New Corn Viruses of Unclear Origin

http://www.psrast.org/cornvir.htm

New corn viruses of unclear origin
Two new corn viruses have been reported recently. "Maize necrotic streak virus" and "Georgia Unkown". There is an unquestionable risk for new viruses to appear as result of recombination of DNA from the Cauliflower Mosaic Virus (CaMV) promoter present in GE crops and infecting viruses (see Comment by PSRAST). Therefore, for every new virus discovered, especially in crops like Corn (Maize) out of which a large part is genetically engineered, there is a good reason to consider the possibility that the virus is derived of said recombination.

"Georgia unknown" is too little known to be possible to comment in this respect.

Please note also our comment in the end of this document.



1. "Maize necrotic streak virus".
"The virus still remains a mystery. It falls into a family of viruses [the family Tombusviridae] that infect tomatoes and peppers, not grain crops", says Peg Redinbaugh, research plant molecular biologist at Ohio University Agricultural Research and Development Center (1).

The virus produced severe symptoms on corn that included pale green, yellow, or cream-colored spots and streaks. Its mode of spread has not yet been identified so it is not possible yet to judge whether it may become a significant agricultural problem.



Comment by Joseph E. Cummins, Professor Emeritus (Genetics) Dept. of Plant Sciences University of Western Ontario
The kind of recombination that we have been concerned about is associated with the CaMV promoter in the nucleus. That is DNA to DNA recombination. What takes place in tombus virus is RNA recombination. However, this does not preclude recombination with the CaMV promoter.

In CaMV replication two kinds of RNA are passed from nucleus to cytoplasm - the RNA template for virus replication into DNA and RNA templates to make viral capsid. Either could provide sequences for the Tombus virus.

Recombination can easily take place between messenger RNA and tombus virus. I think that the CaMV leader sequence just downstream of the promoter and enhancer could act as a hot spot for RNA-RNA recombination but there is no experimental evidence to back up that statement (one way or the other).

The CaMV virus has most recombination in the cytoplasm and that is during reverse transcription of RNA into DNA. Either the master RNA strand or CaMV messenger RNA can also undergo RNA-RNA recombination in presence of an RNA virus.

So it is not impossible that the the maize necrotic streak virus might be the result of recombination of a Tombus virus and genetic material derived from CaMV promoter DNA in GE corn.



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See also Correspondence with the discoverer of this virus, Dr Redinbaugh and commment by Dr Cummins. - We asked if the possibility of recombination had been considered in this case, and the answer was no.



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2. Georgia unknown
First discovered in Georgia, Redinbaugh said the virus has similar symptoms to several corn diseases including maize mosaic virus, maize chlorotic dwarf mosaic virus and maize rayado fino. Insects, namely planthoppers and leafhoppers, easily transmit those diseases. "The Georgia unknown could be a problem if it's transmitted by insects, like the other viruses are," said Redinbaugh. Studies have yet to determine if an insect like the planthopper transmits the unknown virus.


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References
Two New Corn Viruses Discovered by Candace Pollock. Ohioline news, November 21, 2000. Published by Ohio State University, College of Food, Agricultural, and Environmental Sciences.


"Maize necrotic streak virus, a New Maize Virus with Similarity to Species of the Family Tombusviridae". Raymond Louie, M. G. Redinbaugh, D. T. Gordon et al. Plant Disease, 84:1133 - 1139, 2000 (Oct).


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Comment by PSRAST
As explained in the article "The Virus Hazard", it has been known since long that the CaMV promoter, which is used in virtually all varietes of GE plants, has a tendency to combine its DNA with that of infecting viruses so as to generate new viruses that in some cases have been observed to be more virulent and less species specific than the original viruses. This risk is recognised even by the leading biotech company Monsanto and by the US Department of Agriculture.

Recent research at the John Innes Resarch Institue has discovered that the CaMV promoter used in GE crops contains a "recombination hotspot" that considerably enhances the risk of generation of new viruses (1). "It has been noted in experiments involving CaMV, that the frequency of recombination is much higher than for other viruses (2). While recombinant CCMV was recovered from 3% of transgenic N. benthamiana containing CCMV sequences, recombinant CaMV was recovered from 36% of transgenic N. bigelovii. " (3).

In addition, the CaMV Promoter is of such a nature that there is a risk for recombination with many different plant viruses (3). A wide range of recombination possibilities adds considerably to the risk for new viruses to occur in GE crops.


The gigantic numbers of CaMV promoters now released on American fields (about one billion per corn plant), makes it justified to regard the US GE corn crop as a huge "experimental ground" for generation of new viruses with unpredictable and potentially hazardous outcomes.

The question is therefore most probably not if, but when, a new virus will be discovered that is clearly derived from CaMV promoter recombination in GE crops. It cannot yet be excluded that the Maize Necrotic Streak Virus is one.

References of PSRAST comment
1. Kohli, A., Griffiths, S., Palacios, N., Twyman, R.M., Vain, P., Laurie, D.A. and Christou, P. (1999). Molecular characterization of transforming plasmid rearrangements in transgenic rice reveals a recombination hotspot in the CaMV 35S promoter and confirms the predominance of microhomology mediated recombination. The Plant Journal 17, 591-601.

2. Wintermantel WM. and Schoelz JE. Isolation of Recombinant Viruses between Caluiflower Mosaic Virus and A Viral Gene in Transgenic Plants under Conditions of Moderate Selection Pressure. Virology 1996, 223: 156-164.

3. Ho MW, Ryan A, Cummins J. Hazards of Transgenic Plants Containing the Cauliflower Mosaic Viral Promoter. http://www.i-sis.org/camv-mehd.shtml Tweet