Featured Research

from universities, journals, and other organizations

Surprising Symbiosis: Glassy-Winged Sharpshooter Eats With Friends

Date:
June 19, 2006
Source:
The Institute for Genomic Research
Summary:
Like a celebrity living on mineral water, the glassy-winged sharpshooter consumes only the sap of woody plants -- including grapevines in California, where it threatens prized vineyards. Now, in the June 6 Public Library of Science Biology, researchers at The Institute for Genomic Research and colleagues report that the sharpshooter's deprivation diet is sneakily supplemented by two co-dependent bacteria living inside it.

The genomes of two bacterial species that supply essential nutrients for the glassywinged sharpshooter provide potential targets for controlling infestations of this greatly feared agricultural pest. (From: Gross L (2006) Bacterial Symbionts May Prove a Double-Edged Sword for the Sharpshooter. PLoS Biol 4(6): e218)

Like a celebrity living on mineral water, the glassy-winged sharpshooter consumes only the dilute sap of woody plants—including grapevines in California , which is feverishly working to prevent the insect's flight into prized vineyards. Now, in a surprising study published in the June 6 issue of Public Library of Science Biology (PLoS Biology), researchers at The Institute for Genomic Research (TIGR), the University of Arizona , and their colleagues have discovered that the sharpshooter's deprivation diet is sneakily supplemented by not one, but two co-dependent bacteria living inside its cells.

Although insect-bacteria symbiosis is common, this is the first genomic analysis of three partners. In the study, a team of scientists led by TIGR microbiologist Jonathan Eisen, now at the University of California , Davis , uncovered an intimate metabolic co-dependency among the glassy-winged sharpshooter ( Homalodisca coagulata ) and two bacteria, Baumannia cicadellinicola and Sulcia muelleri . The sharpshooter channels the sweets from sap to the bacteria, which in turn feed the insect vitamins, cofactors, and essential amino acids.

“Much as mosquitoes transmit malaria, the sharpshooter transmits plant disease, including Pierce's disease, which threatens vineyards,” Eisen says. “In order to design methods to fight the insect, we've got to understand how it works and its weaknesses. We knew symbionts were doing something for this insect--but until this study, we had no clue what that was.”

In particular, in this case, the threesome came as a surprise. Many insects, such as aphids and cicadas, feed on the sap from a plant's xylem or phloem, pipes that transport water and food within a plant. These sap-feeders are often known to rely on resident bacteria for a balanced diet – especially the synthesis of the “essential” amino-acids that all animals, including humans, cannot make for themselves. But researchers had assumed that the sharpshooter needed just one bacterial symbiont (in this case, B. cicadellinicola ), as does the biologically similar aphid.

University of Arizona evolutionary biologist Nancy Moran, who has extensively studied the co-evolution of insects and their resident bacteria, recruited Eisen to the current project. “My initial interest in sharpshooter symbiosis was in the hope that we could find out exactly how xylem can be used as food,” Moran explains. “It's terribly poor in nutrients.”

In the study, the team first carried out a painstaking forensic type of DNA analysis known as “metagenomics,” in which they sequenced the B. cicadellinicola 's genome from material gathered via dissections of hundreds of insects. The scientists were dumbstruck to find no evidence of the biochemical pathways needed to synthesize amino acids. Could the plant be somehow providing amino acids to its insect predator? Unlikely. Was the sharpshooter somehow cranking out its own amino acids? Doubtful. Could there be something else, some other bacteria, adding these essential ingredients?

Yes. Realizing the amino acid pathways might be carried out by other bacteria living inside the insect, the team began picking through their forensic samples of DNA sequences, removing all the sequence reads that matched neither the insect nor its known symbiotic B. cicadellinicola bacteria. A large amount of the leftover DNA mapped to another bacterium, S. muelleri . Sure enough, when they pooled the bits of sample DNA that came from S. muelleri , the team found all the essential amino acid synthesis pathways.

“When doing this type of forensic metagenomics, some scientists suggest you can just analyze the whole system as one unit—a so-called ‘black-box' approach--without knowing which piece of DNA came from which organism,” Eisen says. “But this black-box ecology just does not work well. To really understand the system, you've got to assign the different bits of DNA to organisms. This study shows why.”

For this particular insect-bacteria trio, genome-based reconstructions of metabolic activity suggest that the two resident bacteria are close neighbors, residing next door within host tissues and feeding each other chemical precursors needed to make nutrients. In the future, Eisen says, the bacteria will likely evolve into organelles of the insect, losing their distinction as bacteria altogether.

Looking ahead, Eisen is continuing to explore the genomes of other animal-bacterial symbioses to understand how such systems originate and work. “Symbiosis is a pervasive strategy in biological systems and we still do not understand the rules of how it works.” “This is why this sharpshooter symbiosis is so important – it has given us a good model system with two co-dependent bacteria rather than just one.”

In addition to TIGR, teams at the University of Arizona 's Department of Ecology and Evolutionary Biology and at the J. Craig Venter Institute's Joint Technology Center contributed to this work. It was funded by a National Science Foundation grant to Nancy Moran.


Story Source:

The above story is based on materials provided by The Institute for Genomic Research. Note: Materials may be edited for content and length.


Cite This Page:

The Institute for Genomic Research. "Surprising Symbiosis: Glassy-Winged Sharpshooter Eats With Friends." ScienceDaily. ScienceDaily, 19 June 2006. <www.sciencedaily.com/releases/2006/06/060619133208.htm>.
The Institute for Genomic Research. (2006, June 19). Surprising Symbiosis: Glassy-Winged Sharpshooter Eats With Friends. ScienceDaily. Retrieved July 31, 2014 from www.sciencedaily.com/releases/2006/06/060619133208.htm
The Institute for Genomic Research. "Surprising Symbiosis: Glassy-Winged Sharpshooter Eats With Friends." ScienceDaily. www.sciencedaily.com/releases/2006/06/060619133208.htm (accessed July 31, 2014).

Share This




More Plants & Animals News

Thursday, July 31, 2014

Featured Research

from universities, journals, and other organizations


Featured Videos

from AP, Reuters, AFP, and other news services

Visitors Feel Part of the Pack at Wolf Preserve

Visitors Feel Part of the Pack at Wolf Preserve

AP (July 31, 2014) Seacrest Wolf Preserve on the northern Florida panhandle allows more than 10,000 visitors each year to get up close and personal with Arctic and British Columbian Wolves. (July 31) Video provided by AP
Powered by NewsLook.com
Florida Panther Rebound Upsets Ranchers

Florida Panther Rebound Upsets Ranchers

AP (July 31, 2014) With Florida's panther population rebounding, some ranchers complain the protected predators are once again killing their calves. (July 31) Video provided by AP
Powered by NewsLook.com
Dangerous Bacteria Kills One in Florida

Dangerous Bacteria Kills One in Florida

AP (July 31, 2014) Sarasota County, Florida health officials have issued a warning against eating raw oysters and exposing open wounds to coastal and inland waters after a dangerous bacteria killed one person and made another sick. (July 31) Video provided by AP
Powered by NewsLook.com
Raw: Thousands Flocking to German Crop Circle

Raw: Thousands Flocking to German Crop Circle

AP (July 30, 2014) Thousands of people are trekking to a Bavarian farmer's field to check out a mysterious set of crop circles. (July 30) Video provided by AP
Powered by NewsLook.com

Search ScienceDaily

Number of stories in archives: 140,361

Find with keyword(s):
Enter a keyword or phrase to search ScienceDaily for related topics and research stories.

Save/Print:
Share:

Breaking News:
from the past week

In Other News

... from NewsDaily.com

Science News

Health News

Environment News

Technology News



Save/Print:
Share:

Free Subscriptions


Get the latest science news with ScienceDaily's free email newsletters, updated daily and weekly. Or view hourly updated newsfeeds in your RSS reader:

Get Social & Mobile


Keep up to date with the latest news from ScienceDaily via social networks and mobile apps:

Have Feedback?


Tell us what you think of ScienceDaily -- we welcome both positive and negative comments. Have any problems using the site? Questions?
Mobile: iPhone Android Web
Follow: Facebook Twitter Google+
Subscribe: RSS Feeds Email Newsletters
Latest Headlines Health & Medicine Mind & Brain Space & Time Matter & Energy Computers & Math Plants & Animals Earth & Climate Fossils & Ruins