The discovery of a single gene that played an important role in the domestication of soybeans is reported in a paper published online this week in Nature Genetics. The version of this gene in wild soybeans leads to hard seeds, but the mutation identified in the study leads to soft seeds, which allows the rapid entry of water and results in faster germination.
Hard-seededness allows plant seeds to lie dormant for long periods and avoid predation. However, it also makes them difficult to cultivate on a large scale, as is needed for agriculture.
Jianxin Ma and colleagues used a gene mapping strategy to locate the genetic change that turned the hard seeds of wild soybeans into the water-permeable soybean seeds grown today for human consumption. They found that a single mutation in the gene GmHs1-1 was able to account for the difference between impermeable and permeable soybeans. When the wild soybean version of GmHs1-1 was introduced into water-permeable (“soft-seeded”) cultivated soybeans, they produced seeds that were hard, like their wild ancestors.
The researchers compared GmHs1-1 sequences between many soybean cultivars, or strains, and concluded that early farmers may have selected for the specific mutation found in the study. However, a few cultivars did not contain the mutation. Instead, they produce seeds that are prone to cracking. This provides another way for water to enter the seeds, making them suitable for agriculture.