A gene known to control production of proteins believed to allow plant cells to elongate during growth also appears to play a key role in fruit ripening, according to researchers at the University of California, Davis.

The researchers, who identified and cloned the gene in tomatoes, suspect the gene could be useful for genetically engineering tomatoes, as well as other fragile and perishable fruit, for which shipping quality and shelf life are critical. The University of California has applied to patent the gene, and the researchers will report their findings in the May 26 issue of the Proceedings of the National Academy of Sciences.

The gene, LeExp1, is a member of a family of genes formerly shown to coordinate production of proteins appropriately named "expansins." These expansin proteins, identified so far in cucumbers, rice, tomatoes and the research plant Arabidopsis, work by loosening the plant cell walls and allowing the cells to elongate during growth.

"The plant cell wall is composed of a complex matrix of compounds," said Jocelyn Rose, a plant biology doctoral candidate, who identified and cloned the newly discovered gene. "A major goal for many scientists in this field has been to find one gene that can be identified as being the major player in causing tissue disintegration that occurs in softening fruit," he explained.

Rose works in the laboratory of Alan Bennett, a professor in the vegetable crops department and associate dean of the plant sciences division of the UC Davis College of Agricultural and Environmental Sciences.

Conventional wisdom among scientists studying plant cells walls has held that pectin was the wall component critical to fruit softening. In fact, a genetically engineered tomato was commercialized in recent years based on that theory. H
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Contact: Patricia Bailey
pjbailey@ucdavis.edu
916-752-9843
University of California - Davis
27-May-1997