Humans and flea beetles seem to share at least one thing in common.
Neither likes to eat hairy food.
That shared culinary preference could one day help canola growers fight off the pesky and costly bug.
Plant scientists at the Agriculture Canada research centre in Saskatoon are working to develop a canola germplasm that will produce a hairy leaf surface at the plant’s seedling stage.
The hair-covered leaves seem to confuse the newly emerged and hungry flea beetles, said Margaret Gruber, lead researcher on the project.
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“They can’t undergo their normal behaviour to touch the plant surface and taste it the way they need to,” she said. “They just run around on it and never start feeding.”
At that point, the puzzled insects head off to find another cruciferous plant to satisfy their ravenous appetites.
Seedling leaves in a traditional canola plant have roughly 0.5 hairs, or trichomes as they are technically called, per sq. centimetre.
The genetically modified seedlings in the research project have more than 2,000 times that number.
Developing a canola variety that is resistant to flea beetles could save huge amounts of money for prairie farmers. It’s estimated that the bugs cause $150 million in damage every year, despite the $40 million a year spent on chemical control.
“Flea beetle resistant canola will provide western Canadian farmers with a means to secure and increase the safe supply of one of their most important crops,” said Gruber.
The researchers will also test the hairy-leaved seedling for drought tolerance.
This project will be financed for the next three years by a grant from the Western Grains Research Foundation’s endowment fund and the canola growers commissions in the three prairie provinces.
The genes being used to stimulate trichome development are from a distant cousin of canola called arabidopsis, a small, easy-to-study plant often used as a model by genetic researchers.
In previous research by Gruber’s team, one gene was found to produce a good density of trichomes but it reduced the plant’s growth potential. This gene was then reintroduced under the control of a promoter to try to deal with the growth problems.
Given the life cycle of the flea beetle, developing resistance at the seedling stage is crucial to reducing losses. The insects over-winter as adults and emerge in the spring just in time to feast on the canola seedlings, causing the greatest damage from early May to mid-June.
The beetles then lay eggs and die. The larvae nibble at the roots of the growing plants but do little damage. They emerge as adults beginning in mid-July and if the canola is growing well, they will eat the greenery.
The research to date has focused on developing hairy leaves at the crucial seedling stage. Gruber said it would be nice to provide similar resistance for the life of the canola plant, but such resistance could come at a price.
“One thing you don’t want to do is divert so much of the plant’s energy into protection that it actually reduces the seed yield.”
Gruber said the next step is to remake the canola plants that have been produced so far to make them bigger than those developed to date. In the initial stages of testing a new trait, the goal is to get results as quickly as possible, which means it’s not considered important to maintain the full integrity of the plant.
Another goal will be to develop trichome development on the cotyledons, the so-called “false leaves” of the embryo that appear before the true leaves, a step considered vital in fending off the flea beetles.
At the end of the three years, said Gruber, the team hopes to have a normal-sized canola plant with lots of trichomes on the seedling leaves, along with an understanding of how those leaves may contribute to drought tolerance.
