Last year I managed to make crosses between some tomatoes and Solanum habrochaites. All were successful. I’m growing them out this seson. They all strongly resemble their daddy (S. habrochaites) - same leaf shape and overall growth habit and flowers with exserted stigmas, some of them strongly so. Not one has set fruit so I’m beginning to suspect they’ve also inherited their daddy’s obligate outcrossing. This is a major disappointment as we have no Blue Banded Bees (our lone buzz pollinator) this year. They disappeared during our very protracted wet period and will probably take several years to recolonise the area. The flowers are also very poor producers of pollen as I’ve been trying to collect some to backcross into S. habrochaites.
It’s looking like there will be no S. habro genes in our tomato gene pool, at least not this year. In order to get more S. habro seeds I will have to hand pollinate.
Note: In the post title, BBF stands for Banded Bee Farm, the name of our small farm.
Exciting and disappointing. I think I remember William talking about exserted stigmas in tomatoes. Seems to me you might be right about the outcrossing.
Sorry to hear about the bees. If you don’t already have plantings on your place of any highly preferred blue banded bee food, I wonder if you could move or acquire any highly desirable nectar sources in containers to near the tomatoes. It’s hard for me to believe they’re all gone.
Losing your local bees sounds heartbreaking! I hope they come back soon. Can it help to encourage them by providing extra habitat for them? Or do you do that already?
These bees are solitary. The males live entirely outdoors, as it were. They sleep grasping a twig with their pincers, no ‘house’. The females burrow into bare dirt where they sleep and care for their brood. We are in a valley bottom so during any protracted wet the ground becomes super saturated and the females (and hence the males) move elsewhere. They’ll be back but it will take a while.
Hmmm. It sounds to me like maybe can can keep some of them around if you provide a habitat that works for both genders. Maybe a mound of dirt (so that the top is likely to stay dried out, even when it’s very wet) with a pile of twigs on top of it?
Well, I spoke too soon. I still haven’t seen any blue banded bees but a few of the Solanum habrochaites crosses appear to have set fruit. And yesterday for the first time I was able to collect enough pollen to backcross to S. habrochaites. Although I have several plants of S. habro only one is in flower so this was the lucky recipient.
Perhaps this season won’t turn out too badly after all!
That is fun! Last year I got my LA2329 habrochaites with known arthropod resistance project to the point where this year I expect to grow plants of several different percentages, deliberate crosses of 5/8, 1/2, and 5 /16ths I think as well as any uncontrolled crosses which could include roughly 3/4 and back crosses. Should be fun over the next few years.
Here’s a shot of some of the tomato x Solanum habrochaites crosses. The flowers are a really bright yellow and have noticeably exserted stigmas. They close up as the sun sets. The leaf shape too is very much like S. habrochaites. Unfortunately, even though I’ve been able to collect pollen from these crosses the lone S. habrochaites plant in flower is not accepting the pollen. I’ll keep trying.
Habrochaites can’t be pollinated by a domestic tomato… lycopersicum or pimpinellifolium… The genetics are probably not habro enough for it to accept pollen from the first cross.
I am curious if we can find out how much habro/domestic the cross has to be before it can pollinate a full habro.
I thought @Joseph_Lofthouse had a successful backcross into habro with a half tomato/half habro. Perhaps he’ll chime in to confirm whether this is the case or not. I’d best cross habro into my F1 to get 3/4 habro for next season, just in case!
Walked around all the tomatoes today looking for exserted stigmas or flowers so open that the stigma is very exposed. Found six all up, three of each. These are now marked for preferential seed saving and sowing next season.
One of the things about this that is great is that seed from one plant can produce a lot of plants. Though exsertion seems to come in different forms in my garden, some like Big Hill seem to have a pretty stable form and others vary with year-to-year temperature fluctuations.
Open flowers and exerted stigmas seem to vary on the same plant in my garden and at different times in the season. My tomatoes tend to make abundant harvest in mid-season and then slow down a lot in late summer, often by that time suffering from heat stress and disease. Then when weather cools a little and with some rain, they shoot out new healthy grow with abundant flowers which are sometimes completely open. Even on plants that earlier had completely closed flowers.
A lot of other things have greatly slowed or stopped blooming by then and the bumblebees swarm the tomato flowers. This generally happens in late September into October and small tomatoes do form but by then it’s too late to mature before frost.
Hi Gregg,
The reason for a backcross into habro is so that I can have habro cytoplasm in my tomato landrace - diversity in all the DNA, not just the nuclear DNA.
Joseph is there but he has been working on it a long time. My approach to it with the LA2329 project has been a bit casual. Though I exposed LA2329 to habrochaites crosses Joseph made. It would be sort of interesting to see now that LA2329 has been through a generation or more in my garden if a big grow out of it would show any signs of back crossing like Joseph has reported a few times. Not in a good spot right now to even grow out pure Solanum habrochaites though with the new job- it can use a extra few weeks inside before planting out and I don’t think I can use my greenhouse like usual for the last couple of weeks either.
And yesterday for the first time I was able to collect enough pollen to backcross to S. habrochaites. Although I have several plants of S. habro only one is in flower so this was the lucky recipient.
