MIAMI - 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 researchers said.
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 extreme temperatures.
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 Diego.
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: Quote) company.
The sweet orange is grown in more than 100 nations and is one of the most widely grown fruit crops in the world.