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An experiment was carried out with North Carolina Mating Design II (NC II) derived F1 progenies along with parents to know nature of gene action in regulating early maturity, yield and yield contributing traits. The principal objective of this research was to identify best parents and specific cross combinations based on combining ability analysis and estimation of heritability. Hybrids and their parents were arranged in a 8 by 8 partially balanced lattice design with two replicates. Kanchan, BARI Gom-25 × BARI Gom-21, BARI Gom-26 × Kanchan, Rawal × Kanchan, Rawal × BARI Gom-22 and BARI Gom-23 × Kheri showed earliness and BARI Gom-25 × BARI Gom-21 showed highest yield potentiality. The genotypes BARI Gom-28 and BARI Gom-30 were used as checks and the selected genotypes performed comparatively better than the checks. The genetic analysis exhibited significant additive and non-additive genetic variations for all the traits. For earliness and yield potentiality the variance due to SCA was highly significant than GCA. Heritability estimates revealed low broad sense heritability except the traits i.e. days to 50% flowering, days to 100% flowering, plant height and 100-grain weight, which exhibited medium heritability. Narrow sense heritability was low for all the traits. The GCA effect of 15 parental genotypes was insignificant for all the traits that were assessed. BARI Gom-25 x BARI Gom-21, BARI Gom-23 x BARI Gom-21, BARI Gom-25 x BARI Gom-27, BARI Gom-26 x Kanchan, BARI Gom-26 x BARI Gom-28, BARI Gom-25 x BARI Gom-27 showed significant SCA effects for earliness. BARI Gom-25 x BARI Gom-22, BARI Gom-26 x CB51 showed significant SCA effects for yield potentiality.

Watermelon (Citrullus lanatus), an economically important and nutritionally rich Cucurbitaceous crop grown worldwide, is severely affected by bacterial fruit blotch (BFB). Development of resistant cultivar is the most eco-friendly, cost-effective, and sustainable way to tackle this disease. This requires wider understanding of the genetics of resistance to BFB. In this study, we identified quantitative trait loci (QTLs) associated with BFB resistance in an F2 mapping population developed from BFB-resistant ‘PI 189225’ (Citrullus amarus) and -susceptible ‘SW 26’ (C. lanatus) genotypes based on the polymorphic markers identified by genotyping by sequencing (GSB). A linkage map covering a total genetic distance of 3377.1 cM was constructed. Two QTLs for BFB resistance, namely, ClBFB10.1 and ClBFB10.2, both located on chromosome 10 explaining 18.84 and 15.41% of the phenotypic variations, respectively, were identified. Two SNP-based high-resolution melting (HRM) markers WmBFB10.1 and WmBFB10.2 having high positive correlation with resistance vs. susceptible alleles were developed. The efficacy of the markers was validated in another F2 population derived from SW34 × PI 189225. The highest phenotypic variation was found in the locus ClBFB10.2, which also contains three putative candidate genes for resistance to BFB. These findings will accelerate the development of BFB-resistant watermelon varieties via molecular breeding.

Powdery mildew (PM), caused by the biotrophic fungus Podosphaera xanthii, drastically reduces the yield and quality of melon (Cucumis melo L.). Knowledge on the genetic control and high throughput molecular markers linked with resistance against this disease are essential for breeding programs. The bioassay study of the F1 and F2 populations derived from the parents, ‘PMR 5’ (♂) and ‘SCNU1154’ (♀) revealed a monogenic dominant nature of resistance to the devastating race, race 5. Besides, we developed three SNP based high resolution melting markers, PMm-HRM-1, PMm-HRM-2, and PMm-HRM-3 based on the previously identified SNPs on chromosome 12 and validated those using 10 melon lines and 137 F2 population. Among these, the SNP of marker PMm-HRM-1 causes a missense mutation (Lysine → Glutamic acid) in the LRR region of MELO3C002393 and were able to distinguish the resistant vs susceptible genotypes from 10 diverse melon population and the segregating F2 population with more than 90% genotyping efficiency. Other two markers were based on intergenic SNPs and had more than 80% genotyping efficiency F2 population. These markers will be helpful to melon breeders to develop melon cultivars resistant to P. xanthii race 5 via marker assisted breeding programs.