I did a little science experiment recently. I think I've learned something new - at least something I could not find the answer to online. Regular leaf is dominant over potato leaf. However, what happens when a carrot leaf is tossed in the mix....
Tomato Leaf-Type Dominance Study – Regular Leaf vs Carrot Leaf vs Potato Leaf
In tomatoes, regular leaf is dominant over potato leaf. That is taught in genetics 101 and known by anyone who has made this simple cross – RL X PL = RL F1. In the F2 generation, the ratio will be a Mendelian 75% RL & 25% PL. In the F3 generation from a PL F2 plant, the offspring will be 100% PL. That plant is homozygous for PL and the trait is fixed for future generations – genetics 101.
But what happens when Carrot Leaf is tossed into the mix? Not being able to find anything online to answer that question, I decided to try to figure it out. I worked with F1, F2 and F3 seed from a cross between a carrot leaf micro X a potato leaf indeterminate. Both parents, while not fully stable were fixed for leaf type.
I did not count how many total seeds were planted, but 641 germinated. I grew each one out long enough to determine whether the leaf type was RL, CL or PL. I also kept track of plant growth type, separating indeterminate vs dwarf/micro. I did not attempt to separate micro from dwarf, as that would have required growing them to maturity and that was beyond the scope of what I was able to do.
The results from Carrot Leaf X Potato Leaf cross:
There is a lot more to learn regarding the CL leaf type – especially as it relates to micro tomatoes. I have seen anecdotal results that seem to indicate that there may be some linkages between CL and genes involved in making the micro. In one CL X RL cross, I noticed that the F2s remaining, after culling heavily for size, and working only with the shortest 10%-15% of seedlings were skewed heavily toward CL – well over 50% instead of the expected 25%. I have seen that in at least two different instances, as has one other breeder I shared F2 seeds with. I did not keep track of leaf types in the plants culled so I can’t speak with certainty to overall leaf type results, but that observation begs for more study.
Tomato Leaf-Type Dominance Study – Regular Leaf vs Carrot Leaf vs Potato Leaf
In tomatoes, regular leaf is dominant over potato leaf. That is taught in genetics 101 and known by anyone who has made this simple cross – RL X PL = RL F1. In the F2 generation, the ratio will be a Mendelian 75% RL & 25% PL. In the F3 generation from a PL F2 plant, the offspring will be 100% PL. That plant is homozygous for PL and the trait is fixed for future generations – genetics 101.
But what happens when Carrot Leaf is tossed into the mix? Not being able to find anything online to answer that question, I decided to try to figure it out. I worked with F1, F2 and F3 seed from a cross between a carrot leaf micro X a potato leaf indeterminate. Both parents, while not fully stable were fixed for leaf type.
I did not count how many total seeds were planted, but 641 germinated. I grew each one out long enough to determine whether the leaf type was RL, CL or PL. I also kept track of plant growth type, separating indeterminate vs dwarf/micro. I did not attempt to separate micro from dwarf, as that would have required growing them to maturity and that was beyond the scope of what I was able to do.
The results from Carrot Leaf X Potato Leaf cross:
- F1 – 12 plants total germinated = 100% Regular leaf
- F2 – 546 plants total germinated
- RL – 343 plants = 62.8%
- CL – 73 plants = 19.6%
- PL – 78 plants = 17.6%
- F3 from PL F2 – 8 plants = 100% PL
- F3 from CL F2 – 75 plants
- CL – 58 plants = 77.3%
- PL – 17 plants = 22.7%
- RL is dominant over both CL and PL – expected
- CL is recessive to RL but dominant to PL – learned
- PL is recessive to RL and recessive to CL – learned.
There is a lot more to learn regarding the CL leaf type – especially as it relates to micro tomatoes. I have seen anecdotal results that seem to indicate that there may be some linkages between CL and genes involved in making the micro. In one CL X RL cross, I noticed that the F2s remaining, after culling heavily for size, and working only with the shortest 10%-15% of seedlings were skewed heavily toward CL – well over 50% instead of the expected 25%. I have seen that in at least two different instances, as has one other breeder I shared F2 seeds with. I did not keep track of leaf types in the plants culled so I can’t speak with certainty to overall leaf type results, but that observation begs for more study.
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