Distribution and differential expression of (E)-4,8-dimethyl-1,3,7-nonatriene in leaf and floral volatiles of Magnolia and Liriodendron taxa

Analyses of volatiles emitted from artificially damaged leaves attached to branches of seven Magnolia taxa revealed the presence of (Z)-3-hexenyl acetate, (Z)-3-hexenol (the green odor compounds), and several mono-and sesquiterpenes, e.g., (Z)- and (E)-beta-ocimene and caryophyllene. An herbivore-induced leaf volatile, (E)-4,8-dimethyl-1,3,7-nonatriene, known as a predator attractant in agricultural plants, was emitted 4-6 hr after leaves were damaged in M. hypoleuca. The damaged leaves of M. grandiflora, however, immediately released (E)-4,8-dimethyl-1,3,7-nonatriene. Undamaged leaves of Magnolia species examined did not emit volatile compounds. In addition, detached flowers of six Magnolia taxa and Liriodendron tulipifera also emit (E)-4,8-dimethyl-1,3,7-nonatriene as a floral volatile (up to 30% in some species); the chemical was also emitted from the intact flowers of M. heptapeta and M. salicifolia.