Melon Genotypes Research Articles

Automatic plant phenotyping analysis of Melon (Cucumis melo L.) germplasm resources using deep learning methods and computer vision

Cucumis melo L., commonly known as melon, is a crucial horticultural crop. The selection and breeding of superior melon germplasm resources play a pivotal role in enhancing its marketability. However, current methods for melon appearance phenotypic analysis rely primarily on expert judgment and intricate manual measurements, which are not only inefficient but also costly. Therefore, to expedite the breeding process of melon, we analyzed the images of 117 melon varieties from two annual years utilizing artificial intelligence (AI) technology. By integrating the semantic segmentation model Dual Attention Network (DANet), the object detection model RTMDet, the keypoint detection model RTMPose, and the Mobile-Friendly Segment Anything Model (MobileSAM), a deep learning algorithm framework was constructed, capable of efficiently and accurately segmenting melon fruit and pedicel. On this basis, a series of feature extraction algorithms were designed, successfully obtaining 11 phenotypic traits of melon. Linear fitting verification results of selected traits demonstrated a high correlation between the algorithm-predicted values and manually measured true values, thereby validating the feasibility and accuracy of the algorithm. Moreover, cluster analysis using all traits revealed a high consistency between the classification results and genotypes. Finally, a user-friendly software was developed to achieve rapid and automatic acquisition of melon phenotypes, providing an efficient and robust tool for melon breeding, as well as facilitating in-depth research into the correlation between melon genotypes and phenotypes.

Gene markers generating polygenic resistance in melon-Fusarium wilt-FOM1.2 interaction pathosystem.

Developing melon genotypes with resistance to Fusarium oxysporum f. sp. Melonis-(FOM) race1.2 is a major goal in any breeding program. In this study, we identified the role of 11 gene markers that contribute to polygenic resistance during the FOM1.2-melon interaction. qRT-PCR analysis elucidated upregulation of candidate marker genes AMT, DXPR, Fom-2, GLUC, GalS, GRF3, MLO, PRK, RuBlsCo, TLP and WRKY in resistant 'Shante-F1' and 'Khatouni', and susceptible 'Shante-T' and 'Shahabadi' at 7, 14 and 21 days post-inoculation (dpi). We also studied changes in defence-related enzyme activity: chitinase (CHI), β-1,3-glucanase (GLU) and peroxidase (POX) in melon roots. AMT, GLUC and DXPR transcripts were upregulatied in leaf and root tissues of the resistant 'Shante-F1' and 'Shahabadi'. Transcript levels for GalS and GRF3 increased 6.77- and 6.83-fold in roots of 'Shante-F1' at 7 dpi, whereas in PRK, TLP and WRKY theye increased by 7.84-, 5.15- and 12.26-fold at 14 dpi, respectively. However, transcript levels increased by 5.18-fold for Fom-2 and 8.46-fold for MLO at 21 dpi. Also, RBC transcript level peaked at 14 dpi with 4.9-fold increase in leaves of resistant genotypes, whereas AMT increased 2.94-fold at 21 dpi, and GLUC and DXPR increased 7.11- and 2.91-fold at 14 dpi in 'Shante-F', respectively. Defence-related-enzyme activity was also upregulated three-fold in resistant varieties. The dynamic shifts in the melon transcriptome induced by FOM1.2 emphasize that resistance mechanisms are predominantly regulated through signalling pathways involving CHI, GLU, and POX defence response. Surprisingly, the AMT gene, basically resistant to downy mildew, Pseudoperonospora cubensis; GLUC, MLO and PRK resistant to powdery mildew (Sphaerotheca fusca); TLP and WRKY resistant to Phytophthora blight (Phytophthora capsici); and GRF3 and RBC resistant to root knot nematodes (Meloidogyne spp.) were upregulated in resistant genotypes, indicating a dual role of these genes in resistance to more than one disease at a time.

Evaluation Tolerant of Four Melon Genotypes in Early Growth Stage under Normal and Drought Stress Conditions

Plant breeding initiative in semi-arid and arid area are primarily focused on developing genotypes at early growth stage under normal conditions and keeping them steady during drought stress conditions. Therefore, four melon genotypes responses to drought stress were evaluated in this study during early growth stage. Two treatments for irrigation rates (Full Irrigation= 100%) and (Deficit Irrigation= 50%) were carried out in randomized complete block design (RCBD) with three biological replications in vermiculite culture in greenhouse in the research farm of faculty of agriculture at Sohag university in Egypt during season 2023. Young plants (45 days old plants) were utilized, and phenotypic traits 1º Leaf Score Tolerance, 2º Leaf Score Tolerance, Flowers Numbers, Vine Length, Green Leaves and Brown Leaves Numbers per vine were calculated by comparing differences in drought stress compared to control to identify tolerant and susceptible genotypes. The findings demonstrated that, in all estimated traits under drought stress conditions, there was significant variation between the studied four melon genotypes. whereas, the best results for all the studied traits were produced under normal conditions. Additionally, the highest significant positive correlation was found between 1º Leaf Score Tolerance and 2º Leaf Score Tolerance (0.966*) under normal conditions, and between Vine Length and Green Leaves Numbers per vine (0.999**) under drought stress conditions. Furthermore, the highest significant negative correlation was observed between 2º Leaf Score Tolerance and Flowers Numbers (-0.974*) and Flowers Numbers and Green Leaves Numbers per vine (-0.960*) under normal conditions, and between Vine Length and Brown Leaves Numbers per vine (-0.974*) and Green Leaves Numbers per vine and Brown Leaves Numbers per vine (-0.981*) under drought stress conditions. Besides, Euclidean heatmap clustering analysis grouped studied genotypes according to their response to normal and drought stress conditions, indicating that, the studied melon genotypes offer high potential for particular breeding purposes. These results have produced helpful framework for breeding strategies in the future under drought stress conditions. Conversely, detailed studies are crucial to predict drought stress tolerance performance in novel breeding strategies.

Stability Analysis of Yield and Its Components in Snap Melon (Cucumis melo var momordica)

Snap melon, scientifically known as Cucumis melo L. var. momordica (Roxb.), is a crop native to India and belonging to Cucurbitaceae family. This study was carried out to assess the nature and magnitude of genotype-environment interaction and stability among some parameters in snap melon genotypes. Twenty five local cultivars along with three standard checks were evaluated in randomized block design with three replications at three environments during summer 2023 at Navsari. The Eberhart and Russell model of stability analysis was employed which has been proved to be a reliable model. The study revealed that the mean sum of squares due to genotypes when tested against pooled deviation were highly significant for all the traits studied. Environment ´ Genotype (linear) showed significant differences for all characteristics except fruit weight and yield per vine, indicating that prediction could be possible by considering individual genotypes for these traits. A significant non-linear component (pooled deviation) was observed for fruit weight and fruit yield per vine, suggesting that genotypes varied considerably in terms of stable performance for these traits. The G ´ E interaction was only significant for flesh thickness and yield per vine, with all other traits being non-significant. The genotypes T 14 (HUB 18) and T 17 (HUB 21) were relatively stable and can be further used as parents to develop a more robust stable genotype. We identified genotypes which could pave way introducing high performing snap melon varieties.

The gene CmPYL6 strongly contributes to cold tolerance in oriental melon.

The current simple and crude facilities make melon production more susceptible to cold stress during off-season cultivation in China. The ABA signalling pathway is an important target for breeding cold-tolerant melon. Cold-tolerant No. 330 and cold-sensitive No. 410 oriental melon genotypes were used to analyse the relationship between ABA and cold tolerance. 12 CmPYLs, ABA receptors, were identified from the melon genome database according to sequence alignment and phylogenetic analysis. Gene function of CmPYL6 in cold tolerance was analysed using VIGS in No. 330 and overexpression in Arabidopsis WT. A total of 12 CmPYL members contain the representative domain and conserved sites. Under cold treatment, No.330 seedlings had lower electrolyte leakage and MDA content, higher ABA content and CmPYL6 expression than seedlings of No. 410. Exogenous application of ABA upregulated expression of CmPYL6 and enhanced cold tolerance of both genotypes, while inhibiting ABA accumulation reduced expression of CmPYL6 and cold tolerance of both genotypes. CmPYL6-silenced No. 330 seedlings had reduced cold tolerance, increased electrolyte leakage and MDA content as well as limited proline and soluble sugar content, while CmPYL6 overexpressed transgenic Arabidopsis plants had enhanced cold tolerance, with limited electrolyte leakage and MDA content, as well as increased proline and soluble sugar content. The CmPYL6 gene is probably an important ABA receptor in regulating cold tolerance of oriental melon. Our study provides a direction for improving breeding of cold tolerance of oriental melon.

Combining Ability and Hybrid Breeding in Tunisian Melon (Cucumis melo L.) for Fruit Traits

A half-diallel cross study of seven melon inbred lines was carried out. The seven parents and their 21 F1 hybrids were evaluated for precocity of maturity, average weight per fruit, and fruit quality (fruit size, rind thickness, and soluble solids). The Diallel analysis was investigated for breeding values of these melon genotypes via general and specific combining ability, relationships between general and specific combining ability, and heterosis for the evaluated traits. The analysis of variance of the traits evaluated indicated highly significant differences among genotypes, suggesting the presence of adequate genetic variation for breeding. Additive genetic effects were most important with respect to fruit weight, while genetic dominance and epistasis effects mainly controlled fruit quality traits (fruit size, rind thickness, and TSS). Parent 1 (P1) and parent 3 (P3) had significant positive general combining ability effects for fruit weight. Also, P3 had positive general combining ability effects for fruit length and diameter, and cavity diameter. P3 was found to show maximum significant GCA in the desirable direction for all the traits except for TSS. Evaluation of heterosis (%) revealed that hybrid P1 × P3 can be considered as the best-performing hybrid for average fruit weight, TSS, and precocity, which also exhibited the highest positive and significant SCA effect for these traits. These results suggested that, among the melon genotypes studied, there is the potential to generate superior new varieties in hybrid production.

Phenotypic Characterization of Citron Watermelon (Citrullus lanatus var. citroides) Genotypes for Bioenergy Production

Citron watermelon (Citrullus lanatus var. citroides) is an important climate smart crop, characterized by high oil content in the seeds and it is a popular fruit in southern Africa. To determine best performing genotypes eight phenotypic traits were assessed to identify cultivars with potential for biodiesel production. A field experiment was conducted at Sebele Agricultural Research Station, in Southern Botswana, during 2019 to 2020 cropping season. Four (4) melon genotypes were planted in a Randomized Complete Block Design replicated three times and eight (8) characters were assessed. Except seed oil content (26.6%) there was significant (P < 0.05) difference among all the traits, an indication of higher genetic diversity in the selected citron watermelon. SC1-Sesoswane, exhibited highest seed yield (1540 kg/ha) and oil yield (435.03 kg/ha) while MMB-280-Lerotse recorded lowest seed yield and oil yield of 548.1 kg/ha and 144 kg/ha respectively. There was a significant correlation of (0.9) between oil yield (kg/ha), number of fruits produced, and seed yield (kg/ha), an indication that increasing the seed yield will positively increase the amount of oil produced. This study revealed the potential bioenergy production of the four cultivars. However, SC1-Sesoswane appears a more promising alternative cultivar for feedstock for biodiesel production.

Deciphering the Traits Association and Path Coefficient Analysis among Yield Attributing Traits of Snap Melon (Cucumis melo var. momordica) Genotypes

An investigation was carried out at the University of Horticultural Sciences, Bagalkot, Karnataka, during the Rabi season of 2021. The experiment employed a randomized complete block design with two replications and aimed to assess twenty-five snap melon genotypes alongside three check varieties, sourced from various regions in India. Seventeen yield-related traits were observed for each genotype, and the mean data was utilized for subsequent analysis. The study on trait associations revealed that genotypic correlations exhibited higher values compared to their respective phenotypic counterparts, indicating stronger, consistent correlations independent of environmental factors. Notably, yield plant-1 exhibited positive and significant correlations with vine length, number of fruits vine-1, fruit weight, length of fruit, fruit circumference, and flesh thickness at both genotypic and phenotypic levels. Path coefficient analysis unveiled that the total number of fruits plant-1 and average fruit weight exerted positive direct effects on yield plant-1. Consequently, the study suggests that selection based on traits such as number of fruits-1 plant and average fruit weight would be effective for enhancing yield in snap melon.

Investigating biological performance, oviposition and diet preference of the twospotted spider mite feeding on various melon genotypes

The twospotted spider mite, Tetranychus urticae Koch, is one of the most dangerous pests for many crops worldwide, including the melon. Here, we raise the hypothesis that the resistance of melon genotypes to the spider mite is associated with the morphological characteristics of the leaves. We determined (i) the feeding preference and oviposition suitability of T. urticae on four melon genotypes, (ii) various biological parameters and population growth rate (ri) of T. urticae on different melon genotypes, (iii) the leaf morphology of the melon genotypes, and (iv) the relationship between the leaf characteristics and resistance to T. urticae. In no choice tests, lower numbers of adults and eggs of T. urticae were found in the genotypes CNPH 06–1047-343, CNPH 11–1071-43, and CNPH 06-1047-341 compared to control (Goldex). Individuals that fed on CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 genotypes had a longer egg incubation time, longer development time, lower immature viability, longer time to reach adult stage (egg–adult) and lower instantaneous rate of increase compared to control. These findings are in line with the fact that these three genotypes had thicker epidermis and greater mesophyll thickness than control genotype “Goldex”. Even the genotypes CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 had higher trichome densities, this morphological characteristic was not related with the resistance to T. urticae. CNPH 06–1047-343, CNPH 06–1047-341, and CNPH 11–1071-43 showed antibiosis and antixenosis against T. urticae and that resistance of the melon to T. urticae wss associated with the greater thickness of the leaf epidermis and mesophyll.

Studies on floral morphology and fruit diversity in wild melon (Cucumis melo L.ssp. agrestis (Naudin) Pangalo var. agrestis Naudin)

Floral morphology and fruit diversity are two essential attributes of a plant to establish mutualistic association with pollinators. Pollinators will have a direct influence on fruit setting and yield. The present paper represents the floral morphology and fruit diversity of six wild melon genotypes (Cucumis melo ssp. agrestis). The staminate and pistillate flowers were analysed for their size, sepal and petal colour and pedicel length. It was observed that female flowers of wild genotypes were longer than male flowers, however male flowers possessed larger diameter, longer pedicel length and corolla length over female flowers. Among the six genotypes studied, HUB-13 produced maximum male flowers per vine (156.75), longest female flower (5.33 cm), longest pedicel and corolla and largest ovary (6.11 mm diameter). Genotype HUB-4 produced maximum female flowers per vine (39.50) with lower male to female sex ratio (2.65:1) and recorded longest male flower length (4.43 cm). Genotype, HUB-2 recorded lowest flower length (2.40 cm, 2.85 cm) and diameter, smallest corolla length (1.25 cm, 1.13 cm) and pedicel length (1.05 cm and 0.50 cm) for male and female flowers respectively. The sepals and petals were green and yellow in colour respectively with varied intensity. The genotype, HUB-9 recorded maximum ovary length (1.83 cm), fruit weight (86.03 g), fruit yield per vine (1.98 kg) and fruit yield per hectare (9.48 t/ha).

Characterization of multiple disease resistance in melons (Cucumis melo L.) against Meloidogyne incognita, Fusarium oxysporum and tomato leaf curl Palampur virus

AbstractMelon is one of the important cucurbitaceous crops being cultivated widely in India and known for its delicious fruits. Crop is threatened by different biotic stresses including nematodes, fungi and viruses. The use of host resistance is the most economical, eco-compatible and long-lasting strategy to combat plant diseases. Keeping in mind this objective, 64 melon genotypes were screened against the prevalent Meloidogyne incognita, Fusarium oxysporum and tomato leaf curl Palampur virus (ToLCPalV) individually as well as with combined inoculations under artificial conditions. Out of 64 genotypes, three genotypes, MCPS, SM2012-1 and WM11 were found moderately resistant to M. incognita, nine genotypes (MM-KP15103, MM327, MM121103, KP4HM15, MM Sel.-103, SM2013-2, SM2012-1, SM2013-9 and WM11) recorded a resistant reaction against Fusarium wilt while four genotypes, WM11, SM2012-1, SM2013-9 and SM2013-2 exhibited a highly resistant reaction against ToLCPalV. A dendrogram constructed based on the resistance response of all the genotypes divided the genotypes into two groups and all resistant genotypes (MM1804, MM120103, SM2012-1, MM121103, SM2013-2, SM2013-9, WM11 and MM Sel.103) clustered in group II. The resistant genotypes when subjected to simultaneous inoculations of all three pathogens showed an increase in disease severity for each pathogen which negatively altered the resistance response of different genotypes. However, the genotypes SM2012-1, SM2013-9, SM2013-2 and WM-11 showing multiple disease resistance exhibited a good level of resistance even after combined inoculations of three pathogens. This study is the first to our knowledge identifying multiple disease resistance against root-knot nematode, Fusarium wilt and tomato leaf curl Palampur virus in muskmelon.

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.

Characteristics and variability of melon genotypes under shade conditions in greenhouse

The utilization of controlled greenhouses can be an alternative for melon (Cucumis melo L.) cultivation. Growing melon in greenhouses lowers the risk of pests and infections by diverse pathogens. Low solar irradiation during the rainy season and pollution in the greenhouse roof, may cause shade stress conditions for the plants inside. This study aimed to elucidate the plant and fruit characteristics of nine genotypes of melon grown under shade conditions in a greenhouse and the variability among them. The experiment was conducted in a greenhouse of Cikabayan Experimental Station, IPB University, Bogor, from November 2016 to January 2017. The genetic materials evaluated were nine melon genotypes from the Center for Tropical Fruit Studies at IPB University. A randomized complete block design with three replicates was followed. Shade intensity in the greenhouse was approximately 25%. The results showed that the genotype effect was significant for internode length, petiole length, plant height fruit, flesh thickness, fruit rind thickness, fruit weight, and total soluble solids. Genotype means for fruit weight were small in this experiment (< 300 g), whereas the total soluble solids were moderate to high (8.7-14.3 °Brix). Fruit diameter had a positive and significant correlation with leaf length, leaf width, and fruit length, whereas fruit weight had a positive and significant correlation with fruit diameter and fruit length.
 Keywords: correlation, honeydew, melon breeding, melon group, traits

Effect of Cucumber mosaic virus on the Content of Some Melon Genotypes of Some Mineral Elements and Plant Hormones

This study was conducted to determine the effect of cucumber mosaic virus (CMV) infection on the levels of some mineral elements and plant hormones in some melon genotypes. All experiments mentioned in this research were conducted in the Laboratory of plant virology and Greenhouses belonging to the Plant Protection Department/ College of the Agriculture/ University of Kerbala. PCR amplification using the complementary DNA (cDNA), synthesized from RNA isolated from an infected plant, produced a 650bp PCR product. A BLAST search using the nucleotide sequence of the PCR product demonstrated that this CMV isolate was previously registered at the National Centre for Biotechnology Information (NCBI) with a similarity of 100% with some CMV isolates identified in Hungary (AJ517802), Australia (U22821), and Slovenia (OL142046). It was also found that all melon genotypes evaluated in this study were susceptible to CMV, and the genotypes HA-144 and HA-609 were the most susceptible to CMV among the other tested genotypes. Results also showed that the CMV infection significantly reduced the levels of some minerals (calcium, magnesium, and manganese), and the genotypes HA-144, GM-3034, and GA-1534 were the most affected by the virus.; whereas the mineral elements sodium and potassium were significantly increased in their levels in infected plants, especially in the genotype HA-609. The CMV infection also clearly reduced the level of the hormone gibberellin in genotypes and the GA-1534 genotype was the most impacted and significantly different from their levels in the uninfected plants. However, the CMVinfected genotypes showed a significant increase in the level of the hormones cytokinin.

Assessment of relationship among traits and genotypes for melon (Cucumis melo) breeding

Abstract. Maghfiroh RN, Suwarno WB, Sobir, Gunawan E. 2023. Assessment of relationship among traits and genotypes for melon (Cucumis melo) breeding. Biodiversitas 24: 4523-4531. Melon (Cucumis melo L.) is widely consumed as fresh fruit or juice, and therefore deeper analyses of fruit quality are needed for future breeding purposes. Breeders have a role in providing improved melon varieties that suit consumer ideotypes or preferences. This study aimed to (i) evaluate the performance of melon genotypes, (ii) estimate the correlation between quantitative traits, and (iii) determine the clustering among genotypes based on plant and fruit traits. This research evaluated 24 genotypes from inodorus, reticulatus, and makuwa groups that were carried out from March to June 2022 at a greenhouse in the Tajur experimental station of the Center for Tropical Horticulture Studies, Bogor, Indonesia. IPB HD 2-111 and IPB HD 2-100 had good quality based on soluble solids content, fruit shape, flesh texture, and rind color, and G30 was relatively superior on flesh thickness, fruit weight, and vitamin C. Based on the multiple regression analysis, it was known that petal width, petiole length, and days to harvest were significantly affected the proportion of fruit cavity width to the fruit diameter. The adjusted coefficient of determination (R2) was 0.569. Cluster analysis grouped 23 genotypes into three main clusters based on the neighbor-joining method. These results may be useful for selection in melon breeding programs.

Deciphering genetic variability in melon (Cucumis melo L.) using morphological characters

Genetic variability, heritability and genetic advance were investigated in 96 melon (Cucumis melo L.) genotypes from 4 horticultural or 6 varietal groups using 10 quantitative traits. The results of the analysis of variance showed that there was enough variation among the genotypes for all the attributes. The highest phenotypic and genotypic coefficients of variations (PCV and GCV) were observed for node to first male flower (40.98 and 31.3%), average fruit weight (36.23 and 30.8%) and total soluble solids (28.01 and 26.67%), while days to first male flower anthesis (10.49 and 8.85%) and days to first female flower anthesis (8.86 and 7.4%) had the least coefficients of variations. The high difference between PCV and GCV estimates exhibited that environmental factors had more influence on trait expression. High heritability coupled with high-moderate GAM was observed for TSS and flesh thickness, indicating that additive genes govern these traits and that these traits could be effectively breed through selective improvement. Nine promising genotypes were identified for further breeding for earliness and lateness in order to extend melon supply in the market.

Optimised Agrobacterium-Mediated Transformation and Application of Developmental Regulators Improve Regeneration Efficiency in Melons.

Melon (Cucumis melo L.) is a protected crop in China with high economic value. Agrobacterium-mediated genetic transformation is a powerful tool to improve agronomic traits and obtain elite germplasm. However, current transformation protocols in melons are inefficient and highly genotype-dependent. To improve transformation in melon, we tested different infiltration methods for Agrobacterium-mediated transformation. Among these methods, micro-brushing and sonication for 20 s, followed by vacuum infiltration at -1.0 kPa for 90 s, resulted in the strongest green fluorescent protein signal and increased the proportion of infected explants. We transformed melon with developmental regulatory genes AtGRF5, AtPLT5, AtBBM, AtWUS, AtWOX5, and AtWIND1 from Arabidopsis and estimated regeneration frequencies as the number of regenerating shoots/total number of inoculated explants in the selection medium. The overexpression of AtGRF5 and AtPLT5 in melon resulted in transformation efficiencies of 42.3% and 33% in ZHF and 45.6% and 32.9% in Z12, respectively, which were significantly higher than those of the control. AtGRF5 and AtPLT5 expression cassettes were added to CRISPR/Cas9 genome-editing vectors to obtain transgenic phytoene desaturase CmPDS knockout mutants. Using AtGRF5 or AtPLT5, multi-allelic mutations were observed at CmPDS target sites in recalcitrant melon genotypes. This strategy enables genotype-flexible transformation and promotes precise genome modification technologies in melons.

The phenotypic and genetic diversity test of several inbred lines on the 7th generation of melon (Cucumis melo)

Abstract. Kustanto H. 2023. The phenotypic and genetic diversity test of several inbred lines on the 7th generation of melon (Cucumis melo). Biodiversitas 24: 2623-2629. The needs for melon (Cucumis melo L.) keep increasing year by year. Some efforts to increase the quality of melon have been carried out to obtain better quality and quantity through plant breeding programs. Providing new melon inbred lines with different phenotypic and genotypic traits is very important in assembling melon hybrid varieties with new genetic characteristics, potentially production superior melon varieties. The study’s objective was to find out the genetic diversity of the tested melon genotypes and to obtain inbred lines of melon, which are the potential to be developed as superior hybrid varieties. The inbred lines of melons showed that the diversity coefficient values of morphological traits ranged from 0.57 to 1.0. There are 3 Groups, namely Group I, II, and III. Group I comprises two genotypes: MJ 34 and HHX 015. Group II is divided into 2, Group A and B. Gaboup A comprises three genotypes: MJ 25, Amanda variety as the standard of comparison, and MO 29, while Group B has one genotype: HHA 02. Group III comprises three genotypes: MSO 12, MSP 13, and HHAL 01. The traits are as follows: leaf length, leaf width, fruit length, fruit diameter, and the fruit flesh thickness have closely related to yield per plant.

Mutagenesis of the melon Prv gene by CRISPR/Cas9 breaks papaya ringspot virus resistance and generates an autoimmune allele with constitutive defense responses.

The majority of plant disease resistance (R) genes encode nucleotide binding-leucine-rich repeat (NLR) proteins. In melon, two closely linked NLR genes, Fom-1 and Prv, were mapped and identified as candidate genes that control resistance to Fusarium oxysporum f.sp. melonis races 0 and 2, and to papaya ringspot virus (PRSV), respectively. In this study, we validated the function of Prv and showed that it is essential for providing resistance against PRSV infection. We generated CRISPR/Cas9 [clustered regularly interspaced palindromic repeats (CRISPR)/CRISPR-associated protein 9] mutants using Agrobacterium-mediated transformation of a PRSV-resistant melon genotype, and the T1 progeny proved susceptible to PRSV, showing strong disease symptoms and viral spread upon infection. Three alleles having 144, 154, and ~3 kb deletions, respectively, were obtained, all of which caused loss of resistance. Interestingly, one of the Prv mutant alleles, prvΔ154, encoding a truncated product, caused an extreme dwarf phenotype, accompanied by leaf lesions, high salicylic acid levels, and defense gene expression. The autoimmune phenotype observed at 25 °C proved to be temperature dependent, being suppressed at 32 °C. This is a first report on the successful application of CRISPR/Cas9 to confirm R gene function in melon. Such validation opens up new opportunities for molecular breeding of disease resistance in this important vegetable crop.

Hydroxy proline and gamma-aminobutyric acid: markers of susceptibility to vine decline disease caused by the fungus Monosporascus cannonballus in melons (Cucumis melo L.).

Vine decline disease caused by the fungus Monosporascus cannonballus, is a threat to melon production (Cucumis melo L.) worldwide. Nonetheless, little is known about the metabolites produced during the host pathogen interaction. Thus, the objective of this study was to measure quantities of amino acids produced over time during such an interaction. Two melon genotypes named TAM-Uvalde (susceptible) and USDA PI 124104 (resistant) were grown and inoculated with M. cannonballus. The metabolites previously stated were measured before inoculation (0 hours) and 24, 48 and 72 hours after inoculation, using high performance liquid chromatography analysis. The production of some amino acids during the interaction of the resistant and susceptible melon genotypes with the fungus M. cannonballus was different regarding quantities over time. Interestingly, hydroxy proline was always up-regulated in higher quantities in response to pathogen infection in the genotype TAM-Uvalde. Also, the up-regulation in higher quantities of gamma-aminobutyric acid in the genotype TAM-Uvalde 48 and 72 hours after inoculation, suggests more penetration of the pathogen in its roots. Hence, taken together, hydroxy proline and gamma-aminobutyric acid levels could be used as markers of susceptibility to vine decline disease caused by M. cannonballus, which could be useful in developing resistant varieties.