Karyotype and C-band Analysis in Two Species of Genipa L. (Rubiaceae, Gardenieae Tribe)

抄録

Genipa L. (Rubiaceae) is a small genera with only three neotropical species. Karyological studies were developed in two of these species, G. americana (2n = 22) and G. infundibuliformis (2n = 20), by acetic orcein 2% and Giemsa C-band techniques. Haploid karyotype formulas were n =11 : 3m + 7sm + 1 sm^s and n =10 : 2m + 7sm + 1 sm^s, respectively. Chromosomes 3, 7 and 11 of G. americana and 3 and 5 of G. infundibuliformis were metacentrics and the others were submetacentrics. Chromosomes 1 and 4 had secondary constriction and according to the cytological observations only chromosome 4 had the NOR. Even so both species are dioecious, it have not been seen any chromosome or heterochromatin heteromorphism that could be associated to sexual differences. Both species had a high amount of heterochromatin revealed by C-band technique. G. infundibuliformis had the more asymmetric karyotype but the lesser chromosome sizes, heterochromatin amount and karyotype length. Preliminar comparative studies were done in both species and it were discussed the possible phylogenetic relationships.