Tomato Research: Ripe for the Picking
Tossed, chopped, or pureed, the well-loved
tomato is one of the more frequently used fruits in American
diets. It's also the subject of basic research funded through
NSF's Directorate for Biological Sciences. The separate findings
of three plant biologists will not only help gardeners, but
will aid in the study of other plants and provide insights
into areas that are seemingly unrelated to agriculture.
Good tasting tomatoes are sweet, according to many tomato-lovers.
But the real key, says Pamela Dunsmuir of the DNA Plant Technology
Corporation in Oakland, California, is acid.
Recent advances in genetics and molecular biology make it
feasible to alter fruit acidity, explains Dunsmuir. Her experiments
will help determine whether biologists can modify citric and
malic acid (two major organic acids in tomatoes) via gene manipulation.
To date, Dunsmuir has isolated the gene for one tomato's malic
acid, and has prepared 100 kinds of genetically altered tomatoes.
She expects her research company and its affiliated commercial
branch to soon produce "new tomatoes with enhanced flavor arising
from altered acidity."
For Rod Wing of Texas A&M, the question isn't just how
the tomato tastes, but when it can be picked.
Wing is investigating the phenomenon of abscission, the process
by which plants shed organs. In terms of ecology and adaptation,
he says, abscission gives plants flexibility in dealing with
stresses, injuries, and pollination failures. "And economically," he
adds, "the study of abscission becomes very important in terms
of knowing when to harvest mature fruit."
Abscission happens in three stages. First, the plant develops
a region where the abscission will occur. Next, the fruit separates
from the plant. And last, the plant forms a protective layer
of cells over the "stump" left behind by the fruit's separation.
Understanding this process will be helpful to many types of
agriculture, says Machi Dilworth, director of NSF's integrated
plant biology program. "This process is at work everywhere
we look, from picking fully ripened tomatoes, to harvesting
Meanwhile, Ruth Stark of the City College of New York, is
investigating the tomato's outer skin and finding applications
outside of agriculture.
Stark's goal is to understand the chemical structures that
protect the fruit from bacteria and fungi. The skin is made
up of waxes that provide "waterproofing" with polymers. Stark
is studying how these polymers are linked, how they are embedded
within wax or cell-wall matrices, and how their molecular "architecture" is
related to their functions.
Her ultimate goal is to design methods to improve the plants'
natural protective process. "And," she says, "since polymer
mixtures are involved in tomato skin membranes, this research
may have future applications in the design of synthetic coatings
for waterproofing and also for the development of adhesives."