World Environment News

INTERVIEW - Brazil tests GM orange tree against "sudden death"

Date: 14-Apr-03
Country: BRAZIL
Author: Reese Ewing

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 a half."

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 currently thought.

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.


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.

© Thomson Reuters 2003 All rights reserved

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