Biology Professor Hopes to Use Plants in the Fight Against Pollution

By Sarah Oktay

“What does phytoremediation have to do with pollution?” a layperson might ask a biologist like UMass Boston’s Adan Colón-Carmona. Phytoremediation is the rehabilitation of contaminated water, air, or soil using plants to extract harmful substances. With the help of talented undergraduate and graduate students, Assistant Professor Colón-Carmona is working on isolating genes in the model plant Arabidopsis thaliana that can be used to identify native plants with inherent abilities to degrade pollutants, or that can provide information needed for genetically engineering plants to clean up soils that are contaminated with polycyclic aromatic hydrocarbons (PAHs).

PAHs are major pollutant byproducts of oil-based manufacturing. As society increases its dependence on oil for energy and for consumer goods, more of these products and their byproducts are entering the environment. PAHs are very pervasive; they are found in asphalt, plastics, and many consumer goods. Animal cells can incorporate these contaminants and accumulate them in their tissues. Toxic effects of pollutants like PAHs include cell death, cell mutations, and cancer. Colón-Carmona’s group is investigating whether plants can metabolize these contaminants and/or remove them permanently from the environment. They are also investigating if some plants are hypersensitive to pollutants and could act as biomonitors, or early warning devices, to signal if pollutants are present.

For example, scientists have recognized that wetlands and marshes act as effective filters for pollution from urban and agricultural sources. Plants can react in different ways to a pollutant introduced in the air, soil, or water. They can sequester the toxin without modifying or degrading it or sequester and biodegrade the toxin, changing it to another type of molecule. They can also exclude or actively remove the toxin after intake and put it back into the watershed or air.

Plants respond to external stimuli such as light, nutrients, water, insects, carbon dioxide, and pathogens, and, since they cannot run away, they must adapt to environmental changes. Plants also naturally produce aromatic hormones such as steroids that can be very similar in structure to PAHs. Colón-Carmona and his students, they have asked vital questions : Do plants actively take PAHs into their tissues? What are their physiological responses to the introduced pollutant? Can they break down the PAHs into less toxic components?

Colón-Carmona’s group has been using Arabidopsis thaliana as a model plant for many reasons. Its genome has been sequenced, and several companies currently supply genetically “pure” plants and mutants from well-established stocks. The plant has a relatively short growth cycle, can grow at room temperature, and produces many seeds. It is also relatively small and can even be grown on a petri dish.

In preliminary experimental data, A. thaliana was found to be unquestionably affected by the introduction of increasing amounts of the PAH phenanthrene. Physiological responses included: shortening of the roots, a loss in color due to a reduction in chlorophyll, a reduction in shoot number and size, and the development of necrotic, dead, spots on the leaves. In addition, the group found that phenanthrene was distributed in areas throughout the plant when they looked for a fluorescent fingerprint that can be seen under fluorescence scans.

Colón-Carmona has been working on this project and others with undergraduates and graduate students since arriving at UMass Boston two and half years ago after earning his PhD from the University of California–Irvine. His lab group includes students participating in the Research Experiences for Undergraduate Program and the Undergraduate Mentoring in Environmental Biology Program, which are projects supported by grants from the National Science Foundation.

Photo by Harry Brett

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