September 10, 2004:
Federal agricultural researchers Vinod Kumar and
Autar Mattoo are experienced biotechnologists with extensive
experience investigating how novel technologies might improve
plant nutrition and production. As such, they represent an
odd couple to pinpoint superior results stemming from more
natural production systems. Nevertheless, the pair did just
that, showing how a natural production system can increase
favorable gene expressions in tomato compared to plastic mulched
plants with synthetic fertilization.
Autar is a plant physiologist interested in plant aging.
He and his co-workers at the USDA's Vegetable Laboratory in
Beltsville found that vetch-mulched tomatoes of the variety
Sunbeam were longer-lived and more productive in the field
than same variety under standard production using black mulch
and synthetic fertilizer. To find out why they got these unexpected
results, the researchers went on to conduct a three-year field
and laboratory study examining the gene product profiles from
Sunbeam tomatoes under the two production systems.
Gene activity profiles showed that tomatoes from the more
natural, vetch-mulched fields were higher in activity than
those from plastic-mulched, synthetically-fertilized fields
for at least 10 genes, including two defensive and two anti-aging
The study also found that vetch-mulched tomatoes were able
to resist fungal diseases more effectively and had delayed
aging compared to their conventionally-grown counterparts.
This USDA report, along with work at University of California--Davis
on phenolic acid increases in plants grown in more naturalistic
production systems, indicates that a subtle interplay of plant
and environmental conditions are crucial to plant health and
plant nutritive values.
Unfortunately, artificial systems are often accepted without
extensive long-term testing or consideration of their potential
side effects. The importance of this work is that it suggests
a mechanism for the observed advantages of natural production
methods compared to more artificial production systems.
Among the genes showing higher activity under more natural
production methods were a chitinase gene, which produces an
enzyme that eats up pathogenic fungal cell walls; osmotin,
a gene regulating water flow into cells; and cytokinin receptor
genes. Cytokinins are key plant hormones that are only produced
by plant roots and serve to prevent premature leaf aging.
They serve as a botanical 'fountain of youth' and help plants
bud and grow optimally.
Thomas Sinclair of USDA-Gainesville has cautioned that studies
of the complex nature of gene activity via gene product analysis
are based on correlations and not on analyses of cause and
effect. Nevertheless, results such as these underscore the
wisdom of adopting precautionary positions with respect to
drastic, uncontrolled changes in our food system.
For a good report on this work by Susan Milius, check out
Science News Online for July 10, 2004.
Paul Reed Hepperly, Ph.D., is research and training manager
at The Rodale Institute.