Calgene Inc. on Monday filed for Food and Drug Administrationpermission to market the first genetically engineered food, atomato containing a gene that extends shelf life.

The company also said it has exclusively licensed theantisense polygalacturonase (PG) gene from Campbell Soup Co.for fresh-market tomatoes in North America. Fresh-markettomatoes represent a $2 billion wholesale market and a $3.5billion retail market in the United States.

Calgene hopes to have its tomato on the market by the fall of1993.

The PG enzyme causes pectin degradation, which results infruit softening due to cell wall breakdown. The antisense PGgene in Calgene's tomato slows rotting by reducing expressionof the PG enzyme by as much as 99 percent.

Calgene hopes the gene will allow consumers to eat vine-ripened tomatoes. Currently, 95 percent of tomatoes are pickedwhile still green.

Still unanswered is whether consumers will accept geneticallyengineered tomatoes, which Calgene and Campbell have spentmore than $10 million to develop. The answer may hinge onhow the food is presented to the public.

Calgene is asking the FDA to determine that its tomato is afood like any other tomato. Alternatively, the FDA couldconsider the new genes as a food additive. That potentiallycould require labelling of the tomatoes as containing antisensePG and another gene, for kanamycin resistance, which Calgeneuses as a marker.

The Environmental Defense Fund (EDF) and the National WildlifeFund (NWF) want engineered tomatoes to be labelled.

In November, Calgene requested an FDA advisory opinion on theuse of a kanamycin marker gene in tomatoes, cotton andrapeseed plants. The marker for antibiotic resistance indicateswhether crops have incorporated desired traits.

That submission was published in the Federal Register on May1. Almost 40 comments were filed during the comment periodthat ended on July 30. Comments on the safety of that genewere almost universally favorable, with the exception ofletters from the EDF, NWF and several private individuals.

One of the criticisms came from Rebecca Goldburg, who headsthe EDF's biotechnology program. Goldburg argued that Calgenehasn't proven the safety of the kanamycin marker gene andshould submit extensive safety data documenting its effects inmammals.

Margaret Mellon, director of the NWF's biotechnology policycenter, said her group's main concern was transfer ofkanamycin resistance to pathogens. But, she said, the NWF wasmore concerned about plants containing genes for Bacillusthuringiensis toxin.

The environmentalists saved most of their criticism for theFDA. "We congratulate Calgene on seeking government approvalwhen they're under no obligation to do this," said Mellon. "TheFDA (should) get on the stick and set up a program to ensurethe safety of genetically engineered food." Mellon said the FDAshould shelve Calgene's application until the agency has abiotech food policy in place.

Calgene expects the two FDA reviews to be completed by theend of 1992, said Roger Salquist, chief executive officer.

Campbell will continue to own the exclusive right to use thePG gene in tomatoes grown for processing. Calgene will pay asmall up-front fee to Campbell and small future royalties,Salquist said. The companies have been jointly developing theantisense tomatoes since the mid-1980s.

Calgene intends to file next year with the U.S. Department ofAgriculture for exemption from plant pest status, which willallow the tomato to be grown as a crop. Calgene has conductedfive USDA-approved field trials of the tomatoes since 1988.

ICI plc of London is Calgene's biggest potential competitor,Salquist said. ICI is developing a tomato with a pectinmethylesterase gene. Monsanto Co. is conducting small-scalefield trials of tomatoes containing a bacterial gene thatinhibits the production of ethylene, a ripening gas produced byplants. Agritope Inc., a wholly owned subsidiary of Epitope Inc.,recently signed a letter of intent with Keygene N.V. to developa tomato similar to Monsanto's.

The Davis, Calif., company's stock (NASDAQ:CGNE) picked up 50cents Monday to close at $7.38.

-- Karen Bernstein BioWorld Staff

(c) 1997 American Health Consultants. All rights reserved.