The paradox of kin avoidance in parasitic plants.

Parasitic plants live off other plants, and among the most destructive are witchweeds (Striga), which devastate Africa's staple cereals and threaten the livelihoods of millions (1, 2). Although many parasitic plants can infect a broad range of hosts, cases of one parasite attacking another are rare, suggesting that they can recognize their kin. Infection depends on the haustorium, a tubelike structure that forms when parasites detect host-derived chemical cues known as haustorium-inducing factors (3, 4). The haustorium extends from the tip of the parasitic plant seedling and penetrates the host root, enabling access to water and nutrient channels (5). Paradoxically, such cues are also produced by parasitic plants (6). On page 405, Xiang et al. (7) report that parasitic plants avoid kin parasitism by inactivating their own cues through a glucose-tagging process called glucosylation. This discovery opens opportunities to breed crops that emit similarly inactive signals to protect them from parasitic plants. [ABSTRACT FROM AUTHOR]