Pears (Pyrus spp.) are economically important fruit trees grown extensively world-wide. To identify QTLs related to key agronomically important fruit traits, we conducted QTL analysis using an interspecific 178 F₁ populations derived from a cross between ‘Manpungbae’ and ‘Oharabeni’. Phenotyping data, including fruit weight, fruit length and diameter, fruit shape index (FSI), soluble sugar content, fruit firmness (FF), and titratable acidity (TA) were investigated from 2016 to 2018. Using the previously constructed genetic linkage map together with the three-year phenotypic dataset, we detected 14 significant QTLs associated with the control of fruit weight, fruit length and diameter, FSI, FF, and TA on linkage groups 3, 10, 11, 12, and 13. These findings provide a useful resource for advancing genetic and genomic studies in pears and will aid breeding efforts to improve major fruit traits.

Grape (Vitis vinifera L.) is a perennial fruit tree with high heterozygosity, consisting of 38 chromosomes (2n=38), and it takes a long time for grape seedlings to grow into fruit-bearing trees. Therefore, it is difficult to study grape genetics and breeding strategies. However, it has recently become possible to discover many SNPs through whole genome resequencing or genotyping-by-sequencing (GBS) analysis. In this study, we aimed to develop high-resolution melting (HRM) markers from the detected SNPs and construct a genetic linkage map using HRM markers. In a previous study, 2,553 SNPs were identified using GBS analysis. In this study, 1,336 SNPs were used to design primer sets for HRM analysis. The developed HRM markers were used for construction of a genetic linkage map in an F₁ segregating population consisting of 192 individuals from a cross between ‘Tano Red’ (V. labrusca×V. vinifera) and ‘Ruby Seedless’ (V. vinifera). A total of 805 polymorphic HRM markers were developed, of which 363 were mapped onto the genetic linkage map of grape, with a total length of 1,453.5 cM consisting of 19 chromosomes. This SNP-based genetic linkage map and HRM markers can be used for QTL identification and marker development for important fruit traits of grape.

Watermelon (Citrullus lanatus) is an economically important vegetable crop all over the world, which has functional compounds such as lycopene and citrulline. Gummy stem blight caused by Didymella bryoniae is one of the most devastative diseases in watermelon. Single nucleotide polymorphisms (SNPs), which are genetic variations occurring between individuals with respect to a single base, were often used to construct genetic linkage maps and develop molecular markers linked to a variety of horticultural traits and resistance to several diseases. In this study, we developed high-resolution melting (HRM) markers based on SNPs generated from NGS resequencing of two parents in watermelon. Plant materials were C. lanatus ‘920533’ (female and susceptible parent), C. amarus ‘PI 189225’ (male and resistant parent), and their F₁ and F₂ progenies. A total of 13.6 Gbp (‘920533’) and 13.1 Gbp (‘PI 189225’) of genomic sequences were obtained using NGS analysis. A total of 6.09 million SNPs between ‘920533’ and ‘PI 189225’ were detected, and 354,860 SNPs were identified as potential HRM primer sets. From these, a total of 330 primer sets for HRM analysis were designed. As a result, a total of 61 HRM markers that have polymorphic melting curves were developed. These HRM markers can be used for the construction of SNP-based linkage maps and for the analysis of quantitative trait loci (QTLs) related to gummy stem blight resistance.