Development of Next-Generation Mapping Populations: Multi-Parent Advanced Generation Inter-Cross (MAGIC) and Marker-Assisted Recurrent Selection (MARS) Populations in Peanut

摘要

Over the past decade, next-generation genetic mapping populations such as Multi-parent Advanced Generation Inter-Cross (MAGIC) and Marker-Assisted Recurrent Selection (MARS) have been proposed and used in many crops to dissect complex traits or QTL. MAGIC allows for dissecting genomic structure, and for improving breeding populations by integrating multiple alleles from different parents. MARS utilizes multiple parents derived from one RIL population and aims to take advantage of QTL information generated in breeding populations to develop superior lines with an optimum combination of favorable alleles. In this study, we constructed MAGIC and MARS populations for peanut using the "funnel" breeding scheme. For MAGIC population construction, eight founder varieties were selected based on genomic and phenotypic information: Tifrunner, GT-C20, SunOleic 97R, NC94022, Georgia 13M, TifNV-High O/L, Florida 07, and SPT0606. MAGIC population design was based on a simple crossing scheme as {[(A ×B) ×(C×D)] × [(E×F) × (G×H)]}, where the matched brackets delineate the (two), [four], and {eight}-way crosses. The four two-way crosses were made in the spring of 2015 and the two four-way crosses were made in the fall of 2015 generating 210 and 172 true four-way hybrids, respectively. The last stage was made in 2016, which involved 172 combinations of crosses. Overall, 144 combinations were successful and 906 eight-way hybrid seeds were generated. In 2017, all eight-way hybrids will be planted, verified, and a F2 MAGIC population (>1000) will be generated. For the MARS population construction, eight RIL lines from the "S" RIL population (SunOleic97R x NC94022) with different traits/QTL including the resistance to TSWV, early and late leaf spot, high oleic acid, and oil content were selected. The first recombination cycle was made between each pair of lines (two-way). The second recombination cycle was made between each group of hybrids (two-way) from the first cycle generating 187 and 122 hybrids (4-way), respectively. The third recombination cycle including at least 100 combinations of crosses is in progress to be completed by the end of 2017 (8-way). These MAGIC and MARS populations will provide a useful genetic resource with diverse allelic combinations to be exploited for "fine" mapping of complex traits for markers and breeding programs.