The Fine Structure of Safflower (Carthamus tinctorius L.) Chromosomes as Revealed by Pachytene Analysis

Abstract

SummaryThe 7 accessions of Carthamus tinctorius from different locations were analyzed in detail for establishing the chromosome and karyotype polymorphism. All 12 pachytene chromosomes were clearly identified on the basis of length, arm ratio, centromeric index, symmetry index, total chromatin length and Percent chromomere per chromosome. The karyotype and heterochromatin distribution patterns reported in this study provide a foundation toward cytological characterization of the Carthamus genome. The chromosome size ranges between 546.53 mm to 933.53 mm. Variability within the individual chromosomes with respect to the size, shape and position of the centromere was found to be well marked. Chromosomes were arranged from 1 to 12 following a descending order of length. At pachytene, the pollen mother cells have 12 bivalents and prominent nucleolus. The accessions exhibited significant variability in their pachytene chromosome characteristics.