Univ. Calif. Davis virus report (no date of preparation given)

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henry kuska
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Univ. Calif. Davis virus report (no date of preparation given)

Post: # 67832Post henry kuska
Sat May 12, 2018 4:39 pm

See:
https://ccuh.ucdavis.edu/sites/g/files/ ... Mosaic.pdf

Since this is a PDF each page can be identified by PDF page number. I would like to start by looking at the co - pot experiments, see pages 32, 34 and 35 (explains the procedure) and page 40 (which gives the results).
For the 20 plants that were infected with ApMv, ELSIA was only able to detect that 17 were infected (in the single pot experiment. The results were even worse for the 20 that were infected with PNRSV, only 10 were found infected by the ELSIA test. I think It would of been useful to check those results with one of the more sensitive PCR tests to see if the missing positive tests were due to the virus concentration dropping below the sensitivity limit of ELSIA.

However, of more interest (to me) is that virus transfer in the 2 plants per pots experiments did not appear to occur unless both ApMv and PNRSV were present in the infected plant ( 2 out of 20 for Dr. Huey and 4 or 5 out of 20 for R. Multiflora).

The above slide data is consistent with what was presented at a 2011 meeting:
"All plants that became infected were potted with ApMV + PNRSV plants. Rose mosaic symptoms were observed only in plants with ApMV + PNRSV.
http://www.apsnet.org/meetings/Document ... 1ma356.htm

I doubt that zero transfer in the single virus double experiments meant that the roots did not graft together. A possible explanation is that the double infection has the ability to better overcome the immune system of the previously clean plant so the infections could be detected by the relatively insensitive ELSIA method. Possibly, a sensitive PCR method could have found transfer in the single virus experiments.

henry kuska
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Re: Univ. Calif. Davis virus report (no date of preparation given)

Post: # 67840Post henry kuska
Mon May 14, 2018 12:10 am

The following Davis link has a 2018 copyright so it should be a reasonably up to date summary of the field.
http://fps.ucdavis.edu/roses.cfm
It has this to say about the historical use of heat treatment to create virus free roses:
"Heat treatment works well for many cultivars but others die in the heat or viruses are still present in the buds that were removed. Although heat therapy was heavily relied on in the past for virus elimination, tissue culture is now the method of choice at FPS."

This is their tissue culture summary:
"In 2007 we reported successful elimination of Apple mosaic virus (ApMV) and Prunus necrotic ringspot virus (PNRSV) using microshoot tip culture for six cultivars. FPS researchers are now working on optimizing rose shoot-tip culture and are starting to treat modern, heirloom and species roses."

This is the latest paper ( June 26, 2017 ) that I could find concerning Davis use of tissue culture to eliminate rose viruses:
https://www.houzz.com/discussions/47179 ... tip-tissue

Please note the following:
"Preliminary testing by ELISA shows that ApMV was eliminated; plants were still infected with PNRSV. Further testing and trials are ongoing."

H. Kuska comment: Please note: "plants were still infected with PNRSV"

Hopefully, updated information will be available at the Tuesday, June 26, 2018 - Wednesday, June 27, 2018 Rose National Clean Plant Meeting"
https://agriliferegister.tamu.edu/produ ... tails/2568
Last edited by henry kuska on Mon May 14, 2018 12:22 am, edited 1 time in total.

henry kuska
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Joined: Thu Dec 15, 2011 9:06 pm
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Re: Univ. Calif. Davis virus report (no date of preparation given)

Post: # 67841Post henry kuska
Mon May 14, 2018 12:15 am

Another interesting point (to me) is on slide 3 of the original link. This slide lists the viruses that they consider belong under the heading "Rose Mosaic Viruses". In addition to the common three (PNRSV, ApMV, and ArMV), they specifically list Prune Dwarf Virus, PDV and also include an "Others".

I Found several other Davis rose mosaic documents that indicate that they test roses for Prune Dwarf Virus, but I could not find any scientific literature from other groups that reported that Prune Dwarf Virus infected roses.

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