Climbing plants, such as kudzu (Pueraria lobata), Japanese honeysuckle (Lonicera japonica), and burr cucumber (Sicyos angulatus) pose serious problems in many countries. They have negative impacts on productivity of crops in farmlands and could alter the landscape of natural habitats. Moreover, these climbing weeds also pose risks to mammalian safety and could potentially reduce the efficiency of power supply in urban communities as they invade electrical grids. In response to the request of electric power companies and government agencies in Japan, we design experimentation for the screening of allelochemicals for the effective management of climbing plants.

We have developed several bioassay systems to evaluate the effect of allelochemicals on gravitropism and climbing. Practical assays to prevent climbing of vine were also developed. We have evaluated the phytotoxicity of reported allelochemicals and new candidates including amino acids, polyphenols, flavonoids, alkaloids, and among others, and have found several candidates. Cis-cinnamic acid and its derivatives from Spiraea thunbergi, hinokitiol and its derivatives from Hiba (Thujopsis dolabrata), and chalcone derivatives from Ashitaba (Angelica keiskei), all native plants to Japan, were among those that impair gravitropic response.

Using transcriptome analysis, the modes of actions of the candidate allelochemicals were evaluated. Cis-cinnamic acid appears to influence the expression of auxin-responsive gene families in Arabidopsis. Auxins are putative mediators of gravitropism in plants. Our results suggest that exogenous application of these allelochemicals may effectively manage climbing plants.

Presently, we plan to develop derivatives by organic synthesis and conduct field evaluations for the development of practical management measures for climbing weedy plants.