Invasive Species Compendium

Detailed coverage of invasive species threatening livelihoods and the environment worldwide

Abstract

Selective phytotoxicity of xanthinin and xanthatin from invasive weed Xanthium italicum Morretti on test plants.

Abstract

Two phytotoxic xanthanolides, xanthinin and xanthatin, were isolated from the leaves and fruits of invasive weed, Xanthium italicum Morretti, commonly known as Italian cocklebur. They slightly inhibited the seedling growth of Italian cocklebur, but were very inhibitory to lettuce, ryegrass and two indigenous species (African rue and redroot pigweed). Xanthinin significantly decreased the growth of lettuce (Lectuca sativa L.), ryegrass (Lolium multiforum Lam.), Syrian rue (Peganum harmala L.) and redroot pigweed (Amaranthus retroflexus L.) even at low concentration (10 µg/mL). In contrast, the root length of Italian cocklebur slightly inhibited (2%) compared to control at 50 µg/mL xanthinin treatment. The application of xanthatin also inhibited the growth of receiver plants. Ryegrass and Syrian rue were most sensitive species, whose root growth was inhibited by 78% and 96%, respectively, at 50 µg/mL dose of xanthatin, while the root length of Italian cocklebur was only inhibited by 23%. In fact, Italian cocklebur was the only receiver species that survived at 1 mg/mL xanthatin and xanthinin treatment. Our results suggested that the selective phytotoxicity of Italian cocklebur and other species facilitated its successful invasion. This is the first report on the phytotoxic activity of xanthatin.