The Genus Collinsia. XIX

“New” genomes from two fertile interspecific hybrids

Abstract

Fertile hybrids with an interchange complex of six chromosomes from crosses between C. corymbosa and either C. tinctoria or C. multicolor yielded progeny with bivalents in the F₂ and F₃ generations. Two lines from the former hybrid had a “new” genome simulating the one in C. multicolor. Of the three lines from the latter hybrid, one had a “new” genome simulating the one in C. heterophylla and the others had a genome corresponding to the one in one or the other parental species.
Chromosome associations in hybrids involving the lines from each interspecific hybrid and either a parental or a non-parental species were the same as those previously observed when these species were hybridized with species having a genome corresponding to the one in each line. The fertility or sterility of hybrids involving each line agreed with expectations based on previous observations on interspecific hybrids.
Certain morphological observations on the lines from the interspecific observations were in accord with those made in species whose genomes were presumably present in each line. The line from C. corymbosa×C. multicolor which simulated the latter species in having its genome and the long flowerpedicel associated with this species included a large number of morphological characters from C. corymbosa.
The origin of “new” genomes from the two interspecific hybrids has not yet been explained. Furthermore, it is not yet possible to determine if the genomes from these interspecific hybrids are structurally identical either with those being simulated or with those corresponding to a parental species.