TSWV Tomato spotted wilt virus

[Tom Wagner]

I am beginning this post due to a General Discussion Post on Spotted Wilt Varieties. As I seldom get to the other forum topics to even visit, therefore, I am hoping that this discussion where I am the moderator will help keep me involved in the direct issues.

I'm searching for additional varieties which are Spotted Wilt Resistant and preferably indeterminate. If anyone knows of any others, please let me know.

This is the starting question that made me convinced to cover the topic. Hat tip to tlcmd.

=================================


As a breeder of tomatoes I was surprised on how few of the TSWV resistant lines I have grown. Even fewer in my crossing programs. Not so many years ago, the general consensus hinted that there were no resistant lines available. The advanced work on developing the resistance has mushroomed the last few years, but not among heirloom growers, alas.



The problem.....





Most of the TSWV resitant tomato cultivars are not very tasty tomatoes.

The list of TSWV resistant tomatoes to date.12-28-07


Sweet Cluster F1
Sebring
Muriel
Health Kick
Cupid F1
Crista F1
BHN-685
BHN-640
BHN 555
BHN-444
Belle Rose
Amelia VR F1
NC 0256
NC 032939
NC 0341
BHN 601
Quincy
SVR 01408426
Topgun
HMX800
HMX9800
HA-3074
HA-3371
WS 4062
Fla 925-2
Stevens
Corrida
Extremo
DRW 7556
DRW 57-19
Kerala
Kamuka
Paradise
Camel (HMX 4793)
El Cano (XP 2508410)

Bullet points about TSWV:

• TSWV first was discovered on tomatoes in 1919
• TSWV infects 300 different hosts
• Had been a problem in subtropical areas.
• 1980s that they began to affect the U.S. greenhouses
• The viruses spread quickly across the United States an
• Now are found everywhere.
• Symptoms of TSWV -- Necrotic spots, streaking, ring spots, stunting and wilting
• TSWV has been reported to be transmitted in the seed of Lycopersicon esculentum.
• It is believed TSWV is carried on the seed coat.
• Suspected that thrips are vectors
• TSWV mostly is spread by movement of plants or cuttings, rather than by seed.

Since precious little work is done with heirloom type tomatoes to introduce disease resistance, I don't suppose that there will be many improved introductions soon. The existing varieties are mostly hybrid as alluded to in the Discussion forum and most are not very tasty to boot.



I would like to do more to help on this matter, but I've found that there is little support to someone like me to do this. My talk in Iowa earlier this year (2007) about introducing hybrid heirlooms with improved disease tolerance and other qualities left me with the impression that I was largely alone in this effort.



I will try to access some of the lines with the TSWV resistance and/or if anyone sends me seed of those. I will try to breed these lines, hybrid or not, to test the single gene dominant trait (published) and to find marker genes associated with resistance. I have some heirloom lines that I will cross, but if others have suggestions on what heirlooms need to be crossed, let me know.

Is the need veritable?
Can the resistant heirloom/commercial hybrids be tested or first releases by 2009?
Can true breeding lines of new TSWV heirlooms be released by 2012?
What support structure can be implemented?
Seed Venues? Who, What, Where,When, and How?

The answers to the above questions could be totally affirmative, however there is this confessional: I have listened to many Inspirational talks by keynoters over the years. I fear that the audiences are somewhat inspired, but left unchallenged. I, unfortunately, am not the inspirational speaker, nor the challenger; if anything I am but a foot soldier in tomato breeding.

The 2008 season is soon to started, let me know how I can help regarding TSWV.


Tom Wagner

[feldon30]

My initial question is how difficult is it to acquire germplasm for the varieties you have listed?

Let's forget the "heirloom" tag for a second and say open-pollinated, and in that regard, there is plenty of desire and activity in finding new tomato varieties that come true from seed from year to year. Look at the dwarf project. It continues to mushroom and there may be two dozen new varieties that get selected out of it.

As much as people are affected by TSWV even on this forum, I'd say that if someone made seeds available of some of the varieties above, we could see our first F1 crosses in 2008 and start getting some stabilized varieties by 2012.

The most challenging part will be confirming TSWV resistance (I am using the word resistance here because to my knowledge, the varieties listed do not succumb to TSWV at all, but instead are just carriers -- someone correct me if I am wrong). With some of the reports posted in the other thread, any tomato variety that is not TSWV-resistant will get wiped out fast enough to be obvious, if not scientifically proven.

Thoughts?

[Tom Wagner]

Morgan, great questions.

My initial question is how difficult is it to acquire germplasm for the varieties you have listed?

Easy to very difficult on some lines. Several people working together to obtain and direct our way would help. I am going to access those that wont affect my already marginal bank resources.

Let's forget the "heirloom" tag for a second and say open-pollinated, and in that regard,

I tend to focus lately on the "Heirloom" moniker as I can't compete with the major seed companies with OP's (open pollinated) as nearly all their release recently are hybrids. And I am leaning more to developing heirloom traits anyway.

there is plenty of desire and activity in finding new tomato varieties that come true from seed from year to year.

Yes, I agree. However, I have been disappointed in the lack of folks venturing with me on releasing my new varieties. The number of times I was going to get help on a website during this last year has greatly frustrated me. A number of events lately have hobbled my options of research activities next year.

Look at the dwarf project. It continues to mushroom and there may be two dozen new varieties that get selected out of it.

Great activities, but it doesn't serve my purposes. Sorry, it is difficult to explain. It's kinda like..been there, done that. As far as I know, there is no money in creating a bank of TSWV/Heirloom hybrids and distributing F-2 seed.

As much as people are affected by TSWV even on this forum

I must be out of the loop on this. How many people are affected by TSWV within the TVille members? The general public? Major growers? Seed producers?

I'd say that if someone made seeds available of some of the varieties above, we could see our first F1 crosses in 2008 and start getting some stabilized varieties by 2012

Very much in agreement with what I said earlier.

The most challenging part will be confirming TSWV resistance

Single gene, dominant. At least that's what I've read. The hybrids that carry TSWV resistance will only throw 1/2 of the resistance to the progeny. That is why I will stress more OP cultivars.
This would require grow outs in several climes to assess.

I am using the word resistance here because to my knowledge, the varieties listed do not succumb to TSWV at all, but instead are just carriers -- someone correct me if I am wrong

Carriers, resistant, whatever, as long as results are promising and seed treatment (hot water, TSP, chlorine) and multiple year seed storage diminishes seed coat infestation.

With some of the reports posted in the other thread, any tomato variety that is not TSWV-resistant will get wiped out fast enough to be obvious, if not scientifically proven.

As the unfortunate result of TSWV, but allowing for the benign, seed is extracted from selected vines.

The last few years have been devoted to things like organic gardening adaptations, Late Blight resistance, recombination of Heirloom hybrids, and filial advancement. Should I devote time and energy to the issues of TSWV?
The readership here on TVille is small compared to the general public and global researcher, and getting the message out is next to impossible for me.

Tom Wagner

[Fusion_power]

TSWV affects my garden every year and has done so since 2003. It is endemic throughout the SouthEast U.S. and also along most of the Atlantic coast. Infection in the MidWest has been reported in the last few years.

It is obvious from this that incorporation of the S5 gene into some of the heirloom cultivars would be desirable.

The major issue with S5 is that it is linked to several undesirable genes. This linkage has only recently been broken to some extent with resulting releases of varieties such as Amelia and Health Kick. I would suggest making a simple cross of Amelia with some of the larger and better flavored heirlooms. Brandywine, Daniels, Cherokee Purple, etc would be good starters.

The initial cross should be followed with backcrosses to the heirloom parent once confirmed tolerant lines are available. It is simple to test a plant for tolerance. all you need is an infected plant and a knife. slice off a sprig from the infected plant and make small notches in healthy plants, then rub the cut sprig in the wound.

DarJones

[kktwahoo]

Tom,

We were wiped out last summer, near Wahoo, Nebraska, by TSVW.

This started before we saw you at SSE meeting in July, and just got worse after we returned home.

If you are just a foot soldier, I do not know what I am - let me think on this one!

Keep thinking,

Kent & Kathy

P.S. Tom, I will send you a PM now, k?

[feldon30]

Tom,

I think you are misunderstanding me. I am not asking you to perform any pro bono work, research, or growouts. You responded to the question regarding TSWV with a volunteer of information, and that is exactly what I am hoping for. Oh and seeds.

If there are any costs involved in acquiring these seeds, or you would rather refer us to the direct sources to get them, I'm sure the people who have posted in this thread and the other TSWV thread who are currently getting NO tomatoes despite growing dozens of them would be happy to cough up a few bucks to acquire seeds.

I can buy Amelia and Health Kick plants here in Houston and have seeds for ~140 varieties, although I have no clue how to do crosses myself.

TSWV is not a problem in Houston -- yet -- but it could be, and I'd like to have seeds ready for some tomatoes that don't taste like licking a fencepost.

[Tom Wagner]

To Darrel, Kent, and Morgan, and anyone else reading,



Sorry to hear so many folks are affected adversely by TSWV. I have not lived in Kansas since 1988, so I am out of the loop what is going on back there too! I live in Everett, Washington.

It is obvious from this that incorporation of the S5 gene into some of the heirloom cultivars would be desirable.

That is what I am thinking. I had forgotten that I was in contact with Randy Gardner last spring with the thought of doing a pollen transfer agreement with him to obtain the Sw-5 genes (not S5) of several OP lines he has. About the time I thought I would do this things weren't looking too fine to proceed; then I just forgot about it. I was definitely planning to cross the spotted wilt resistant pollen lines with a whole aray of heirloom and proprietary material.

The major issue with S5 is that it is linked to several undesirable genes. This linkage has only recently been broken to some extent with resulting releases of varieties such as Amelia and Health Kick.

I will have to analyze this myself with some grow outs of OP and hybrid material. I found some more lines that carry the SW-5 gene. With so many more lines to my list of options to access, I don't think we will have a problem. I will have to see if the linkage is such that a hybrid is OK, but if the inbred (homozygous) show severe linkage and quality problems in developing heirlooms with resistance...uh oh! It just may be that desirable lines of heirlooms will have to fall into the hybrid category or strategeries. I will ask Dr. Gardner, about this as he sent me an email just a while ago.

The list to add to 12-28-07:TSWV res.Most are F-1s

'Crista' = (NC 0256
NC 0227
NC 0236
NC 0367
NC 0377
NC 0392
NC 056
Fla. 7964
Fla. 8042
NC 032939
NC 0341
PSR 55289
HMX 5790
HMX 5790
Sophya
HMX 3861
Nico
Red Defender
Picus (XP 01429864)
PS 01522942
PS 01522935
Quincy (XP 01408383)
Redline (formerly RFT 4971)
HMX 5790
NC 58S(2002)-1A (parent of NC 0392)
NC 123S(2002)-1C (parent of NC 0256 which is named Crista
NC 127S(2002)-BK (parent of NC 0227 and NC 0236)
NC 58S(2002)-1A
NC 123S(2002)-1C
NC 127S(2002)-BK


I want to access the Daddy of some of the lines with SW-5 resistance, namely, Accession: LA3667 from the Donor Mikel Stevens. It originated from an F5 of Stevens x Rodale
It is identified with the Locus name: Spotted wilt resistance-5
Chromosome: 9 Arm: L.

Now all I have to find out is what else in on the long arm of chromosome 9, as in what is missing and what else is there. Did just a snippet of this chromosome get involved or did the whole darn chromosome carry down?

The Sw5 gene, which I just mentioned, has been mapped near the telomere of the long arm of chromosome 9 back in 1995. I wonder if there has been any translocations, ie, breakage and reconnection of odd pieces of the chromosome 9? Being so close to the telomere (that's the end of the chromosome) I am thinking deletions, additions, and translocations are bit more likely. The early resulting lines have been used in so many warmer climates that I am afraid of hearing more reports of the resistance of these new varieties becoming overcome by the virus. This is where TVille could help us triangulate the research data.

The initial cross should be followed with backcrosses to the heirloom parent once confirmed tolerant lines are available.

Crossing OP lines of TSWV lines would work more direct, since 100% of the offspring will carry the resistance. The hybrid backcrosses only 50%. However, there may be one or more hybrids that have traits I want anyway, like the nipple gene, large slicing sizes, etc.

It is simple to test a plant for tolerance. all you need is an infected plant and a knife. slice off a sprig from the infected plant and make small notches in healthy plants, then rub the cut sprig in the wound.

I will have to see if there are any TSWV infected tomatoes here in the Seattle area to do a proper test. I may not find any local sources here, but let me google this or maybe our readers can fill me in as to the nearest TSWV area!

This started before we saw you at SSE meeting in July, and just got worse after we returned home. If you are just a foot soldier, I do not know what I am

Yes, I remember you well Kent. We had some longs chats back in Iowa, didn't we? What I did not remember is that TSWV was your enemy! Foot soldier? I take no commands and give none either, so maybe I am less than a foot soldier?

I think you are misunderstanding me. I am not asking you to perform any pro bono work, research, or growouts. You responded to the question regarding TSWV with a volunteer of information, and that is exactly what I am hoping for. Oh and seeds.

Big deal! I am doing, essentially, all kinds of pro bono work, research, and grow outs anyway. I hope to volunteer information, copious amounts if possible, since precious few folks do. The seeds and the sharing thereof may lie in a formalized TSWV PROJECT or an advance website offering a service trade or sorts. Who knows?

If there are any costs involved in acquiring these seeds, or you would rather refer us to the direct sources to get them, I'm sure the people who have posted in this thread and the other TSWV thread who are currently getting NO tomatoes despite growing dozens of them would be happy to cough up a few bucks to acquire seeds.

Interesting concept, especially the part where folks have problems with TSWV and are willing to share some of their hard fought for seeds with me in the beginning with hopes of obtaining segregating heirloom types tomatoes with 75% TSWV resistance. Good Website Proposal, huh?



I suppose I should list where many of the current TSWV resistant lines may be obtained, requested, or bought?

Lord, I need an editor to help me sort out my ramblings, good thing I don't really care if I goof up a bit. Thanks for reading this far!

Tom Wagner

[Rena]

I am almost certain this is what kills my tomatoes each year. I have noticed that certain varieties DO seem to live longer and one of them is Big Boy. I also noticed Red Zebra gave it a good go this last year. Last year was my last for trying to plant in ground. Another one that lasted was Amulet (from Andrey). I would love to participate in such a trial. My first year growing here was the best then year after year it got worse and now you can't plant at all in the soil.

[feldon30]

Some of the descriptions I have found of TSWV don't seem very useful to me. The thing I look for, because I am a visual person, is a bronzing or purpling of the leaves. That is the one sign that I can tell even from far away or a thumbnail image that a plant may have TSWV.

Tom,

We do not have TSWV here in Houston, and I don't really have a dog in this fight. Anyway, I've responded to your e-mail regarding getting you a website built. I don't want to step on any toes, but if all other leads are dead, I will gladly step in and get you started.

[RandyG]

To Tom Wagner and other breeders

I have released several op lines with the Sw-5 gene for TSWV resistance and these lines have other useful resistance genes also. All of my Sw-5 lines originated from the hybrid Amelia which I co-developed with a seed company breeder. All of the lines I have released so far are determinate and some of them are used in commercial hybrids such as Fletcher, Mountain Glory, Crista and a new plum tomato hybrid, Plum Regal, which should be on the market next year. I am also working on getting TSWV resistance into good grape tomatoes. If you type NC tomato breeding program into Yahoo or Google, you will see the link to my website. All the TSWV resistant lines require a signed seed tranfer agreement (available for download at the website with instructions for submitting) and are intended for use as parent materials for hybrids and as a source of resistance for developing new varieties. They are not available to growers who just want to grow them for production of fruit and not use them in breeding. It would be easy to develop op heirloom types by backcrossing the Sw-5 gene into heirloom varieties. There is a good molecular marker for the Sw-5 gene and there are commercial labs that will test your backcross lines for a reasonable fee to help you identify your segregating lines with the Sw-5 gene. The TSWV resisatnt lines I have worked with have been crossed and selected enough that I don't see any bad traits associated with the resistance. The backcross into heirloom varieties would be very straightforward. The newest line I have released, NC 1CS, has the crimson gene for increased lycopene. This gene would also be useful to cross into some heirlooms. I am presently working on early blight and late blight resistance in heirloom types and plan on putting the Sw-5 gene into some of these lines.
Tom, I hope to hear from you with an update on your breeding.
Randy

[Tom Wagner]

Randy,

Good to hear from you!

Thanks for clarifying the TSWV issue with regards to your work. I have been crossing Sophya and hybrids of it to a number of different lines. It is good to know that there are some marker genes associated with it.

There is a good molecular marker for the Sw-5 gene and there are commercial labs that will test your backcross lines for a reasonable fee to help you identify your segregating lines with the Sw-5 gene.

Since I have not come across the virus here in the PNW, my options for screening for actual resistance is not an option. To know that someday I can go through the heirloom breeding work and pay a fee to find out which has it and which doesn't is indeed a good thing.

As I travel the next two months in Europe, I will undoubtedly get questions about TSWV, and I feel more prepared to answer folks more forthright. Thanks.

Tom Wagner

BTW, the Late Blight res. material is showing great results out of the material you sent a few years ago.

[travis]

What is the ratio of seedlings one might expect to find Sw-5 gene expressed as a dominant pair in the F2 from an original F1 Sw5 hybrid x an heirloom cross?

About how much would the lab charge to test say 8 plants for Sw-5 dominant, or can that be done at the F2?

If an F2 plant tests "positive" for Sw-5 dominant (if I'm saying that right or if my assumption is correct), will all the F3s from that plant's seed be Sw-5 dominant?

Has Bolseno been tested and confirmed to carry Sw-5?

[Tom Wagner]

The dominant nature of this Sw-5 gene is particularly useful to select
resistant heterozygous/homozygous plants from a hybrid such as Bolseno. Fully 3/4 of the F-2's will be resistant, and logically 1/4 will be not. Only one third of the resistant plants will be homozygous and true breeding. The other 2/3 will segregate again for the 1:2:1


An inoculation test with a TSWV virus strain also may be performed
to confirm the successful introgression of resistance in breeding lines. Who does this service?

One of the reasons I have made a number of crosses with Sophya, is that in addition to the intermediate resistance to TSWV, it carries resistances to
Fusarium crown & root rot
Fusarium wilt 1 and 2
Root knot
Gray leaf spot
Tomato mosaic
Tomato yellow leaf curl
Verticillium wilt
and is a rare indeterminate line.

Therefore, half of the crosses to other lines will carry a heterozygous gene. Furthermore, half of those crosses to yet other lines will 1:1 hit or miss. That is OK since look at all the other traits that may pull through.

I put these crosses away and may send them out to areas where TSWV is a problem. If the heirloom quality of the tomatoes meet acceptance AND is resistant to TSWV, I must have great numbers of crosses and segregating selfed lines to obtain even a modicum of cool lines.

Tom Wagner

[RandyG]

Tom, thanks for responding to the question posed about the Sw-5 gene in segregating generations. The lab I am familiar with and have used in the past is STA Laboratories. The beauty of the marker assisted breeding is that the test for Sw-5 and most of the other markers are co-dominant markers so the results tell you not only whether the selection is resistant but also whether it is homozygous or heterozygous for the gene. Another nice thing is that the same sample can be tested at the same time for markers for multiple genes. Using the marker assisted selection(MAS), I was able very quickly to combine Sw-5, Mi, and I-3 genes into one useful breeding line (NC 123S). Your material with potential for several combined genes would be ideal for use of MAS. However, to test the number of lines you would need to combine several genes in one line would start to become expensive. Please look at the website for STA Laboratories. It has a lot of good information about their services and contact information for them so you can find out how much they currently charge for testing.
Randy

[carolyn137]

http://www.ces.ncsu.edu/fletcher/programs/tomato/

IN a post above Randy referred those interested to the above link which describes in detail the work in progress and information about what's been developed and what might be developed.

This summer I'm trialing Mountain Magic F1 and Plum Regal F1 as well as Smarty F1 which is currently offered by Johnny's Selected Seeds, the other two to be introduced commercially next year. These seeds sent to me as I think thanks for several heirloom varieties I sent to Randy for some of his breeding projects.

Randy, I'm delighted to see you posting here and I'll just sit on the sidelines and watch you and Tom discuss genetics and hopefully learn as I read, as I hope others will as well.

No TSWV here but I'm fighting the good fight against Late Blight as you know, and nothing so far but I'm surrounded with it on all sides and so am having Freda, who does all my gardening for me, pay close attention to any leaf/stem problems as well as keeping a close look at Mountain Magic with its LB tolerances. She comes today to spray and scout the plants. Everything is so behind that unless we get a very late first Fall frost I might not have tomatoes this year.

Fingers crossed. And welcome to Tomatoville!

And Freda just arrived, telling me of two others nearby who had to pull ALL of their plants, so we have to do the tomato stuff right now.