Bacterium disables tomato plant’s defences - stealthily

December 8th, 2008 - 1:27 pm ICT by IANS  

London, Dec 8 (IANS) A bacterium disables the tomato plant’s defences stealthily, activating disease and blight, according to a new study.The new finding focuses on a pathogen which causes bacterial speck disease in tomato plants. This bacterial invasion causes black lesions on leaves and fruit.

Scientists found the pathogen is very effective at attacking tomato plants because it deactivates and destroys receptors which normally alert the plant to the presence of a dangerous disease - in the same way that an intruder would deactivate the burglar alarm before gaining entry to a house.

Severe infection can cause extensive and costly damage to tomato crops, and researchers believe that understanding more about how this microbe works could lead to new ways of tackling it and other plant diseases.

John Mansfield professor at Imperial College London’s Department of Life Sciences, co-author of the paper, said “once the receptors have been taken out, the plant’s defences are ‘offline’ and the bacterium is able to spread rapidly, feeding on the plant without encountering any kind of resistance.”

Together with colleagues at the Max Planck Institute in Cologne and Zurich-Basel Plant Science Centre, Mansfield used an experimental model plant called Arabidopsis, which is also affected by the disease, to examine what happens at the molecular level when bacterial speck infects a plant.

The team found that the pathogen injects a protein into the host cell, which then deactivates and destroys, from the inside, receptors on the cell’s surface which are designed to alert the plant to the presence of invading microbes, said an Imperial College release.

These findings were published in Current Biology.

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