Green Flesh seedling test

[Roland]

Introduction to Seedling gf test:
https://academic.oup.com/jxb/article/50/336/1115/515722?login=false



I want to grow gf Green Flesh in my tomato variety using the BackCross method.

I have 10 plants of which statistically 5 plants should carry gf heterozygous.
To find out which 5 plants are carriers, I pollinated them with a homozygous gf gf plant.

I tested the germ leaves of these seedlings in the dark method.
The germ leaves are left in the dark for 11 days at 20 to 25C.

From left to right in the photo:
Seedlings of plant 1 x homozygous gf
Seedlings of plant 2 x homozygous gf
Etc.
Seedlings of plant 10 x homozygous gf

All these seedlings are at least heterozygous for gf and some are homozygous.

Top left you see the variety without gf and top right 2 germ leaves of the homozygous gf plant.
There is a clear difference between these two.

It is expected that with 5 plants, half of the seedlings should retain green leaves and the other half should get yellow.
For the other 5 plants, all seedlings should turn yellow because they are only heterozygous.

To my surprise, only a few of the germ leaves are yellow and the majority have turned light yellow and not as dark green as the top right of the homozygous gf gf plant.

Which seedlings do you think are homozygous for gf gf?




https://postimg.cc/Yjr0r2rz

[Maf]

9 looks like the only one with all homozygous gf leaves. 1, 6 and 8 look like they have some homo gf leaves among them.

My experience of gf is that there are 3 stages of chlorophyll retention; homo, hetero and wild type. Hetero and wild type are close to each other but not exactly the same, while homozygous is distinctly different.

Also, there are about five different alleles of gf and I do not know if they all act exactly the same way.

[Roland]

Here the last foto of the cotyledons at 14 days in the dark.


https://postimg.cc/307VsDGQ

Because of mold i will remove all cotyledons.

What do u think at this moment for homozygous gf gf plants?

[Roland]

Here is an update of the fruit color. The green flesh gf gene is hidden in plants 1 and 9.
Plant 1 with some plants that produce green striped fruits. Plant 1 also has a yellow fruit.
Plant 9 has a few brown fruits but no yellow fruits.

[Roland]

In the end it turned out that I was just unlucky and only 2 out of 10 plants carry the gf gene.

On to the next BC generation.