Virus and Nutritional problems

Bessie

Continuing the conversation about virus, coming from the "Taking Dahlia Cuttings" thread...
I found this video a beginner's overview of Dahlia virus. There's a small discussion of how to tell the difference between nutritional issues and virus symptoms.
Virus in Dahlias by Hanu Pappu - YouTube
https://m.youtube.com/watch?v=UrvnptVmIOU
The video recommend this video
Dahlia Nutrient Disorders - YouTube
https://youtu.be/qPVb7XnUMX4

SteveM

Bessie thanks for starting this thread, it will be great to have information and discussion of viruses in one place for future reference.

JessE

Both of those are excellent. I've watched Dr Pappu's several times.

Cosey

I just caught up on the cuttings thread where the virus discussion started.
Two things to add to the body of evidence -
1) there are older studies that show how long TSWV lives on surfaces and what disinfectants will kill the virus. I believe this is one body of evidence researchers cite when saying a 10% bleach solution is adequate for controlling that specific virus.

One thing that makes my common sense flag fly is when presentations state only ___ insect can be a vector for a virus. If a blade or a finger tip can carry a virus from one plant to another then how is an insect's piercing mouth part any different regardless of species? This is not a rhetorical question. I want to understand.

2) From my Google doctorate in plant virus and speaking with one researcher in person, DMV/DCMV isn't the worst virus in terms of economic impact. At this point, this DNA virus seems to prefer dahlias and dahlias only. The risk of this virus infecting other crops is currently low. (As always, science and time can change current understanding.) DMV/DCMV is a hot topic now because it's "newer" and also harder to test and diagnosis. DNA diagnostic testing is evolving. Prevalence will only increase as more testing happens. Don't misinterpret the data as the virus is all the sudden spreading. It's already there. Now you know about it.

SteveM

Cosey Google doctorate in plant virus

Ha! Good for you! I barely have my Google BS degree in plant virus. And most of what I know is about the tomato viruses.

If anyone has any links to current research on DMV (and variants) transmission in the field either through : 1. normal cutting of dahlias, moving up and down a row with no sterilization of clippers. and 2. Transmission by normal handling of a dahlia in a commercial operation (disbudding, weeding staking, etc.) with no hand sanitation.

Emilyp

Cosey I want to understand too! Why can a thrip transfer TSV, but only an aphid can transfer DMV? The literature makes it sound like certain insects transmit particular viruses, but human can spread them all. I need more facts!

Ailhad

Cosey
One thing that makes my common sense flag fly is when presentations state only ___ insect can be a vector for a virus.
Great point. This paper might help a little: https://www.sciencedirect.com/science/article/pii/S0042682215001622
Viruses have adapted to interact in specific ways with their insect vectors and can bind to receptors inside the insect or found different approaches to avoid getting digested in the insect's gut. It's more complicated than insects sticking their dirty virus-infested mouths into fresh leaves. If a particular virus species doesn't have the tools to survive in thrips for example, this virus will probably be digested or inactivated in the thrips before it can hop to a new leaf, and the virus wouldn't be transmitted by them. But a lot probably also depends on how stable a particular virus particle is in the environment and by what mechanism it infects a plant cell. TMV is very stable and designed to infect and replicate in many different plant species - so some dirty insect feet or mouths can probably carry TMV from plant to plant.🐾

Emilyp

I spoke with the Agdia lab this week, and they are seeing around 85% positive rates for DMV/DCMV - this encompasses the different versions of symptomatic DMV (Portland and Holland) but not the one that is integrated into the genome.

I once aske Dr. Pappu if the virus could be spread through "double dipping" into liquid rooting hormone gel. He said he didn't think so. I do not double dip just in case. I have started using the powder, and I sprinkle a little on a square of paper for each cutting and roll the cutting around on the paper and then toss the paper and leftover powder.

Cosey

Emilyp

Emilyp seeing around 85% positive rates for DMV/DCMV - this encompasses the different versions of symptomatic DMV

Emilyp I spoke with the Agdia lab this week, and they are seeing around 85% positive rates for DMV/DCMV

I wish I could round up every one sending in samples so we can form a cohort to help each other move forward. Combining our results and experiences would prove extremely educational.

SteveM

Cosey Has anyone sent in samples for DMV or DCMV, I'm curious what they charge. I see Agdia has the DIY kits available now. The AmplifyRP® XRT for DMV & DCMV is $695 for 48 reactions but the required AmpliFire® Isothermal Fluorometer (wasn't that used in the "Back to the Future"movie?) is $9850.00. I would have to start selling tubers to justify that expense.🙂
It would be niceto know if DMV/DCMV are transmitted by cutting/pruning instruments or (like TMV) are extremely contagious and can be transmitted on hands and clothing.
Probably those studies have been done, it's just a matter of finding them.

Cosey

SteveM
I sent in sample for DMV this year.

Not only is that kit expensive and requires specialized equipment but I started to read the manual and it's not a "set it and forget it" type of test. Experience and skill is necessary.

As far as I know, DMV et al is transmitted just like any other virus including cutting tools.

SteveM

Cosey As far as I know, DMV et al is transmitted just like any other virus including cutting tools.

But to what extent? Will handling the plants while staking/disbudding transfer the virus. What about brushing against an infected plant and then brushing against a clean plant. Not all virus are created equal when it comes to ease of transmission. I was very wary of TMV when raising tomato plants and would rinse my gloves in milk between plants when planting. (I don't know if milk is still considered an effective way to deactivate virus on hands). TMV is one virus that is transmitted extremely easily.

Cosey

SteveM

I was told it is a sap to sap transmission. Cutting tool to cutting tool.

Emilyp

SteveM https://wsu.zoom.us/rec/play/8TOawpSPeTjlitDb5rfwI6YGZJZhGROSYsaaTYXiiSb5eUQRXi2JJ66pmCZd85klLC3gQZikd5Mxqque.R6OVDJUtnEsPAPyZ?continueMode=true&_x_zm_rtaid=bmSx8bCnTjCW2KmNZTVyhg.1678059953171.34879af0723111413faf7829d073c8d9&_x_zm_rhtaid=517

Here is a zoom talk that covers this with DMV. It sounds like leaf transmission by plants touching is unlikely to pass DMV between plants, but cutting them does transfer it. They talk about it about an hour in.

Bessie

Cosey This conversation reminds me... I was looking at Dahlia leaves under a little 120x microscope yesterday... I saw little barbed clear structures that appeared to be filled with fluid. Perhaps when/if those structures get injured they will have a fluid that contains the virus. If that fluid comes in contact with another plant's injury point, then virus transmission might be facilitated. I'm transplanting up seedlings today, but I'll see if I can get a photo posted a little later today.

Bessie

Microscope photo of a Dahlia leaf's edge, 120x, taken by my cell phone camera. There are many of these "hairs" on the leaf. Some are visible to the naked eye if you look closely. They look to me to contain plant juices. Researching the image... they are called Cystolithic trichomes

Emilyp

It looks like they protect the plant. Here is some general information about them.

https://propg.ifas.ufl.edu/01-biology/02-cell-types/11-celltypes-trichome.html

SteveM

And some more info that suggests they may also be infection site for some pathogens, possibly including virus:
https://wp.ufpel.edu.br/lipp/files/2020/03/Semin%C3%A1rio-2.pdf

Cosey

Ailhad

Thanks! I'll read the link tonight. I usually spend the winter researching different points of interest. I have some rabbit trails of study pertaining to how other crops have managed virus at a commercial scale and I'll add this into that mix.

SteveM

Ailhad That looks like a great article and one to wade through on these cold, winter nights. I used to have to Google the meaning of every other word when I read a scientific paper but now I only have to Google every third word. Is there somewhere in this paper that indicates some viruses REQUIRE passing through a specific vector for successful transmission to plants but can not be transmitted through the exchange of sap mechanically (with cutting tools). Seems like I heard that many years ago but I might have dreamt it.

Bessie

I came across this interesting research paper (link) discussing how TSVdahlia virus may affect flower color.

There are also purple-flowering plants that have emerged from a black cultivar ‘Kokucho’. We report that the purple color is not caused by a mutation, as previously thought, but by infection with tobacco streak virus (TSVdahlia), which suppresses the PTGS of DvFNS. When TSVdahlia was eliminated from the purple-flowering ‘Kokucho’ by leaf primordia-free shoot apical meristem culture, the resulting flowers were black.

calico20hill

Hmmm, could this have anything to do with "The Curse of the Purples"?

Bessie

calico20hill what comes to my mind is how it's reported to sometimes be difficult to vegetatively capture sports. The sport may be the result of an infectious agent such as a virus, which may be transient.