2-Plants: Brazil tests GM orange tree against "sudden death"
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TITLE: INTERVIEW - Brazil tests GM orange tree against "sudden death"
SOURCE: Reuters, by Reese Ewing
DATE: Apr 14, 2003
------------------ archive: http://www.gene.ch/genet.html ------------------
INTERVIEW - Brazil tests GM orange tree against "sudden death"
SAO PAULO, Brazil - A Brazilian genome scientist says his firm is close
to marketing genetically modified orange trees that could save the
world's largest orange crop from destruction by "sudden death" disease.
The disease, now believed to be a human-caused, virulent mutation of an
older plague that wiped out Brazil's orchards in the 1950s, has surfaced
across an area holding about 22 million trees in Brazil's main orange
state of Sao Paulo.
"The idea is to create a tree that is immune to the citrus tristeza virus
(CTV) and sudden death, as if we were creating a human into which the
cold virus could not enter and mutate," Fernando Reinach, the chief
executive officer of Allelyx, told Reuters in a phone interview.
Allelyx, launched in 2001 with $11 million from venture capital fund
Votorantim Ventures, develops biotech solutions for Brazil's orange industry.
"We've created the first round of genetically modified test trees that
should resist the disease," said Reinach, also a former researcher in
Brazil's orange genome project that mapped the genetic code of the CTV
virus and another called Xyllela. "We expect to market them in a year and
Brazil's government says it will uphold a ban on GM but "a disease like
this may soften its position," said Reinach.
Brazil's orange groves account for about one out of two glasses of orange
juice drunk in the world and may see its current groves of 185 million
plus trees wiped out if the sudden death virus is more widespread than
The latest outbreak turned up last week outside the government's
containment area in prime orange country in Sao Paulo, despite attempts
to quarantine infected areas.
VIRUS SOUP RECIPE
After inoculating orange trees with live CTV virus in the past 40 years,
Brazil accidentally bred a new virulent strain of the disease called
"sudden death", Reinach said.
"When you use live virus as a vaccine you create a trap for yourself.
Inevitably you will create virulent mutations," said Reinach. "CTV is
like HIV: it mutates very quickly."
Examinations of orange trees turn up "a soup of viruses - all kinds of
different mutations of the CTV disease," he said.
But, Brazil is not alone in this dilemma.
"In some areas of Florida, growers have encountered a virulent strain of
CTV very similar to sudden death," he said.
In the 1950s, CTV wiped out 90 percent of Brazil's orange crop. It also
spread to other countries such as the United States. The industry-wide
response was to inject a mild, live form of the virus into young trees to
beef up resistance.
CTV and sudden death spread and strangle tree's roots in the same way.
Sudden death, however, kills quickly within a month of the first
symptoms, hence the name. The fruit is fine while the tree is alive and
poses no threat for humans.
"Allelyx compared the genetic code of CTV used as vaccine and sudden
death and found that the latter is a variant of the other," said Reinach.
Sudden death first appeared in 2001 in Brazil but has spread to 14
municipalities, half of which are in Sao Paulo's main orange region. The
rest are to the north in Minas Gerais.
The government announced measures to halt the transport of trees within
the infected region but this may not be enough, as the disease is also
transmitted by little aphid bugs that feed on orange leaves.
"The sudden death incubation period is about two years, so many more
trees may be infected that we don't know about," said Reinach.