Researchers find gene responsible for “Hard Seededness”

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.