Experiments were carried out aiming to optimize procedures for cytological preparations of root tips with high frequency of metaphase cells showing clear features of chromosome morphology, in species belonging to two genera of plants, Passiflora (Passifloraceae) and Crotalaria (Leguminosae). For the accumulation of metaphases, as well as prophases and prometaphases with well condensed chromosomes, pretreatments of root tips with different combinations of 8-hydroxiquinoline, a mitotic fuse inhibitor and with cycloheximide, a protein synthesis inhibitor, were evaluated in Feulgen stained preparations. The treatments with 8-hydroxiquinoline at 300ppm + cycloheximide at 3.125ppm, and with 8hydroxiquinoline at 300ppm + cycloheximide at 6.25ppm, both for 1 hour and 30 minutes, were more effective respectively for Passiflora and Crotalaria species. This investigation illustrates a case of differences of pretreatment procedures between two genera of plants, as well as represents a basic work for studies involving the comparison of the karyotype of species belonging to these genera, and especially, for the detection of chromosome markers via several cytogenetic methods (C-banding, fluorescent-chromosome banding and in situ hybridization).
Passiflora; Crotalaria; plant cytogenetics; mitotic chromosomes; 8-hydroxiquinoline; cycloheximide
