That orange you’re enjoying may have been grown in Florida, but its deepest ancestral roots stretch back more than 5 million years, all the way to two wild citrus species from Southeast Asia.
University of Florida scientists led an international research team that analyzed the genome sequences of 10 diverse citrus varieties for the first time.
Their findings, published online Sunday by the journal Nature Biotechnology, could help the citrus industry find and deploy genes for resistance to citrus greening, a bacterial infection devastating crops in North America.
Fred Gmitter, a UF Institute of Food and Agricultural Sciences faculty member, led the team of researchers from the United States, France, Italy, Spain and Brazil as part of a decade-long project to sequence and understand citrus genomes.
They analyzed and compared the genome sequences of sweet and sour oranges, along with several important mandarin and pummelo varieties. By understanding the relationships between the various cultivated species they describe as having “very narrow genetic diversity,” the researchers hope to enable genetic modifications and traditional breeding, which could lead to crops more resistant to disease and environmental stress, as well as better flavor and health-promoting benefits.
“Citrus has incestuous genes - nothing is pure,” said Gmitter, who is based at UF’s Citrus Research and Education Center in Lake Alfred. “Now that we understand the genetic structure of sweet orange, for example, we can imagine reproducing early citrus domestication using modern breeding techniques that could draw from a broader pool of natural variation and resistance.”
New citrus trees are almost always produced by grafting, a method of propagation that binds the fruit bearing part of one tree to the root system of another. That produces trees that more quickly bear genetically identical, uniform, high quality fruit. But because of that uniformity, if one tree is susceptible to disease, they all are.
Citrus is the world’s most widely cultivated fruit crop. In Florida, it is a $9 billion industry, employing 75,000. But it is under attack from a tiny bug, the Asian citrus psyllid, which sucks on leaf sap and leaves behind the citrus greening bacteria.
The disease, which renders fruit unsuitable for sale and eventually kills trees, could wipe out the industry in the next decade if a viable treatment is not found.
UF/IFAS researchers have attempted everything from trying to eradicate the psyllid to breeding citrus rootstocks that show better greening resistance. Current control methods include removing and destroying infected trees, controlling the psyllid, and providing additional nutrition in an attempt to keep infected trees productive.
Citrus was first domesticated in Southeast Asia thousands of years ago before spreading throughout Asia, Europe, and the Americas via trade.
One of the two wild species, Citrus maxima, gave rise to today’s cultivated pummelo, the largest citrus fruit, which can often weigh 2 to 4 pounds or more. The small, easily peeled mandarins were, in contrast, found to be genetic mixes of a second species (Citrus reticulata, the ancestral mandarin species) and pummelo. Sweet orange, the world’s most widely grown citrus variety, was found to be a complex hybrid, with mixed bits and pieces of the mandarin and pummelo genomes. Seville, or sour orange, commonly used in marmalade, is a simple hybrid between the two ancestral species.
The U.S. Department of Energy’s Joint Genome Institute, Genoscope in France, the Institute for Genomic Applications in Italy, and 454 Life Sciences, a Roche company, contributed to the citrus genome project.
Kimberly Moore Wilmoth | newswise
Water forms 'spine of hydration' around DNA, group finds
26.05.2017 | Cornell University
How herpesviruses win the footrace against the immune system
26.05.2017 | Helmholtz-Zentrum für Infektionsforschung
Staphylococcus aureus is a feared pathogen (MRSA, multi-resistant S. aureus) due to frequent resistances against many antibiotics, especially in hospital infections. Researchers at the Paul-Ehrlich-Institut have identified immunological processes that prevent a successful immune response directed against the pathogenic agent. The delivery of bacterial proteins with RNA adjuvant or messenger RNA (mRNA) into immune cells allows the re-direction of the immune response towards an active defense against S. aureus. This could be of significant importance for the development of an effective vaccine. PLOS Pathogens has published these research results online on 25 May 2017.
Staphylococcus aureus (S. aureus) is a bacterium that colonizes by far more than half of the skin and the mucosa of adults, usually without causing infections....
Physicists from the University of Würzburg are capable of generating identical looking single light particles at the push of a button. Two new studies now demonstrate the potential this method holds.
The quantum computer has fuelled the imagination of scientists for decades: It is based on fundamentally different phenomena than a conventional computer....
An international team of physicists has monitored the scattering behaviour of electrons in a non-conducting material in real-time. Their insights could be beneficial for radiotherapy.
We can refer to electrons in non-conducting materials as ‘sluggish’. Typically, they remain fixed in a location, deep inside an atomic composite. It is hence...
Two-dimensional magnetic structures are regarded as a promising material for new types of data storage, since the magnetic properties of individual molecular building blocks can be investigated and modified. For the first time, researchers have now produced a wafer-thin ferrimagnet, in which molecules with different magnetic centers arrange themselves on a gold surface to form a checkerboard pattern. Scientists at the Swiss Nanoscience Institute at the University of Basel and the Paul Scherrer Institute published their findings in the journal Nature Communications.
Ferrimagnets are composed of two centers which are magnetized at different strengths and point in opposing directions. Two-dimensional, quasi-flat ferrimagnets...
An Australian-Chinese research team has created the world's thinnest hologram, paving the way towards the integration of 3D holography into everyday...
24.05.2017 | Event News
23.05.2017 | Event News
22.05.2017 | Event News
26.05.2017 | Life Sciences
26.05.2017 | Life Sciences
26.05.2017 | Physics and Astronomy