DIVERSE HETEROCHROMATIN IN LATHYRUS

Constitutive heterochromatin was observed in Lathyrus aphaca, L. cicer a, L. odoratus, L. sativus and L. tingitanus. C-bands in L. odoratus a nd L. tingitanus are centromeric or proximal in location. In L. tingit anus, only the short arm of Chromosome 3 showed a large telomeric band ; this was detected by C-banding following Q-banding but not in direct ly C-banded preparations. In L. odoratus, while most C-bands showed as positive Q-bands with enhanced fluorescence, small telomeric bands sh owed no differentiation with quinacrine. In L. tingitanus, constitutiv e heterochromatin showed two types of Q-band: one negative with quench ed fluorescence at the centromeric regions of all the chromosomes and the other, positive with enhanced fluorescence at one or both sides of the negative bands. No other species of Lathyrus investigated showed discrete negative Q-bands. In L. aphaca and L. cicera. Q-banding patte rns are characterized by large telomeric positively fluorescent bands on most members of each complement. Some chromosomes have proximal and /or intercalary bands. In L. cicera, some C-bands showed no differenti ation with quinacrine staining. In L. aphaca, a large positive Q-band normally at the end of the short arm of Chromosome 6 is sometimes repl aced by two small intercalary bands. Prominent telomeric positive Q-ba nds were also detected in L. sativus together with small proximal band s and intercalary bands. Whole short arms of Chromosomes 3 and 4 and t he long arm of Chromosome 6 in L. sativus showed slightly quenched qui nacrine fluorescence. The evolutionary implications of these observati ons are discussed.