Tomato Brown Rugose Fruit Virus (ToBRFV) Breeding

So in 2022 one of my sub-projects was to breed in some resistance to the ToBRFV virus a new virus rapidly spreading worldwide for which there is or was until recently no existing resistance in domestic tomatoes.

A research paper with a list of resistant wild accessions was published and I saw it shared on Facebook. It is also important because it gives us an idea of just how rare resistance is even in wild tomatoes. From 636 wild species accessions they found about 31 resistant accessions or about 5 per 100 accessions.

Winter of 2021-2022 I was able to request this toBRFV resistant accession from the USDA ARS-GRIN which is on the list.

LA1375 PI 365967 Solanum pimpinellifolium

I’ve grown out some seed but not much because of poor pollination in the greenhouse. Plants got enormous though.

I’ve managed to successfully cross it with my Mission Mountain Morning F1 line within my Mission Mountain project, so I have F1 seed for that to grow next year. I would like to share the F2 generation widely- ideally through Experimental Farm Network.

I expect the F1 to be a red currant tomato and not really very interesting.

I have another accession Solanum chilense LA1932 from that same published work that so far, I have failed to grow successfully. 2022 was the closest. The plants got big but just as they flowered it froze inside the mostly unheated greenhouse. I might need some heated greenhouse space or another proper growing area to get it to set seed and live long enough to replenish my seed supply. Originally, I wanted this accession because it is known to be easier to cross with domesticated tomato then other peruvianum group wild tomato species.

There is an existing thread about this here:

Importantly a number of large tomato breeding companies who both started earlier and breed faster by growing multiple generations a year and genotyping them have already introduced commercial resistant varieties to large growers in at least Israel, Italy, and Mexico. I expect that somewhere in the tomato sections at the grocery stores there are a few resistant varieties already available as fresh fruit. In a worst case scenario we could propagate resistant plants from that, but I suspect that resistant seed packets will soon become available to home gardeners.

However, we get some resistance genes the next step is huge: we need to cross them into large numbers of heirloom varieties just as Carol Deppe suggested is necessary for Late Blight resistance.

It is important not to spread the virus as well- one of the more dangerous things towards making the spread more rapid is reciprocal international tomato seed trades.


I should correct my wording just a little after rereading that article about the 600 wild accessions that were assayed for survival and only 30 some were found. Most of those save for a few from an extremely difficult to work with species (Solanum ochranthum) were more what the author termed tolerances.

That could be important to folks who want their resistances to come from multiple genes.

I’ve been eyeballing the store tomatoes lately.

We import lots of tomatoes from Mexico.

Mexico has some TOBRFV infection.

Resistant varieties are being marketed there already but not here so far as I have read.

So I imagine some of the tomatoes in the stores might have resistance and also some of them might have infection with TOBRFV.

So most are perfect because consumers tend to reject anything but. However I did spot one tomato with a big brown spot after looking a few different times.

I’m sure the inspectors are on heightened alert for tomato brown rugose virus and that keeping it out is a priority. I bet they do a great job.

However resistance is often tolerance with infection still possible.

The virus is seed borne.

So if any infection sneaks through it will soon be in our compost piles etc.

I’m just curious here how long it will be before we all have this virus?

Note: I did some looking at photos of the infection online and I don’t think my grocery store tomato looks right for it- so probably just a bad one.

I went back to the store today. I think I may just be seeing infection. However this blotchy green uneven ripening looks more like some of the pathology photos.

I noted it on three different tomato types all from Mexico. Same store could be the same supplier or different but still sort of intrigued. I wonder if there is a test for it. When I buy tomatoes, I often throw the stem the core and anything that goes bad into the compost. Since this is seed transmitted, I imagine that if there is any in the stores that it will spread.

I also asked my plant pathology-oriented wife what she thought, and I showed her some of the splotchy green photos of the fruits online and she agreed there was a strong resemblance.

So I did some googling about testing. The visual symptoms aren’t enough apparently a test needs to be run. It sounds like they are a bit larger scale than say a single tomato. I think if you were a large company you could buy the tests and run them to make sure your tomatoes were staying uninfected. Some ag departments might be willing to run the tests if you sent them a grocery store tomato you thought was suspicious.

I would love to find some website where someone is monitoring this in the tomato supply just to know if there is some infection that does show up in stores. There is this site which I suspect will someday move the U.S. into the fully infected category. We are kind of light tan now and the known infestations are considered eradicated. Tomato brown rugose fruit virus (TOBRFV)[World distribution]| EPPO Global Database

1 Like

Thank you for creating this thread. I don’t have any contributions to make at this point but I appreciate the information.

Mark, for US growers since ToBRFV isn’t really upon us yet thinking about ToBRFV is more of a exercise in preparing for future potential challenges. So honestly, I don’t know if I will have very many meaningful updates myself. I hope to avoid the virus as long as possible- this may mean no longer composting tomatoes from the store and not saving any seeds from storebought tomatoes. It may also mean not seed trading so much for tomatoes since even though I don’t seed trade internationally I know some folks do. If some international forum members start to encounter severe ToBRFV problems long before gardeners in the US, they have my blessing to take over this thread so to speak as they will likely have many more updates.

I found ToBRFV looking tomatoes at the store again last week. So yesterday I thought to ask the local extension agents if we can test for it here in Montana. We can they sent instructions on mailing in a sample or said I could bring the sample to them and they would. So I plan to purchase a sample and send it in for testing.


Agdia has a dipstick test for ToBRFV:

I saw that, but it requires sign in to even see the price. I think I will send my grocery store sample into the state of MT diagnostic lab or drop it off with the extension agent. Which will be free.

Sure, you can’t beat free. Of course, any positive results obtained in a lab will be reported to regulators, which is worth considering if you have irreplaceable germplasm. The Agdia tests are $185/25.

1 Like

I think that given I sold $65 worth of tomato seed last year I will try to avoid paying for that Agdia test!

However, the tomatoes I am currently concerned about are the ones at the grocery store. So I feel pretty confident about using the state testing service. If the very large grocery store chain in question has a ToBRFV problem I have no problem letting the state of MT know about it.

If I see signs of this in my own tomatoes, I would be more inclined to buy the tests- I would also immediately stop the selling, gifting, trading, or exchange of seed for tomato or any other solanaceous crops.

I’m thinking about trying to stop myself from acquiring more tomato seed (I say as I have already acquired several packets recently). I think it would be best with ToBRFV and Purple Snapdragon Gene tomatoes in the world and I know I have many years’ worth of tomato germplasm- even if I could retire from field botany tomorrow and devote myself full time to tomato breeding! To only send tomato seed out. I talked to my wife today about not buying any fresh tomatoes while we have tomato seedlings and she agreed.

This might be a little silly in a few years if ToBRFV is really widespread then.

1 Like

Hi William! Did the test results come back?

We sort of double wrapped them and then kept forgetting to take them to the extension agent. They rotted and went in the trash. Then I banned all commercial tomatoes from the house until my seedlings are free in the gardens.

1 Like

Earlier this season I attempted to cross the MMM x LA1375 F1’s with a wide assortment of tomatoes. Eight of those new crosses have proven successful and have now been picked! Two of those new F1’s and the F2 of the original cross are back in seed packets already.

Though I don’t think LA1375 with its tolerance is adequate potential protection, even for those offspring that segregate out with it, but it is a start.