Figure 25.2 Nickel Is an Essential Element for Plants

For an element to be classified as an essential nutrient in plants, two criteria must be satisfied. Specifically, one must demonstrate that a plant cannot complete its life cycle in the absence of the element, and that no other element can substitute for the test element. To determine if nickel is an essential element for plants, Patrick Brown and colleagues tested whether barley could complete its life cycle in the absence of nickel. The researchers grew barley plants for three generations in nutrient solutions that contained 0, 0.6, or 1.0 μM NiSO₄. Seeds from each group were then harvested from third generation plants, and the level of nickel present in the seeds was determined. The remaining seeds from the same plants were allowed to germinate, and the success of germination was plotted against nickel concentration. The results indicated a positive correlation between seed germination and nickel concentration. Importantly, low germination was observed in seeds from plants grown in the absence of nickel. Together with results from another study showing that no other element could substitute for nickel, the investigators concluded that nickel is an essential micronutrient. What role does nickel play in plant nutrition? In addition to nickel’s function in the production of viable seeds, further studies have demonstrated that nickel deficiency has a wide range of effects on plant growth and metabolism, including nitrogen metabolism and iron absorption. Other investigations into the function of nickel at the molecular level demonstrate that nickel is a cofactor for the enzyme urease, a nickel metalloenzyme. Because of its role as a cofactor for urease, nickel is an essential micronutrient.

Original Paper

Brown, P. H., R. M. Welch and E. E. Cary. 1987. Nickel: A Micronutrient Essential for Higher Plants. Plant Physiology 85: 801–803.
http://www.plantphysiol.org/cgi/reprint/85/3/801

Links

Eskew, D. L., R. M. Welch, and E. E. Carey. 1983. Nickel: An essential micronutrient for legumes and possibly all higher plants. Science 222: 621–623.
http://www.sciencemag.org/cgi/content/refs/222/4624/621
http://www.jstor.org/stable/1691986

Eskew, D. L., R. M. Welch, and W. A. Norvall. 1984. Nickel in higher plants. Further evidence for an essential role. Plant Physiology 76: 691–693.
http://www.plantphysiol.org/cgi/reprint/76/3/691

Gerendás, J., J. C. Polacco, S. K. Freyermuth, and B. Sattelmacher. 2000. Significance of nickel for plant growth and metabolism. Journal of Plant Nutrition and Soil Science 162: 241–256.
http://www3.interscience.wiley.com/journal/71005139/abstract

Dixon, N. E., C. Gazzola, R. L. Blakely, and B. Zerner. 1975. Jack bean urease (EC 3.5.1.5). Metalloenzyme. Simple biological role for nickel. Journal of the American Chemical Society 97: 4131–4133.
http://dx.doi.org/10.1021/ja00847a045

The Orchid House: Dorothy Morgan: What is Plant Nutrition?
http://retirees.uwaterloo.ca/~jerry/orchids/nutri.html

Universität Hamburg: Botany Online: Mineral Nutrients
http://www.biologie.uni-hamburg.de/b-online/e16/16a.htm

Kimball’s Biology Pages: Transport of Water and Minerals in Plants
http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/X/Xylem.html