Plant-plant interactions mediated by volatiles emitted from plants infested by spider mites

In an earlier study, we demonstrated plant-plant interactions mediated by v olatiles released from lima bean leaves infested by spider mites (Tetranych us urticae) (Nature 406 (2000a) 512, Biochem. Biophys. Res. Commun. 277 (20 00b) 305). In the present study, we further show that, under laboratory con ditions, volatiles emitted from T. urticae-infested lima bean plants activa te transcription of genes encoding pathogenesis-related proteins and phenyl alanine ammonia-lyase in leaves of intact neighboring plants. This finding indicates that intact lima bean plants may be responsive to volatile signal s. Further, as green leaf volatiles (GLVs) are released from green plants i n response to mechanical damage caused by herbivores, we studied possible i nvolvement of GLVs in plant-plant interaction. We found that (Z)-3-hexenol, (E)-2-hexenal, and (Z)-3-hexenyl acetate, induced the expression of defens e genes in uninfested leaves. This finding suggests that GLVs may act as si gnal compounds in plant-plant interactions. (C) 2001 Elsevier Science Ltd. All rights reserved.