MIAMI Jan 18 Scientists have completed the
genetic sequencing of two varieties of citrus trees, a key step
in fighting diseases that threaten the global citrus fruit
industry, researchers said on Tuesday.
They assembled the genome sequences for sweet orange and
Clementine mandarin trees, the first sequencing of any citrus
plants, according to University of Florida researchers who led
the international team that completed the work.
The Clementine mandarin sequence is the higher quality of
the two, but both are expected to help scientists find new ways
to fight diseases such as citrus greening, as well as help
those working to improve fruit flavor and quality, the
Greening is a bacterial disease spread by an insect, the
citrus psyllid. It makes the fruit unpalatable and kills the
tree within a few years. It has wiped out some citrus crops in
Asia, Africa, the Arabian Peninsula and Brazil, and has spread
rapidly in Florida since its discovery there in 2005.
Sequencing the plants' genomes involves determining the
exact order of the millions of chemical building blocks that
make up the genes. Scientists hope to use the data to produce
genetically modified trees that resist disease, produce tastier
and more nutritious fruit and better tolerate salt, bad soil or
Geneticists sequenced the DNA of the greening bacterium in
2009 and expect to soon do the same for the citrus psyllid,
data that could help control the pests.
The citrus genome sequences were announced on Saturday at
the International Plant and Animal Genome Conference in San
Officials associated with Florida's $9 billion citrus
industry officials said they were thrilled.
"The publication of the sweet orange and tangerine genomes
will accelerate the discovery of innovative solutions to a
myriad of pest and disease problems that threaten citrus
production," said Dan Gunter, chief operating officer of the
Citrus Research and Development Foundation Inc.
Michael Sparks, chief executive of the Florida Citrus
Mutual growers group, called the research an exciting
breakthrough for "the future of not only Florida citrus, but
the entire global citrus industry."
The team that worked to obtain the gene sequence for the
Clementine mandarin included scientists from the University of
Florida, Italy, Brazil, France and Spain and the U.S.
Department of Energy's Joint Genome Institute (JGI).
The sweet orange sequencing was done by scientists from the
University of Florida, JGI, the Georgia Institute of Technology
and 454 Life Sciences, a Roche (ROG.V) company.
The sweet orange is grown in more than 100 nations and is
one of the most widely grown fruit crops in the world.
(Reporting by Jane Sutton; Editing by Cynthia Osterman)