Vaccinating plants against future attack.

Vaccinating plants against future attack.

Exposing corn plants to some naturally occurring volatile chemicals can prime their defences to respond more strongly to attack from herbivorous insects such as beet armyworms. One day it might be possible to use green leafy volatiles (GLVs) to protect plants from pest attack, thereby reducing the use of chemical pesticides. Now US researchers claim to have discovered how the chemicals protect corn plants, bringing commercial GLV use a step closer to reality.

A team of researchers led by James Tumlinson at Pennsylvania State University, US, suggests that GLVs perform a ’vaccination’ process by increasing jasmonic acid biosynthesis and volatile organic compounds. Like vaccines in animals, GLVs turn on the plant defence mechanism, but do not push it to full strength. If the plant is not attacked, then it does not waste energy producing defences, but if attacked, the response is more rapid and stronger. According to the researchers, primed plants also attract almost twice as many natural parasites and insect predators as unprimed plants do, thus enhancing the defensive armoury.

The researchers now intend to extend the work to other crops such as cotton and tobacco.

John Pickett, head of the biological chemistry division at Rothamsted Research, UK, says: ’This paper shows for the first time in nature a role for GLVs in plant-plant interactions. It demonstrates clearly the induction of defence potential before attack takes place’.

Hamish Kidd