Dahlia mutations

[Jonny.D]

This link has an explanation about dahlia flower variation that might help,part of it says -
“Dahlias (Dahlia variabilis) exhibit a wide range of flower colors because of accumulation of anthocyanin and other flavonoids in their ray florets.”
& further on in the text -
“Flower color variegation is often caused by recurrent excision of transposable elements in a pigment biosynthesis gene.”
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3193017/

After reading Jungle Jane's link in this thread

https://www.growfruitandveg.co.uk/gr...dahlias-9.html

I did a search for Dahlia Mutations and found some interesting pages covering the subject of Dahlias changing their colors in language more easily understood.

Canoe Corner: A Dahlia of Two Colours

https://davesgarden.com/community/forums/t/913277/

https://davesgarden.com/community/fo.../#post_7246559

. . . and also a link on how Dahlias were irradiated back in the 1960's

https://link.springer.com/article/10.1007%2FBF00043451

[Jonny.D]

Best answer I found that was this one

Dahlia, like some other Asteraceae and very hybridized plants, are prone to colour and bloom shape mutations.

A change of colour in the bloom can be caused by many factors such as soil and/or air chemicals and nutrients, a wobbly genetic pigment code, natural background radiation levels etc. Some cultivars mutate more often than others. If your plants are unnamed cultivars then they probably haven't gone through the vigorous tests most breeders put their plants through before releasing them to the market although even that is no guarentee they don't sport much.

I would suspect, although I'm no expert at this and could be way off target, that the red streaking was a pale anthocyanin pigment waiting for the right environment to shine in.

[Jonny.D]

Another piece of good information from a Dahlia group on facebook

It takes years to learn the art of hybridization.....every seed will produce a NEW variety different from the parent. Not all blooms will be worth saving as the majority of them will be open faced, loose and not nice. But out of 100 seeds you might find one beauty worth saving and growing another year. It takes several years for a new variety to stabilize as they can change a bit in year two - color, form etc - the slowly stabilize and stay the same from year to year.