This finding, published in the current issue of The Plant Cell, provides an important new insight for the development of plants that could be used to help clean polluted sites. The work also answers a fundamental question for researchers studying how certain types of plants tolerate levels of metals in their tissues that are toxic to most other plants.
"We were able to clearly establish for the first time that plants that create and accumulate high cellular levels of the antioxidant glutathione are much more nickel tolerant," said David Salt, associate professor of plant molecular physiology in Purdue's horticulture department.
The term antioxidant generally refers to a broad class of compounds that protect cells from damage otherwise caused by exposure to certain highly reactive compounds.
Understanding the mechanism behind nickel tolerance provides an important tool for researchers like Salt, whose goal is to develop plants that remove toxic metals from the environment in a process known as phytoremediation, or extract useful metals from soil, a process known as phytomining.
While previous research has shown where metals reside in a plant's cell, this is some of the first data showing how plants protect themselves from the damaging effects of those metals.
"One major hurdle to developing hyperaccumulating plants is toxicity," said John Freeman, first author of the paper and a doctoral student working with Salt. "For a plant to hyperaccumulate metal, it has to be able to tolerate metal toxicity."
A nearly ubiquitous antioxidant, glutathione plays a critical role in minimizing oxidative stress, or damage caused by highly reactive compounds, Salt said.