In a message dated 4/16/2010 7:24:51 AM Mountain Daylight Time, firstname.lastname@example.org writes:
Not quite the same as compatible chromosomes to me, but yes, involved here as some of my theories :), and others :>). That's always at work with the OGB- type seedlings. I nearly always make the TBxAB rather than ABxTB direction for that reason. I think it probably won't affect how the bloom appears so much, but might improve the 'skin' on ABs. Tough to know. Everything gets so diluted.
Not the same, of course, perhaps more accurately described as related genetic effects. Sometimes I try too hard to restrict my posts on the list to less technical matters. In my own work, this type of cross was one component of a more comprehensive experimental program. I found that to assess the effects of chromosome compatibility and extra-chromosomal inheritance I had to take both into account.
Chromosomal compatibility obviously comes first. Without it, there would be no seedlings to assess. We tend to classify chromosomes as homologous or non-homologous when discussing meiosis and it serves quite effectively for conveying the essential concepts. Delving deeper into karyotype analysis, interspecies hybridization, and the evolution of iris, we recognize that we are really dealing with a continuum. That's why I also prefer to use the term "compatible chromosomes" for experimental families like this.
Now imagine that we're evaluating seedlings from one of these wide crosses and spot a breakthough. Sometimes, its own fertility is of primary concern. Sometimes, its greatest value is in what we can learn from it. If we suspect the incorporation of one or more partially homologous chromosomes, we look to sibs, half-sibs, half-cousins and sometimes even more distant relatives for clues. If we suspect exta-chromosomal inheritance we hope that we have a reciprocal cross for comparison and, if not, we look to related reciprocals for clues. We'll probably even analyze more pedigrees, because we want to improve the odds of obtaining a similar breakthrough in future crosses.
I am especially interested in the results of your TB X AB crosses because this is the type I found most difficult to make.