The bean yellow mosaic virus (BYMV) is a pathogenic virus that can affect any pulse crop. It creates mosaic patterns on the plant leaf, causing leaf curling, stunted growth, flower and pod abortion, and reduced seed quality and yield losses.
It can even cause the loss of the entire plant.
Yet, only preliminary research has begun on the virus, as it has only recently been found in the Canadian prairies.
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Simin Sabaghian is a post-doctoral fellow in molecular plant pathology and insect vectors at the University of Saskatchewan, working in Dr. Sean Prager’s lab.
Sabaghian’s research focuses on studying early signs of infection, then breaking the plant down to understand how the virus attacks the plant.
“The virus hijacks the plant cell to make copies of itself, which makes the visible symptoms such as the mosaic patterns,” she said.
To test for virus infection, they are using a PCR test similar to what was used to test for COVID-19.
With funding from the Western Grains Research Foundation (WGRF), the Saskatchewan Pulse Growers (SPG) and the Ministry of Agriculture through the Agriculture Development Fund (ADF), she is trying to get ahead of the virus by studying its transmission and symptoms.
“Early detection,” said Sabaghian. “If we detect the virus early, we can propose management strategies so farmers have a chance.”
There are 14 different locations in which samples were collected from, trying to cover as many regions as possible.
At the annual Soils and Crops Conference in Saskatoon March 4, Sabaghian presented her work on the damage BYMV can cause on peas.
After seven days, early symptoms appeared on the plant. The yellow mosaic pattern on the leaves appeared after two weeks, and after a month there is nearly nothing left of the plant.
The virus is commonly carried by pea aphids, which means it can quickly transmit between plants and cause extensive damage to peas, lentils, soybeans and faba beans.
The virus can also be transmitted through equipment use, as the equipment can touch and rub one plant, then touch another and pass on the virus.
Once the plant is infected, there is no application or treatment to cure the plant. The best management practice then is to remove the plant from the field, or prevent the possible vectors, such as spraying aphids or other pest vectors.
Otherwise, it comes down to using more resistant varieties to prevent infection.
“It’s the early detection. For example, if I found this virus from a field, I can tell the farmer to not use that variety next year,” said Sabaghian. “If they don’t know what the virus is, if they keep using the same variety, they are just unintentionally causing the spread of the virus.”
Then they extract RNA and DNA, and sequence the full genome and cross-check it against the National Center for Biotechnology Information (NCBI) and Geneva databases to confirm its identity.
“We perform different tests in the lab,” said Sabaghian. “First of all, we need to infect the healthy plant the samples we detected before. We need to study to potential insect vectors, such as aphids, then we test the transmission.”
Studying the transmission and symptoms of the virus, coupled with the genetic sampling can provide a better understanding of what parts of the plant the virus attacks, allowing geneticists to create a more resistant plant.
“This phase is crucial because it helps us to identify the weak points,” said Sabaghian.
So why hasn’t this virus been an issue in pulses in years past?
“It was not common to find a virus around the Prairies, especially in Saskatchewan,” said Sabaghian.
“Climate change. The weather is warmer, so we have more aphids in the summer, which is the main vector of the virus, transmitting it from each plant. The last two, three years, the reporting of the virus for the first time in Canada is higher than the past.”
Bean yellow mosaic virus isn’t the only potential pathogen endangering pulse crops across the prairies. Also being studied for early detection and potential resistance genetics are pea seedborne mosaic virus (PSbMV), bean leaf roll virus (BLRV) and pea streak virus (PSV), which have all been found and observed in the prairies.
But like the BYMV, these haven’t been a prominent issue for farmers in the past. The potential danger of these viruses is why research continues, so agronomists and farmers can get ahead of these viruses before they become a larger issue for pulse growers.
