Plants use antibiotic-producing bacteria to protect themselves against infection.
We’re all used to taking antibiotics when we are ill, but did you know that plants use them too? New research from scientists in the Netherlands and USA published this month in Science has revealed that antibiotic-producing bacteria that live in the soil can protect plants roots from infection.
One of the most important new fields of biology is the study of microbiomes – communities of microorganisms that are closely associated with animals and plants. The human microbiome is vital to our health, with the microorganisms in our gut helping us to digest food, for example.
The trouble is, most of the bacteria and fungi that make up these microbiomes cannot be grown in a laboratory, as we simply don’t know the conditions in which they are able to grow. Thankfully with the rapid advancement of DNA and RNA sequencing technologies it is possible to identify the microbes without ever having to grow them – known as metagenomics.
The new study, lead by Dr Rodrigo Mendes, looked at the bacteria associated with the plant rhizosphere, the region of soil close to the roots. The team compared two types of soil: one with disease-suppressive qualities, able to prevent the growth of fungal plant-pathogens, and another which was not able to impede fungal growth.
By comparing the microbes present in each soil type the researchers identified antibiotic-producing bacteria belonging to the Pseudomonadaceae that might protect plant roots from fungal infection. They went on to engineer a strain of this bacterium that could no longer make the antibiotic and found that although it could colonise the rhizosphere efficiently, it no longer offered protection to the plant against fungal infection.
This work expands our knowledge of the plant rhizosphere and antibiotic use, once thought to be restricted to human medicine, but now known to be used by both plants and insects as protection against infection of themselves, their offspring or the organisms they use as food.
Mendes R., Kruijt M., de Bruijn I., Dekkers E, van der Voort, M, Schneider, JHM et al. (2011). Deciphering the Rhizosphere Microbiome for Disease-Suppressive Bacteria. Science 10.1126/science.1203980
Posted by Matt Hutchings