. Phylogenic reconstruction of 34 protein homologs of Vat-1PI 161375 and Pm-wWMR 29 identified in 24 melon accessions revealed an ancestor with four R65aa-a specific motif in the LRR domain, evolved towards aphid and virus resistance, while an ancestor with five R65aa evolved towards PM resistance. The complexity of the cluster comprising the Vat/Pm-w genes and its diversity in melon suggest that Vat homologs may contribute to the recognition of a broad range of yet to be identified pests and pathogens.

Telomere-to-telomere genome assembly of melon (Cucumis melo L. var. inodorus) provides a high-quality reference for meta-QTL analysis of important traits.

Melon is an important horticultural crop with extensive diversity in many horticultural groups. To explore its genomic diversity, it is necessary to assemble more high-quality complete genomes from different melon accessions. Meanwhile, a large number of QTLs have been mapped in several studies. Integration of the published QTLs onto a complete genome can provide more accurate information for candidate gene cloning. To address these problems, a telomere-to-telomere (T2T) genome of the elite melon landrace Kuizilikjiz (Cucumis melo L. var. inodorus) was de novo assembled and all the published QTLs were projected onto it in this study. The results showed that a high-quality Kuizilikjiz genome with the size of 379.2Mb and N50 of 31.7Mb was de novo assembled using the combination of short reads, PacBio high-fidelity long reads, Hi-C data, and a high-density genetic map. Each chromosome contained the centromere and telomeres at both ends. A large number of structural variations were observed between Kuizilikjiz and the other published genomes. A total of 1294 QTLs published in 67 studies were collected and projected onto the T2T genome. Several clustered, co-localized, and overlapped QTLs were determined. Furthermore, 20 stable meta-QTLs were identified, which significantly reduced the mapping intervals of the initial QTLs and greatly facilitated identification of the candidate genes. Collectively, the T2T genome assembly together with the numerous projected QTLs will not only broaden the high-quality genome resources but also provide valuable and abundant QTL information for cloning the genes controlling important traits in melon.

QTL Mapping and Genome-Wide Association Study Reveal Genetic Loci and Candidate Genes Related to Soluble Solids Content in Melon.

Melon (Cucumis melo L.) is an economically important Cucurbitaceae crop grown around the globe. The sweetness of melon is a significant factor in fruit quality and consumer appeal, and the soluble solids content (SSC) is a key index of melon sweetness. In this study, 146 recombinant inbred lines (RILs) derived from two oriental melon materials with different levels of sweetness containing 1427 bin markers, and 213 melon accessions containing 1,681,775 single nucleotide polymorphism (SNP) markers were used to identify genomic regions influencing SSC. Linkage mapping detected 10 quantitative trait loci (QTLs) distributed on six chromosomes, seven of which were overlapped with the reported QTLs. A total of 211 significant SNPs were identified by genome-wide association study (GWAS), 138 of which overlapped with the reported QTLs. Two new stable, co-localized regions on chromosome 3 were identified by QTL mapping and GWAS across multiple environments, which explained large phenotypic variance. Five candidate genes related to SSC were identified by QTL mapping, GWAS, and qRT-PCR, two of which were involved in hydrolysis of raffinose and sucrose located in the new stable loci. The other three candidate genes were involved in raffinose synthesis, sugar transport, and production of substrate for sugar synthesis. The genomic regions and candidate genes will be helpful for molecular breeding programs and elucidating the mechanisms of sugar accumulation.

Pan-genome analysis sheds light on structural variation-based dissection of agronomic traits in melon crops.

Sweetness and appearance of fresh fruits are key palatable and preference attributes for consumers and are often controlled by multiple genes. However, fine-mapping the key loci or genes of interest by single genome-based genetic analysis is challenging. Herein, we present the chromosome-level genome assembly of one landrace melon accession (Cucumis melo ssp. agrestis) with wild morphologic features and thus construct a melon pan-genome atlas via integrating sequenced melon genome datasets. Our comparative genomic analysis reveals a total of 3.4 million genetic variations, of which the presence/absence variations (PAVs) are mainly involved in regulating the function of genes for sucrose metabolism during melon domestication and improvement. We further resolved several loci that are accountable for sucrose contents, flesh color, rind stripe and suture using a structural variation (SV)-based genome-wide association study (GWAS). Furthermore, via BSA-seq and map-based cloning, we uncovered that a single gene, (CmPIRL6), determines the edible or inedible characteristics of melon fruit exocarp. These findings provide important melon pan-genome information and provide a powerful toolkit for future pan-genome-informed cultivar breeding of melon.

DNA primase large subunit is an essential plant gene for geminiviruses, putatively priming viral ss-DNA replication.

The family of Geminiviridae consists of more than 500 circular single-stranded (ss) DNA viral species that can infect numerous dicot and monocot plants. Geminiviruses replicate their genome in the nucleus of a plant cell, taking advantage of the host's DNA replication machinery. For converting their DNA into double-stranded DNA, and subsequent replication, these viruses rely on host DNA polymerases. However, the priming of the very first step of this process, i.e. the conversion of incoming circular ssDNA into a dsDNA molecule, has remained elusive for almost 30 years. In this study, sequencing of melon (Cucumis melo) accession K18 carrying the Tomato leaf curl New Delhi virus (ToLCNDV) recessive resistance quantitative trait locus (QTL) in chromosome 11, and analyses of DNA sequence data from 100 melon genomes, showed a conservation of a shared mutation in the DNA Primase Large subunit (PRiL) of all accessions that exhibited resistance upon a challenge with ToLCNDV. Silencing of (native) Nicotiana benthamiana PriL and subsequent challenging with three different geminiviruses showed a severe reduction in titers of all three viruses, altogether emphasizing an important role of PRiL in geminiviral replication. A model is presented explaining the role of PriL during initiation of geminiviral DNA replication, i.e. as a regulatory subunit of primase that generates an RNA primer at the onset of DNA replication in analogy to DNA Primase-mediated initiation of DNA replication in all living organisms.

Genetic Diversity and Molecular Breeding of Melon (Cucumis melo L.): A review

Cucumis melo L. is an important horticultural crop that is widely cultivated for its edible fruit. The breeding of melon crop in order to improve its qualitative and quantitative yield is the objective of the current research. The recent melon breeding majorly focused on identification of novel genes, novel QTLs, and differentially expressed genes among the various populations. The publication of melon genome sequence in 2012, substantially accelerated the genetic dissection of candidate genes responsible for various desirable traits such as yield and yield contributing traits, fruit quality, disease resistance (Powdery mildew and Downey mildew resistance), salinity and temperature stress, and the genes involving in melon plant physiology. The molecular biology approaches such as whole-genome resequencing, bulked segregant analysis sequencing and the transcriptome analysis have been widely used to explore the genetic basis for the observed desirable phenotypic characteristics of the melon accessions in the germplasm to further aid in future molecular breeding of melon. Here, we summarized such research reports and categorized them under various sub sections. Overall, this current review presents the overview of very recent advances in melon crop improvement and developments in melon molecular breeding approaches as well as it provides the future directions for melon breeding. It would probably provide recent updates on melon crop improvement and help melon breeders to plan for their future breeding programmes.

Melon diversity on the Silk Road by molecular phylogenetic analysis in Kazakhstan melons.

To uncover population structure, phylogenetic relationship, and diversity in melons along the famous Silk Road, a seed size measurement and a phylogenetic analysis using five chloroplast genome markers, 17 RAPD markers and 11 SSR markers were conducted for 87 Kazakh melon accessions with reference accessions. Kazakh melon accessions had large seed with exception of two accessions of weedy melon, Group Agrestis, and consisted of three cytoplasm types, of which Ib-1/-2 and Ib-3 were dominant in Kazakhstan and nearby areas such as northwestern China, Central Asia and Russia. Molecular phylogeny showed that two unique genetic groups, STIa-2 with Ib-1/-2 cytoplasm and STIa-1 with Ib-3 cytoplasm, and one admixed group, STIAD combined with STIa and STIb, were prevalent across all Kazakh melon groups. STIAD melons that phylogenetically overlapped with STIa-1 and STIa-2 melons were frequent in the eastern Silk Road region, including Kazakhstan. Evidently, a small population contributed to melon development and variation in the eastern Silk Road. Conscious preservation of fruit traits specific to Kazakh melon groups is thought to play a role in the conservation of Kazakh melon genetic variation during melon production, where hybrid progenies were generated through open pollination.