Development and validation of InDel markers for identification of QTL underlying flowering time in soybean

Soybean [Glycine max (L.) Merrill] is a major plant source of protein and oil. An accurate and well-saturated molecular linkage map is a prerequisite for forward genetic studies of gene function and for modern breeding for many useful agronomic traits. Next-generation sequence data available in public databases provides valuable information and offers new insights for rapid and efficient development of molecular markers. In this study, we attempted to show the feasibility and facility of using genomic resequencing data as raw material for identifying putative InDel markers. First, we identified 17,613 InDel sites among 56 soybean accessions and obtained 12,619 primer pairs. Second, we constructed a genetic map with a random subset of 2841 primer pairs and aligned 300 polymorphic markers with the 20 consensus linkage groups (LG). The total genetic distance was 2347.3 cM and the number of mapped markers per LG ranged from 10 to 23 with an average of 15 markers. The largest and smallest genetic distances between adjacent markers were 52.3 cM and 0.1 cM, respectively. Finally, we validated the genetic map constructed by newly developed InDel markers by QTL analysis of days to flowering (DTF) under different environments. One major QTL (qDTF4) and four minor QTL (qDTF20, qDTF13, qDTF12, and qDTF11) on 5 LGs were detected. These results demonstrate the utility of the InDel markers developed in this work for map-based cloning and molecular breeding in soybean.