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.

Genome-Wide Analysis of the LBD Gene Family in Melon and Expression Analysis in Response to Wilt Disease Infection.

LBD transcription factors are a class of transcription factors that regulate the formation of lateral organs, establish boundaries, and control secondary metabolism in plants. In this study, we identified 37 melon LBD transcription factors using bioinformatics methods and analyzed their basic information, chromosomal location, collinearity, evolutionary tree, gene structure, and expression patterns. The results showed that the genes were unevenly distributed across the 13 chromosomes of melon plants, with tandem repeats appearing on chromosomes 11 and 12. These 37 transcription factors can be divided into two major categories, Class I and Class II, and seven subfamilies: Ia, Ib, Ic, Id, Ie, IIa, and IIb. Of the 37 included transcription factors, 25 genes each contained between one to three introns, while the other 12 genes did not contain introns. Through cis-acting element analysis, we identified response elements such as salicylic acid, MeJA, abscisic acid, and auxin, gibberellic acid, as well as light response, stress response, and MYB-specific binding sites. Expression pattern analysis showed that genes in the IIb subfamilies play important roles in the growth and development of various organs in melon plants. Expression analysis found that the majority of melon LBD genes were significantly upregulated after infection with wilt disease, with the strongest response observed in the stem.

Transcriptomic analysis provides an insight into the function of CmGH9B3, a key gene of ß-1, 4-glucanase, during the graft union healing of oriental melon scion grafted onto squash rootstock.

The melon (Cucumis melo L.) is a globally cherished and economically significant crop. The grafting technique has been widely used in the vegetative propagation of melon to promote environmental tolerance and disease resistance. However, mechanisms governing graft healing and potential incompatibilities in melons following the grafting process remain unknown. To uncover the molecular mechanism of healing of grafted melon seedlings, melon wild type (Control) and TRV-CmGH9B3 lines were obtained and grafted onto the squash rootstocks (C. moschata). Anatomical differences indicated that the healing process of the TRV-CmGH9B3 plants was slower than that of the control. A total of 335 significantly differentially expressed genes (DEGs) were detected between two transcriptomes. Most of these DEGs were down-regulated in TRV-CmGH9B3 grafted seedlings. GO and KEGG analysis showed that many metabolic, physiological, and hormonal responses were involved in graft healing, including metabolic processes, plant hormone signaling, plant MAPK pathway, and sucrose starch pathway. During the healing process of TRV-CmGH9B3 grafted seedlings, gene synthesis related to hormone signal transduction (auxin, cytokinin, gibberellin, brassinolide) was delayed. At the same time, it was found that most of the DEGs related to the sucrose pathway were down-regulated in TRV-CmGH9B3 grafted seedlings. The results showed that sugar was also involved in the healing process of melon grafted onto squash. These results deepened our understanding of the molecular mechanism of GH9B3, a key gene of ß-1, 4-glucanase. It also provided a reference for elucidating the gene mechanism and function analysis of CmGH9B3 in the process of graft union healing.

Sequence characteristics, genetic diversity and phylogenetic analysis of the Cucurbita ficifolia (Cucurbitaceae) chloroplasts genome.

BACKGROUND: Curcubita ficifolia Bouché (Cucurbitaceae) has high value as a food crop and medicinal plant, and also has horticultural value as rootstock for other melon species. China is home to many different cultivars, but the genetic diversity of these resources and the evolutionary relationships among them, as well as the differences between C. ficifolia and other Cucurbita species, remain unclear. RESULTS: We investigated the chloroplast (cp) genomes of 160 C. ficifolia individuals from 31 populations in Yunnan, a major C. ficifolia production area in China. We found that the cp genome of C. ficifolia is ~151 kb and contains 128 genes, of which 86 are protein coding genes, 34 encode tRNA, and eight encode rRNAs. We also identified 64 SSRs, mainly AT repeats. The cp genome was found to contain a total of 204 SNP and 57 indels, and a total of 21 haplotypes were found in the 160 study individuals. The reverse repeat (IR) region of C. ficifolia contained a few differences compared with this region in the six other Cucurbita species. Sequence difference analysis demonstrated that most of the variable regions were concentrated in the single copy (SC) region. Moreover, the sequences of the coding regions were found to be more similar among species than those of the non-coding regions. The phylogenies reconstructed from the cp genomes of 61 representative species of Cucurbitaceae reflected the currently accepted classification, in which C. ficifolia is sister to the other Cucurbita species, however, different interspecific relationships were found between Cucurbita species. CONCLUSIONS: These results will be valuable in the classification of C. ficifolia genetic resources and will contribute to our understanding of evolutionary relationships within the genus Cucurbita.

Integrative analysis of the metabolome and transcriptome provides insights into the mechanisms of lignan biosynthesis in Herpetospermum pedunculosum (Cucurbitaceae).

BACKGROUND: Herpetospermum pedunculosum (Ser.) C. B. Clarke is a traditional Chinese herbal medicine that heavily relies on the lignans found in its dried ripe seeds (Herpetospermum caudigerum), which have antioxidant and hepatoprotective functions. However, little is known regarding the lignan biosynthesis in H. pedunculosum. In this study, we used metabolomic (non-targeted UHPLC-MS/MS) and transcriptome (RNA-Seq) analyses to identify key metabolites and genes (both structural and regulatory) associated with lignan production during the green mature (GM) and yellow mature (YM) stages of H. pedunculosum. RESULTS: The contents of 26 lignan-related metabolites and the expression of 30 genes involved in the lignan pathway differed considerably between the GM and YM stages; most of them were more highly expressed in YM than in GM. UPLC-Q-TOF/MS confirmed that three Herpetospermum-specific lignans (including herpetrione, herpetotriol, and herpetin) were found in YM, but were not detected in GM. In addition, we proposed a lignan biosynthesis pathway for H. pedunculosum based on the fundamental principles of chemistry and biosynthesis. An integrated study of the transcriptome and metabolome identified several transcription factors, including HpGAF1, HpHSFB3, and HpWOX1, that were highly correlated with the metabolism of lignan compounds during seed ripening. Furthermore, functional validation assays revealed that the enzyme 4-Coumarate: CoA ligase (4CL) catalyzes the synthesis of hydroxycinnamate CoA esters. CONCLUSION: These results will deepen our understanding of seed lignan biosynthesis and establish a theoretical basis for molecular breeding of H. pedunculosum.

Genomic and pangenomic analyses provide insights into the population history and genomic diversification of bottle gourd.

Bottle gourd (Lagenaria siceraria (Mol.) Strandl.) is an economically important vegetable crop and one of the earliest domesticated crops. However, the population history and genomic diversification of bottle gourd have not been extensively studied. We generated a comprehensive bottle gourd genome variation map from genome sequences of 197 world-wide representative accessions, which enables a genome-wide association study for identifying genomic loci associated with resistance to zucchini yellow mosaic virus, and constructed a bottle gourd pangenome that harbors 1534 protein-coding genes absent in the reference genome. Demographic analyses uncover that domesticated bottle gourd originated in Southern Africa c. 12 000 yr ago, and subsequently radiated to the New World via the Atlantic drift and to Eurasia through the efforts of early farmers in the initial Holocene. The identified highly differentiated genomic regions among different bottle gourd populations harbor many genes contributing to their local adaptations such as those related to disease resistance and stress tolerance. Presence/absence variation analysis of genes in the pangenome reveals numerous genes including those involved in abiotic/biotic stress responses that have been under selection during the world-wide expansion of bottle gourds. The bottle gourd variation map and pangenome provide valuable resources for future functional studies and genomics-assisted breeding.

Identification and characterization analysis of the HDM gene family in melon (Cucumis melo L.).

Histone demethylase (HDM) play crucial roles in regulating plant growth and environmental adaptation. In this study, the HDM gene family in melon was identified by bioinformatics methods and the expression patterns of the CmHDM family members in different melon tissues were analyzed using transcriptome data. The results showed that 20 CmHDM genes were identified in the melon genome, which were unevenly distributed across each chromosome. These members fall into two major categories: LSD1 and JmjC. The JmjC group could be further divided into five subgroups with different numbers. The results of collinearity analysis of intraspecific and interspecific relationships showed that there were only one pair of segmental duplication in melon HDM genes, and more collinearity in genetic relationship of HDM genes between melon and tomato. The numbers of conserved domains, exons and introns in each member vary and various cis-acting elements responding to hormones and environmental signals existed in the respective promoter regions. Expression analysis showed that the respective gene members were expressed at different levels in male flowers, female flowers, roots, stems, leaves, ovary, and mature fruits of melon. These results will contribute to the understanding on the potential functions of the HDM genes and their potential functions in regulating melon growth and environmental adaptation.

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.

The maturation profile triggers differential expression of sugar metabolism genes in melon fruits.

Melons are commercially important crops that requires specific quality attributes for successful commercialization, including accumulation of sugars, particularly sucrose. This trait can be influenced by various factors, such as the type of ripening. Cucumis melo L. is an ideal species for studying sugar metabolism because it has both climacteric and non-climacteric cultivars. Thus, this study aimed to examine the gene expression of sucrose metabolism candidates using RT-qPCR, in conjunction with postharvest physiological analyzes and high-performance liquid chromatography-based sugar quantification, in the melon cultivars 'Gaúcho' (climacteric) and 'Eldorado' (non-climacteric). The results showed that sucrose synthase 1 played a role in the synthesis and accumulation of sucrose in both cultivars, whereas sucrose synthase 2 was more highly expressed in 'Gaúcho', contributing to lower hexose content. Invertase inhibitor 1 was more highly expressed in 'Eldorado' and may be involved in sugar-induced maturation. Neutral α-galactosidase had distinct functions, playing a role in substrate synthesis for the growth of young 'Eldorado' fruits, whereas in mature 'Gaúcho' fruits it participated in the metabolism of raffinose family oligosaccharides for sucrose accumulation. The expression of trehalose-6-phosphate synthase genes indicated a greater involvement of these enzymes in the sugar regulation in 'Gaúcho' melons. These findings shed light on the intraspecific differences related to fruit quality attributes in different types of maturation and contribute to a deeper understanding of the underlying molecular mechanisms involved in the metabolism of sugars in melons, which can inform breeding programs aimed at improving fruit quality attributes in this crop.

Insights into the early transcriptomic response against watermelon mosaic virus in melon.

BACKGROUND: Watermelon mosaic virus (WMV) is one of the most prevalent viruses affecting melon worldwide. Recessive resistance to WMV in melon has previously been reported in the African accession TGR-1551. Moreover, the genomic regions associated to the resistance have also been described. Nevertheless, the transcriptomic response that might infer the resistance to this potyvirus has not been explored. RESULTS: We have performed a comparative transcriptomic analysis using mock and WMV-inoculated plants of the susceptible cultivar "Bola de oro" (BO) and a resistant RIL (Recombinant inbred line) derived from the initial cross between "TGR-1551" and BO. In total, 616 genes were identified as differentially expressed and the weighted gene co-expression network analysis (WGCNA) detected 19 gene clusters (GCs), of which 7 were differentially expressed for the genotype x treatment interaction term. SNPs with a predicted high impact on the protein function were detected within the coding regions of most of the detected DEGs. Moreover, 3 and 16 DEGs were detected within the QTL regions previously described in chromosomes 11 and 5, respectively. In addition to these two specific genomic regions, we also observde large transcriptomic changes from genes spread across the genome in the resistant plants in response to the virus infection. This early response against WMV implied genes involved in plant-pathogen interaction, plant hormone signal transduction, the MAPK signaling pathway or ubiquitin mediated proteolysis, in detriment to the photosynthetic and basal metabolites pathways. Moreover, the gene MELO3C021395, which coded a mediator of RNA polymerase II transcription subunit 33A (MED33A), has been proposed as the candidate gene located on chromosome 11 conferring resistance to WMV. CONCLUSIONS: The comparative transcriptomic analysis presented here showed that, even though the resistance to WMV in TGR-1551 has a recessive nature, it triggers an active defense response at a transcriptomic level, which involves broad-spectrum resistance mechanisms. Thus, this study represents a step forward on our understanding of the mechanisms underlaying WMV resistance in melon. In addition, it sheds light into a broader topic on the mechanisms of recessive resistances.

Reliable reference gene selection for quantitative real-time PCR (qRT-PCR) in floral developmental phases of dioecious species Coccinia grandis.

The flowering process is intricate and regulated by a combination of external and internal factors. Delving into gene expression research has the potential to enhance our comprehension of the molecular foundations underlying floral development. Because of its accuracy, specificity, reproducibility, and efficiency, qRT-PCR is now a biological research tool for studying expression pattern of desired genes. The gene expression investigations using qRT-PCR required a reference gene with relatively uniform expression levels in multiple biological samples, including different developmental stages, tissues, and experimental conditions. In this study, experimental sets offloral and floral organ development in the male and female plants of C. grandis, a dioecious Cucurbitaceae species, qRT-PCR profiling was performed using six reference genes as internal control with B-class floral identity gene, PISTILLATA (PI). To analyse the data, algorithms such as geNorm, NormFinder, RefFinder, and BestKeeper were used to pick out the best internal controls from a group of candidates. The optimal reference gene for qRT-PCR studies with floral samples has been recommended as ß-actin combined with ß-tubulin. This is the first report on the validation of candidate reference genes across flower developmental stages in the dioecious species C. grandis, which will provide basic data for research on the molecular mechanism underlying flower development in this species and lay the groundwork for similar studies in other related species.

Developmental stages and episode-specific regulatory genes in andromonoecious melon flower development.

BACKGROUND AND AIMS: Given the lack of specific studies on floral development in melon (Cucumis melo L.), we carried out an extensive study involving morphological and transcriptomic analyses to characterize floral development in this species. METHODS: Using an andromonoecious line, we analysed the development of floral buds in male and hermaphrodite flowers with both light microscopy and scanning electron microscopy. Based on flower lengths, we established a correlation between the developmental stages and four main episodes of floral development and conducted an extensive RNA sequencing analysis of these episodes. KEY RESULTS: We identified 12 stages of floral development, from the appearance of the floral meristems to anthesis. The main structural differences between male and hermaphrodite flowers appeared between stages 6 and 7; later stages of development leading to the formation of organs and structures in both types of flowers were also described. We analysed the gene expression patterns of the four episodes in flower development to find the genes that were specific to each given episode. Among others, we identified genes that defined the passage from one episode to the next according to the ABCDE model of floral development. CONCLUSIONS: This work combines a detailed morphological analysis and a comprehensive transcriptomic study to enable characterization of the structural and molecular mechanisms that determine the floral development of an andromonoecious genotype in melon. Taken together, our results provide a first insight into gene regulation networks in melon floral development that are crucial for flowering and pollen formation, highlighting potential targets for genetic manipulation to improve crop yield of melon in the future.

Resolving the phylogeny of Thladiantha (Cucurbitaceae) with three different target capture pipelines.

BACKGROUND: Despite recent advances, reliable tools to simultaneously handle different types of sequencing data (e.g., target capture, genome skimming) for phylogenomics are still scarce. Here, we evaluate the performance of the recently developed pipeline Captus in comparison with the well-known target capture pipelines HybPiper and SECAPR. As test data, we analyzed newly generated sequences for the genus Thladiantha (Cucurbitaceae) for which no well-resolved phylogeny estimate has been available so far, as well as simulated reads derived from the genome of Arabidopsis thaliana. RESULTS: Our pipeline comparisons are based on (1) the time needed for data assembly and locus extraction, (2) locus recovery per sample, (3) the number of informative sites in nucleotide alignments, and (4) the topology of the nuclear and plastid phylogenies. Additionally, the simulated reads derived from the genome of Arabidopsis thaliana were used to evaluate the accuracy and completeness of the recovered loci. In terms of computation time, locus recovery per sample, and informative sites, Captus outperforms HybPiper and SECAPR. The resulting topologies of Captus and SECAPR are identical for coalescent trees but differ when trees are inferred from concatenated alignments. The HybPiper phylogeny is similar to Captus in both methods. The nuclear genes recover a deep split of Thladiantha in two clades, but this is not supported by the plastid data. CONCLUSIONS: Captus is the best choice among the three pipelines in terms of computation time and locus recovery. Even though there is no significant topological difference between the Thladiantha species trees produced by the three pipelines, Captus yields a higher number of gene trees in agreement with the topology of the species tree (i.e., fewer genes in conflict with the species tree topology).

Genome-wide identification and expression analysis of the JMJ-C gene family in melon (Cucumis melo L.) reveals their potential role in fruit development.

BACKGROUND: Proteins with the jumonji (JMJ)-C domain belong to the histone demethylase family and contribute to reverse histone methylation. Although JMJ-C family genes have an essential role in regulating plant growth and development, the characterization of the JMJ-C family genes in melon has not been uncovered. RESULTS: In this study, a total of 17 JMJ-C proteins were identified in melon (Cucumis melo L.). CmJMJs were categorized into five subfamilies based on the specific conserved domain: KDM4/JHDM3, KDM5/JARID1, JMJD6, KDM3/JHDM2, and JMJ-C domain-only. The chromosome localization analyses showed that 17 CmJMJs were distributed on nine chromosomes. Cis-acting element analyses of the 17 CmJMJ genes showed numerous hormone, light, and stress response elements distributed in the promoter region. Covariance analysis revealed one pair of replicated fragments (CmJMJ3a and CmJMJ3b) in 17 CmJMJ genes. We investigated the expression profile of 17 CmJMJ genes in different lateral organs and four developmental stages of fruit by RNA-seq transcriptome analysis and RT-qPCR. The results revealed that most CmJMJ genes were prominently expressed in female flowers, ovaries, and developing fruits, suggesting their active role in melon fruit development. Subcellular localization showed that the fruit-related CmJMJ5a protein is specifically localized in the cell nucleus. CONCLUSIONS: This study provides a comprehensive understanding of the gene structure, classification, and evolution of JMJ-C in melon and supports the clarification of the JMJ-C functions in further research.

The effect of environmental factors on the genetic differentiation of Cucurbita ficifolia populations based on whole-genome resequencing.

BACKGROUND: Cucurbita ficifolia is one of the squash species most resistant to fungal pathogens, and has especially high resistance to melon Fusarium wilt. This species is therefore an important germplasm resource for the breeding of squash and melon cultivars. RESULTS: Whole-genome resequencing of 223 individuals from 32 populations in Yunnan Province, the main cucurbit production area in China, was performed and 3,855,120 single-nucleotide polymorphisms (SNPs) and 1,361,000 InDels were obtained. SNP analysis suggested that levels of genetic diversity in C. ficifolia were high, but that different populations showed no significant genetic differentiation or geographical structure, and that individual C. ficifolia plants with fruit rinds of a similar color did not form independent clusters. A Mantel test conducted in combination with geographical distance and environmental factors suggested that genetic distance was not correlated with geographical distance, but had a significant correlation with environmental distance. Further associations between the genetic data and five environmental factors were analyzed using whole-genome association analysis. SNPs associated with each environmental factor were investigated and genes 250 kb upstream and downstream from associated SNPs were annotated. Overall, 15 marker-trait-associated SNPs (MTAs) and 293 genes under environmental selection were identified. The identified genes were involved in cell membrane lipid metabolism, macromolecular complexes, catalytic activity and other related aspects. Ecological niche modeling was used to simulate the distribution of C. ficifolia across time, from the present and into the future. We found that the area suitable for C. ficifolia changed with the changing climate in different periods. CONCLUSIONS: Resequencing of the C. ficifolia accessions has allowed identification of genetic markers, such as SNPs and InDels. The SNPs identified in this study suggest that environmental factors mediated the formation of the population structure of C. ficifolia in China. These SNPs and Indels might also contribute to the variation in important pathways of genes for important agronomic traits such as yield, disease resistance and stress tolerance. Moreover, the genome resequencing data and the genetic markers identified from 223 accessions provide insight into the genetic variation of the C. ficifolia germplasm and will facilitate a broad range of genetic studies.

Comparative Analysis of Transcriptomics and Metabolomics Reveals Defense Mechanisms in Melon Cultivars against Pseudoperonospora cubensis Infection.

Melon (Cucumis melo L.) represents an agriculturally significant horticultural crop that is widely grown for its flavorful fruits. Downy mildew (DM), a pervasive foliar disease, poses a significant threat to global melon production. Although several quantitative trait loci related to DM resistance have been identified, the comprehensive genetic underpinnings of this resistance remain largely uncharted. In this study, we utilized integrative transcriptomics and metabolomics approaches to identify potential resistance-associated genes and delineate the strategies involved in the defense against DM in two melon cultivars: the resistant 'PI442177' ('K10-1') and the susceptible 'Huangdanzi' ('K10-9'), post-P. cubensis infection. Even in the absence of the pathogen, there were distinctive differentially expressed genes (DEGs) between 'K10-1' and 'K10-9'. When P. cubensis was infected, certain genes, including flavin-containing monooxygenase (FMO), receptor-like protein kinase FERONIA (FER), and the HD-ZIP transcription factor member, AtHB7, displayed pronounced expression differences between the cultivars. Notably, our data suggest that following P. cubensis infection, both cultivars suppressed flavonoid biosynthesis via the down-regulation of associated genes whilst concurrently promoting lignin production. The complex interplay of transcriptomic and metabolic responses elucidated by this study provides foundational insights into melon's defense mechanisms against DM. The robust resilience of 'K10-1' to DM is attributed to the synergistic interaction of its inherent transcriptomic and metabolic reactions.

Simple, fast and inexpensive hot sodium hydroxide and tris DNA extraction method for genotyping tomato and melon seeds.

Seed commerce is a highly profitable global market. Most commercialized seeds are hybrid seeds originating from a controlled cross between two selected parental lines. The market value of hybrid seeds depends on their hybrid genetic purity. DNA molecular markers are a reliable and widespread tool to genotype plant materials; however, DNA extraction from seeds is challenging, often laborious and expensive. With the ultimate goal of creating a tomato and melon hybrid seeds purity test, various challenges arise. To overcome these problems and with the purpose of crude DNA extraction, a simple, fast, inexpensive and easily scalable adaptation of the hot sodium hydroxide and tris method coupled to a competitive allele-specific PCR genotyping method is proposed.

Molecular Marker-Assisted Mapping, Candidate Gene Identification, and Breeding in Melon (Cucumis melo L.): A Review.

Melon (Cucumis melo L.) is an important crop that is cultivated worldwide for its fleshy fruit. Understanding the genetic basis of a plant's qualitative and quantitative traits is essential for developing consumer-favored varieties. This review presents genetic and molecular advances related to qualitative and quantitative phenotypic traits and biochemical compounds in melons. This information guides trait incorporation and the production of novel varieties with desirable horticultural and economic characteristics and yield performance. This review summarizes the quantitative trait loci, candidate genes, and development of molecular markers related to plant architecture, branching patterns, floral attributes (sex expression and male sterility), fruit attributes (shape, rind and flesh color, yield, biochemical compounds, sugar content, and netting), and seed attributes (seed coat color and size). The findings discussed in this review will enhance demand-driven breeding to produce cultivars that benefit consumers and melon breeders.

A Genome-Wide Identification and Comparative Analysis of the Heavy-Metal-Associated Gene Family in Cucurbitaceae Species and Their Role in Cucurbita pepo under Arsenic Stress.

The heavy-metal-associated (HMA) proteins are a class of PB1-type ATPases related to the intracellular transport and detoxification of metals. However, due to a lack of information regarding the HMA gene family in the Cucurbitaceae family, a comprehensive genome-wide analysis of the HMA family was performed in ten Cucurbitaceae species: Citrullus amarus, Citrullus colocynthis, Citrullus lanatus, Citrullus mucosospermus, Cucumis melo, Cucumis sativus, Cucurbita maxima, Cucurbita moschata, Cucurbita pepo, and Legenaria siceraria. We identified 103 Cucurbit HMA proteins with various members, ranging from 8 (Legenaria siceraria) to 14 (Cucurbita pepo) across species. The phylogenetic and structural analysis confirmed that the Cucurbitaceae HMA protein family could be further classified into two major clades: Zn/Co/Cd/Pb and Cu/Ag. The GO-annotation-based subcellular localization analysis predicted that all HMA gene family members were localized on membranes. Moreover, the analysis of conserved motifs and gene structure (intron/exon) revealed the functional divergence between clades. The interspecies microsynteny analysis demonstrated that maximum orthologous genes were found between species of the Citrullus genera. Finally, nine candidate HMA genes were selected, and their expression analysis was carried out via qRT-PCR in root, leaf, flower, and fruit tissues of C. pepo under arsenic stress. The expression pattern of the CpeHMA genes showed a distinct pattern of expression in root and shoot tissues, with a remarkable expression of CpeHMA6 and CpeHMA3 genes from the Cu/Ag clade. Overall, this study provides insights into the functional analysis of the HMA gene family in Cucurbitaceae species and lays down the basic knowledge to explore the role and mechanism of the HMA gene family to cope with arsenic stress conditions.

Embryonic microinjection of ribonucleoprotein complex (Cas9+sgRNA) of white gene in melon fly, Zeugodacus cucurbitae (Coquillett) (Diptera: Tephritidae) produced white eye phenotype.

Melon fly, Zeugodacus cucurbitae (Coquillett) is a major pest of cucurbitaceous crops, and causes substantial yield losses and economic costs. CRISPR/Cas9 is a rapid and effective site-specific genome editing tool for the generation of genetic changes that are stable and heritable. The CRISPR/Cas9 tool uses synthetically designed single guide RNA (sgRNA) that is complementary to the target gene and guides the Cas9 enzyme to perform nuclease activity by making double-strand breaks in the target DNA sequences. This tool can be effectively exploited to improve traits critical for the management of insect pests by targeting specific genes encoding these traits without the need of extensive genetic information. The white gene is an important gene responsible for the transport of body pigment precursor molecules. In this study, we produced effective mutagenesis of the white gene of Z. cucurbitae using the CRISPR/Cas9 tool with double sgRNA to target multiple sites of white to increase the efficiency in the generation of frame-shift mutations resulting in the white eye phenotype in adults. This was achieved through embryonic microinjection of the ribonucleoprotein (RNP) complex in the pre-blastoderm embryo stage 1 h after embryo laying. Our success with the production of a white eye mutant fly by CRISPR/Cas9 mutagenesis is important for the research on gene function and protein-level modifications in melon fly and forms the basis for the development of new genetic control strategies such as precision guided sterile insect technique (pgSIT) for this pest of economic significance.