AUTHOR=Gao Huirong , Mutti Jasdeep , Young Joshua K. , Yang Meizhu , Schroder Megan , Lenderts Brian , Wang Lijuan , Peterson Dave , St. Clair Grace , Jones Spencer , Feigenbutz Lanie , Marsh Wally , Zeng Min , Wagner Susan , Farrell Jeffry , Snopek Kay , Scelonge Chris , Sopko Xiaoyi , Sander Jeffry D. , Betts Scott , Cigan A. Mark , Chilcoat N. Doane TITLE=Complex Trait Loci in Maize Enabled by CRISPR-Cas9 Mediated Gene Insertion JOURNAL=Frontiers in Plant Science VOLUME=11 YEAR=2020 URL=https://www.frontiersin.org/journals/plant-science/articles/10.3389/fpls.2020.00535 DOI=10.3389/fpls.2020.00535 ISSN=1664-462X ABSTRACT=

Modern maize hybrids often contain biotech and native traits. To-date all biotech traits have been randomly inserted in the genome. Consequently, developing hybrids with multiple traits is expensive, time-consuming, and complex. Here we report using CRISPR-Cas9 to generate a complex trait locus (CTL) to facilitate trait stacking. A CTL consists of multiple preselected sites positioned within a small well-characterized chromosomal region where trait genes are inserted. We generated individual lines, each carrying a site-specific insertion landing pad (SSILP) that was targeted to a preselected site and capable of efficiently receiving a transgene via recombinase-mediated cassette exchange. The selected sites supported consistent transgene expression and the SSILP insertion had no effect on grain yield. We demonstrated that two traits residing at different sites within a CTL can be combined via genetic recombination. CTL technology is a major step forward in the development of multi-trait maize hybrids.