Tomatoes Get Genetic "Boost" Under
Sustainable Ag System By
July 6, 2004
Tomatoes grown in a sustainable agricultural system using a
legume cover crop as fertilizer had better disease resistance and lived longer
than tomatoes grown on black polyethylene mulch with chemical fertilizer,
Agricultural Research Service scientists
Based on a five-year sustainable agriculture study, the results
are published in the current issue of the Proceedings of the National Academy of
Sciences. ARS is the U.S. Department of
Agriculture's chief scientific research agency.
The scientists showed that at least 10 genes in the leaves of
tomatoes grown in the sustainable system were turned on longer, or
"over-expressed," allowing those tomatoes to live longer than tomatoes grown on
the plastic mulch. These "over-expressed" genes may respond to signals
emanating from the specific ratio of nitrogen, carbon and other elements
provided by the cover crop.
The researchers compared the two tomato cultivation systems at
the ARS Henry A. Wallace Beltsville (Md.)
Agricultural Research Center. In one system, tomatoes were grown under the
traditional method of black polyethylene mulch with chemical fertilizer, a
common planting regimen in the Middle Atlantic and Southeastern states.
In the other planting system, the scientists grew tomatoes in
the sustainable system, in which the plants received half the chemical
fertilizer and fungicide applied in the traditional system. The sustainable
system relied on hairy vetch--a nitrogen-fixing legume cover crop--to provide
soil nutrients and some natural leaf disease protection.
The scientists also believe the cover crop allows the tomato
root system to produce increased levels of cytokinins, a class of plant
hormones that delay senescence and let the plant live longer.
With the genes identified that impart disease tolerance and
longevity, researchers may be able to use that knowledge to breed plants that
are even more highly responsive to sustainable production systems.
The research was conducted by Autar K. Mattoo and Vinod Kumar of
the ARS Vegetable Laboratory,
Beltsville; James D. Anderson of the ARS Plant Sciences Institute,
Beltsville; and Douglas J. Mills, now at