麻豆传媒AV

WESTERN PRODUCER — Bacteria have been on Earth for much longer than humans.

The first ancestors of humans with the ability to walk on two legs arrived about four million years ago, says the Smithsonian Museum of Natural History.

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In comparison, fossil evidence suggests that microbes and bacteria first appeared about 2.5 to 3.5 billion years ago.

In between those two extremes, land plants likely appeared 500 million years ago, according to science.org.

During those billions of years, where plants and bacteria co-existed before the arrival of humans, the two groups learned how to cooperate and live in synergy.

That co-operation is still happening in 2024.

“Bacteria were on earth for two billion years before higher organisms including plants. And plants evolved within and with a sea of bacteria,” said Manish Raizada, a University of Guelph scientist who specializes in microbes that inhabit plants.

“I think we are tremendously underestimating the extent to which plants already … rely on bacteria (and) are manipulated by bacteria.”

Raizada gave the example of the plant hormones that stimulate growth, noting they are connected to microbes.

“They actually come from bacteria, in terms of evolution,” he said. “We are certainly underestimating the power and potential of bacteria.”

Raizada and thousands of other scientists in North America, Asia and elsewhere are trying to exploit the relationship between plants, bacteria and other microbes.

Major crop science companies are also investing billions into biological products in efforts to improve crop health and food production.

In 2022, for instance, Corteva Agriscience spent US$1.2 billion to acquire Stoller, a biologicals firm from Texas.

“Biologicals provide farmers with sustainably advantaged tools that complement crop protection technologies, and collectively, can work to address global challenges around food security and climate change,” said Chuck Magro, Corteva chief executive, in 2022.

This sort of investment and the scientific focus on bacteria, fungi and micro-organisms has exploded in the last five to seven years, thanks to a number of factors.

One of those is DNA sequencing.

The cost to sequence the genetic code of a single organism has dropped dramatically since about 2017. It used to cost thousands or tens of thousands of dollars. Now it could be $50 or less.

“The cost and power of those technologies and the data processing (needed) to interpret that (genetic) sequencing, has really dramatically improved,” Raizada said. “What’s possible today was impossible five years ago.”

Another factor is increased public attention on climate change and the global desire to cut greenhouse gas emissions from agriculture. The thinking is that biologicals could reduce the use of fertilizer, pesticides and other crop inputs, thus reducing emissions.

More biologicals and fewer crop inputs could be possible, but so far, the performance of biological products is mixed at best.

Field trials on nitrogen-fixing biologicals, conducted by the Manitoba Pulse & Soybean Growers from 2019-23, found the commercial products were not effective on peas, dry beans and soybeans.

“So far, we’ve tested 12 products over 28 trials in three different crops …. We’ve not seen a yield increase with any of these products that we’ve tested,”” said Laura Schmidt, a production specialist with MPSG, earlier this year.

Despite such results, biological products do work in some situations but they rarely perform in all situations, because an individual bacterium is not adapted for wide range of growing conditions and environments, Raizada said.

“A seed company would not put (out) a single variety of canola across (different) environments. They would never expect that to work. The whole basis of seed companies is breeding. You have to adapt to different environments and needs.

“That’s the mistake that’s been made in biologicals.”

For instance, a barley variety that produces 150 bushels per acre in France is not going to perform the same way in southern Saskatchewan.

Plant breeders in Canada must modify and adapt the French barley so it’s suited for the drier and shorter growing season of Saskatchewan. The same sort of thing is needed with bacteria and microbes, Raizada said.

As well, testing shows a certain species of bacteria will collaborate with one variety of wheat, but not another.

“We have biologicals that do great outdoors in certain wheat or corn varieties. And they do terribly … in other varieties,” Raizada said, explaining that dozens of genes are involved in the plant-microbe relationship.

“A plant doesn’t just let every microbe in. There’s a little dance that goes on …. ‘Hey, are you my friend?’”

In an ideal world, biological products would be sold with a disclaimer saying they work well with certain crop varieties but not others, Raizada added.

“A biological (should) come with those recommendations.”

Many scientists are studying soil micro-organisms and how they could be used to deliver more nutrients to the crop or protect the crop from disease.

Raizada is less interested in the soil.

In his research at the U of Guelph, he spends most of his time on the plant microbiome – the community of microbes that live within and on plants.

“I’ve shied away from soil microbes because soil is the most microbially rich habitat on earth,” he said.

“To me, the complexity of the soil microbiome is beyond my capacity …. I’m much more optimistic that in the short run … the microbes that inhabit plants, we can manipulate or select for those.”

He’s particularly interested in micro-biome inheritance in crops.

The basic idea is that plants will pass certain bacteria to the next generation through the seed.

If scientists can modify which bacteria are inherited, maybe they can design plants more resistant to disease or better at retrieving nutrients from the soil.

Researchers might know that 15 types of bacteria in the plant help control fusarium head blight in cereal crops, Raizada said.

Maybe it’s possible to design plants that pass those beneficial microbes to the next generation, creating a crop with the ability to resist fusarium head blight.

“Through breeding, you’re hoping to select for heritable (microbes) in the seed …. Let’s select for more of those bacteria.

“(But) the concrete results of heritability (is) in its infancy. There’s not a lot known. That’s a big focus of my lab.”

There are examples in which biologicals don’t meet grower expectations, but there are also plenty of success stories.

Many corn seeds sold in North America are coated with bacteria that help ward off diseases in the soil.

Syngenta sells a seed treatment called Draco.

“Draco features the bacteria Bacillus licheniformis and Bacillus subtilis. In corn and soybeans, it provides partial suppression of seed rot and seedling blight caused by Rhizoctonia solani and root knot nematode,” says a Syngenta press release.

Raizada explained that Bacillus is commonly used in agriculture because it can withstand a range of conditions.

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“They are coated onto seeds …Think of Bt (corn). The B in Bt is Bacillus,” he said.

“The Bacillus family, they can form spores … they can withstand drought …. Bacilli are here in agriculture. And the lesson is, you need to have bacteria that are resilient to the environment.”

With many biologicals on the market and more to come, it’s difficult to sort out what works and what’s a waste of money.

One key word is ‘adapted.’

Some bacteria and biologicals are adapted for the conditions on a zero tillage, wheat-canola farm in Alberta, but not adapted for a corn-soybean-canola farm in southern Manitoba.

If growers are curious, they should try a biological on a small plot or test strip, Raizada said. It might perform as advertised, but a lot depends on crop variety, farm practices and soil conditions.