Skip to main content
ARS Home » Northeast Area » Ithaca, New York » Robert W. Holley Center for Agriculture & Health » Emerging Pests and Pathogens Research » Research » Publications at this Location » Publication #309763
Title: Invasive Swallow-worts: An allelopathic role for -(-) antofine remains unclear

Author
item Gibson, Donna
item Vaughan, Richard
item Milbrath, Lindsey

Submitted to: Journal of Chemical Ecology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/23/2015
Publication Date: 3/7/2015
Citation: Gibson, D.M., Vaughan, R.H., Milbrath, L.R. 2015. Invasive Swallow-worts: An allelopathic role for -(-) antofine remains unclear. Journal of Chemical Ecology. 41:202-211. DOI: 10.1007/s10886-015-0552-3.

Interpretive Summary: Two emerging invasive plant species in the northeastern United States and southeastern Canada are pale swallow-wort and black swallow-wort. Both species have multiple growth and reproductive characteristics that may play an important role in their invasiveness, including the potential to produce antofine, a known phytotoxin that has been shown in laboratory studies to affect growth of native plant species co-located in similar habitats. In these laboratory and field studies, we evaluated whether the swallow-wort-produced phytotoxin antofine was released from root surfaces into the surrounding soil environment and whether the released concentrations could affect plant growth. We also determined antofine stability under light and ambient temperatures and whether breakdown products still retained activity. Although the concentrations released from plants were much lower than that required to greatly affect plant growth, these levels might be an underestimate of what may accumulate over time in an undisturbed environment, based on the rate of breakdown of the phytotoxin under mild conditions.

Technical Abstract: Pale swallow-wort (Vincetoxicum rossicum) and black swallow-wort (V. nigrum) are two invasive plant species in the northeastern United States and eastern Canada that have undergone rapidly expanding ranges over the past 30 years. Both species possess a highly bioactive phytotoxin -(-) antofine in root tissues that has been shown to exhibit pronounced inhibition of native plant species that are co-located in habitats where swallow-wort is found. Seeds and young seedlings were found to have approximately 2-3 times the level of -(-)antofine in tissues in comparison to roots of adult plants, representing a significant increase in allelopathic specific activity. Breakdown products of antofine accumulated rapidly with exposure to light at ambient temperatures and these products did not retain biological activity. Extraction efficiencies of control soil spiked with -(-) antofine were low but easily detectable by hplc. Soil samples collected over two growing seasons at four different sites where either pale swallow-wort or black swallow-wort populations are present were negative for the presence of -(-) antofine. When pale swallow-wort and black swallow-wort plants were grown in hydroponic cultivation, however, -(-) antofine was found in root exudates and in the growing medium in the nM range. Although the concentrations in exudate were much lower than that needed for biological activity (micromolar), these levels might be an underestimate of what may accumulate over time in an undisturbed rhizosphere.