Did abnormal 10 arise from a translocation between Tripsacum and Maize Chromosomes?
The two kinds of chromosomes 10 found in races of maize clearly differ structurally and genetically. Since N10 is much more frequently encountered, it presumably, although not necessarily, is the ancestral form. What can be said about the source of the differential segment and the large heterochromatic knob which characterize abnormal chromosome 10? Not much, but certain speculations may be fruitful. The K10 knob is unique in that it has specific genetic properties not possessed by any other knob found in races of maize. Although it contains the same highly repetitive 185 bp sequence of satellite DNA in all knobs of maize (Peacock, Dennis, Rhoades and Pryor, in press) it cannot be identical to them in DNA composition. It is not a typical maize knob. The origin of the differential segment is likewise obscure but its insertion into 10L and the translocation of the piece with the K10 knob may have taken place at the same time, both being contributed by the same chromosome. Of possible sig