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

In an earlier study, we demonstrated plant-plant interactions mediated by volatiles released from lima bean leaves infested by spider mites (Tetranychus urticae) (Nature 406 (2000a) 512, Biochem. Biophys. Res. Commun. 277 (2000b) 305). In the present study, we further show that, under laboratory conditions, volatiles emitted from T. urticae-infested lima bean plants activate transcription of genes encoding pathogenesis-related proteins and phenylalanine ammonia-lyase in leaves of intact neighboring plants. This finding indicates that intact lima bean plants may be responsive to volatile signals. Further, as green leaf volatiles (GLVs) are released from green plants in response to mechanical damage caused by herbivores, we studied possible involvement of GLVs in plant-plant interaction. We found that (Z)-3-hexenol, (E)-2-hexenal, and (Z)-3-hexenyl acetate, induced the expression of defense genes in uninfested leaves. This finding suggests that GLVs may act as signal compounds in plant-plant interactions. (C) 2001 Elsevier Science Ltd. All rights reserved.