Abstract

Out of 140 Caesalpinia s.l. species, only 20 species have the chromosome numbers presently known, and nine species have the karyomorphological studies available. We determine the karyotype and the chromosome morphometry in five Caesalpinia s.l. spp., and we describe the heterochromatin pattern in four of them. The diploid chromosome number of 24 was reported for the first time in Caesalpinia calycina, Caesalpinia microphylla and Caesalpinia pluviosa var. peltophoroides, and confirmed in Caesalpinia ferrea var. leiostachya and Caesalpinia pulcherrima. Different karyotype formulae were obtained for each of these five species. The chromosome asymmetry index varied from 34.94 % in C. pluviosa to 39.45 % in C. ferrea. The average chromosome length among the five species differed significantly (P<0.010). The heterochromatin blocks were evidenced by C-banding in both terminal and proximal regions of the Caesalpinia spp. chromosomes. This study represents a contribution toward an increased knowledge on cytogenetics and evolution of this genus.

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