Making My Own Carrots 5

I've been thinking about what my plans are for the carrots I've been working with. Because it is a biennial crop, I can split the project into two distinct directions. Alternating, growing the seeds from one project and the other.

1. Blush carrots.

I really liked the purple-blushed roots (fig 1.) that turned up in my first generation population. By comparing to the parental types, these were obviously hybrids between "Cosmic Purple" (which have a thin layer of anthocyanin-purple skin over an orange core) and one of "Solar Yellow" or "Lunar White". I initially was sad that I wouldn't be able to stabilize this really pretty color combination because it was a hybrid. Today I realized there is a way to develop a [more or less] stable variety with this color scheme.

2. Production of F1.

The F1 (fig 1 & 2.) shows us the intensity of purple skin pigment is incompletely dominant. One copy of the allele gives the blush skin color and two gives the full purple skin color. (This gene acts like the "P₁" mutation.) The F1 also shows us that the white flesh trait is dominant to the orange flesh trait. (Acting like one of the carotenoid inhibitors named with "Y".)

3. F2 population.

With these genes driving the colors, we can predict what the F2 population would look like (fig 3.). 25% of the population will have orange flesh; 75% will have white flesh. 25% will have dark-purple skin; 25% will have clear skin; 50% will have blush-purple skin. (Hopefully 25% will be sweeter, like "Cosmic Purple" was compared to "Lunar White". The F1 wasn't terribly sweet of a carrot.)

Over several generations of selecting roots with white-flesh and blush-purple skin, the proportion of the recessive orange-flesh trait will diminish slowly. If I use a small number of roots for each parent generation, the likelihood of losing the orange trait would be better. (I could use "Power Breeding" to help ensure the loss of the recessive trait.) Eventually, I would end up with a new "stable" variety that would consistently be 50% the blush-purple color I found so attractive. (If the blush-purple color were to look really nice on an orange carrot, I could easily stabilize that trait even faster since orange is the recessive trait.)

Thinking through the genetics like this is making me less annoyed that all the odd little hybrid roots I saved from last year ended up not surviving. The large orange/yellow hybrid root also rotted out, so my second generation parent population is already reduced to just the two blush-carrots in fig 1. These two roots are basically identical, so them crossing would essentially be the same as selfing a F1 hybrid. They're both growing new roots and greens, so I'm pretty confident I can keep them alive until they produce seeds.

While they're growing for seed production, I can also grow a whole new diverse population from saved first generation seed. Then I'll get to determine some other selection criteria for a second carrot variety. Oooh! I can even add in some of the lycopene-red "Atomic Red" carrots (the ones that didn't make it the first year) to this year's population. This would let me try again to get that lovely color in my alternate-year carrot variety.


References:

• Cartoon carrot source: cargocollective.com/rufuskim/Heirloom-Vegetables
• Carrot genetics:
• link.springer.com/article/10.1007/BF00025121
• www.plantsciences.ucdavis.edu/vc221/carrot/Carrot.htm
• biology.about.com/od/geneticsglossary/g/incompletedom.htm
• www.biology-online.org/dictionary/Dominant_trait
• "Power Breeding": toads.wordpress.com/2011/09/25/eggplant-harvest/
• "Atomic Red": www.gardensalive.com/product/organic-atomic-red/carrot-seeds?p=0152227
• Previous posts:
• the-biologist-is-in.blogspot.com/2014/02/making-my-own-carrots.html
• the-biologist-is-in.blogspot.com/2014/05/making-my-own-carrots-2.html
• the-biologist-is-in.blogspot.com/2015/08/making-my-own-carrots-3.html
• the-biologist-is-in.blogspot.com/2016/03/making-my-own-carrots-4.html