Indole is a constituent of herbivore-induced volatiles of many
plant species.Volatile indole is not emitted from physically wounded rice
plants. However, the emission was detected from both insect infested
and JA treated plants (Fig. 4B). This finding implies that an
elictor might be present in the regurgitate of the herbivore and
jasmonate may be involved in signal transduction. However, it
has been shown that simple mechanical damage is not sufficient
to induce emission of volatiles while continuous mechanical damage
might be sufficient trigger release of specific volatiles (Bricchi
et al., 2010). This extensive type of wounding has not yet been assayed
for indole emission in rice. Volatile emission in maize is induced
by the elicitor volicitin (Alborn et al., 1997) and ZmIgl
transcript is elicited by the application of related fatty acid-amino
acid conjugates (Frey et al., 2004). Fatty acid-amino acid conjugates
(FACs) have been identified in the oral secretion of several
Lepidotera species (Spiteller and Boland, 2003); however, at present
the nature of the proposed elicitor in the FAW oral secretion
is unknown.