The eucalypt karyogram resolved

Abstract

The genus Eucalyptus L’Herit. is the most cytologically studied group of plants in the family Myrtaceae. Despite the ecological and economic importance of this genus, much of its biology remains poorly understood. Cytological methods are useful in evolutionary studies; however, karyomorphological descriptions of the Eucalyptus species are limited. In this study, we developed a cytogenetic methodology that facilitates karyogram assembly and chromosome classification of Eucalyptus citriodora. The protocol includes treatment of root tips with amiprophos-methyl in Hoagland’s solution, slide preparation by cell dissociation, and an air-drying technique. Using this method, well-resolved metaphasic chromosomes with different compaction levels were obtained. A chromosome number of 2n = 22 was confirmed. On the basis of metaphasic chromosomes with limited condensation, E. citriodora showed six metacentric and four submetacentric chromosomes, and one submetacentric chromosome with a nucleolus organizer region (NOR). Thus, the informative chromosomes obtained in this study has enabled the most precise karyotype description of a Eucalyptus species, to date.