[Press and Publications] 'Mutant' Plants Spring From Nuclear Disaster [Genetics]



September 2000

No 176

NATURE PRESS EMBARGO: UNTIL 7PM ON 4 OCTOBER

A team of scientists from the University of Leicester and Friedrich Miescher Institute, Switzerland, has found that mutation rate in plants exposed to ionising radiation after the Chernobyl disaster of 1986 is unusually high.

Experts in the world-renowned Department of Genetics, where DNA fingerprinting was discovered, carried out tests following concern over the genetic consequences of chronic radiation exposure.

Researcher Dr Yuri Dubrova, writing in today's edition of Nature (October 5), describes a new approach for monitoring germline mutation in plants.

He said: We have found evidence for a remarkably strong induction of germline mutation in wheat upon chronic exposure to ionizing radiation from the Chernobyl accident.

We compared wheat plants descended from two genetically identical populations, derived from the same homogeneous parental line.

One population was grown for one generation (10 months) in a heavily contaminated plot near the Chernobyl nuclear power plant, the other was sown in a clean control area 30 km away in soil of comparable agro-chemical characteristics.

The offspring of exposed and control plants were profiled using 13 highly variable microsatellite loci. Despite the initial genetic identity of two wheat populations planted in the control and radioactive-contaminated areas, a marked three-fold increase in heterozygosity was found among the offspring of exposed plants.

Our estimates show that this increase can be attributed to a massive six-fold increase in the mutation rate over the single generation of exposure to ionising radiation.

We have also evaluated the absorbed dose for plants grown on the contaminated plot. Our estimates show that plants grown on the contaminated plot have been exposed to relatively low doses of ionising radiation, which theoretically should not result in such large increase in the mutation rate. The results of our study therefore point at as yet unknown effects of low-dose chronic exposure to ionising radiation, which make it substantially more mutagenic than previously thought.

These surprising findings also raise an important issue of the genetic hazard of chronic radiation exposure to the germline. Currently, the main concern of radiation protection is the mutagenic effects of chronic ionising radiation at low and intermediate doses, but there is little experimental data on the induction of mutations at these doses.

Our results showing that the apparent rate of induced germline mutation is far higher than can be predicted from existing estimates of absorbed doses of exposure show that future studies are clearly needed to analyse the genetic effects of chronic radiation exposure in greater detail.

NOTE TO NEWSDESKS: For more information, please contact Dr Yuri Dubrova on:

Phone: +44 116 252 5654, Fax: +44 116 252 3378, E-mail: yed2@le.ac.uk, www http://www.le.ac.uk/genetics/

You may also find the following press notice from Nature useful:

Fourteen years after the Chernobyl nuclear accident, crops grown in contaminated land surrounding the former power station show a mutation rate six times higher than normal, a Brief Communication shows this week.

Olga Kovalchuk from the Friedrich Miescher Institute, Basel, Switzerland, and colleagues investigated the effect of chronic radiation exposure on wheat plants. Identical populations were planted in heavily contaminated land near Chernobyl and in clean soil roughly 30 kilometres away.

The increased mutation rate was seen after just one plant generation (ten months). Each plant received relatively low radiation doses, which theoretically should not cause so many mutations: suggesting that chronic exposure to ionizing radiation has effects that are as yet unknown, Kovalchuk's team says.

CONTACT:

Olga Kovalchuk tel +41 61 697 7493, fax +41 61 697 3976, email olga.kovalchuk@fmi.ch


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