Breeding credentials

[RosieC]

Originally Posted by Royal

Some crosses are purely speculative, but some will produce predictable results. Getting specific is tough, but we know how some traits are passed on. Using Rosie's human analogy, we wouldn't be able to do a sketch of a person's face before they where born, but we could predict hair color because we know how that trait is inherited. We couldn't predict exact height, but we could guess that two tall parent will have a tall child. Similarly, we know how certain plants breed and what traits prevail in their offspring. We know crossing a big white phal with a harlequin will probably give us more harlequins. We know that yellow doesn't get passed on as effectively (or reliably) via the pollen parent. We know B. nodosa dilutes color and it's shape dominates. We know using P. venosa lowers flower count and P. equestris increases it. etc, etc. It's not cut and dry, but it's not a total guessing game either. A little research goes a long way.

Good explanation. Yes, like people while you can't know exactly what you are getting various traits will generally override other traits. In people genes for blue eyes will be hidden by genes for brown eyes, similar with hair colour. Other traits have more complex interactions but you can study what does what.

My statement of 'can't be predicted' was not really what I meant. I meant that without looking at the specific parents you can't predict if it will be the seed or pollen parent that gives each feature (I don't believe it's fixed across all orchids that certain features come from a certain parent). But looking at the specific parents, certain traits will be known (from study) to take precedence. But just like with people it's not always known which traits will be passed on and which won't. Two people with brown eyes can have a blue eyed child or a brown eyed child. They are more likely to have a brown eyed one, but blue is possible if both parents carry the gene for blue.

I sometimes wish I had studied this stuff more in school. But our school did not promote biology much and I concentrated on Physics instead... not that I remember much of that 13 years after getting my degree

[PaphMadMan]

Originally Posted by Ray

I'm no expert in that area at all, but my understanding is that the mitochondrial DNA in the "female" parent plays a bigger role than the pollen parent in color and form.

Pretty close, but allow me to expand. Most plants, including orchids, get their mitochondria and plastids from the female parent only. Within every cell mitochondria are responsible for aspects of energy processing, and plastids are responsible for photosynthesis (chloroplasts), starch storage (leucoplasts) and some coloration (chromoplasts).

Both mitochondria and plastids have a few genes that are independant of the chromosomes of the plant and come only from the female parent. This means the female parent may have a little more influence on the light and temperature preferences of the plant, general vigor, and some aspects of color mostly in greens and yellows. There may also be some unexpected interactions when mitochondria and plastids end up in the company of chromosomal genes they didn't evolve with (male sterility in maize, for example), or indirect affects like vigor improving flower quality. Any other influences that are said to depend on the female parent may be more folktale than science.