Washington, DC
October 27, 2008
With high hopes and shopping
basket in hand, many consumers search for that classic icon of
summer-the perfect, round, ripe tomato. Many are unaware,
however, that this fruit was not always so robust.
With funding from USDA’s
Cooperative State Research, Education, and Extension Service (CSREES)
National Research Initiative (NRI), scientists in New York have
done their part to ensure consumers get their fill by unlocking
the genetic secrets that control inherited traits important to
growing the classic tomato.
Using selective breeding, early agricultural workers
domesticated wild tomatoes by growing plants that enhanced
specific traits, specifically fruit size. Wild-type tomatoes are
often small, round berries, but today’s domesticated plants
produce the large, round tomatoes commonly found on the store
shelf.
Steven Tanksley and colleagues at Cornell University took on
this largely unexplored aspect of plant development to address
fruit size and shape–two major factors that control the final
yield, quality, and consumer acceptability of many crops.
Scientists hope biotechnology will increase their understanding
of the genetic blueprint behind natural variation. This
knowledge, they believe, will help breeders improve key traits,
such as yield, fruit size, nutritional value, and drought
resistance, in agriculturally important crops through natural
breeding techniques.
Tanksley's team used high-resolution genetic mapping to
pinpoint, within the chromosome, the position of the 'large
fruit' gene. "Plant transformation confirmed the results and
proved that the candidate gene was actually the cause of large
fruit," Tanksley said. "We identified the possible mutations
responsible for the evolution of large fruit by examining the
sequence of the ‘small-fruit’ allele and the ‘large-fruit’
allele."
By unraveling the molecular and developmental processes that
control fruit development, the team identified and isolated key
fixed positions on the tomato gene that determine the final size
and shape of tomato fruit.
Tanksley believes this study is the first step toward
reconstructing events that led to the domestication of fruit
development. The mechanisms identified through this study will
be applied to other agriculturally important crops, such as
coffee, pepper, eggplant, and potato.
This study also demonstrates the feasibility of isolating the
key genes involved in the domestication of crop species from
their wild plant ancestors. This information is valuable to
agriculture because identification of these genes could lead to
advances in plant breeding and the future domestication of new
crop plants.
CSREES funded this research project through the NRI Plant Genome
program. Through federal funding and leadership for research,
education, and extension programs, CSREES focuses on investing
in science and solving critical issues that impact people’s
daily lives and the nation’s future. For more information, visit
www.csrees.usda.gov.
By Stacy Kish, CSREES Staff |
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