S.M. Vargas, G.A. Torres, F.S. Sobrinho, A.V. Pereira,  L.C. Davide
Published September 30, 2007
Genet. Mol. Res. 6 (3): 707-712 (2007)

About the authors
S.M. Vargas, G.A. Torres, F.S. Sobrinho, A.V. Pereira,  L.C. Davide

Corresponding author
G.A. Torres
E-mail: gatorres@ufla.br

ABSTRACT
Cratylia argentea and C. mollis (Fabaceae-Papilionoide- ae) are legume shrubs native to the Cerrado and Caatinga, respectively. Both species show great resistance to drought and high nutritive value, which makes them a valuable forage resource in tropical regions. Cy- togenetic studies were carried out on accessions of C. argentea and C. mollis from Germplasm Banks of Embrapa Gado de Leite (Juiz de Fora, MG) and Embrapa Semi-Árido (Petrolina, PE), respectively. Root tips were treated with 3 mM 8-hydroxyquinoline and slides were made us- ing the air-dry technique. Karyotype description for each accession took into account the following features: chromosome number; total length, relative length and arm ratio of each chromosome; haploid set length, and degree of asymmetry. Mitotic metaphases in both species showed 2n = 22 chromosomes, where this is the first report of diploid number for C. mollis. Chromosome length was also quite similar for the two species, ranging from 5.08 to 2.50 µm in C. argentea and 5.12 to 2.51 µm in C. mollis, with haploid sets of equal size, measuring 38.10 and 37.85 µm, respectively. However, they did not show the same karyo-typic formula, which was 5 m + 4 sm + 2 st for C. argentea and 7 m+2 sm + 2 st for C. mollis. This indicates the occurrence of rearrangements within chromosomes I and VI. Both karyotypes showed a tendency for asymmetry.

Key words: Cratylia argentea, Cratylia mollis, Cytogenetics, Tropical forage, Karyotype, Chromosome evolution