Undwarfing a micro

[Frosti]

I feel like most of the micros I've tried weren't as tasty as larger tomato plants. I believe this is due to their limited root and leaf growth. When I'm transplanting dwarfs and micros it is always apparent, that their roots are a lot less developed than normal tomato plants. Such little plants also tend to end up with a smaller leaf area to fruit weight ratio than normal. I have no concrete evidence to support this claim, but I believe the smaller this ratio, the less tasty the fruits.

However, I do grow one micro that has a very pleasant taste: "Herzensbrecher" / (little) heart breaker(s)
I do not know if it is a hybrid or not, I've grown seeds for a few years and did not notice a big difference.

Given that I believe micros have an inherent disadvantage taste-wise, would it not be reasonable to assume that the very same micro but with normal growth would yield better tasting fruits?

I believe the process of "undwarfing" should be pretty simple and fast. Simply take the original dwarf / micro as female parent each season. Use the pollen from any normal tomato plant for the first cross and the pollen from a normal growth offspring every following year. The key is that it's possible to cross each and every year, instead of every other year, as would be the case when trying to turn a variety into a dwarf version of itself via backcrossing. All one would have to do is to select for normal growth, thats all. Each generation (other than F1) will yield 50% dwarfs and 50% normal plants.

Herzensbrecher a few years ago:

IMG_20200823_112115.jpeg

Herzensbrecher this season:

IMG_9156.jpeg

F1 plants:

IMG_9157.jpeg

[DriftlessRoots]

I wonder if grafting it to a normal sized tomato plant would work. Sort of like the reverse of the way apples are grafted to dwarfing rootstock.

[Frosti]

I wonder if grafting it to a normal sized tomato plant would work. Sort of like the reverse of the way apples are grafted to dwarfing rootstock.

hmm, that would probably solve the root development issue, but I don't think it would address the leaf to fruit ratio. Interesting idea though!

[KaguyaCloud]

I feel like most of the micros I've tried weren't as tasty as larger tomato plants. I believe this is due to their limited root and leaf growth. When I'm transplanting dwarfs and micros it is always apparent, that their roots are a lot less developed than normal tomato plants. Such little plants also tend to end up with a smaller leaf area to fruit weight ratio than normal. I have no concrete evidence to support this claim, but I believe the smaller this ratio, the less tasty the fruits.

According to KarenO, most micro-dwarf breeders are mainly focusing on using existing micros as parents instead of outcrossing them with more flavorful varieties. From a podcast on Craig LeHoullier and Mrs.Tomatohead, Craig mentioned a micro breeder friend of his isolating flavor with little success. On top of that, there's isn't a lot of characterization in terms of selecting micro traits based off of what is published on the internet. My own micro x indet project is to determine if there's any linkage between flavor and dwarfing genes.

One of the defining traits involved Micro-Tom was reduced root size regardless of pot size from the original article that was written about it. However, I found this trait quite difficult to isolate and link to compact growth habit within my F2 trials, as the vast majority of the individuals have shown to grow medium to long roots compared to their micro parent.

Given that I believe micros have an inherent disadvantage taste-wise, would it not be reasonable to assume that the very same micro but with normal growth would yield better tasting fruits?

From my experience in the F2 trials of my micro x indeterminate, it doesn't seem to be strongly linked. I had a large regular indeterminate F2 that produced very bland tomatoes and extremely very compact indeterminate F2s that produced very sweet tomatoes. I do like the idea of introgressing the non-dwarf gene onto Herzensbrecher, as this has been done before for Micro-Tom. At the very least, you may be able to obtain a very compact regular plant with non-dwarfing genes. Brix doesn't seem to be effected too much when selecting towards certain micro traits.

[KaguyaCloud]

Here's an image of the wild type non-dwarf gene introgressed into micro-tom after 6 generations(image A):


Source:
https://plantmethods.biomedcentral.com/ ... /figures/5
https://www.esalq.usp.br/tomato/Dwarf.pdf

[Frosti]

@KaguyaCloud thanks for your comment! I wasn't aware of the undwarfed micro tom.
I suppose it's no guarantee that the undwarfed plant produces better tasting fruits, but one thing that seems obvious to me is a decreased susceptibility to fungal diseases, since air circulation will be a lot better with larger internodal distances. I tried growing micros outside (unsheltered from rain) last season, and it was a total disaster. Late blight struck very early for those tiny plants.

[wykvlvr]

Interesting thread.
@KaguyaCloud is correct most new work has been micro x micro since it is extremely hard to get out the large plant genes. In fact the Micro Tomato Diversity Project is now working more with lines developed from a single cross then talking about possible crosses to large plants. But it was originally founded on the idea that the micro dwarfs needed more genetic diversity. Since the founding more micro dwarf varieties have come out that were either in Europe or were part of projects being worked on in silence. AND it has been proven how difficult it is to get back to micro size once you introduce big plant genes.
I will admit that I planted experimental seeds this year that I had gotten from the MMMM Swap. Both are from micro plants, one is a carrot leaf and one is a potato leaf so both are the results of folks doing most of the hard work in the past... Neither are from lines that I am aware of being worked with at this time. but I LOVE potato leaves AND I have a question in my head about what do the leaves on a tomato plant look like if it has both potato leaf AND carrot leaf genes... These two micros will help me answer that question and I may go back to silvery fir tree and a determinate or dwarf potato leaf cross just to have two lines and sizes to play with.

[bower]

This is a fun project, and what a beautiful plant that Herzensbrecher!
Another possibility is that fruits will be not tastier but equally as tasty, but there will also be many more of them.
Since the fruit is already tasty, having a non micro version should be a plus, whether they are 'tastier' or not.

[Frosti]

This is a fun project, and what a beautiful plant that Herzensbrecher!
Another possibility is that fruits will be not tastier but equally as tasty, but there will also be many more of them.
Since the fruit is already tasty, having a non micro version should be a plus, whether they are 'tastier' or not.

agreed!

[KaguyaCloud]

@KaguyaCloud thanks for your comment! I wasn't aware of the undwarfed micro tom.
I suppose it's no guarantee that the undwarfed plant produces better tasting fruits, but one thing that seems obvious to me is a decreased susceptibility to fungal diseases, since air circulation will be a lot better with larger internodal distances. I tried growing micros outside (unsheltered from rain) last season, and it was a total disaster. Late blight struck very early for those tiny plants.

If you can fully introgress out chromosome 2(where the dwarf gene "d" is) with a more disease resistant variety, that can also provide more resistances to fusarium wilt. Your F1s may have higher yields, as most micro-dwarfs yield more fruits for the amount of leaves. I've notice over the years that my F1 cross had the tendency to flower and develop their fruit more frequently than their large parent.

Craig also had the same issue with micros as well, very susceptible to disease outdoors. However, this could be attributed to the very low genetic diversity and normally indoor/protected growth environment. Any introduction of new genes will probably make the subsequent generations more robust. I'm all for crossing micros with tasty and larger varieties!