Improving the Tomato Genome by breeding with wild tomatoes [2017]

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Solanum peruvianum (wild tomato with desert tolerance)

So i haven’t written a blog post in some time. Sorry about that. It has been very hectic this year. That’s not to say that i’m completely dead. And despite my busyness and absence i am still dabbling a little bit in the garden and plant breeding scene. I didn’t have the time, energy, or space to work on my purple Indian Corn or Teosinte this year. I barely made room for beans, peas, tomatoes, and a row of watermelon.

The beans are my special four corners native beans which include, New Mexico Red Appaloosa (aka. Gila River bean), Anasazi, Zuni Gold, Rio Zape, and maybe a few others. The Peas are a large growout of my 17-23 different varieties of genetically unique and rare pea varieties, some of which are segregating crosses that i did two seasons ago. And tough i don’t have many pictures i will post one below of a purple podded umbellatum-type (aka. crown pea) where all the pods come out in a jumble all at once. To have a purple podded one of these is new and kind of cool. I hope to have a yellow and red-podded umbellatum-type pea someday. The watermelon are the result of mine and Joseph Lofthouse’s Watermelon Landrace project. Joseph Lofthouse seems to be world famous now for his widely successful landrace seed varieties and breeding techniques.

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Purple Podded Umbellatum Crown Pea

Anyway, back to the tomatoes. The Tomatoes are a brand new project and sort of an offshoot of one of Joseph’s new landrace breeding projects as well and a few other fellow collaborators and breeders as well. It all started when Joseph was working on wanting to convert tomatoes to a landrace like many of his other successful crops. But there are a number of problems with that and domestic tomatoes in general.

The first problem is that domestic tomatoes are entirely self pollinating and don’t outcross all that much and have tiny closed-up flowers. Another problem is that domestic tomato flowers are not very attractive to pollinators. And the third major problem is that domestic tomatoes went through several genetic bottleneck selection events when they were domesticated that they have a very narrow genetic base. This narrow genetic base means that 1. Most tomatoes are subject to easily succumbing to disease and 2. that when they do outcross there is not much variation anyway. An average bad-tasting disease susceptible red tomato that crosses with another average bad-tasting disease susceptible red tomato means that in the end all you really get is more of the same.

My interest in all of this starts with the basic fact that in my climate here in Northern Colorado with my soil (mostly a dry clayish sandy soil where mostly desert plants grow), and the high altitude with intense sunlight and UV and the dry wind that wicks moisture out of the ground means that most garden varieties of anything don’t do all that well here unless intensely babied. This applies most especially to tomatoes. Even worse when it comes to Heirloom tomatoes. Sure heirloom tomatoes generally taste better, but to have a tomatoe plant produce like ONE good tomato through a whole season… That’s a MAJOR FAILURE in my book.

There are lots of tomato freaks out there that try to tell me that here in Colorado i can grow ANY tomato variety and be successful. And while that might be true if i replaces all my soil with compost or potting mix and provided massive amounts of water, and started them all early and planted them all out perfectly then yes maybe that would be true. But that’s not what i want to do, not should i have to do that. I should be able to just start a tomato plant and plant it where i want and not have to worry about it all that much and have it produce a decent harvest (whatever that happens to be). And not have to worry about disease, or growing slow, or not being adapted to my soil or the intense UV light or whatever. That’s where all this plant breeding comes in.

The goal(s)

  • To breed a superior tomato variety that does well for me (in dry N. Colorado)
  • To increase the genetic diversity in the tomato genome by using wild tomatoes
  • To create or recreate a tomato that is highly attractive to pollinators
  • To create a population of tomatoes that are highly outcrossing
  • To create a tomato that i actually think tastes good and NOT like cardboard

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wild tomato seeds. photo courtesy of Joseph Lofthouse

This project is still in it’s early stage, but it is progressing nicely. On Joseph’s end he is having huge success by using wild tomatoes bred with domestic tomatoes that have large showy flowers with exerted stigmas and have lots of pollen available that make them attractive to bumblebees. He is using mostly Solanum habrochaites but is starting to branch out to other wild tomatoes as well. Others are working on breeding tomatoes that produce a good harvest in under 100 days from being direct seeded and that have frost tolerance.

On my end i am experimenting with as many wild tomatoes that i can. I am evaluating several accessions of wild Galapagos tomatoes which so far are not doing much. The S. habrochaites also are not doing much. The ones i am having excitement from are the Solanum peruvianum which have silvery leaves and desert tolerance (in the roots) and a F1 hybrid between a domestic tomato and Solanum pennellii which has a different form of desert tolerance (in the leaves). I am excited about these genetics since they seem to be growing very well in my garden. The largest of any of my tomatoes is this F1 hybrid of S. pennellii. It is HUGE!!

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F1 hybrid between domestic tomato and Solanum pennellii
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Flowers of an F1 hybrid between domestic tomato and Solanum pennellii
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F2 cross of domestic tomato and Solanum habrochaites