CRISPR/Cas9‐mediated targeted mutagenesis of GmFT2a delays flowering time in soya bean

Summary Flowering is an indication of the transition from vegetative growth to reproductive growth and has considerable effects on the life cycle of soybean (Glycine max). In this study, we employed the CRISPR/Cas9 system to specifically induce targeted mutagenesis of GmFT2a, an integrator in the photoperiod flowering pathway in soybean. The soybean cultivar Jack was transformed with three sgRNA/Cas9 vectors targeting different sites of endogenous GmFT2a via Agrobacterium tumefaciens-mediated transformation. Site-directed mutations were observed at all targeted sites by DNA sequencing analysis. T1 generation soybean plants homozygous for null alleles of GmFT2a frameshift mutated by a 1-bp insertion or short deletion exhibited late flowering under natural conditions (summer) in Beijing, China (N39°58′, E116°20′). We also found that the targeted mutagenesis was stably heritable in the following T2 generation, and the homozygous GmFT2a mutants exhibited late flowering under both long-day and short-day conditions. We identified some “transgene-clean” soybean plants that were homozygous for null alleles of endogenous GmFT2a and without any transgenic element from the T1 and T2 generations. These “transgene-clean” mutants of GmFT2a may provide materials for more in-depth research of GmFT2a functions and the molecular mechanism of photoperiod responses in soybean. They will also contribute to soybean breeding and regional introduction. This article is protected by copyright. All rights reserved.