Characterization of somatic chromosomes of two diploid species ofCoffeaL. with acetic orcein and C-band techniques

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 + lsm s for C. canephora, and 3m + 7sm + lsm s 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.

Orcein, C- and NOR-banding on mitotic chromosomes of some wild diploid coffee species (CoffeaL.)

“…Despite the small size of coffee chromosomes, it was possible to obtain C-bands. C. congensis, C. eugenioides, C. liberica and C. stenophylla displayed a remarkable similar banding pattern resembling those obtained from C. canephora and C. dewevrei (Pierozzi et al 1999). Although the secondary constrictions and satellite segments were not C-banded, in pachytene nucleolar chromosomes from these coffee species Pinto-Maglio and Cruz (1987) observed heterochromatic chromomeres densely stained with propionic carmine in these regions and segments.…”

“…These sites can be detected by NOR-banding (Besendorfer et al 2002). C. congensis, C. eugenioides and C. liberica showed only one pair of chromosomes following silver impregnation, which may be chromosome number 3 as detected in C. canephora and C. dewevrei (Pierozzi et al 1999). Pinto-Maglio and Cruz (1987) and Lombello and Pinto-Maglio (2004a, 2004b, 2004c) also reported one pair of nucleolar chromosome after in situ hybridization for these species.…”

“…For cytological preparations, fixed root tips were softened in 20% pectinase and 2% cellulase for 40 min at 34°C. The following were applied: (1) the conventional 1% acetic orcein technique for the obtainment of chromosome measures; (2) adapted C-banding (Pierozzi et al 1999) for heterochromatin visualization; and (3) NOR-banding (50% AgNO 3 aqueous solution and gelatin) as described in Howell and Black (1980) for location of NORs.…”

“…Pierozzi (1993) and Pierozzi et al (1999) in an extensive effort demonstrated the possibility of characterizing coffee mitotic chromosomes using chromosome measures and heterochromatin localization through the C-banding technique in two diploid species, C. canephora and C. dewevrei. In this study, to continue the characterization of mitotic chromosomes in the genus and to aid in further comparative studies, other coffee diploid species are analyzed by acetic orcein staining and C-and nucleolar organizer region (NOR)-banding (silver staining).…”

Cytogenetics of coffee

“…Subsequent modifications to the C band methodology which were particularly appropriate for plants with small chromosomes like coffee, produced better C banding patterns for some wild species, and the description of the complete karyotypes for the species C. canephora and C. dewevrei. All the species Lombello and Pinto-Maglio, 2004a) studied presented the chromosomes with uniform pericentromeric patterns of C banding, suggesting that during evolution, the wild species have retained not only the same chromosome number but also the same pattern of distribution of heterochromatin as revealed by the C bands (Pierozzi et al, 1999;. The characterization of the longitudinal differentiation of the mitotic chromosomes of coffee has progressed using other techniques such as fluorescent banding with DAPI (4'-6-diamidino-2-phenylindole) and CMA 3 (Chromomycin A 3 ) that identify chromatin regions rich in A-T and G-C bases, respectively; in addition, cytomolecular techniques such as fluorescent in situ hybridization (FISH) and genomic in situ hybridization (GISH) have also been applied (Pinto-Maglio et al, 2000;Lombello and PintoMaglio, 2004a,b,c).…”