MORPHOLOGY OF THE PACHYTENE CHROMOSOMES IN PRUNUS PERSICA

Abstract

Morphology of the pachytene chromosomes was studied in three genotypes of Prunus persica (L.) Batsch. Each of the eight bivalents has been identified by its distinctive morphological features such as length, position of the centromere, and distributional pattern of the heterochromatic chromomeres. On the basis of total length the chromosomes were numbered from one to eight, the last being the shortest of the complement. In all bivalents the heterochromatin is clustered around the centromere. The chromosomes of the three clones are alike. A heterochromatic knob is present in the distal part of the shorter arm of chromosome five from 'Raritan Rose'. This knob was not present in the other two genotypes studied.Two pairs of chromosomes participate in the organization of a single nucleolus. At pachytene and later stages of prophase, small nucleoli-like bodies associated with or close to the bivalents were frequently observed.