Plant parasite victims learn to share chemical information

Wizard’s net, devil’s guts, and witch’s hair are just a few of the common names for dodder, a nefarious rootless and leafless parasitic plant that sucks the water and nutrients out of its plant victims using a penetrating organ called a haustorium. Masses of the spaghetti-like dodder can smother crops, including soybeans, clover, and alfalfa. New research suggests that dodder’s victims try to make the best of a miserable situation. Because dodder’s haustoria bridge the vasculatures of multiple plants, the victims can use the parasite as a conduit to share chemical information about herbivorous insect pests when they try to invade, reports a team led by Ian T. Baldwin of the Max Planck Institute for Chemical Ecology and Jianqiang Wu of the Chinese Academy of Sciences’ Kunming Institute of Botany (Proc. Natl. Acad. Sci. USA 2017, DOI: 10.1073/pnas.1704536114). Working with two soybean plants connected by dodder, the team found that when insects start attacking one soybean plant, that plant employs jasmonic acid and other molecules to ignite a chemical alert that, for example, increases the activity of trypsin proteinase inhibitors, chemical weapons against insect digestive enzymes. Dodder parasites negatively influence host plants, but “under certain circumstances, they may also provide ecologically relevant information-based benefits,” the team notes.