Monoecious Lines Research Articles

Development of wilt resistant parental lines through mutagenesis in castor(Ricinus communis L.)

The present study was taken up to diversify the pistillate and monoecious lines to be used in hybridization programme. Mutagenesis was carried out using the chemical mutagen ethyl methane sulfonate (EMS) to induce mutation in popular pistillate line DPC 9 and land race Rasipuram local. The segregating mutant population was evaluated for their wilt resistance by screening in wilt sick plot. Plant to progeny row was continued up to M5 generation by selecting superior progenies in terms of yield and wilt resistance. Skewness and kurtosis indicated the presence of gene interactions for most of the traits studied. The pistillate progeny M5 29-11-5 (YRCP 2) and the monoecious progeny M4 106-2-3(YRCS 1904) were found to be the promising one and this could be further utilized as parents in hybrid development process.

A point mutation in MC06g1112 encoding FLOWERING LOCUS T decreases the first flower node in bitter gourd (Momordica charantia L.).

In Cucurbitaceae crops, the first flower node (FFN) is an important agronomic trait which can impact the onset of maturity, the production of female flowers, and yield. However, the gene responsible for regulating FFN in bitter gourd is unknown. Here, we used a gynoecious line (S156G) with low FFN as the female parent and a monoecious line (K8-201) with high FFN as the male parent to obtain F1 and F2 generations. Genetic analysis indicated that the low FFN trait was incompletely dominant over the high FFN trait. A major quantitative trait locus (QTL)-Mcffn and four minor effect QTLs-Mcffn1.1, Mcffn1.2, Mcffn1.3, and Mcffn1.4 were detected by whole-genome re-sequencing-based QTL mapping in the S156G×K8-201 F2 population (n=234) cultivated in autumn 2019. The Mcffn locus was further supported by molecular marker-based QTL mapping in three S156G×K8-201 F2 populations planted in autumn 2019 (n=234), autumn 2020 (n=192), and spring 2022 (n=205). Then, the Mcffn locus was fine-mapped into a 77.98-kb physical region on pseudochromosome MC06 using a large S156G×K8-201 F2 population (n=2,402). MC06g1112, which is a homolog of FLOWERING LOCUS T (FT), was considered as the most likely Mcffn candidate gene according to both expression and sequence variation analyses between parental lines. A point mutation (C277T) in MC06g1112, which results in a P93S amino acid mutation between parental lines, may be responsible for decreasing FFN in bitter gourd. Our findings provide a helpful resource for the molecular marker-assisted selective breeding of bitter gourd.

Genetics of cluster bearing habit and fruit surface morphology in ridge gourd (Luffa acutangula Roxb.)

Luffa acutangula or ridge gourd generally produces solitary and ribbed or ridged fruit, but Satputia a feral form of ridge gourd with hermaphrodite sex form produces non-ribbed fruits in cluster. The present study was conducted to determine the inheritance cluster bearing habit and non-ridge fruit in ridge gourd from the crosses of two hermaphrodite lines (Satputia Long and Satputia Small) which produced small numerous non-ribbed fruits in cluster and five monoecious lines (DRG-2, Pusa Nasdar, Utkal Tripti, Arka Summet and HARG-110), produced solitary long fruit with ten prominent ridges. It was observed that all the F1 plants were solitary bearer and produced ridged fruit. In F2 generation, the observed distribution of plant phenotypes for bearing habit and fruit surface morphology fitted well to the expected ratio of 3:1 (solitary vs cluster) and 15:1 (ridge vs non-ridge) for bearing habit and fruit surface morphology, respectively. The segregation pattern suggested monogenic recessive control of cluster bearing habit, while duplicate recessive genes control ridged fruit surface in Luffa acutangula.

Fine mapping and candidate gene analysis of gynoecy trait in chieh-qua (Benincasa hispida Cogn. var. chieh-qua How).

Gynoecy demonstrates an earlier production of hybrids and a higher yield and improves the efficiency of hybrid seed production. Therefore, the utilization of gynoecy is beneficial for the genetic breeding of chieh-qua. However, little knowledge of gynoecious-related genes in chieh-qua has been reported until now. Here, we used an F2 population from the cross between the gynoecious line 'A36' and the monoecious line 'SX' for genetic mapping and revealed that chieh-qua gynoecy was regulated by a single recessive gene. We fine-mapped it into a 530-kb region flanked by the markers Indel-3 and KASP145 on Chr.8, which harbors eight candidate genes. One of the candidate genes, Bhi08G000345, encoding networked protein 4 (CqNET4), contained a non-synonymous SNP resulting in the amino acid substitution of isoleucine (ATA; I) to methionine (ATG; M). CqNET4 was prominently expressed in the female flower, and only three genes related to ethylene synthesis were significantly expressed between 'A36' and 'SX.' The results presented here provide support for the CqNET4 as the most likely candidate gene for chieh-qua gynoecy, which differed from the reported gynoecious genes.

Fine-mapping and candidate gene analysis of the Mcgy1 locus responsible for gynoecy in bitter gourd (Momordica spp.).

The Mcgy1 locus responsible for gynoecy was fine-mapped into a 296.94-kb region, in which four single-nucleotide variations and six genes adjacent to them might be associate with sex differentiation in bitter gourd. Gynoecy plays an important role in high-efficiency hybrid seed production, and gynoecious plants are excellent materials for dissecting sex differentiation in Cucurbitaceae crop species, including bitter gourd. However, the gene responsible for gynoecy in bitter gourd is unknown. Here, we first identified a gynoecy locus designated Mcgy1 using the F2 population (n = 291) crossed from the gynoecious line S156G and the monoecious line K8-201 via bulked segregant analysis with whole-genome resequencing (BSA-seq) and molecular marker linkage analysis. Then, a large S156G × K8-201 F2 population (n = 5,656) was used for fine-mapping to delimit the Mcgy1 locus into a 296.94-kb physical region on pseudochromosome MC01, where included 33 annotated genes different from any homologous gynoecy genes previously reported in Cucurbitaceae species. Within this region, four underlying single-nucleotide variations (SNVs) that might cause gynoecy were identified by multiple genomic sequence variation analysis, and their six neighbouring genes were considered as potential candidate genes for Mcgy1. Of these, only MC01g1681 showed a significant differential expression at two-leaf developmental stage between S156G and its monoecious near-isogenic line S156 based on RNA sequencing (RNA-seq) and qRT-PCR analyses. In addition, transcriptome analysis revealed 21 key differentially expressed genes (DEGs) and possible regulatory pathways of the formation of gynoecy in bitter gourd. Our findings provide a new clue for researching on gynoecious plants in Cucurbitaceae species and a theoretical basis for breeding gynoecious bitter gourd lines by the use of molecular markers-assisted selection.

Evaluation of various monoecious and gynoecious genotypes of bitter gourd (Momordica charantiaL.) for yield and attributing traits

Bitter gourd is one of the significant cucurbitaceous crops with high economic importance. Exploitation of novel traits like gynoecism in particular and yield in general can substantially contribute to the future crop improvement programmes in bitter gourd. In the present investigation, 38 monoecious lines and 6 gynoecious lines were evaluated pertaining to 9 important quantitative morphological traits at the experimental farm of ICAR-Indian Institute of Vegetable Research, Varanasi across two seasons of spring-summer and kharif. From the mean performance analysis of all the accessions under study, VRBTG-5 was found to be the best performer among the monoecious lines, whereas, Gy-323 was the best peforming gynoecious line concerning the yield per plant (g). Moreover, for all other major yield-contributing traits, both of these lines have exhibited superior performance over all other accessions across the seasons and can be exploited further in crop improvement programmes.

Candidate gene based SSR and SNP markers for gynoecy in bitter gourd (Momordica charantia L.).

Even though the bitter gourd hybrids are shown to have significant heterosis for many of the economic traits, processes such as manual bagging and hand pollination make the hybrid seed production labour-intensive. Use of gynoecious line as female parent makes hybrid seed production more economical. This work was performed with the objective to identify the candidate gene based molecular markers for gynoecy in bitter gourd. Seven putative genes for flowering and sex expression, isolated from the monoecious (MC-136) and gynoecious (KAU-MCGy-101) bitter gourd accessions, were sequence characterized. MADS-box transcription factor genes AG6 and McAG2 had nucleotide polymorphisms at five sites each and were potential candidates for marker development. An In/Del polymorphism of 48bp ([TC]24) in AG6 gene was used to develop an SSR marker and a transition mutation of [A/G] in this gene was used to develop a set of SNP markers. These markers have developed distinct polymorphism between the monoecious and gynoecious genotypes and were found suited for the marker assisted selection. MADS box transcription factor genes AG6 and McAG2 are identified as candidates for sex expression in bitter gourd. Based on the InDels and transition in the intronic region of AG6, SSR marker BGAG6 and an SNP marker set segregating with the sex forms were developed. The markers have been validated using four other monoecious lines and are routinely used in our bitter gourd hybrid seed production programmes.

Seed morphological characterization, genetic diversity and association analysis in late flowering monoecious lines of castor (Ricinus communis L.)

Castor is an important industrial oilseed crop utilized for multivarious applications. Augmenting seed yield in long duration castor varieties is of utmost importance to meet the increasing oil demand and also to make them suitable for inter/border cropping. Understanding the genetic diversity in base population of monoecious lines and interrelationship between economic traits are very much important to formulate suitable genetic improvement programmes. In this regard, seed morphological characterization and genetic diversity was assessed in 62 late flowering monoecious lines. Predominance of brown colour, ellipsoid shape and conspicuous mottling with caruncle was observed among the genotypes. Cluster analysis grouped them into eight different clusters. Maximum inter cluster distance was found between cluster VI and VIII, whereas intra cluster distance was high in cluster II. Cluster VI recorded the highest cluster mean for 100 seed weight and seed yield per plant (44.56 g and 174 g, respectively). Association studies revealed 100 seed weight and shelling percentage to be the significant traits for indirect selection of yield. In conclusion, the cluster VI has potential genotypes to utilize in developing high yielding varieties and male parent donor for hybrid breeding. The diverse genotypes identified from this study could be given priority during recombination breeding to get diverse segregants and for further molecular analysis like mapping population development and QTL/gene identification.  Keywords:  Castor, Monoecious lines, Diversity, Correlation, Path analysis

Generation mean analysis of important yield traits in Bitter gourd (Momordica charantia)

Generation mean analysis study in bitter gourd was undertaken using six basic generations viz. P1, P2, F1, F2, B1 and B2 population derived from crossing gynoecious line (IIHRBTGy - 491) with two monoecious lines (IIHR Sel -19 -1 and IIHR Sel-78-4). The gynoecious parent was superior for node for first female flowering, number of fruits and yield/plant whereas the monoecious parents were superior for fruit length, fruit diameter and fruit weight. The superior performance of F1 over better parent indicated over-dominance of these traits. F2 plants were significantly diverse. B1 and B2 population exhibited mean value closure to their recurrent parents. Significance of one or more scaling tests, i.e. A, B, C and D in most of the traits revealed the presence of epistasis in both the crosses except for node bearing 1st male flower. Days to 1st female flower opening, node bearing 1st female flower, fruit diameter and yield showed presence of duplicate epistasis whereas days to 1st male flower opening, number of fruits per plant, fruit length and fruit weight showed complimentary epistasis in IIHRBTGy - 491 × IIHR Sel -19 -1 cross. Node bearing 1st female flower, fruit length, fruit diameter and yield showed presence of duplicate epistasis whereas days to 1st female flower opening, days to 1st male flower opening, number of fruits and fruit weight showed complimentary epistasis in IIHRBTGy - 491× IIHR Sel-78-4 cross. Additive gene action may be predominant for inheritance of node bearing 1st male flower.

Potential of Gynoecious Line in Generating Superior Heterotic Hybrids in Bitter Gourd (Momordica charantia L.)

An experiment was designed to find out the extent of heterosis in bitter gourd using gynoecious line, KAU- MCGy-101 and three monoecious lines viz., Preethi, Priyanka, and MC133. Hybrids were generated by both direct and reciprocal crosses. All the hybrids exhibited earliness in terms of days to first female flower opening, node bearing first female flower, and days to first harvest. The hybrid KAU-MCGy-101 × Priyanka exhibited significantly higher heterosis with regard to heterobeltiosis (-16.03 %) and standard heterosis (-18.63 %) for days to first female flower opening. All the six hybrids manifested significant standard heterosis for sex ratio in the desirable negative direction, ranged from 44.25 to -55.52 %. The highest yield was recorded in the hybrid KAU-MCGy-101 × Priyanka (22.88 t/ha) and was followed by KAU-MCGy-101 × Preethi (20.42 t/ha) and KAU-MCGy-101 × MC 133 (20.05 t/ha). Heterobeltiosis for yield (t/ha) varied from 14.72 to 57.85 % and the standard heterosis ranged between 37.59 to 89.31 %. The best performing hybrids were KAU-MCGy-101 × Preethi, KAU-MCGy-101 × Priyanka, and KAU-MCGy-101 × MC 133 with respect toearliness, number of fruits per plant, and yield. Thus, the superiority of hybrids having gynoecious line as a maternal parent is prominent in the present study.

Combining ability analysis of newly developed monoecious lines of castor (Ricinus communis L.) in Rajasthan

Genetic parameters of 50 castor hybrids developed from 10 newly developed monoecious lines and 5 stable pistillate lines were estimated in line x tester design. Analysis of combining ability depicted significant mean sum of squares for both general combining ability (GCA) and specific combining ability (SCA) for all the characters which indicated the presence of both additive and non-additive gene actions. The high amount of s 2 SCA and ratio of GCA to SCA variances near to zero indicated that the dominance gene effect was predominant in newly developed lines for all the characters under study. The highest positive gca effect was exhibited by MCP-1-1, for seed yield and number of capsules on primary raceme, effective length of primary raceme and height up to primary raceme. SKP-84 was also a good general combiner for 100 seed weight, number of capsules on primary raceme, nodes to primary raceme and height up to primary raceme. Among the male parents, MP-11-17 was found the best general combiner for cumulative seed yield, raceme length and numbers of capsules. Cross M-574 x MP-17-17 was the best cross for cumulative seed yield followed by MCP-3 x MP-7-17 and SKP-84 x MP-11-17. These combinations would be useful in breeding programme for improvement in seed yield of castor.

Studies on heterosis for seed yield and its component traits in castor (Ricinus communis L.) hybrids suitable for Odisha state

The experimental material consisted of 40 entries which included two pistillate lines (DPC-23 and M-571) and 12 monoecious lines (DCS-64, DCS-86, DCS-102, DCS-105, DCS-107, DCS-108, DCS-109, DCS-110, DCS-112, DCS-118, DCS-119, DCS-123), their resultant 24 hybrids developed through a line x tester mating design and two check hybrids (DCH-177 and DCH-519). These entries were tested in a randomized block design with three replications at AICRP centre on Castor, Bhawanipatna, Odisha over three years (2014-15 to 2016-17) during kharif season. Considering per se performance of hybrids, eleven hybrids recorded higher seed yield per plant than the check hybrid DCH-177 of which four hybrids viz., M-571 x DCS-110 (102.8 g/plant), M-571 x DCS-112 (100.6 g/plant), M-571 x DCS-105 (93.8 g/plant) and DPC-23 x DCS-110 (93.4g/plant) had high per se performance along with significant positive heterobeltiosis and standard heterosis for seed yield. The range of heterosis over better parent varied from -25 to 31.6%, while over standard check, it ranged from -30.1 to 24.3 %. The cross M-571 x DCS-110 depicted significantly the highest and positive heterobeltiosis (31.6%), standard heterosis (24.3 %) as well as the highest seed yield per plant (102.8g). Other cross combinations viz., M-571 x DCS-112, M-571 x DCS-105 and DPC-23 x DCS-110 were with significant and positive heterobeltiosis (28.7%, 20.1% and 24.0%, respectively), standard heterosis (21.6, 13.4 and 13.0%, respectively) and per se performance (100.6, 93.8 and 93.4 g/plant, respectively). The expression of heterotic response over better parents and standard check indicated the realsuperiority of the hybrids which could be exploited further through multilocational testing over different environments for judging their importance from the commercial point of view.

Mean performance of gynoecious cucumber hybrids in sub-tropical climate of eastern India

A field study was conducted in zaid season of 2019 to investigate the mean performance of 27 diverse genotypes (5 parents, 20 F1 crosses and 2 standard checks) of cucumber for earliness, growth and yield attributing traits following full diallel mating design by utilizing two gynoecious lines, two monoecious lines and one parthenocarpic gynoecious line. Analysis of variance in randomized block design suggested that there were significant differences among the genotypes for 10 quantitative traits out of 13 traits used in the study. Results showed that gynoecious hybrids (involving both gynoecious parents) expressed earliness for flowering and fruiting, i.e., took minimum days to first female flower anthesis, node to first female flower, and days to first fruit harvest. The result of the present study showed that hybrid BRPCU-8 × BRGCU-4 was found to be better for earliness related traits viz., days to first flowering, first fruit harvest, and node to first female flower. Hybrid BRCU-10 × BRCU-1 was the better performer for fruit morphological traits viz., fruit length, fruits per plant, average fruit weight and yield-related traits; hybrid BRCU-1 × BRPCU-8 was superior for vegetative growth traits, namely crop duration and vine length. Monoecious cucumber hybrids involving both monoecious parents such as Punjab Naveen × BRCU-1 outperformed gynoecious hybrids involving gynoecious parents for growth characteristics such as vine length and crop duration. Overall, hybrid BRGCU-10 × BRCU-1 was observed as the best genotype.

BCAT- based marker for marker-assisted selection in Vietnam cucumber breeding

Yield imporovement is one of major breeding objectives of cucumber improvement. Gynoecious, an important agricultural trait which highly correlates with yield, was proved to be controlled by F locus. Conventional plant breeding approach has some limitations in terms of potential inaccuracies and time-consuming. Molecular marker - assisted breeding is, therefore, an effectively alternative solution. F locus– linked molecular marker was previously reported. The main aim of this project was to evaluate the potential applicability of this F locus– specific marker for marker–assisted selection in Vietnam cucumber breeding program. Three different cucumber populations <i>e.g.,</i> pure lines, F2 and F3 population were utilized with 13, 131 and 84 plants, respectively for each population. Plant sexual phenotypes were determined. Sequencing reactions were performed for <I>BCAT</I> 3’UTR of 3 gynoecious and 2 monoecious pure lines. Plant genotypes were determined by standard PCR with a primer pair amplifying a 56 bp-deletion region in <I>BCAT</I> 3’UTR. A 56 bp-deletion was found in <I>BCAT</I> 3’UTR of gynoecious pure lines as compared with monoecious lines. The marker based on this 56 bp-deletion region in <I>BCAT</I> 3’UTR could help to separate cucumber plants having homozygous and heterozygous sex phenotypes. The marker genotype absolutely corresponded with monoecious trait. Especially, the marker could precisely explain for 80 % gynoecious trait. The marker highly explained for Vietnam cucumber sex traits and could be applied for marker-assisted selection in cucumber breeding program in Vietnam in future.

Development and evaluation of diverse wilt resistant monoecious lines in castor

Since 1990s, development of wilt resistant and high yielding hybrids has played an important role in increasingthe productivity of castor from around 320 kg/ha to 1700 kg/ha. Eleven elite monoecious lines having wilt resistance were developed by hybridization using five germplasm and seven elite monoecious lines. The elite lines viz., ICS- 303, ICS-304, ICS-315 and ICS-318 had better yield traits like spike length, seed weight and seed yield per plant. ICS-320 and ICS-321 derived from 48-1 and RG-2991 had the highest oil content (&gt;50%) than the checks 48-1 and DCS-107. These elite lines will help in development of wilt resistant and high yielding hybrids and varieties in castor.

Combining ability for seed yield and its component traits in castor (Ricinus communis L.)

Combining ability analysis was carried out using five pistillate lines as female and 13 monoecious lines as malefor seed yield and component traits in castor. The result indicated that both gca and sca variances were important in the expression of all the traits. Non-additive gene action was predominant for seed yield and oil content, while additive gene action was more important in the expression of length of main spike, number of capsules on main spike, number of effective spikes/plant and 100-seed weight. Three pistillate lines, JP-96, JP-106 and SKP-84 and five male lines, JI454, JI-455, JI-456 and JI-457 were good general combiners for yield and its contributing traits.

Ứng dụng chỉ thị phân tử SSR13251 và SSR18956 trong nhận diện giới tính hoa dưa leo

In the cucumber hybrid breeding process, the use of gynoecious lines as a maternal line has many advantages such as decreasing the breed confusion caused by self-pollination, requiring lesss labor for removing male or covering female flowers, making use of insects for pollinating, and ensuring high yield. Molecular marker is a useful tool to early and accurately identify cucumber gynoecious lines. This study investigated the correlation between the two molecular markers e.g. SSR13251 and SSR18956 with the sex of flowers of 50 pure cucumber samples (19 gynoecious lines, 31 monoecious lines). PCR reactions were performed to amplify the target sequences. The results showed that SSR13251 marker did not distinguish the different cucumber lines. Meanwhile, the PCR product size of SSR18956 marker differed among cucumber lines that helped to exactly identify the gynoecious lines. After screening 50 pure cucumber samples with SSR18956 marker, the compatibility between this marker and the sexual phenotype of cucumber flowers was 84%. Therefore, the SSR18956 marker could be a potential marker to identify the gynoecious lines in cucumber.

Exploitation of heterosis in cucumber for earliness, yield and yield contributing traits under protected structure

The research was conducted at Vegetable Research Centre, Gobind Ballav Pant University of Agriculture and Technology, Pantnagar, Uttarakhand during 2015-16. Fourteen parental lines including eight parthenocarpic lines, three gynoecious lines and three testers of monoecious lines were used to develop 33 F1 hybrids of cucumber by Line × Tester mating design to determine the magnitude of heterosis for earliness, yield and yield related traits during March-June and August –December in protected structures. The mean sum of squares were highly significant for all the characters indicated a wide genetic variation for the characters studied and the Parthenocarpic parental lines (PCUCP-2, PCUCP-3 and PCUCP-8) and monoecious parent (Pant Khira-1, PCUC-8, and PCUC-25) were observed to be the three top performing parents for yield per plant. Appreciable heterosis was observed over better parent and standard parent for most of the characters studied. The best F1 hybrid PCUCP-4 × PCUC-8, promising in both E1 and E2 showing 835% and 453% heterosis, respectively for yield per plant followed by PCUCP-3 x PCUC-8 (769%, 559%) for average fruit weight and PCUCP-1 × PCUC-8 (-98.77%, -95.53%) for node number to first female flower over standard check Pant Khira-1. So, PCUCP-4 × PCUC-8 can be tested as most stable genotype across the spring –summer and kharif-winter environments under polyhouse condition in northern plains and three hybrids viz., PCUCP-4 × PCUC-8, PCUCP-3 × PCUC-8 and PCUCP-1 × PCUC-8 may be exploited for commercial cultivation.

Chỉ thị phân tử CsFemale-1 và giới tính của dưa leo

In breeding programs, it is important to accurately identify crop phenotypes. The purpose of this study was to determine the correlation between marker CsFemale-1 and sex phenotype of different cucumber lines. PCR with CsFemale-1 marker was applied for 120 samples from 12 pure cucumber lines (5 gynoecious and 7 monocecious lines, ten plants for each). In 50 samples of 5 gynoecious lines, PCR results showed that the correlation between marker CsFemale-1 and female phenotype was 100%. However, it was found that in 70 samples of 7 monoecious lines, the correlation between marker CsFemale-1 and monoecious lines was 42%. These data suggest that CsFemale-1 precisely identify gynoecious cucumber. However, in order to be utilized for breeding, CsFemale-1 should be combined with other markers specific for monoecious lines.

A RAD-Based Genetic Map for Anchoring Scaffold Sequences and Identifying QTLs in Bitter Gourd (Momordica charantia).

Genetic mapping is a basic tool necessary for anchoring assembled scaffold sequences and for identifying QTLs controlling important traits. Though bitter gourd (Momordica charantia) is both consumed and used as a medicinal, research on its genomics and genetic mapping is severely limited. Here, we report the construction of a restriction site associated DNA (RAD)-based genetic map for bitter gourd using an F2 mapping population comprising 423 individuals derived from two cultivated inbred lines, the gynoecious line ‘K44’ and the monoecious line ‘Dali-11.’ This map comprised 1,009 SNP markers and spanned a total genetic distance of 2,203.95 cM across the 11 linkage groups. It anchored a total of 113 assembled scaffolds that covered about 251.32 Mb (85.48%) of the 294.01 Mb assembled genome. In addition, three horticulturally important traits including sex expression, fruit epidermal structure, and immature fruit color were evaluated using a combination of qualitative and quantitative data. As a result, we identified three QTL/gene loci responsible for these traits in three environments. The QTL/gene gy/fffn/ffn, controlling sex expression involved in gynoecy, first female flower node, and female flower number was detected in the reported region. Particularly, two QTLs/genes, Fwa/Wr and w, were found to be responsible for fruit epidermal structure and white immature fruit color, respectively. This RAD-based genetic map promotes the assembly of the bitter gourd genome and the identified genetic loci will accelerate the cloning of relevant genes in the future.