Finding plants that eat metals: The story behind this important new discovery.

By Augustine Doronila PhD, UP Visting Professor 2013/2014

22 May 2014

Scientists from the University of the Philippines, Los Baños have discovered a new plant species with an unusual lifestyle — it eats nickel for a living — accumulating up to 18,000 ppm of nickel in its leaves without itself being poisoned, says Professor Edwino Fernando, botanist and lead author of the report.  Such an amount is approximately a thousand times higher than in most other plants. According to Dr Marilyn Quimado, one of the lead scientists of the research team, the new species was discovered in the western part of Luzon Island in the Philippines, an area known for soils rich in heavy metals. The study titled “Fernando ES, Quimado MO, Doronila AI (2014) Rinorea niccolifera (Violaceae), a new, nickel-hyperaccumulating species from Luzon Island, Philippines” was published recently in the open access journal PhytoKeys  37: 1–13.

This recently described species is called Rinorea niccolifera reflecting its rare ability to absorb nickel in very high amounts.  Nickel hyperaccumulation is such a rare phenomenon with only about 0.5-1% of plant species native to nickel-rich soils having been recorded to exhibit the ability. Throughout the world, only about 450 species are known with this unusual trait, which is still a small proportion of the estimated 300,000 species of vascular plants.How it has been discovered is an interesting story in itself and is significant for our efforts in the conservationand sustainable harnessing of our country’s biological resources.

Lets go back to 1986 when a British scientific expedition lead by now deceased Professor John Proctor of University of Stirling and Emeritus Professor Alan Baker from University of Melbourne discovered the 1st four nickel hyperaccumulators of the Philippines. They conducted a month long survey on several forest plots on Mt Bloomfield, Palawan. This area is geologically classified as ultramafics which comprise 5% of the nation’s land surface area. These are low in silica but rich in iron and magnesium minerals, Hence, the serpentine soils (term given to soils above ultramafic rocks) have excess concentrations of magnesium and are depleted in calcium and silica minerals. Moreover, these usually are very poor in essential mineral nutrients and have a strong tendency to be drought prone. These soils are quite variable but their combination of adverse chemical and physical conditions presents a major challenge to plant growth and hence they can bear open, stunted vegetation that has a distinct composition and a high proportion of endemic or disjunctly distributed species. This major finding had gone un-noticed to the Filipino scientific community for 25 years.

Together with Professor Baker, researchers at the University of Melbourne had been active in past decade the quest and understanding of these “metal-eating plants” and have indeed been instrumental in discovering these species in many parts of the world. In 2009 I accepted the invitation to contribute to science capacity building through the Balikscientist program where I was hosted by the Institute of Chemistry in UP Diliman and Institute of Biological Sciences in UPLB and Ateneo de Manila and more recently the College of Forestry and Natural Resources for the UP visiting professor program. With the environmental scientists from ADMU, I went on an initial field trip to mining areas of Zambales and this resulted in an immediate discovery of new Ni hyperaccumulator, which was recently published in the peer review journal, Asia Life Science. The following year, I was invited by Emeritus Professor Asuncion Raymundo, former Dean of the College of Arts and Science, to give a lecture at the Institute of Biological Sciences, UP Los Baños. It was a serendipitous occasion as Dr’s Quimado and Fernando had just received a DOST research grant to investigate the potential of Philippine plants to accumulate metals. At that meeting with the UPLB scientists I recall this anecdote “They greeted me warmly after my lecture and said: We would like you to work with us and learn about your experience but they said that the only catch was they had no funding to support my involvement. To me it was an offer too good to refuse!!!” The rest is history! This subsequently led to many conversations, emails on how to best strategize the research project in order to systematically discover these unique species.

To date, the UPLB team has already discovered more than 20 new hyperaccumulator species in the country with some that are also new to science such as the Rinorea niccolifera (an extreme hyperaccumulator) and are currently being describe systematically by Professor Fernando. These are all considered rare and exist in very small patches of remnant vegetation subjected to surface mining of nickel. Significant nickel accumulating flora exist in New Caledonia (65) and Cuba (145) where most of the known tropical species have been discovered to date. As you can see the Philippines will be easily become the 3rd major world biodiversity hotspot of these unique species.

The concept of using plants to clean up contaminated environments is not new. About 300 years ago, plants were proposed for use in the treatment of wastewater in Berlin, Germany. The idea of using plants to extract metals from contaminated soil was subsequently revived about 25 years ago. Despite significant success, the understanding of the how a plant does metal extraction is still emerging. The agronomic practices to improve the extraction are still being optimized. According to the USEPA, the U.S. phytoremediation market has grown significantly, for example from $30–49 million from 1995 to 1999. This may also become a technology of choice for remediation projects in developing countries because it is cost-efficient and easy to implement. It has only been in the past 10 years that phytoremediation studies have been undertaken in tropical regions. These are invariably emerging nations which are experiencing major pollution problems due to rapid industrialization. Countries, which have taken the lead in harnessing this green technology are China, Thailand, Brazil, and India. These fast growing high biomass plants may provide a harvestable valuable ‘metal crop from spent mineral resources’ for post mining communities. What is significant about this newly described species is it is a tree as most of the other species previously discovered are shrubs.

Adequate funding of meticulous research by the UPLB team needs to come from our own national sources in order to demonstrate that we as a society can take ownership and responsibility of our own natural heritage rather than expecting foreigners to do it and they receive the kudos and prestige of doing such research work.

The understanding why and how these plants have been able to tolerate these toxic conditions is important in order to provide a better solution in restoring highly disturbed areas such as mined out or deforested areas. There are very few examples in the tropical world and Philippines has had very few of these species discovered in a systematic way. This new research on these ‘metal-eating plants’ is an important window of opportunity for creating novel avenues for long term and also economically sustainable end land uses for local communities affected by mining as well discovering new biologically active compounds, which can confer tolerance to toxic compounds such as heavy metals.

On the 9-12 of June, we will be presenting other aspects of our research work at the International Conference on Serpentine Ecology in Kuta Kinabalu and Mt Kinabalu National Park, which is one of the most important serpentine ecosystems of the tropics. The organizers are very pleased that we, Filipinos can now present our own original work after the very 1st conference in 1992 in Davies California when Dr Baker presented the study the on the discovery of 1st Philippines Ni hyperaccumulators from one locality in Palawan.


Photo caption: The UPLB research team on field trip in an ultramafic mining tenement. Right to Left: Dr Doronila, Dr Fernando, Dr Quimado and research assistants.


Photo caption: Rinoreaniccolifera Fernando, shown as a nickel hyperaccumulator by a field test using filter paper impregnated with 1% dimethylglyoxime dissolved in 95% ethanol. Scale bar = 10 mm. Fernando 2421 (LBC). Photograph by Edwino S. Fernando.