This press release is available in German.
They dominated the earth for 200 million years and numerous different species can still be found all over the world: mosses, horsetails and ferns. Researchers from the Max Planck Institute for Chemical Ecology in Jena, Germany, have now found out that bracken ferns (Pteridium aquilinum) do not release any volatiles when they are attacked − unlike many of the now dominant and evolutionary younger flowering plants. Such an emission of volatile compounds may attract the pest insects' enemies, such as ichneumon wasps or predatory bugs, that parasitize herbivores. Nevertheless, volatile emission could be also elicited in fern fronds, if they had been treated with plant hormone jasmonic acid. Jasomonic acid induces the synthesis of volatile substances in flowering plants. This suggests that ferns can in principle mobilize this kind of defense reaction. However, they do not use this indirect defense to fend off herbivores.
Only few herbivores attack ferns
Ferns are so-called vascular cryptogams, because they don't produce flowers and seeds like the currently largest group of plants, the spermatophytes or seed plants. Ferns reproduce and spread entirely via spores. Their metabolic activities and especially their defenses against herbivores, however, are similarly efficient in comparison to flowering plants. Ferns can be found in large populations all over the world, although their evolutionary age is more than 400 million years.
Botanists consider the bracken fern Pteridium aquilinum as one of the most widely distributed plant species. It can be found in the most different habitats. Herbivores attack bracken ferns strikingly less often than flowering plants. One explanation for this phenomenon could be that fern fronds contain especially toxic substances that keep pest
|Contact: Dr. Wilhelm Boland|
Max Planck Institute for Chemical Ecology