Subscribe free to our newsletters via your
. Space Travel News .




FARM NEWS
Retracing early cultivation steps: Lessons from comparing citrus genomes
by Staff Writers
Walnut Creek CA (SPX) Jun 10, 2014


Citrus is the world's most widely cultivated fruit crop but it is under attack from citrus greening, a disease that is destroying entire orchards. Image courtesy Roy Kaltschmidt and LBNL.

Citrus is the world's most widely cultivated fruit crop. In the U.S. alone, the citrus crop was valued at over $3.1 billion in 2013. Originally domesticated in Southeast Asia thousands of years ago before spreading throughout Asia, Europe, and the Americas via trade, citrus is now under attack from citrus greening, an insidious emerging infectious disease that is destroying entire orchards.

To help defend citrus against this disease and other threats, researchers worldwide are mobilizing to apply genomic tools and approaches to understand how citrus varieties arose and how they respond to disease and other stresses.

In a study published in the June 2014 edition of Nature Biotechnology, an international consortium of researchers from the United States, France, Italy, Spain, and Brazil analyzed and compared the genome sequences of ten diverse citrus varieties, including sweet and sour orange along with several important mandarin and pummelo cultivars.

The consortium, led by Fred Gmitter of the University of Florida Citrus Research and Education Center, found that these diverse varieties are derived from two wild citrus species that diverged in Southeast Asia over five million years ago.

The U.S. Department of Energy Joint Genome Institute (DOE JGI) contributed to the citrus pilot project, Gmitter said, harnessing their expertise in plant genomics and capacity for high throughput sequencing.

Initial support for the citrus effort arose 10 years ago under the auspices of the inaugural round of the Community Science Program (CSP-formerly the Community Sequencing Program), which seeks to build scientific communities around cornerstone species of relevance to DOE missions in bioenergy, carbon cycling and biogeochemistry.

There is a fledgling industrial effort underway in Florida to redirect the five million tons of annual citrus waste generated there from low-value cattle feed to produce ethanol for fuel. The research team's citrus trait analysis will inform breeding strategies beyond important agronomic traits.

One of these wild species gave rise to cultivated pummelo, the largest citrus fruit that can often range from two to four pounds. Surprisingly, the small, easily peeled mandarins were, in contrast, found to be genetic mixtures of a second species and pummelo.

Sweet orange, the most widely grown citrus variety worldwide, was found to be a complex genetic hybrid of mandarin and pummelo, presumably accounting for its unique qualities. Seville or sour orange, commonly used in marmalade, was found to be an unrelated interspecific hybrid.

Since citrus varieties are reproduced asexually by vegetative propagation, trees producing a specific type of fruit are typically genetically identical. This growing strategy produces a uniform, high-quality fruit, but has the drawback that if one tree is susceptible to disease, they all are.

By inferring the past hybridization events that gave rise to these common citrus varieties -- either in the wild populations before domestication, or in early undocumented human-directed breeding efforts -- the team hopes to enable strategies for improving citrus, including resistance to greening and other diseases.

"Now that we understand the genetic structure of sweet orange, for example, we can imagine reproducing the unknown early stages of citrus domestication using modern breeding techniques that could draw from a broader pool of natural variation and resistance," Gmitter said.

The genomes presented in the published study included pummelos, oranges and mandarins. One of the sequences was the high-quality reference genome of Clementine mandarin sequenced by an international consortium including Genoscope in France, the Institute for Genomic Applications in Italy, the DOE JGI, and the HudsonAlpha Institute for Biotechnology, with contributions from researchers in Spain and Brazil. Another was the sweet orange genome, produced jointly by researchers at the DOE JGI, the University of Florida, and 454 Life Sciences, a Roche company.

By understanding the relationships between the various cultivated species with what they describe as "very narrow genetic diversity," the researchers hope to enable sequence-directed improvement, which could lead to crops that are more resistant to disease and stresses such as environmental changes.

The analyses revealed that while pummelos represent a single citrus species (Citrus maxima), the same cannot be said of cultivated mandarins, even those long held as not having intermixed with other varieties. Comparing sequences of so-called "traditional" mandarins such as the Asian cultivar Ponkan and the Mediterranean cultivar Willowleaf with mandarins known to be developed hybrids indicated that all contain segments of the pummelo genome.

The "wild" Mangshan mandarin from China is an exception to the rule, as its genome revealed it was in fact a separate species from other cultivated mandarins.

The findings echo Gmitter's quip when he spoke at the DOE JGI's 7th Annual Genomics of Energy and Environment Meeting in March 2012. "Citrus has incestuous genes," he told the audience. "Nothing is pure."

.


Related Links
DOE/Joint Genome Institute
Farming Today - Suppliers and Technology






Comment on this article via your Facebook, Yahoo, AOL, Hotmail login.

Share this article via these popular social media networks
del.icio.usdel.icio.us DiggDigg RedditReddit GoogleGoogle




Memory Foam Mattress Review
Newsletters :: SpaceDaily :: SpaceWar :: TerraDaily :: Energy Daily
XML Feeds :: Space News :: Earth News :: War News :: Solar Energy News





FARM NEWS
Drones give farmers an eye in the sky to check on crop progress
Champaign IL (SPX) Jun 05, 2014
This growing season, crop researchers at the University of Illinois are experimenting with the use of drones - unmanned aerial vehicles - on the university's South Farms. Dennis Bowman, a crop sciences educator with U. of I. Extension, is using two drones to take aerial pictures of crops growing in research plots on the farms. He presented his findings to farmers and other researchers at t ... read more


FARM NEWS
Roscosmos Scolded for 'Pestering Society' with Proton Crash Theories

SpaceX unveils capsule to ferry astronauts to space

Elon Musk to present manned DragonV2 spacecraft on May 29

Russia puts satellite in orbit from sea platform after 2013 flop

FARM NEWS
Rover Corrects its Spacecraft Clock

NASA Should Maintain Long-Term Focus on Mars as "Horizon Goal"

LDSD Testing for Large Payloads to Mars

New Mars Lander to Probe Interior of Red Planet

FARM NEWS
NASA Missions Let Scientists See Moon's Dancing Tide From Orbit

Earth's gravitational pull stretches moon surface

Water in moon rocks provides clues and questions about lunar history

NASA Invites Public to Select Favorite Moon Image for Lunar Orbiter Anniversary Collection

FARM NEWS
Dwarf planet 'Biden' identified in an unlikely region of our solar system

Planet X myth debunked

FARM NEWS
Astronomers Confounded By Massive Rocky World

Astronomers find a new type of planet: The 'mega-Earth'

Because you can't eat just one: Star will swallow two planets

'Neapolitan' exoplanets come in three flavors

FARM NEWS
Airbus's SpacePlane demonstrator tested in South China Sea

Private Space Race Heats Up

Proton Rocket Failure Probe Finds No Evidence of Deliberate Misconduct

XCOR Raises Investment Capital Led by Dutch Investors

FARM NEWS
Chinese lunar rover alive but weak

China's Jade Rabbit moon rover 'alive but struggling'

Chinese space team survives on worm diet for 105 days

Moon rover Yutu comes closer to public

FARM NEWS
To Catch a Comet by the Tail

NASA aims to land on, capture asteroids within next 15 years

Rosetta's target comet is becoming active

NASA Astronauts Go Underwater to Test Tools for a Mission to an Asteroid




The content herein, unless otherwise known to be public domain, are Copyright 1995-2014 - Space Media Network. All websites are published in Australia and are solely subject to Australian law and governed by Fair Use principals for news reporting and research purposes. AFP, UPI and IANS news wire stories are copyright Agence France-Presse, United Press International and Indo-Asia News Service. ESA news reports are copyright European Space Agency. All NASA sourced material is public domain. Additional copyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement, agreement or approval of any opinions, statements or information provided by Space Media Network on any Web page published or hosted by Space Media Network. Privacy Statement All images and articles appearing on Space Media Network have been edited or digitally altered in some way. Any requests to remove copyright material will be acted upon in a timely and appropriate manner. Any attempt to extort money from Space Media Network will be ignored and reported to Australian Law Enforcement Agencies as a potential case of financial fraud involving the use of a telephonic carriage device or postal service.