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From: "J.E. Shields" <jshields at INDY.NET>
Subject: Re: Plant Viruses.
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Henry,

This sounds very interesting.  I'd love to hear more (much more!) about t=he
work the Minnesota prof is doing.

I tried to word my comments so that they applied to most case in a genera=l
way but not all.  Also, I'm not familiar with the intricacies of Hosta
reproduction and diseases, let alone of aroids.  Although a great many
plants do not usually transmit plant viruses through their pollen and
seeds, nevertheless some can do this, at least occasionally.

However, the effect you suggest would be analogous to what people think i=s
the origin of new influenza viruses -- co-infection of one cell by an old
human flu virus and a non-human (i.e., pig or bird) flu virus.  When the
pieces -- genes -- of the two virus types are mixed and matched,
occasionally you get a new combination of human and pig or bird flu genes
that can infect humans and against whose pig or bird genes the human
population has little or no existing immunity.

I'm eager to hear with the study did and what was found.

Best regards,
Jim Shields
in chilly central Indiana (USA)

At 08:42 AM 12/5/2008 -0800, you wrote:
>Jim,
>
>A professor here in Minnesota has been studying plant viruses.
>
>I learned about his study in relation to hosta Virus X.
>
>And there has been a recent dialogue about viruses in Arisaema so I
>thought it might be relevant.
>
>--Henry
>
>
>
> > From: J.E. Shields <jshields at INDY.NET>
>
> > Hi Henry,
> >
> > No one has addressed your virus question yet, so I'll
> > take a shot at it.
> >
> > In many plant families, viruses tend to be excluded from
> > germ cells. Whether actively or passively, I'm not sure;
> > but most probably passively. Still, you can often raise
> > virus-free plants from seed produced by virus-infected
> > parents.
> >
> > This by itself precludes the in vivo recombination you ask
> > about. However, I am not familiar with the germ cell
> > generating process in Cactaceae, so I can't say whether
> > my comments above apply to cacti.
> >
> > Then there is the matter of the practical aspects of
> > creating a recombinant virus. This happens relatively easily
> > in viruses that have multiple strands of DNA or RNA in each
> > particle. I don't think plant viruses have that
> > characteristic (but I can't swear to how universal this
> > is). Dual infections by defective viruses could result in
> > rescuing one or both, but again if the viruses are defective
> > they are not (very) infectious.
> >
> > Latent viruses -- where the virus genes have been
> > incorporated into the host DNA -- are another matter.
> > I'm not at all sure about the occurrence of latent
> > viruses in the genomes of higher plants. It certainly
> > happens in microorganisms. If it occurs in plants, the
> > latent virus would naturally be included in the genes of
> > germ cells and would be transmitted to the plants offspring.
> >
> > Hope this helps.
> >
> > Jim Shields
> > in cold central Indiana (USA)
> >
> >
> >
> > At 12:25 PM 12/4/2008 -0800, you wrote:
> > > Has anyone heard the theory that by crossing
> > dissimilar plants we create plant viruses from the unmatched
> > genetic material?
> > >
> > > --Henry Fieldseth
> > > Minneapolis, Minnesota, USA, zone 4/5
> >
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>
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>
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*************************************************
Jim Shields             USDA Zone 5             Shields Gardens, Ltd.
P.O. Box 92              WWW:    http://www.shieldsgardens.com/
Westfield, Indiana 46074, USA
Tel. ++1-317-867-3344     or      toll-free 1-866-449-3344 in USA

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