JAN 22, 2019 7:08 PM PST

Towards a Better Understanding of Genetic Modifications in Plants

WRITTEN BY: Carmen Leitch

Scientists have taken a close look at what happens on the molecular level when DNA is inserted into the genome of a plant. They determined the genetic sequence and epigenetic features of plants that had been genetically modified using routine methods, and have shown that it’s possible to find out exactly how genetic engineering affects plants. The work has been reported in PLOS Genetics.

  Arabidopsis thalania flower / Credit: Pixnio

"This was really a starting point for showing that it's possible to use the latest mapping and sequencing technologies to look at the impact of inserting genes into the plant genome," said Joseph Ecker, a professor in the Salk Institute's Plant Molecular and Cellular Biology Laboratory and head of the Genomic Analysis Laboratory and Howard Hughes Medical Institute Investigator.

Scientists use a bacterium called Agrobacterium tumefaciens when they want to insert a gene into a plant, whether to change a plant’s growing conditions, nutritional content, or for research purposes (as explained in the video). The bacterium is naturally able to transfer genetic material into the plant genome, which was discovered after the microbe was found causing tumors in trees.

Scientists have learned that the transfer-DNA (T-DNA) capabilities of Agrobacterium might also cause unintended changes to the physical and chemicals characteristics of plant DNA. "Biotech companies spend a lot of time and effort to characterize transgenic plants and disregard candidates with unwanted changes without understanding from a basic biological perspective why these changes may have occurred," said Ecker. "Our new approach offers a way to better understand these effects and may help to speed up the process."

"The biggest unknown was whether, and how many copies of, the T-DNA were inserted at the same time as the piece you wanted," noted the co-first author of the work Florian Jupe, a former Salk research associate now with Bayer Crop Science. Because many copies of a gene might be inserted, it can be challenging to understand exactly what’s happened using typical molecular techniques; repetitive stretches are tough to sequence.

In this work, the scientists combined cutting-edge tools - nanowire sequencing and optical mapping to a typical plant research model, Arabidopsis thaliana. The team found that between one and seven different insertions or rearrangements happened in a range of patterns including inversions and scrambles.

After also looking at histones, the proteins that help package DNA and in turn, impact gene activity, the researchers found other changes due to T-DNA. Some histone modifications near the insertion disappeared or appeared. "Now we have the first high-resolution insights on how T-DNA insertions can shape the local epigenome environment," said Zander.

The ideal situation would be for T-DNA to only insert one functional copy of the gene of interest, without causing other effects, the researchers said. Their work shows that to be an unlikely scenario; however, it is possible to fully assess the impact of the insertion.

"With Arabidopsis, it's relatively easy because it has such a small genome, but because of continued improvements in DNA sequencing technology, we expect this approach will also be possible for crop plants," added Ecker. "Current methods require screening of hundreds of transgenic lines to find good performing ones, such as those without extra insertions, so this technology could provide a more efficient approach."

Sources: AAAS/Eurekalert! via Salk Institute, PLOS Genetics

About the Author
  • Experienced research scientist and technical expert with authorships on 28 peer-reviewed publications, traveler to over 60 countries, published photographer and internationally-exhibited painter, volunteer trained in disaster-response, CPR and DV counseling.
You May Also Like
APR 21, 2020
Health & Medicine
How to Read COVID-19 News (Without Going Crazy)
APR 21, 2020
How to Read COVID-19 News (Without Going Crazy)
  It can feel like COVID-19 news is consuming the country, and taking all the toilet paper and N95-masks with it. N ...
MAY 15, 2020
Genetics & Genomics
It Only Takes One Gene For Virgin Birth in Honey Bees
MAY 15, 2020
It Only Takes One Gene For Virgin Birth in Honey Bees
Cape honey bees are found in South Africa, and while they look similar, they are very different from other subspecies of ...
JUN 22, 2020
Microbiology
A Human Gut Microbe Can Help Maintain Healthy Cholesterol Levels
JUN 22, 2020
A Human Gut Microbe Can Help Maintain Healthy Cholesterol Levels
The world is full of microorganisms, and our bodies are one of the many places they have colonized. These gut microbes c ...
JUN 01, 2020
Neuroscience
New Path to Gene Therapy for ALS
JUN 01, 2020
New Path to Gene Therapy for ALS
Video: Todd Cohen, PhD (UNC) discusses GA protein accumulation.  At the time of this video promising research was a ...
JUN 26, 2020
Genetics & Genomics
Sled Dogs & an Ancient Siberian Dog Have a Lot in Common Genetically
JUN 26, 2020
Sled Dogs & an Ancient Siberian Dog Have a Lot in Common Genetically
Dogs have held special significance in many people's lives for thousands of years. Dogs are thought to have been domesti ...
JUL 30, 2020
Genetics & Genomics
How Are DNA Testing Companies Helping the Fight Against COVID?
JUL 30, 2020
How Are DNA Testing Companies Helping the Fight Against COVID?
One of the most puzzling characteristics of coronavirus is how some people develop severe symptoms and die from the dise ...
Loading Comments...