Pod vs pollen parent when breeding xanthic orchids

[Andrew]

I’m assuming that most people on this forum don’t hybridise Pterostylis but I would think this question is applicable for other genera. Can anyone with experience breeding xanthic orchids, or albas for that matter, tell me how important plastids/mitochondria are in maintaining the yellow colour/losing the red colour? I know the carotene production involves chloroplasts but I don’t really know how much of the anthocyanin/flavonol production pathway involves genes from the plastids.

I have a xanthic Pterostylis concinna (the normal form is here ) that I have crossed/looking to cross with some of the larger, redder species like coccina and hamiltonii with the aim of selfing the F1 and hopefully getting some F2’s that are (a) larger and (b) have the red coloured areas in the larger parent’s flowers replaced with yellow. From there I aim to backcross and self to keep the colour and increase the size further so I have some a number of large yellow greenhoods for future hybrids. I have hedged my bets by doing reciprocal crosses of the crosses involved but given that will mean I need a lot more space to grow out seedlings I’d like some idea of whether it’s worth paying attention to which plants I’m using as pod parents on the basis of colour?

Andrew

[FairyInTheFlowers]

Now I am not sure if it is the same for all genera, but from what I have learned from Big Leaf Orchid Forum is that more yellow will come through in a Phal. cross if you use it as the pod parent. I don't know the scientific reason behind this, but that is what I have learned.

[Andrew]

Blazing August,
There's two potential yellow colours that my mind is battling with. The yellow coming from flavonols which are produced by the same pathway that produces anthocyanins (reds) and the yellow coming from carotene, which is produced by chloroplasts. I think the carotene yellow is the reason why people say that the maternal plant is important for yellows.

The yellow in my concinna is produced in the same parts of the flower where the red is normally produced. If the yellow is coming from carotenes, and is normally masked by the red anthocyanins I'm not sure I can judge whether the yellow flowers of my concinna are producing more yellow than the larger, red species to make a reliable call about which parent would produce better yellows.
I have a suspicion that the flavonols might be producing a lot of the yellow colour though because the yellow is being produced where the red should be, it stands to reason that if the anthocyanin production pathway is blocked more substrate could be channeled into making flavonols, and the leaves of the plant are unusually yellow compared to the normal form and other alba Pterostylis that I grow. However, I don't know whether chloroplasts are also important for flavonol production.