A particular strain of the hardy weed Arabidopsis is one of the very
few plants that can thrive on soils badly contaminated with heavy-metal
waste. A paper online in this week?s Nature has worked out the genetic
changes underlying this remarkable adaptation - findings that could be
useful in the design of better technologies for bioremediation.
Arabidopsis halleri accumulates the pollutants in its leaf cells,
enabling it to tolerate high concentrations of zinc and cadmium - something
its close, and better known, relative A. thaliana is unable to do.

Ute Kraemer and colleagues compared the genetic make-up of the two
plant species and found that the metal-accumulating species has three copies
instead of one of a gene called HMA4; the regulatory elements controlling
these are also slightly different. The team showed that A. thaliana
acquired metal tolerance when transplanted with HMA4 from A. halleri.

These cunning modifications apparently help the plant to survive under
hostile conditions. HMA4 encodes a pump that uploads heavy-metal compounds
from the soil into the root system, and probably originally evolved to
rectify trace-metal deficiencies in the plant.

[www.nature.com]