Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:

 

Unusual soybean coloration sheds a light on gene silencing

20.06.2017

Today's soybeans are typically golden yellow, with a tiny blackish mark where they attach to the pod. In a field of millions of beans, nearly all of them will have this look. Occasionally, however, a bean will turn up half-black, with a saddle pattern similar to a black-eyed pea.

"The yellow color is derived from a natural process known as gene silencing, in which genes interact to turn off certain traits," explains Lila Vodkin, professor emerita in the Department of Crop Sciences at the University of Illinois. "Scientists make use of this process frequently to design everything from improved crops to medicines, but examples of naturally occurring gene silencing - also known as RNA interference, or RNAi - are limited. A better understanding of this process can explain how you can manipulate genes in anything from soybeans to humans."


Researchers at the University of Illinois have discovered the molecular mechanisms behind unusual saddle patterns on soybeans.

Credit: Lila Vodkin

The RNAi pathway was discovered about 20 years ago as a naturally occurring process in a tiny roundworm. The discovery and follow-up work showing its biomedical potential won scientists the Nobel Prize in 2006. In plants, RNAi was discovered in petunias. When breeders tried to transform one gene to cause brighter pinks and purples, they wound up with white flowers instead. The gene for flower color had been silenced.

"Before they were domesticated, soybeans were black or brown due to the different anthocyanin pigments in the seed coat," says Sarah Jones, a research specialist working with Vodkin on the study. "Breeders got rid of the dark pigments because they can discolor the oil or soybean meal during extraction processes."

Vodkin clarifies, "The yellow color was a naturally occurring RNAi mutation that happened spontaneously, probably at the beginning of agriculture, like 10,000 years ago. People saw the yellow beans as different. They picked them up, saved them, and cultivated them. In the germplasm collections of the wild soybean, Glycine sojae, you don't find the yellow color, only darkly pigmented seeds."

Previous work from the team showed that yellow soybeans result from a naturally occurring gene silencing process involving two genes. Essentially, one of the genes blocks production of the darker pigment's precursors. But the researchers weren't sure why black pigments sometimes reappear, as in saddle-patterned beans. Now they know.

Vodkin and her team searched for beans with unusual pigmentation in the USDA soybean germplasm collection, housed at U of I. The collection contains thousands of specimens, representing much of the genetic diversity in domesticated soybean and its wild relatives.

"We requested beans with this black saddle pattern," Jones recalls. "We wanted to know if they all get this pattern from the same gene." Some of the samples had been collected as far back as 1945.

The team used modern genomic sequencing techniques, quickly sifting through some 56,000 protein-coding genes to identify the one responsible for the pattern. The lead author, Young Cho, made the discovery as a graduate student when he noticed a defect in the Argonaute5 gene. The team looked at additional beans with the saddle and found that the Argonaute5 gene was defective in a slightly different way in each of them.

"That's how you prove you found the right gene," Vodkin says, "because of these independent mutations happening at different spots right in that same gene."

When the Argonaute5 gene is defective, the silencing process - which normally blocks the dark pigment and results in yellow beans - can no longer be carried out. The gene defect explains why the dark pigments show up in the saddle beans.

Before the team's discovery, there were very few examples of how gene interactions work to achieve silencing in naturally occurring systems. Today, bioengineers use genetic engineering technologies to silence genes to produce a desired outcome, whether it's flower color, disease resistance, improved photosynthesis, or any number of novel applications.

"The yellow color in soybeans could have been engineered, if it hadn't occurred naturally," Vodkin says, "but it would have cost millions of dollars and every yellow soybean would be a genetically modified organism. Nature engineered it first." She says this study also emphasizes the value of the soybean germplasm collection, which preserves diversity for research and breeding purposes.

###

The article, "Mutations in Argonaute5 illuminate epistatic interactions of the K1 and I loci leading to saddle seed color patterns in Glycine max," is published in The Plant Cell. The study's lead author, Young Cho, is now a postdoctoral researcher for the Institute of Genomic Biology at the University of Illinois. The work was funded by the United Soybean Board, the USDA, and the Illinois Soybean Association.

Media Contact

Lauren Quinn
ldquinn@illinois.edu
217-300-2435

 @ACESIllinois

http://aces.illinois.edu/ 

Lauren Quinn | EurekAlert!

Further reports about: Agricultural Environmental Sciences RNAi beans genes pigments silencing soybean

More articles from Agricultural and Forestry Science:

nachricht New study shows producers where and how to grow cellulosic biofuel crops
17.01.2018 | University of Illinois College of Agricultural, Consumer and Environmental Sciences

nachricht Robotic weeders: to a farm near you?
10.01.2018 | American Society of Agronomy

All articles from Agricultural and Forestry Science >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Scientists decipher key principle behind reaction of metalloenzymes

So-called pre-distorted states accelerate photochemical reactions too

What enables electrons to be transferred swiftly, for example during photosynthesis? An interdisciplinary team of researchers has worked out the details of how...

Im Focus: The first precise measurement of a single molecule's effective charge

For the first time, scientists have precisely measured the effective electrical charge of a single molecule in solution. This fundamental insight of an SNSF Professor could also pave the way for future medical diagnostics.

Electrical charge is one of the key properties that allows molecules to interact. Life itself depends on this phenomenon: many biological processes involve...

Im Focus: Paradigm shift in Paris: Encouraging an holistic view of laser machining

At the JEC World Composite Show in Paris in March 2018, the Fraunhofer Institute for Laser Technology ILT will be focusing on the latest trends and innovations in laser machining of composites. Among other things, researchers at the booth shared with the Aachen Center for Integrative Lightweight Production (AZL) will demonstrate how lasers can be used for joining, structuring, cutting and drilling composite materials.

No other industry has attracted as much public attention to composite materials as the automotive industry, which along with the aerospace industry is a driver...

Im Focus: Room-temperature multiferroic thin films and their properties

Scientists at Tokyo Institute of Technology (Tokyo Tech) and Tohoku University have developed high-quality GFO epitaxial films and systematically investigated their ferroelectric and ferromagnetic properties. They also demonstrated the room-temperature magnetocapacitance effects of these GFO thin films.

Multiferroic materials show magnetically driven ferroelectricity. They are attracting increasing attention because of their fascinating properties such as...

Im Focus: A thermometer for the oceans

Measurement of noble gases in Antarctic ice cores

The oceans are the largest global heat reservoir. As a result of man-made global warming, the temperature in the global climate system increases; around 90% of...

All Focus news of the innovation-report >>>

Anzeige

Anzeige

Event News

10th International Symposium: “Advanced Battery Power – Kraftwerk Batterie” Münster, 10-11 April 2018

08.01.2018 | Event News

See, understand and experience the work of the future

11.12.2017 | Event News

Innovative strategies to tackle parasitic worms

08.12.2017 | Event News

 
Latest News

Gran Chaco: Biodiversity at High Risk

17.01.2018 | Ecology, The Environment and Conservation

Only an atom thick: Physicists succeed in measuring mechanical properties of 2D monolayer materials

17.01.2018 | Physics and Astronomy

Fraunhofer HHI receives AIS Technology Innovation Award 2018 for 3D Human Body Reconstruction

17.01.2018 | Awards Funding

VideoLinks
B2B-VideoLinks
More VideoLinks >>>