Plants on warpath

Plants use all means possible to keep herbivores at a distance. Professor Ian Baldwin from the Max Planck Institute for Chemical Ecology studies the survival methods of plants. Baldwin spoke at the Viikki campus on 14 November.

 Spodoptera exigua larva feeding on Nicotiana attenuata.

Not many know that they are surrounded by a constant battle when walking in nature. Plants use any means available to save themselves from being eaten, and herbivores try their very best to get a decent meal. Professor Ian Baldwin from the Max Planck Institute for Chemical Ecology studies the plants' means to survive in the crossfire of herbivores.

Ian Baldwin spoke at the Viikki Campus Monday seminar of the Department of Biosciences on 14 November 2011.

In his own research work, Baldwin has used Nicotiana attenuata, the wild tobacco. Wild tobacco defends itself against herbivores by excreting nicotine into its leaves.

– Nicotine, which is poisonous to people as well as other living creatures, is an effective pesticide, Baldwin says.

Recognition through saliva

Plants recognise their enemies, such as maggots, by their saliva. The various ingredients of the saliva cause a chain reaction in the plant, leading to the formation of toxic substances. The maggot saliva leaves a memory imprint in the plant, helping the plant to recognise the various herbivores and react accordingly.

Some plants suffer in silence under the attack of herbivores, but store important nutrients into their roots, which the maggots do not eat. When herbivores have disappeared from the area, these plants use their reserves and bloom free of bothersome leaf-eaters.

When necessary, plants may also change their daily rhythm. The moth acting as the pollinator of wild tobacco may leave behind an abundant supply of eggs during its nightly nectar-gathering rounds. Later, maggots galore will hatch from the eggs, ready to fill their stomachs with the leaves of the plant. If this happens, the wild tobacco may push forward its blooming time by up to 12 hours to avoid moths in the future.

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Text: Ulla Tuomainen
Photo: Wikimedia Commons
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