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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How to make rice healthier for you and the environment

Credit: Rob & Dani (CC BY 2.0)
Credit: Rob & Dani (CC BY 2.0)

What do congee, paella, risotto, and chimichangas have in common?

Rice.

Nearly half of the world’s population eats rice on a daily basis, making it a staple food for roughly 3.5 billion people. As delicious and filling as rice is, it is also the main source of arsenic for humans and its cultivation is one of the greatest contributors of methane emissions in the atmosphere. Two papers published last week in the journals PLoS ONE and Nature highlight the most recent efforts by researchers to find solutions for rice’s arsenic and methane problems. Continue reading

Protecting crops by blocking insect genes: the case for RNA interference

From the potato farms of Prince Edward Island to the cornfields of Iowa, there is a never-ending struggle between farmers and insects. Farmers apply chemical pesticides to protect their crops, which drive the evolution of more insecticide-resistant pests. This, in turn, forces farmers to use insecticides more frequently and at higher doses, which then selects for even more resistant insects. And so on and so on.

In an effort to gain the upper hand, researchers are turning to transgenic plants as a way to increase crop yield while reducing pesticide use. For example, some species of corn, cotton, and potato plants have been engineered to produce a bacterial toxin called Bt that is lethal to insects. Insects that eat leaves from Bt-producing plants ingest the toxin and are killed. But Bt isn’t effective against all agricultural pests and resistance has already been documented in some insects.

Left uncontrolled, potato beetles can completely destroy crops.
Left uncontrolled, potato beetles can completely destroy crops.

A promising area of transgenic plant research is focused on the use of RNA interference, or RNAi, to control insect pests. For any gene to be expressed, the DNA must first be read and converted into RNA. The RNA message is then decoded to produce a protein. Think of your cell as a house and the DNA as the master building plan for that house. Every time you need to make a repair, the general contractor consults the building plan and sends a message to the tradesperson to make the component that is needed. The RNA is the message that your cell uses to produce the parts needed to keep everything running smoothly. In RNAi, the RNA message is intercepted and the proper parts are not made. When the RNA message is for an essential cellular component, blocking the message can lead to cell death and if enough cells are affected, the death of the entire organism. Continue reading