Construction of high-density genetic linkage maps and QTL analysis in almond

Almond (Prunus dulcis (Mill) D.A. Webb) is the only nut tree species in Rosaceae family and it is one of the most important nut crops in Turkey. Cultivar breeding programs in almond take a long time due to its long juvenile period. So, it is necessary to use molecular approach to overcome such problems. Construction of genetic linkage maps and quantitative trait locus (QTLs) analysis are important tools to develop markers linked to economically important phenotypic characters, which can significantly shorten the breeding efficiency. Therefore, in this study, we aimed (1) to construct a high-density genetic linkage map and (2) to detect QTLs associated with economically important phenotypic characters in almond. 'Gülcan-2 x Lauranne' and 'Guara x Nurlu' F1 populations were used in genetic linkage mapping and QTL analysis. The phenotypic data obtained from 2015, 2016, 2017 and 2018 growing seasons and from 21 characters were used. SSR, DArT and SNP markers were used for high-density genetic linkage map construction. In 'Gülcan-2 x Lauranne' population, the Gülcan-2 maternal linkage map included 3,338 markers, and the total map length was 469.86 cM with 7.1 marker density (marker/cM), whereas the Lauranne male genetic map contained 3,442 markers, and the total map length was 572.27 cM with 6.23 marker density. In 'Guara x Nurlu' population, the Guara maternal linkage map included 2,563 markers, and total map length was 443.92 cM with 5.79 marker density (marker/cM), whereas the Nurlu male genetic map contained 3,135 markers, and the total map length was 516.02 cM with 6.14 marker density. QTL analysis was conducted using genetic linkage maps and phenotypic data analysis. As a result, a total of 12, 11, 23 and 22 major QTLs were detected in Gülcan-2, Lauranne, Guara and Nurlu maps, respectively. The data produced in this study will be very useful for breeding and genetic studies in the future for almond. Key words: Almond, SSR, SNP, genetic mapping, QTL