Construction of a High-density Linkage Map and QTL Analysis for pistil abortion in apricot ( Prunus armeniaca L.)

A high-density genetic map of apricot (Prunus armeniaca L.) was constructed using an F1 population constructed by crossing two main Chinese cultivars 'Chuanzhihong' and 'Luotuohuang', coupled with a recently developed reduced representation library (RRL) sequencing. The average sequencing depth was 38.97 in 'Chuanzhihong' (female parent), 33.05 in 'Luotuohuang' (male parent), and 8.91 in each progeny. Based on the sequencing data, 12 451 polymorphic markers were developed and used in the construction of the genetic linkage map. The final map of apricot comprised eight linkage groups, including 1991 markers, and covered 886.25 cM of the total map length. The average distance between adjacent markers was narrowed to 0.46 cM. Gaps larger than 5 cM only accounted for <0.33%. To our knowledge, this map is the densest genetic linkage map that is currently available for apricot research. It is a valuable linkage map for quantitative trait loci (QTLs) identification of important agronomic traits. Moreover, the high marker density and well-ordered markers that this linkage map provides will be useful for molecular breeding of apricot as well. In this study, we applied this map in the QTL analysis of an important agronomic trait, pistil abortion. Several QTLs were detected and mapped respectively to the middle regions of LG5 (51.005 similar to 59.4 cM) and LG6 (72.884 similar to 76.562 cM), with nine SLAF markers closely linked to pistil abortion. The high-density genetic map and QTLs detected in this study will facilitate marker-assisted breeding and apricot genomic study.