By Revving Up Key Gene, Researchers Discover They Can Manipulate The Size Of Cells In Plants

November 05, 1998

CHAPEL HILL - By revving up a key gene in plants - making it produce more protein than it would naturally -- University of North Carolina at Chapel Hill scientists and colleagues have discovered that they can manipulate the size of plant cells without changing the overall size of the plant itself.

The discovery is something of a scientific breakthrough, the researchers say, because one day it could lead to food crops more resistant to overly dry or wet conditions and enable horticulturists to manipulate plants in other useful ways.

"Before long, we should be able to control the size of wood cells in trees," said Dr. Alan M. Jones, associate professor of biology at UNC-CH. "Since soft wood is better for making paper, for example, we could grow softer woods by increasing the size of cells in a tree trunk, or we could produce harder woods for furniture by making their cells smaller."

A report on the discovery appears in the Nov. 6 issue of the journal Science. Besides Jones, UNC-CH authors are Drs. Kyumg-Hoam Im and Ming-Jing Wu, postdoctoral fellows in biology, and graduate student Gregory DeWitt. Others are Drs. Andrew Binns and Michael Savka of the University of Pennsylvania, and Dr. Raymond Shillito, of AgrEvo, a Pikeville, N.C., agricultural development company.

In research completed in 1989, Jones identified a protein he believed to be the receptor to auxin, a major plant hormone that causes cells to grow, expand and change form. At the time, he could not link the protein to the hormone by genetic methods to prove that it was a genuine auxin receptor.

Now, using what is called a reverse genetic approach, he and his colleagues have been able to demonstrate the protein is exactly what they thought.

"We over-expressed -- or excessively turned on -- a special gene we created that makes this important receptor in tobacco," the scientist said. "Expression of this special gene, which we call a transgene, can be turned on or off by feeding plants the drug tetracycline. When we added tetracycline to the transgenic plants, what we found in both cultured cells and whole plants was remarkable."

The team discovered it could produce an over-abundance of the auxin receptor, but more interestingly, they found they had created normal-looking tobacco plants that were not normal at all. Individual plant cells were two to four the size of natural tobacco cells. As a result, plants contained fewer cells.

"We also found we could control the size of the cell by controlling expression of our transgene," Jones said. "We didn't get any effect unless we also added the hormone auxin, and that proves the protein is definitely the auxin receptor. It is the hormone and the receptor that bind together that cause the cell expansion response."

The work is a breakthrough in the field of plant hormones that will allow the field to move forward, he said.

"Farmers have been doing genetic engineering since before the time of Jesus Christ by selecting seeds from larger fruits or particular fruits to plant," he said. "That is essentially all we are doing today in plant biotechnology, except that now we have become much more sophisticated. We are extremely excited about this work."

Although plants and animals produce some similar hormones, no hormone receptor comparable to the auxin receptor exists in human or other animals, Jones said. He and his colleagues work with tobacco cells because they are easy to transform genetically.
-end-
Note: Jones can be reached at (919) 962-6932 (w) or 942-7505 (h).
Contact: David Williamson



University of North Carolina at Chapel Hill

Related Protein Articles from Brightsurf:

The protein dress of a neuron
New method marks proteins and reveals the receptors in which neurons are dressed

Memory protein
When UC Santa Barbara materials scientist Omar Saleh and graduate student Ian Morgan sought to understand the mechanical behaviors of disordered proteins in the lab, they expected that after being stretched, one particular model protein would snap back instantaneously, like a rubber band.

Diets high in protein, particularly plant protein, linked to lower risk of death
Diets high in protein, particularly plant protein, are associated with a lower risk of death from any cause, finds an analysis of the latest evidence published by The BMJ today.

A new understanding of protein movement
A team of UD engineers has uncovered the role of surface diffusion in protein transport, which could aid biopharmaceutical processing.

A new biotinylation enzyme for analyzing protein-protein interactions
Proteins play roles by interacting with various other proteins. Therefore, interaction analysis is an indispensable technique for studying the function of proteins.

Substituting the next-best protein
Children born with Duchenne muscular dystrophy have a mutation in the X-chromosome gene that would normally code for dystrophin, a protein that provides structural integrity to skeletal muscles.

A direct protein-to-protein binding couples cell survival to cell proliferation
The regulators of apoptosis watch over cell replication and the decision to enter the cell cycle.

A protein that controls inflammation
A study by the research team of Prof. Geert van Loo (VIB-UGent Center for Inflammation Research) has unraveled a critical molecular mechanism behind autoimmune and inflammatory diseases such as rheumatoid arthritis, Crohn's disease, and psoriasis.

Resurrecting ancient protein partners reveals origin of protein regulation
After reconstructing the ancient forms of two cellular proteins, scientists discovered the earliest known instance of a complex form of protein regulation.

Sensing protein wellbeing
The folding state of the proteins in live cells often reflect the cell's general health.

Read More: Protein News and Protein Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.