Field of Science

A real resurrection (fern)

Is there a plant grower anywhere who has never accidentally let a plant dry out and die? Doh! Dehydration is such an annoyance. Yet there are a number of organisms that can dry out and survive quite well. Slime molds and yeasts can be dehydrated and survive for months. Some mosses and leafy liverworts can dehydrate, and rehydrate, on a daily basis, and sometimes for even longer periods of time. But when you get to vascular plants the ability to survive dehydration becomes rare perhaps because the whole idea of vascular tissue, cuticle, and stomata is to maintain a hydrated state, as long as the roots can replace the water being continually lost through transpiration. Of course comparing vascular plants to mosses and liverworts is not fair because the former are diploids and the latter haploids (explanatory link). But the point is that among vascular plants the ability to dehydrate and survive is rare, and no matter what, no one really seems to understand how even a slime mold can dehydrate into a brittle piece of yellow cytoplasm and then blob itself back to life when water is added.
One exception among vascular plants is the resurrection fern, Polypodium polypodioides. Sometimes they are sold as novelty items; just add water and the brittle fern rehydrates and greens up (see image). Cool. A recent report suggests that this ability is linked to appropriately named proteins called dehydrins, which appear to prevent cell wall damage from the “wrinkling up” that occurs when cells dry out. Could such a gene be used to engineer drought resistant crops? Maybe. And this is another example of why the powers that be, and that includes all of the people holding the purse strings, should encourage, rather than discourage, biologists to study a diversity of organisms. You can just imagine the derision a grant proposal would get from the USDA if you said you were going to study a cute little fern. Sure kid, how nice, now if you want money from us study corn, which never, ever suffers from droughts.

1 comment:

Rhizowen said...


I've noticed the epiphytic polypodies round here (UK) seem particularly adept at shriveling during dry spells and then going all green and lush afterwards. Often wondered how they did it. Thanks.