Last weekend I found triplets among the embryos I was excising. The mother is ‘Polstjarnan’ and the father was an unknown tea.
In previous years I remember to have seen twin embryos occasionally among my hybrids. Sadly I have not kept track of them and I doubt any of them survived the extraction process (I am slowly but surely training my extraction technique) or later culling.
The three embryos were all in the same testa and had all started to lengthen the radicle while they were in weak hydroperoxide solution. They seemed quite healthy at that stage. Two of the embryos were of the same size and bigger than the third. According to what I have read and gathered here on this forum, one or even two of the synergid cells can occasionally form embryos alongside the fertilised egg cell. As the formation of embryos from these synergid cells happen without fertilisation, they are haploids and are often smaller. Previous discussions on this forum have also mentioned twin embryos in the same testa where the haploid (or dihaploid) is smaller than the diploid (or tetraploid). If the two unfertilised embryos are generally smaller, I would have suspected to have two small embryos and one big in the case of the triploids, not vice versa.
This is an interesting question and one that can have an answer by putting a bit of root tissue under a microscope. Hopefully that will be later on after they get to be plants because then you will also have the advantage of being able to make some crosses with them. Haploidized plants can be useful tools.
Perhaps one of our visiting professors can weigh in on technique for this.
Wow, triplets!! That is great. I hope all three make it. If the smaller ones are actually haploids, that would be very special. With Polstjarnan being diploid, if they truly are monoploid they could be very helpful. This is how the rose genome was sequenced using ‘Old Blush’. They generated monoploids from pollen to simplify the sequencing process in tissue culture.
They are the slowest embryos I have ever grown to either start growing or start perishing. Normally it takes a week to see where it is headed. The small one seems now, more than three weeks later, not be able to make it (in the picture it is just left to the lower one). The bigger two linger on and four days ago one of them finally grew a real leaf. I will wait for the other one to show some signs of growth before I repot it/them.
They have had intensive care with a drop of weak solution of hydroperoxide dropped by their base every second to fourth day.