A group of Chinese and US scientists have recently succeeded in jointly producing the world' s first transgenic tobacco plant which is capable of reducing mercury in soil and water.
The research program, carried out by the Chinese Academy of Sciences (CAS) and the South Carolina State University, has demonstrated the potential value of transgenic plants in the detoxification of mercury-polluted soil, at a time when pollution is receiving universal attention, according to a recent issue of Current Opinion in Plant Biology, a British science magazine.
"Rehabilitating the polluted environment with plants is a new biological technology," said He Yuke, leader of the group's Chinese side.
Scientists have succeeded in separating from microorganisms a gene which can turn inorganic mercury into gas, said He, a research fellow with the Shanghai Institute of Plant Physiology and Ecology under CAS.
After sequential alterations, the gene can be transplanted into tobacco plants so that the plants become capable of devouring mercury contained in the soil and water and turning the heavy metal into gas, he explained.
"Aeriform mercury, once dispersed in the atmosphere, does not harm the human body or the environment," he said.
An experiment shows that transgenic tobacco plants are five to eight times more effective than normal tobacco plants in absorbing mercury.
"Further sequential alterations may further increase the plants ' mercury consumption capacity," said He.
To achieve that effect, scientists are seeking to relocate the "cleansing workshop" of transgenic plants from their roots to their leaves.
The plants, which can also absorb other heavy metals such as gold and silver, will hopefully be planted widely in mining areas in some inland provinces.
In the meantime, scientists plan to implant the gene into high- yield trees such as poplars to increase their action.
Though the mercury fed tobacco plants do not contain excessive heavy metal, scientists do not recommend they be used for cigarette production.
"These transgenic plants are used exclusively for environment rehabilitation and should be incinerated after being harvested," said He.
Mercury is a poisonous heavy metal which does not dissolve in water. An excessive intake of mercury contaminated food can lead to infantile paralysis and chondropathy.
Mining industries produce mercury pollution as does the careless disposal of batteries and fluorescent tubes.
Statistics show that China produces 13.8 billion batteries and 800 million fluorescent tubes each year. Proper reclamation, therefore, is crucial for reducing heavy metal pollution.
(People's Daily March 17, 2002)
