Bok choy breeding

[Theo W]

I am interested in experimenting with developing a grex/landrace bok choy/ pak choi.  However, it seems that there are very few OP bok choys which I could use to begin the project, especially if I want to distinguish between different types of bok choy (e.g. white vs. green petioles).  I expect that hybrid parents could be fine for this project, but I know that many brassica hybrids are made using cytoplasmic male sterile lines.  Is it likely that hybrid bok choys are bred this way?

[Diane Whitehead]

There is a Canadian company that specializes in Asian vegetables:    https://agrohaitai.com/

A quick look shows a lot of hybrids, but they do have some OPs as well.

[Cathy A]

Baker Creek, rareseeds.com, has quite a few varieties available. They don't sell hybrids, so these would all be OP.

Suzhou Baby
Hedou Tiny
Shanghai Green
Purple Lady
Choy Sum
Yellow Heart Winter
Chinese Flowering Cabbage
Chijimsai

Most of these appear to be bok choy, with the last two possibly being related plants.

[Steph S]

There are CMS genes for B. rapa, so a hybrid bok choy would probably be made using CMS.
But I wouldn't discount the possibility that Rf (restore fertility) genes are also commonly used in conjunction with the CMS genetics, in order to avoid the adverse effects associated with CMS in brassicas (at least, when the CMS is introduced from another species cytoplasm).

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4031109/

If I read correctly, you may end up with only half the pollen being fertile, that being the pollen carrying the Rf genes to restore fertility.   Where these genes are present you won't get sterility, so the CMS doesn't segregate.

I saved some Napa cabbage seed last season from a hybrid F1 which I allowed to self.  The seeds are fertile.  Maybe some pheno variation in plants growing now, to suggest they are segregating for other traits. So perhaps the Rf genes are there, and CMS a non issue?