Allelopathy and Identification of Volatile Components from the Roots and Aerial Parts of Bunge.

The volatile compounds produced by plants play an important role in plant growth, plant communication, and resistance to biological and abiotic stresses. var. () is a perennial herbaceous plant (Leguminosae) that is widely cultivated in northwest China. The bioactive compounds in its root have shown various pharmacological activities. Root rot disease caused by spp. often occurs in planting with increasing severity in continuous monoculture. It is currently still unclear what are the effects of the volatile compounds produced by fresh on itself, other crops cultivated on the same field after , pathogen, and rhizobia. In this study, we found that seed germination and seedling growth of , lettuce ( L.), and wheat ( L.) could be affected if they were in an enclosed space with fresh tissue. Additionally, 90 volatile compounds were identified by SPME-GC-MS from whole plant during the vegetative growth, 36 of which were specific to aerial parts of (stems and leaves, AMA), 17 to roots (AMR), and 37 were found in both AMA and AMR. To further identify the allelopathic effects of these volatile compounds, five compounds (1-hexanol, ()-2-hexenal, (,)-2,4-decadienal, hexanal, and eugenol) with relatively high content in were tested on three receptor plants and two microorganisms. We found that (,)-2,4-decadienal and ()-2-hexenal showed significant inhibitory effects on the growth of and lettuce. One-hexanol and hexanal suppressed the growth of wheat, while eugenol showed a similar effect on all three plant species. Moreover, the activities of these compounds were dose dependent. Notably, we discovered that ()-2-hexenal and eugenol also inhibited the growth of the pathogen by as high as 100%. Meanwhile, all five compounds tested suppressed the rhizobia . In summary, this study furthered our understanding of the comprehensive allelopathic effects of the main volatile components of .