Virus resistance in plants holds promise for agricultural crops

In searching for ways to improve crop production and, ultimately, address food security in an era of climate change, three intrepid biologists from York University – Professor Katalin Hudak, researchers Kira Neller and Alexander Klenov (who are based in the Hudak Lab) – focused their research on the American pokeweed plant. Why? This plant is recognized for a protein that inhibits the replication of several plant and animal viruses. What the trio found was how the genes in the plant work in concert to stave off viruses.

This discovery, if applied to agriculture, has great potential. “We anticipate the discovery could improve the resiliency of agricultural crops,” Hudak explains. “Our research has become increasingly relevant given the impacts of climate change,” she adds.

green plant with red stems
American pokeweed. Image: Wikipedia

This vital work, published in Frontiers in Plant Science, was funded by the Natural Sciences and Engineering Research Council of Canada (NSERC) and scholarships from the Canada Graduate Scholarships-Master’s (CGS-M) Program.

Climate change and food production are intimately connected. A long, hot summer without rain or a spring with too much rain and extreme flooding will have a profound effect on crops and livestock. Warmer weather also expands the habitat of insect pests, which are important vectors  ̶  organisms that don’t cause disease but spread infection by conveying diseases from one host to another  ̶   for plant diseases.

“Our research has become increasingly relevant given the impacts of climate change.” – Katalin Hudak

Concern over climate change and its impact on food production have increased our need to develop crops plants better able to survive stress. Some plants are remarkably hardy, being able to produce dozens of defense compounds essential for their survival. These factors help the plants respond to environmental changes and to fend off viruses. For example, American pokeweed, native to the eastern United States but also found in southern Ontario, has potent defence proteins against a range of viruses, fungi and insects.

Above: From left, Katalin Hudak, Kira Neller and Alexander Klenov

Pokeweed foliage and fruit are highly toxic to animals and humans. The compounds it contains can cause nausea, vomiting, low blood pressure and possible death due to arrhythmia of the heart. Interestingly, pokeweed has been used in traditional medicine to treat a variety of ailments from tonsillitis to mumps to acne. It was even used as a weight loss drug in the 1890s.

Hudak, Neller and Klenov were interested in this plant, which can grow up to 8 feet tall, because of its unique properties – particularly, the ability to fight viruses.

Researchers treated plants with jasmonic acid, a stress hormone

In this study, the researchers sprayed plants with jasmonic acid, a plant hormone important in defense against viruses and insects. Twenty-four hours after treatment, the researchers harvested leaves from the plants. Samples were sent to Toronto’s Hospital for Sick Children for RNA sequencing  ̶  a new and revolutionary technology that determines the genetic sequence, letter by letter, of every ribonucleic acid (RNA) message in the plant. This essentially provides a snapshot of the gene regulation, and stress response, going on at the time when the plants were harvested. Remarkably, the trio of researchers was able to examine over 400 million reads using sophisticated computer algorithms.

The researchers used a new and revolutionary technology that determines the genetic sequence, letter by letter, of every ribonucleic acid (RNA) message in the plant.

Findings could lead to improvements in agricultural crops

The researchers discovered that while the untreated plants had relatively balanced gene expression, the jasmonic-acid-treated plants had a significantly higher abundance of defense proteins. “We identified genes that are significantly affected by jasmonic acid and could mediate defense against disease, and herbivores, in American pokeweed,” Hudak explains. This was a first.

The trio believes this discovery of beneficial genes in this plant could improve the resiliency of agricultural crops. It may be especially promising for sugar beet production because sugar beets are closely related to pokeweed.

two sugar beets complete with foliage
Sugar beets

Hudak’s research team intends to undertake further research on pokeweed. “A wealth of genomic knowledge remains unknown in this species, as large-scale sequencing projects have not been reported for pokeweed or any other members of its plant family,” Hudak says.

The article, “The pokeweed leaf mRNA transcriptome and its regulation by jasmonic acid,” was published in Frontiers in Plant Science (2016). For more information on Hudak’s work, visit her faculty profile. For more information on the Canada Graduate Scholarships-Master’s (CGS-M) Program, visit the CGS-M website.

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By Megan Mueller, manager, research communications, Office of the Vice-President Research & Innovation, York University,