Dutch study unlocks key to firm tomatoes

LONDON (Reuters) - Dutch scientists said on Friday they have identified a key gene that protects tomatoes against a common fungus that causes the plants to wilt.

The fungus Fusarium oxysporum can make a compound that overcomes two of three genes in tomatoes that help ward off disease.

But a third tomato gene targets the protein and keeps tomatoes firm, said Petra Houterman, a molecular biologist at the University of Amsterdam who worked on the study.

She said her team's report in the Public Library of Science journal PLoS Pathogens provides insight on how certain types of fungus do their damage and could lead to more robust varieties of tomato and other crops.

"It leads to a better understanding of how resistance works," Houterman said in a telephone interview. "It could be used one day by crop breeders to understand what genes are most important to make a species more valuable."

Farmers often cross-breed their plants to grow varieties better able to withstand drought and disease.

One of the first questions for the Dutch researchers was why the fungus infected one tomato plant but not another. To answer this, they studied the xylem vessels that carry nutrients throughout a plant, and where the fungus makes its home.

They found that a protein called Avr1 helps the fungus overcome two of three of the plant's resistance genes, Houterman said.

This explained why some tomatoes wilt and others do not because the third resistance gene specifically targeted the Avr1 protein and enabled the plant to fight off the fungus, said the study, published online here .

(Reporting by Michael Kahn; Editing by Maggie Fox and Peter Blackburn)