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【Objective】A major gene and polygenes genetic analysis on the chlorophyll content in the pulp of cheih-qua was conducted to study the relationship and genetic mechanism between pulp color and chlorophyll content, with an aim to lay a foundation for the breeding of high-quality cheih-qua varieties.【Method】In the study, cheih-qua inbred lines J16 (white pulp) and FJ5 (green pulp) were used to form four generation populations, P1, P2, F1 and F2. The pulp color of the chieh-qua was observed by naked eye and the chlorophyll content was measured. The genetic model analysis software package was used to analyze the chlorophyll content of the pulp, and the maximum likelihood function value and AIC value were obtained. Then, the three models with the smallest AIC values were selected as alternate models and the suitability test was carried out. Finally, the first- and second-order genetic parameters of the optimal genetic model were calculated, and the genetic effect values of major genes and polygenes were analyzed.【Result】The results showed that chlorophyll content was the key factor in the formation of green pulp of the chieh-qua. The color and chlorophyll content of the F1 generation were between the parents and slightly inclined to the white pulp parents (P1), and the color and chlorophyll content of the F2 generation showed quantitative characteristics. The optimal genetic model for chlorophyll content in the pulp was MX2-ADI-ADI, that is, 2 pairs of additive - dominant - epistatic major gene + additive - dominant - epistatic polygene models. In the first-order genetic parameters, the sum of absolute additive effects (da+db) of the two major genes was greater than the sum of absolute dominant effects (ha+hb), and da > db, indicated that the negative additive effect of the first major gene was dominant. In epistatic genetic effects, gene additive-additive interactions were the main positive effects. The second-order genetic parameters indicated that the genetic variance of the major gene was 32.1590, the genetic variance of the polygenes was 1.1540, and the heritability rates of the major gene and the polygenes were 93.69% and 3.36%, respectively.【Conclusion】The heritability of major genes for the pulp color of chieh-qua is much higher than that of polygenes, and the major genes are dominant. Therefore, we should pay attention to the use of major genes in the process of high-quality breeding of chieh-qua, and we can select in early generations and improve chieh-qua by combined breeding.

IntroductionChieh-qua (Benincasa hispida Cogn. var. Chieh-qua How) is a wax gourd variety that is generally susceptible to infection and damage by Fusarium oxysporum during its cultivation. Therefore, analyzing the adaption mechanism of chieh-qua to F. Oxysporum infection is of great significance for cultivating resistant varieties.MethodsThrough comparative transcriptome analysis, comparative metabolome analysis, integrated analysis of transcriptome and metabolome and between F. Oxysporum infected samples and control samples of susceptible linesResultsThis study found that proteins such as NPR1, TGA and PR1 in plant hormone signal transduction pathway were up-regulated after infection, which may activate a series of plant secondary metabolic synthesis pathways. In addition, the expression of 27 genes in the flavonoid biosynthetic process in resistant lines after infection was significantly higher than that in susceptible lines, indicating that these genes may be involved in fungal resistance. This study also found that alternative splicing of genes may play an important role in responding to F. Oxysporum infection. For example, plant protein kinase genes such as EDR1, SRK2E and KIPK1 were not differentially expressed after F. Oxysporum infection, but the transcripts they produced differ at the transcription level. Finally, through comparative metabolome analysis, this study identified potentially functional substances such as oxalic acid that increased in content after F. Oxysporum infection. Through integrated analysis of transcriptome and metabolome, some differential expressed genes significantly related to differential metabolites were also identified.DiscussionThis study provides a basis for understanding and utilizing chieh-qua’s infection mechanism of F. Oxysporum through analysis of the transcriptome and metabolome.

IntroductionFlesh color is an essential trait in chieh-qua (Benincasa hispida Cogn. var. Chieh-qua How); however, the inheritance and molecular basis of green flesh trait remain unclear.MethodsIn the present study, two F2 populations, derived from 1742 (white flesh) × FJ3211 (green flesh) and J16 (white flesh) × FJ5 (green flesh), were used to identify the green flesh (Cqgf) locus.ResultsGenetic analysis revealed that the presence of green flesh was a quantitative trait that closely followed a normal distribution. Combining the results from QTL mapping and BSA-seq analysis, the Cqgf locus was preliminarily determined to be located on chromosome 05 and was narrowed down to a 2.55-Mb interval by linkage analysis. A large J16 × FJ5 F2 population comprising 3,180 individuals was subsequently used to screen the recombinants, and the Cqgf locus was fine-mapped to a region of 329.70 kb that harbors six genes. One of the candidate genes, Bch05G003700, the zinc-finger transcription factor LOL1 (lsd one like 1 protein; CqLOL1), was the strongest candidate gene for the Cqgf locus according to sequence variation and expression analysis. Additionally, a point mutation (A > C) in CqLOL1 resulted in the substitution of threonine (T) with proline (P) in the amino acid sequence, showing a complete relationship linked with flesh color in a panel of 45 germplasms.DiscussionThe study suggests that CqLOL1 promotes the accumulation of chlorophyll content in chieh-qua and lead to green flesh. Our findings establish a theoretical and technical foundation for breeding different flesh color lines and elucidating the underlying mechanisms of flesh color in chieh-qua.

【Objective】Genetic analysis of major gene and polygenes was conducted on the length, width, and quality of Chieh-qua seeds to study the genetic rules of seed size and select high-quality Chieh-qua varieties.【Method】Chieh-qua inbred line J16 (big seed) was used as female parent and 18FJ5 (small seed) as male parent to hybridize, and the length, width and seed quality of F2 generation seeds were determined. What's more, the optimal genetic model and genetic law of each trait were obtained by using the mixed model of main gene+polygene.【Result】The most suitable genetic model for Chieh-qua seed length and width was MX2-ADI-AD, that is, two pairs of additive-dominant-epistatic main genes+additive-dominant polygenes genetic model, with the main gene heritability of 87.07% and 90.79%, respectively, and the polygene heritability of both was 0. The most suitable genetic model for the quality of 30 seeds was MX1-AD-ADI, that is, a pair of additive-dominant major genes+additive-dominant-epistatic polygenes genetic model, with the heritability of major genes and polygenes being 79.96% and 8.73%, respectively.【Conclusion】The major gene heritability of the above traits is far greater than the polygene heritability, and the main gene inheritance is dominant. Therefore, in the process of high-quality breeding of Chieh-qua, we should pay attention to the use of major genes, which can be selected in the early generation.

Abstract Background The preferred choice for molecular marker development is identifying existing variation in populations through DNA sequencing. With the genome resources currently available for bitter gourd (Momordica charantia), it is now possible to detect genome-wide insertion-deletion (InDel) polymorphisms among bitter gourd populations, which guides the efficient development of InDel markers. Results Here, using bioinformatics technology, we detected 389,487 InDels from 61 Chinese bitter gourd accessions with an average density of approximately 1298 InDels/Mb. Then we developed a total of 2502 unique InDel primer pairs with a polymorphism information content (PIC) ≥0.6 distributed across the whole genome. Amplification of InDels in two bitter gourd lines ‘47–2–1-1-3’ and ‘04–17,’ indicated that the InDel markers were reliable and accurate. To highlight their utilization, the InDel markers were employed to construct a genetic map using 113 ‘47–2–1-1-3’ × ‘04–17’ F2 individuals. This InDel genetic map of bitter gourd consisted of 164 new InDel markers distributed on 15 linkage groups with a coverage of approximately half of the genome. Conclusions This is the first report on the development of genome-wide InDel markers for bitter gourd. The validation of the amplification and genetic map construction suggests that these unique InDel markers may enhance the efficiency of genetic studies and marker-assisted selection for bitter gourd.

Bitter gourd (Momordica charantia) is widely cultivated as a vegetable and medicinal herb in many Asian and African countries. After the sequencing of the cucumber (Cucumis sativus), watermelon (Citrullus lanatus), and melon (Cucumis melo) genomes, bitter gourd became the fourth cucurbit species whose whole genome was sequenced. However, a comprehensive analysis of simple sequence repeats (SSRs) in bitter gourd, including a comparison with the three aforementioned cucurbit species has not yet been published. Here, we identified a total of 188,091 and 167,160 SSR motifs in the genomes of the bitter gourd lines ‘Dali-11’ and ‘OHB3-1,’ respectively. Subsequently, the SSR content, motif lengths, and classified motif types were characterized for the bitter gourd genomes and compared among all the cucurbit genomes. Lastly, a large set of 138,727 unique in silico SSR primer pairs were designed for bitter gourd. Among these, 71 primers were selected, all of which successfully amplified SSRs from the two bitter gourd lines ‘Dali-11’ and ‘K44’. To further examine the utilization of unique SSR primers, 21 SSR markers were used to genotype a collection of 211 bitter gourd lines from all over the world. A model-based clustering method and phylogenetic analysis indicated a clear separation among the geographic groups. The genomic SSR markers developed in this study have considerable potential value in advancing bitter gourd research.