Talking different languages: The role of plant–plant communication when
an invader beats up a strange neighborhood
Abstract
Chemical interaction through airborne volatile organic compounds (VOCs)
and root exudates plays a vital role in the mutualistic interactions
between plants. In response to these chemical cues, a single plant can
exhibit a multitude of adaption responses. Nowadays, one of the most
troublesome invasive alien species (IAS) in agriculture is common
ragweed ( Ambrosia artemesiifolia L.), which causes severe yield
losses in various crops. Given that little is known about how chemical
cues of this invader contribute to its invasiveness, we investigated the
effects of airborne VOCs and root exudates released by common ragweed on
growth and allocation patterns of wheat, soybean and maize, and the
effects of these crops on common ragweed. Exposure to VOCs released by
ragweed induced a significant reduction in the aboveground dry mass of
soybean and wheat, whereas maize showed no changes in its biomass
production. In contrast, ragweed itself was completely unaffected when
exposed to crops or a conspecific. We observed significant changes in
plant traits, such as lower biomass production, lower specific leaf area
or higher chlorophyll contents after exposure to VOCs of ragweed, all of
which can be linked to an increase in stress. Root choice test showed
that all crops and ragweed significantly avoided root exudates of common
ragweed, indicating that the root exudates as belowground cues play a
vital role in ragweed and crop chemical interactions. The present study
shows that the plant response to either above or below ground chemical
cues is highly dependent not only on the presence but also on the
identity of the neighbor pointing out the complexity of plant–plant
communication.