Dodgy Dodders
A 5-angled dodder swirls its shoots about, reaching with orange tentacles to grasp the slim stems of nearby tomato plants and suck them for nourishment.
While dodders have roots that provide some nutrients, they don’t bother with photosynthesis. If a young dodder can’t find a plant to parasitize, it doesn’t have long to live.
A dodder is careful in its search. It won’t touch a leaf so as not to tip off its prey. It instead sinks down to grab the stem.
A dodder knows where to go by scent. It sniffs its way to a meal, then makes its move.
A dodder is selective: picking the most nutritious prey. Given a choice of wheat or tomato, a dodder will put the squeeze on marinara, passing by pasta.
The dodginess is just getting started once a dodder has its grips on a host plant. Dodders directly manipulate their victims genetically to keep nutrients flowing to them – something the hosts would dearly like to thwart.
A dodder passes microRNAs into its host plant that regulate the expression of host genes in a very direct way. The microRNAs specifically target host genes that are involved in the plant’s defense against the parasite. ~ American plant pathologist James Westwood
