[aresant]

That's what I call fun Saturday reading . . .

"GM mangroves that can grow in salinated intertidal zones and synthesize gasoline, shipping it out via their root networks, is one option."

That one sentence overloaded my system with a visual day-dream about the potential for our future - the way it's written evokes that famous Bladerunner line:

"I've seen things you people wouldn't believe. Attack ships on fire off the shoulder of Orion. I watched C-beams glitter in the dark near the Tannhauser gate. . ."

A few dozen words in both quotes that evoke such richness. Beautiful work.

[to3m]

As a later comment points out, in a manner as arresting as the vision it criticises, roots are how plants get their inputs. The soil feeds the plants! - not the other way around.

But, maybe in 500 years they'll have fixed this.

[InclinedPlane]

This is factually inaccurate. Plants are not built out of soil, they are built out of air and water, the contribution from the soil is comparatively minor. Especially if symbiotic mycorrhiza are in play in which case only a tiny handful of minerals and phosphorous is pulled from the ground. The great bulk of the mass of a tree is cellulose and lignin, and that comes straight out of photosynthesis and from atmospheric CO2 and ground water.

[samatman]

The actual relationship is more two-way, as plant roots exist in symbiosis with mycorrhizae, providing sugar in exchange for minerals and other micronutrients.

[wtracy]

http://en.wikipedia.org/wiki/Aerenchyma

Wetland plants (like Mangroves) already transport substances from their leaves to their roots.