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| Image of gene
mapping by FISH. |
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In regard to plants, your institute is very
well known for genome analysis of Arabidopsis thaliana, a model
plant.
Yes, we have targeted the Arabidopsis thaliana
as a model higher plant to decipher all the genetic information
of plants. This research was conducted as joint research among
six groups from research institutes in America, Europe and us in
Japan. As a result, we were able to sequence all 125 million base
pair in the plant with five chromosomes. This was simultaneously
announced at press conferences on December 14, 2000 in Washington,
Tokyo, London and Brussels. At about the same time, we also announced
the completion of the sequencing genome of leguminous bacterium
involved in the nitrogen fixation, a process directly fixes nitrogen
from air. We are also analyzing the genomes of Lotus japonicus.
We intend to improve agricultural products in the future based
on the information obtained from various plant genomes.
How many genes does a plant contain? And why
did your institute select Arabidopsis thaliana?
Arabidopsis thaliana genome contains 25,498
genes among 125 million base pairs. Interestingly, genomes of some
plants such as lilies and wheat have more than 10 billion base pairs
which are far greater than the 3 billion that human genome has. However,
their actual number of genes in higher plants is believed to be somewhere
between 20,000 and 50,000, so in this sense they aren't much different
from other plants.
Arabidopsis thaliana is not a special plant, but we find it to be an excellent
model plant. In fact, most basic molecular biologists specializing in plants
use Arabidopsis thaliana as a model. Among many advantages in using Arabidopsis,
first is that the generation time of the plant is very short, less than two months.
This is very convenient to see the experimental results. Second, it is also very
easy to manipulate its genes. Furthermore, there is a considerable amount of
experimental evidence that Arabidopsis thaliana genes function even when inserted
into other plants, for example, poplar. We are currently using genomic information
from Arabidopsis thaliana to attempt to create agricultural products resistant
to various pathogens.
You are referring to genetically modified agricultural
products. These are becoming a hot topic in Japan.
In my opinion, the claim that genetically modified
food products are hazardous to health is nonsense. Mankind has always
been breeding may agricultural plants by mating to create better
plants in many senses. The new genome-oriented approach is that,
for example, we find a gene that is resistant to certain disease,
insert it into the genome and create a disease resistant plant. Therefore,
it is essentially the same as the conventional breeding in respect
to the introduction of a decease resistant gene. However, people
say that human should not do this.
We wonder how science has been taught in Japanese
schools. This is such a primitive issue.
Since returning from U.S. 20 years ago, I have
taken every opportunity to state that there is no danger with genetically
modified agricultural plants. I would like to emphasize that we
must not be swayed by unscientific claims. As you may know, U.S.
has proactively tackled all the genetically modified agricultural
product because this is the only practical and scientifically meaningful
way to solve environmental issues and expected food shortage.
This means we should be able to grow agricultural
products without using pesticides.
Exactly. There is an another major issue. Plant
cells have vacuole in which nutrients are pooled. In particular,
nitrogen fertilizers are converted and pooled there. In addition,
this nitrogen fertilizer is created as ammonia compounds using
nitrogen from the air through the Harvey method. At this time,
enormous electric power equaling 3-4% of all electricity used in
the world is used. However, the actual amount of nitrogen fertilizer
needed by plants is only about 1/10 of the amount actually given.
The rest is wasted or pooled by the plant. That's why we are now
searching for possibilities of plants that grow well with minimum
amount of nitrogen fertilizer and do not pool excess nitrogen compound.
Yes, nitric acid is dangerous it converts to
nitrous acid and the like which are carcinogens and the vacuoles
of vegetables contain large amounts of these. |
