High-density genetic linkage map construction and identification of fruit-related QTLs in pear using SNP and SSR markers

Hydrangea (Hydrangea macrophylla) is an important ornamental crop that has been cultivated for more than 300 years. Despite the economic importance, genetic studies for hydrangea have been limited by the lack of genetic resources. Genetic linkage maps and subsequent trait mapping are essential tools to identify and make markers available for marker-assisted breeding. A transcriptomic study was performed on two important cultivars, Veitchii and Endless Summer, to discover simple sequence repeat (SSR) markers and an F1 population based on the cross ‘Veitchii’ × ‘Endless Summer’ was established for genetic linkage map construction. Genotyping by sequencing (GBS) was performed on the mapping population along with SSR genotyping. From an analysis of 42,682 putative transcripts, 8780 SSRs were identified and 1535 were validated in the mapping parents. A total of 267 polymorphic SSRs were selected for linkage map construction. The GBS yielded 3923 high quality single nucleotide polymorphisms (SNPs) in the mapping population, resulting in a total of 4190 markers that were used to generate maps for each parent and a consensus map. The consensus linkage map contained 1767 positioned markers (146 SSRs and 1621 SNPs), spanned 1383.4 centiMorgans (cM), and was comprised of 18 linkage groups, with an average mapping interval of 0.8 cM. The transcriptome information and large-scale marker development in this study greatly expanded the genetic resources that are available for hydrangea. The high-density genetic linkage maps presented here will serve as an important foundation for quantitative trait loci mapping, map-based gene cloning, and marker-assisted selection of H. macrophylla.

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High-density Genetic Linkage Map Construction in Sunflower (Helianthus annuus L.) Using SNP and SSR Markers

Current Bioinformatics ◽

10.2174/1574893615666200324134725 ◽

2021 ◽

Vol 15 (8) ◽

pp. 889-897

Author(s):

Pin Lyu ◽

Jianhua Hou ◽

Haifeng Yu ◽

Huimin Shi

Keyword(s):

Linkage Map ◽

Helianthus Annuus ◽

Ssr Markers ◽

Genetic Map ◽

Genetic Linkage ◽

Genetic Linkage Map ◽

Snp Markers ◽

High Density ◽

Helianthus Annuus L ◽

Density Maps

Background: Sunflower (Helianthus annuus L.) is an important oil crop only after soybean, canola and peanuts. A high-quality genetic map is the foundation of marker-assisted selection (MAS). However, for this species, the high-density maps have been reported limitedly. Objective: In this study, we proposed the construction of a high-density genetic linkage map by the F7 population of sunflowers using SNP and SSR Markers. Methods: The SLAF-seq strategy was employed to further develop SNP markers with SSR markers to construct the high-density genetic map by the HighMap software. Results: A total of 1,138 million paired-end reads (226Gb) were obtained and 518,900 SLAFs were detected. Of the polymorphic SLAFs, 2,472,245 SNPs were developed and finally, 5,700 SNPs were found to be ideal to construct a genetic map after filtering. The final high-density genetic map included 4,912 SNP and 93 SSR markers distributed in 17 linkage groups (LGs) and covered 2,425.05 cM with an average marker interval of 0.49 cM. Conclusion: The final result demonstrated that the SLAF-seq strategy is suitable for SNP markers detection. The genetic map reported in this study can be considered as one of the most highdensity genetic linkage maps of sunflower and could lay a foundation for quantitative trait loci (QTLs) fine mapping or map-based gene cloning.

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