Jianxin Ma believes he can explain why ancient farmers 5,000 years ago took certain steps when domesticating soybeans. Will that make you more money in 2018? No, but discoveries like this could lead to untold changes in the future that could eventually add more income by making soybeans more valuable.

Plant breeders continuously strive to increase soybean oil content, Ma says. He is a professor in Purdue University’s Agronomy Department, and has gained recognition for his work with ancient, Chinese soybeans in his quest for diverse genetics.

When plant breeders set out to increase oil content, they focus on genes known to impact seeds, Ma says. His recent discoveries indicate that genes affecting other plant parts deserve more attention if the goal is increasing soybean oil content.

Wild soybeans contain a substance called “bloom” that originates in the pods and coats the seeds, Ma explains. Don’t confuse it with plant blooms. In fact, while plant blooms are highly visible, the purpose of the bloom substance is to make seeds less visible.

Bloom favors survival in the natural environment, Ma says. The catch is that bloom also contains allergens that could be harmful when ingested by people and animals. That’s why Ma believes ancient farmers selected for a soybean with a naturally occurring mutation that eliminated bloom. They may not have understood about genes and alleles 5,000 years ago, but they figured out that by picking seeds from plants without bloom, they could grow soybeans that didn’t make them sick.

Find the why
Some 5,000 years later, Ma and his co-workers discovered what changed to produce soybeans without bloom. It was a mutation of a single nucleotide within a gene called B1. Once that occurred, bloom was no longer produced.

In making this discovery, Ma found that B1 does more than eliminate bloom. It also results in substantial increases of seed oil content in cultivated soybeans vs. ancient, wild types. He suspects that selection for this mutation over time explains why soybeans are a valuable oil crop today.

What Ma didn’t necessarily expect was to discover that the B1 gene doesn’t seem to affect oil biosynthesis within seeds. Instead, the mutation that causes loss of bloom and higher oil content heightens the activity of what Ma calls “master regulators” of oil biosynthesis. They’re located in the endocarp of pods, not in the seeds. However, the heightened activity in pods appears to result in enhanced oil accumulation in soybean seeds, Ma says.

Outcome
The takeaway is that it may be possible and even practical in the future to increase soybean oil content by focusing on genes other than just those in the seed. Ma will continue studying genetic control of seed oil content in soybeans as mediated by the B1 gene. He will zero in on ways in which it interacts with other genes in a network to affect pod and seed traits.

This work is funded by the North Central Soybean Research Program and the Indiana Soybean Alliance, with funding support from other groups, as well.

Solving a 5,000-year-old mystery is intriguing, if not profitable. Learning where to focus to increase soil oil content more efficiently could add to your bottom line in the future.

Brian Wallheimer of Purdue Ag Communications provided information for this story.