A University of Florida-led group of international scientists has assembled the genome sequences for two citrus varieties — sweet orange and Clementine mandarin — marking a first for citrus.

The Clementine mandarin sequence is the higher quality of the two, but both are expected to help scientists unravel the secrets behind citrus diseases such as greening, a deadly threat to the state’s $9 billion citrus industry, as well as aiding those working to improve fruit flavor and quality.

Florida citrus industry officials said they were thrilled, and relieved, by the news.

“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 W. Sparks, executive vice-president and CEO of Florida Citrus Mutual, a trade organization comprised of 8,000 members, called genomics “the future of not only Florida citrus, but the entire global citrus industry.”

“It is exciting to see breakthroughs such as the release of these (genome) assemblies and I am confident the talented scientists working on this project will eventually propagate a citrus cultivar that withstands disease pressure and allows consumers worldwide to continue enjoying nutritious citrus products,” he said.

The genome sequences, the result of at least four years’ worth of study and $3.5 million invested by several countries, were announced at the International Plant and Animal Genome Conference in San Diego.

The announcement comes just weeks after a similar announcement that another international team, led by UF Institute of Food and Agricultural Sciences and Virginia Tech scientists, had published the DNA sequence for the strawberry.

The Clementine mandarin genome came from a haploid, meaning it has a single set of chromosomes. The scientists used a more detailed method of obtaining its genome sequence, which was more expensive, but provides longer strings of DNA, said UF’s Fred Gmitter, a horticultural sciences professor and Institute of Food and Agricultural Sciences member who led the effort.