[Scpg] gene shape-shifting

seedmind at usa.net seedmind at usa.net
Thu Mar 24 00:13:46 PST 2005

plants be cool.

Plants Challenge Genetic Inheritance Laws 

Wed Mar 23, 3:54 PM ET   Science - AP 

By JOSEPH B. VERRENGIA, AP Science Writer 

Challenging a scientific law of inheritance that has stood for 150 years,
scientists say plants sometimes select better bits of DNA in order to develop
normally even when they inherited genetic flaws from their predecessors. 

The conclusion by Purdue University molecular biologists contradicts at least
some basic rules of plant evolution that were believed to be absolute since
the mid-1800s when Austrian monk Gregor Mendel experimented with peas and saw
that traits — good or bad — are passed on from one generation to the next.
Mendelian genetics has been the foundation of both crop hybridization and the
understanding of basic cell mutations and trait inheritance. 

In the Purdue experiment, researchers found that a plant belonging to the
mustard and watercress family sometimes corrects the genetic code it inherited
from its flawed parents and grows normally like its unflawed grandparents and
other ancestors. 

Scientists said the discovery raises questions of whether humans also have the
potential for avoiding genetic flaws or even repairing them, although the
plant experiments did not directly address the possibility in higher
organisms. They said the actual proteins responsible for making these fixes
probably would be different in animals, if the capacity exists at all. 

Details of the experiments appear in Thursday's issue of the journal Nature. 

"This means that inheritance can happen more flexibly than we thought," said
Robert Pruitt, the paper's senior author. 

The Purdue experiments were conducted on Arabidopsis thaliana, a member of the
watercress and mustard family that is commonly grown in the lab, but is not
planted commercially. 

Researchers found that in 10 percent of Arabidopsis thaliana plants with two
copies of a mutant gene called "hothead" didn't always blossom with deformed
flowers like their parents, which carried the mutant genes. Instead, those
plants had normal white flowers like their grandparents, which didn't carry
the hothead gene. So the deformity appeared only for a single, previous

The scientists believe the plants with hothead genes appear to have kept a
copy of the genetic coding from the grandparent plants and used it as a
template to grow normally, perhaps when living conditions are not ideal. 

However, Pruitt's team didn't find the template in the plants' DNA or
chromosomes where genetic information is stored and they did not determine
whether a particular gene is encoded to carry out the recovery of the normal

Finding where the normal genetic template is stored and determining how it is
triggered will take additional research and probably involve more genes,
Pruitt said. 

Humans and other animals do not carry the hothead gene, so if this process
occurs in higher organisms it must use a different trigger, he said. 

The research was funded by the National Science Foundation (news - web sites).
The Purdue team submitted their preliminary lab observations and requested
additional funding in 2002. But NSF program director Rita A. Teutonico said
the proposal initially was rejected because the review panel "thought it was a

The researchers submitted it for a second review six months later and she
decided to fund the experiment despite lingering doubts. The subsequent
experiments took about 18 months. 

"They had to rule out every possibility of contamination," Teutonico said. 

For now, she said additional experiments probably will be conducted on plants
to fully describe the genetic template. But experiments on mice and other
organisms could be funded in parallel with the plant tests, she said. 

Other scientists described the result as "spectacular" because it reveals a
novel way in which the genome can heal itself. 


Detlef Weigel and Gerds Jurgen of the Max Planck Institute for Developmental
Biology in Germany wrote in an accompanying commentary in Nature that the
mechanism for recovering the normal DNA in the plants might be lurking in the
plant's RNA, which carries out genetic orders in cells, but is less stable
than DNA. 


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