Characterization of somatic chromosomes of two diploid species of<i>Coffea</i>L. with acetic orcein and C-band techniques

Abstract

Abstract Two diploid (2n=22 chromosomes) and self-incompatible coffee species, Coffea canephora Pierre ex Froehner and C. dewevrei De Wild, et Th. Dur., were subjected to 2% acetic orcein and C- banding techniques with the purpose of mitotic chromosome characterizations. Karyological analysis were done in root cell chromosomes. These two diploid species of coffee could be distinguished mainly by some chromosome absolute (u,m) and relative (%) lenght mean values. In both species chromosome 5, 10 and 11 were metacentrics and the others were submetacentries; chromosomes 1 and 3 had secondary constriction beside centromere. The data suggested chromosome 3 had the NOR. Haploid karyotype formula was 1M + 2m + 7sm + lsms for C. canephora, and 3m + 7sm + lsms for C. dewevrei. Total karyotype length mean values were 16.97 ± 0.95u,m for C. canephora and 15.60± l.ll|imfor C. dewev rei and the difference was not significant. C-banded karyotypes were very similar in both species with prevailing centromeric/pericentromeric C-bands. The total C-band heterochromatin values expressed in percentage were 15.76 + 0.32% for C. canephora and 16.11 ± 0.26% for C. dewevrei. These values were not significantly different to separate both species. Similarly, no distinction could be made on karyotype asymmetry index mean values between the two species.