Perhaps cold and hot weather might not matter soon for many gardeners...
Bonnie 6+ ETN
March 9, 2003, NYT
A Frog Lends a Hand to Rhododendrons
By HENRY HOMEYER
FOR the past four years, Dr. Mark Brand has been inserting genes derived
from an African frog into rhododendrons, trying to create a plant with
extra resistance to the root rot caused by Phytophthora cinnamomi. A common
soil fungus, Phytophthora does hundreds of thousands of dollars of damage
to rhododendrons every year.
Dr. Brand is a horticulturist and a director of the plant biotechnology
facility at the University of Connecticut in Storrs. And he is able to do
what seems impossible to an old-fashioned gardener like myself: implant
something he cannot see - a modified frog gene - into something else he
cannot see, the DNA of a flowering bush.
Creating a transgenic plant is so far beyond what traditional gardeners and
hybridizers have done it seems, at first, incomprehensible. But Dr. Brand
was able to make it seem, to use his words, more like baking a cake. Or
Genetic modification has stirred protests in Europe, and some
environmentalists believe it presents risks that outweigh benefits. But
scientists are unlikely to stop experimenting, and from talking to Dr.
Brand, I began to see why. The technology offers scientists the chance to
create their dream plants.
Dr. Brand chose to introduce a frog protein because other scientists had
already noticed that it worked against other fungi. The challenge was to
take the gene that creates the protein and fit it into the genetic
sequences of a rhododendron.
Though university labs are able to create DNA sequences, these days a
researcher can pick up the phone and have a biotech company send one over
for about $50. Once Dr. Brand had the frog protein DNA sequence in hand, he
inserted it into an E. coli bacteria, which let him easily create all the
DNA he needed.
After determining which bacteria had been successfully married to the new
gene, Dr. Brand placed them in a rich broth, allowing them to reproduce
many times over. He was fattening them for slaughter. The unsuspecting
bacteria were centrifuged and lysed with an enzyme, splitting them open so
that he could harvest the DNA.
The next step was shooting the DNA into rhododendron cells with the
potential to develop into complete plants.
Dr. Brand's gene gun is nothing like the six-shooters that boys have been
known to lug around in second grade. A small plastic and metal box that
fits easily on the counter, his gene gun is powered by high-pressure helium.
His ammo is gold dust covered with frog DNA. It goes onto a thin piece of
red mylar that sits on a screen above the tissue sample. A burst of helium
knocks the gold off the mylar, sending it flying at the speed of sound.
The target is a petri dish with callus cells from a rhododendron leaf.
Callus cells are the equivalent of stem cells in animal research. Each can
multiply quickly, developing into an entire plant if given the right
signals by plant hormones.
If all goes well in the petri dish, a few cells are penetrated by motes of
gold carrying the specially prepared DNA. Some cells will incorporate the
DNA into their own gene sequence at this point, copying it into every cell
of the plants to-be.
EVENTUALLY, after considerable testing to see if the gene is indeed in the
plants, these test-tube babies grow into ordinary-looking rhododendron
plants. The ultimate test is to inoculate them with the Phytophthora fungus
to see if they will develop root rot - or not. Dr. Brand does this by
contaminating their soil with kernels of ordinary Uncle Ben's rice that
have been inoculated with Phytophthora, 36 grains per pot. Controls are
Dr. Brand said other scientists were genetically modifying roses in hopes
of developing varieties resistant to powdery mildew and black spot. Still
others imagine a rose with a new perfume, or maybe an unusual hue. (But if
you are picturing a perfect black rose, don't count on that happening soon;
roses are difficult to work with, and black is the toughest color to create.)
Easy-to-manipulate petunias and geraniums have been changing colors in labs
for years. How soon will they, or the new improved rhododendrons, appear at
the local garden center? Not soon. Testing will take eight years, and more
time will be needed for government approval of commercial products.
But success seems likely in the end. Dr. Brand is determined to build a
better rhodie, and the technology is there to do so. He pointed to a row of
quart-size pots in a temperature- and climate-controlled chamber at his lab
with the proud look of a new father. The shiny-leaved young rhodies leaved
looked pest-free to this gardener.
Copyright 2003 <http://www.nytco.com/>The New York Times Company | Privacy
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