Parasite eavesdrops on host to reproduce

Most plants produce flowers when their leaves detect environmental cues that indicate the time is right. Parasitic dodder plants cheat. These plants don’t have leaves or roots of their own. Instead, they siphon nutrients from a host plant by grafting themselves to its vasculature. A team of researchers led by Jianqiang Wu, a botanist and chemical ecologist at the Chinese Academy of Sciences, has now shown that a species of dodder called Cuscuta australis eavesdrops on its host’s protein messengers to know when to produce flowers (Proc. Natl. Acad. Sci. USA 2020, DOI: 10.1073/pnas.2009445117). They found that C. australis relies on a host-produced protein called flowering locus T (FT) that’s made in the leaves when the host is ready to flower. As FT is transported through the host, C. australis absorbs the protein to induce flower generation of its own. This allows the dodder parasite to synchronize its flowering period with a wide variety of hosts, because FT is produced by many species. Further, genetic analysis shows that the C. australis genome has lost the ability to produce its own FT. “The dodder plant gave up its own flowering mechanism in order to gain ecological benefit,” namely adjusting its life cycle with respect to its host, Wu says. The team is investigating whether a similar communication strategy is used by other plant parasites that plague crops.