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Abstract:
Volatile organic compounds (VOCs) released
from plants are known to mediate indirect defense against herbivores and trigger intra- and interplant signaling. While
systemic defense response can be mediated both via volatile
and vascular signals, it is not clear whether common
ancestry and/or plant growth forms influence the choice of
either mode in planta. We hypothesize that larger woody
plants with a complex anatomy should rely more on
volatile-mediated signaling, apparently to circumvent vascular
restrictions that slow down the communication over a
large distance. On the other hand, in smaller herbaceous
plants faster systemic response can be achieved via vascular
signaling. To investigate whether plant VOCs emission
is related to plant phylogeny or growth form, we
studied the composition of herbivory-induced plant volatiles
in 13 Brassicaceae species representing all four evolutionary lineages, because this family is characterized
by both a well-resolved phylogeny and highly diverse
growth forms. Our results revealed that woody species
consistently emitted a more complex blend of volatiles than
herbaceous species. However, phylogenetic relatedness of
the species did not explain the observed volatile emission
patterns. This emphasizes the influence of growth form,
rather than phylogenetic relationships on the variation in
plant volatile emissions. Our findings suggest that woody,
perennial plant species emit diverse VOCs, likely because
these compounds comprise a more efficient mode of defense response in these large, anatomically complex plants.
