Natural GMOs Part 189. Pathogenic plant virus jumps to honeybees

21-Jan-2014 American Society for Microbiology

A viral pathogen that typically infects plants has been found in honeybees and could help explain their decline. Researchers working in the U.S. and Beijing, China report their findings in mBio, the online open-access journal of the American Society for Microbiology.

The routine screening of bees for frequent and rare viruses "resulted in the serendipitous detection of Tobacco Ringspot Virus, or TRSV, and prompted an investigation into whether this plant-infecting virus could also cause systemic infection in the bees," says Yan Ping Chen from the U.S. Department of Agriculture's Agricultural Research Service (ARS) laboratory in Beltsville, Maryland, an author on the study.

"The results of our study provide the first evidence that honeybees exposed to virus-contaminated pollen can also be infected and that the infection becomes widespread in their bodies," says lead author Ji Lian Li, at the Chinese Academy of Agricultural Science in Beijing.

"We already know that honeybees, Apis melllifera, can transmit TRSV when they move from flower to flower, likely spreading the virus from one plant to another," Chen adds.

Notably, about 5% of known plant viruses are pollen-transmitted and thus potential sources of host-jumping viruses. RNA viruses tend to be particularly dangerous because they lack the 3'-5' proofreading function which edits out errors in replicated genomes. As a result, viruses such as TRSV generate a flood of variant copies with differing infective properties.

One consequence of such high replication rates are populations of RNA viruses thought to exist as "quasispecies," clouds of genetically related variants that appear to work together to determine the pathology of their hosts. These sources of genetic diversity, coupled with large population sizes, further facilitate the adaption of RNA viruses to new selective conditions such as those imposed by novel hosts. "Thus, RNA viruses are a likely source of emerging and reemerging infectious diseases," explain these researchers.

Toxic viral cocktails appear to have a strong link with honey bee Colony Collapse Disorder (CCD), a mysterious malady that abruptly wiped out entire hives across the United States and was first reported in 2006. Israel Acute Paralysis Virus (IAPV), Acute Bee Paralysis Virus (ABPV), Chronic Paralysis Virus (CPV), Kashmir Bee Virus (KBV), Deformed Wing Bee Virus (DWV), Black Queen Cell Virus (BQCV) and Sacbrood Virus (SBV) are other known causes of honeybee viral disease.

When these researchers investigated bee colonies classified as "strong" or "weak," TRSV and other viruses were more common in the weak colonies than they were in the strong ones. Bee populations with high levels of multiple viral infections began failing in late fall and perished before February, these researchers report. In contrast, those in colonies with fewer viral assaults survived the entire cold winter months.

TRSV was also detected inside the bodies of Varroa mites, a "vampire" parasite that transmits viruses between bees while feeding on their blood. However, unlike honeybees, the mite-associated TRSV was restricted to their gastric cecum indicating that the mites likely facilitate the horizontal spread of TRSV within the hive without becoming diseased themselves. The fact that infected queens lay infected eggs convinced these scientists that TRSV could also be transmitted vertically from the queen mother to her offspring.

"The increasing prevalence of TRSV in conjunction with other bee viruses is associated with a gradual decline of host populations and supports the view that viral infections have a significant negative impact on colony survival," these researchers conclude. Thus, they call for increased surveillance of potential host-jumping events as an integrated part of insect pollinator management programs.


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mBio® is an open access online journal published by the American Society for Microbiology to make microbiology research broadly accessible. The focus of the journal is on rapid publication of cutting-edge research spanning the entire spectrum of microbiology and related fields. It can be found online at http://mbio.asm.org.

The American Society for Microbiology is the largest single life science society, composed of over 39,000 scientists and health professionals. ASM's mission is to advance the microbiological sciences as a vehicle for understanding life processes and to apply and communicate this knowledge for the improvement of health and environmental and economic well-being worldwide.

@ Pathogenic plant virus jumps to honeybees:

ASM Press Release
Contact: Jim Sliwa
jsliwa@asmusa.org
202-942-9297
H/T Andy Apel on Twitter

Natural GMOs Part 188. Red Queen Redux. Jungle Chemical Warfare Battle for Survival May Yield the Rain Forest’s Diversity

Image, Tenial, Copyright expired.

Carl Zimmer explains the jungle chemical warfare story:

...Plants are not helpless victims, however. They have evolved a staggering variety of defenses. Some grow cups of nectar on their leaves to attract sugar-hungry ants, which also attack insects feeding on the leaves. Some plants defend themselves by sprouting hairs. “To us they seem soft and fuzzy,” Dr. Coley said, “but to a small caterpillar with a soft belly, they can be more like meat hooks.”
The most impressive defenses in tropical plants are invisible, however. A plant may pack each of its leaves with hundreds of kinds of insect poisons. Those toxins can make up half the dry weight of a tropical plant leaf.
As farmers know all too well, insects can evolve resistance to pesticides. A similar evolution plays out in tropical forests, where insects can disarm many of the chemicals that plants use against them.
Of course, plants in temperate regions face attacks from insects, too. But Dr. Coley and Dr. Kursar argue that those plants are more adapted to the bigger threats they face, from the bitter cold of winter and other environmental challenges. In the tropics, plants enjoy a balmy climate year-round. While the physical environment poses less of a threat to tropical plants, it makes insects a bigger danger. They can grow faster in the warm, moist climate; without killing frosts, they can produce more generations each year.
The tropics have thus become host to an arms race. Each species of plant is evolving defenses against its enemies, which evolve counterdefenses in turn. This arms race would explain why tropical plants have become so loaded with toxic compounds...

More @ Battle for Survival May Yield the Rain Forest’s Diversity - NYTimes.com:

About On Tropical Forests and Their Pests
Phyllis D. Coley, Thomas A. Kursar
Science 3 January 2014: Vol. 343 no. 6166 pp. 35-36 DOI: 10.1126/science.1248110

Key Quote

"Evidence from several lineages of tropical trees and shrubs shows that closely related species have diverged in defenses while differing little in nondefense traits (9–12). This supports the Red Queen hypothesis (13), which states that antagonistic interactions between hosts and their pests lead to natural selection for beneficial adaptations and counter-adaptations in both groups. Because herbivores are continually evolving counter-adaptations to plant defenses, plant defensive traits should evolve faster than adaptations to a more static abiotic environment."

References and Notes

1. S. J. Wright, Oecologia 130, 1 (2002).
2. C. Baralotoet al., J. Ecol. 100, 690 (2012).
3. D. T. Palowet al., Funct. Ecol. 26, 1144 (2012).
4. B. E. Sedioet al., J. Ecol. 100, 1183 (2012).
5. X. Liuet al., Funct. Ecol. 27, 264 (2013).
6. E. G. Leighet al., Biotropica 36, 447 (2004).
7. D. W. Schemskeet al., Annu. Rev. Ecol. Evol. Syst. 40, 245 (2009).
8. J. X. Becerra, Proc. Natl. Acad. Sci. U.S.A. 104, 7483 (2007). The impact of herbivore–plant coevolution on plant community structure
9. T. A. Kursaret al., Proc. Natl. Acad. Sci. U.S.A. 106, 18073 (2009). The evolution of antiherbivore defenses and their contribution to species coexistence in the tropical tree genus Inga
10. B. E. Sedio, thesis, University of Michigan (2013)
11.  J. X. Becerra, K. Noge, D. L. Venable, Proc. Natl. Acad. Sci. U.S.A. 106, 18062 (2009). Macroevolutionary chemical escalation in an ancient plant–herbivore arms race
12. P. V. A. Fineet al., Ecology 94, 1764 (2013).
13. L. Van Valen, Evol. Theory 1, 1 (1973).
14. M. R. Servedioet al., Trends Ecol. Evol. 26, 389 (2011).

See also previous GMO Pundit posts: 

• Natural GMOs Part 19. The Evolutionary Arms Race.
• Natural GMOs Part 20. The Red Queen. 
• Natural GMOs Part 170. The Red Queen was right: We have to run to keep in place

Natural GMOs Part 187. The Amborella tree Genome shows Flowering Plant Evolution is Genome duplication and Gene Transfer

Amborella trichopoda /Wikipedia

Shaping Plant Evolution
Amborella trichopoda is understood to be the most basal extant flowering plant and its genome is anticipated to provide insights into the evolution of plant life on Earth (see the Perspective by Adams). To validate and assemble the sequence, Chamala et al. (p. 1516) combined fluorescent in situ hybridization (FISH), genomic mapping, and next-generation sequencing. The Amborella Genome Project (p.10.1126/science.1241089) was able to infer that a whole-genome duplication event preceded the evolution of this ancestral angiosperm, and Rice et al. (p. 1468) found that numerous genes in the mitochondrion were acquired by horizontal gene transfer from other plants, including almost four entire mitochondrial genomes from mosses and algae.

@ The Amborella Genome and the Evolution of Flowering Plants: at Science Magazine