A "public bulk" strategy identifies the causal gene for male sterility in ms1 soybean

As soybean is an extremely photoperiod-sensitive and self-pollinated crop which lacks any functionally confirmed male sterility genes, the scope of genetic diversity that soybean breeders have harnessed to date is much narrower than in other major crops. The ms1 mutant was the first genic male sterile mutant discovered for soybean and this mutant has been deployed in breeding, but its causal locus remains unknown. Here, by using a "control dominant homozygous bulk" or "public bulk" that we prepared in silico from public resequencing datasets in combination with sequencing data for a small ms1 recurrent breeding population, we found that a deletion fragment containing a soy homolog of AtNACK2, a microtubule motor kinesin-7 family protein, is the causal locus for male sterility in ms1 soybean materials. We used CRISPR/Cas9 gene editing technology to edit multiple deletion alleles of this 'GmMS1' (Glyma.13G114200) locus into an elite soybean cultivar, and found that the GmMS1 knockout plants phenocopy ms1 materials. Thus, beyond illustrating how an easy-to-implement in silico bulking strategy can be used to rapidly identify (potentially any) casual loci for recessive male sterility traits in a recurrent population, our study opens the door for large-scale hybridization breeding in soybean, the world's most economically important eudicot crop.