Stem parasitic plant Cuscuta australis (dodder) transfers herbivory-induced signals among plants

Dodders (Cuscuta spp) are parasitic plants, which absorb water and nutrients from their host. Their vines can embrace, and in this way connect, more than one host. Hettenhausen et al. showed that in certain situations these connections serve as communication routes. In their experiment a pair of soybean plants were parasitized by Cuscuta australis and thereafter one plant from each pair was subjected to caterpillar attack. The herbivore action led to increase in the expression of various defense related genes. The response was observed not only in caterpillar-attacked plants but also in the undamaged ones. Importantly the previously undamaged plants showed higher resistance to subsequent herbivore treatment. The results indicate that the herbivory-induced signal was transmitted by Cuscuta australis vines leading to the activation of defense mechanisms. The study reveals new aspects of signaling and communication and shows that in certain conditions plants can benefit even from parasitic infection. (Summary by Jagna Chmielowska-Bąk) Proc. Natl. Acad. Sci. USA 10.1073/pnas.1704536114