Jianxin Ma holds a dish of seeds from cultivated soybeans (right) and from their wild, hard-coated r
Jianxin Ma holds a dish of seeds from cultivated soybeans (right) and from their wild, hard-coated relatives (left).

Wild soybean seeds are expert survivalists. Encased in a tough waterproof and airtight coat, they are well protected from severe conditions and inhospitable environments and can remain viable for decades.

But the hard skin that lends wild soybeans and many other undomesticated seeds their resilience is a thorny problem for agricultural producers. It prevents seeds from germinating quickly and in a predictable pattern.

Millennia ago, farmers in Asia recognized the value of seed permeability and artificially selected the trait to produce the predecessors of modern cultivated soybean varieties, whose seeds can begin absorbing water in a minute.

The genetic factors underpinning seed coat permeability remained a mystery until professor of agronomy Jianxin Ma and his team used a map-based cloning approach to hone in on GmHs1-1 as the gene responsible for hard seededness.

Understanding this genetic mechanism could help unlock the largely untapped genetic diversity of wild soybeans to enrich cultivated varieties and could be a valuable tool for breeders as they develop better soybean varieties for southern and tropical regions. GmHs1-1 is also associated with calcium content, offering a genetic target for boosting the calcium levels and cooking quality of soybeans and other legumes.

"This is the first gene associated with hard seededness to be identified in any plant species," Ma says. "This discovery could help us quickly pinpoint genes that control this trait in many other plants. We're also excited about the potential applications for modifying the calcium concentration in seeds."

Ma's work is a vital part of the Purdue College of Agriculture's Plant Sciences Research and Education Pipeline, providing the foundational genetic work that plant breeders can use to develop hardier, more nutritious crops.

"I hope our research findings will not only advance the field of knowledge, but also be transferred into practical applications, developing high-yielding soybean varieties with desirable traits for producers around the world," Ma says.

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Purdue Agronomy

The Efforts

The hard seed coats of wild soybeans protect them from severe or inhospitable environments, but prevent quick, predictable germination. Jianxin Ma, Purdue professor of agronomy, and his team, honed in on the gene responsible for hard-seededness.

The Impact

Uncovering the genetic mysteries of the soybean can also help unlock wild soybeans’ largely untapped genetic diversity to enrich cultivated varieties and help breeders improve varieties for southern and tropical regions.

The Numbers

82.7 million. Acres of soybeans planted in the United States in 2015 according to the American Soybean Association.

$34.5 billion. Total value of United States soybeans in 2015 according to the American Soybean Association.

The Future

Through further work in the Purdue College of Agriculture’s Plant Sciences Research and Education Pipeline, Ma and his team will continue foundational genetic research that breeders can use to develop hardier, more nutritious crops.