Bacteria from tobacco plant roots provide protection against sudden-wilt disease

A tobacco field in Tennessee (Credit: ajgarrison3. CC BY 2.0)
A tobacco field in Tennessee (Credit: ajgarrison3 via Flickr. CC BY 2.0)

As humans, we rely on the community of microbes in our gut to help us thrive. These microorganisms, collectively known as the gut microbiome, serve many purposes. Chief among them are helping us breakdown food into nutrients that our bodies can absorb and use and preventing harmful pathogens from taking hold.

So what is a poor plant to do without a gut? Use its root microbiome of course! The root microbiome is the collection of bacteria and fungi that live in the soil in and around the plant’s roots. The root microbiome is remarkably diverse and fluid in its composition. One gram of soil from the roots can contain up to one billion bacteria from as many as 10,000 different species. To compare, one millilitre of intestinal fluid from a human contains similar numbers of microbial cells but they represent only 500 to 1000 different species.1

The relationship between a plant and its microbial co-dwellers is generally one of give and take—the plant secretes carbon-rich sugars through its roots to feed the microbes and the microbes help the plants take up more nutrients from the soil and prime its immune system. Beyond this, we know surprisingly little about just what and how exactly all those microbial partnerships are contributing to plant health.

Dr. Ian Baldwin leads a group of researchers in the department of molecular ecology at the Max Planck Institute for Chemical Ecology in Germany. His team uses the wild tobacco plant Nicotiana attenuata to study the complex interactions between plants and microbes. In a paper published last week in the Proceedings of the National Academy of Sciences, the researchers describe how the root microbiome rescued plants from sudden-wilt disease. Continue reading

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Between the Pages: Missing Microbes

Welcome to the first instalment of Between the Pages, where I read and review books about science. 

Missing Microbes:  How the overuse of antibiotics is fueling our modern plagues. By Martin J. Blaser, MD. (HarperCollins)
Missing Microbes: How the overuse of antibiotics is fueling our modern plagues. By Martin J. Blaser, MD. (Source)

If science was Hollywood, the microbiome would be its new It Girl. The paparazzi report on its every move to see which new disease or condition it will be associated with next. Fans clamor to buy the newest supplement that promises to restore your microbiome to a “healthy” state.

Feeling a bit late to the party? Let’s bring you up to speed. Simply put, the human microbiome is the collection of microorganisms that share our body. These include the bacteria, viruses, and fungi that live on our skin, in our mouths and digestive tracts, and in all our bodies’ little nooks and crannies. Even though they are microscopic in size, their numbers are daunting: there are 10 microbial cells for every human cell in our body! Most of these microorganisms are beneficial to us. They help us digest food and extract nutrients that we wouldn’t be able to get on our own. They strengthen our immune system so that it can better recognize and fight off invading pathogens. They prevent harmful microbes from taking hold in our bodies by depriving them of important nutrients. So, that’s great! Three cheers for our microbiome!

But what happens when our microbiome changes and the balance of species is shifted? As Dr. Martin Blaser argues in his book Missing Microbes, that’s when things start to go wrong. Continue reading