CYTOGENETIC STUDIES IN ELEVEN CANOLA (BRASSICA NAPUS L.) CULTIVARS

Meiotic study was performed in 11 Brassica napus cultivars considering chiasma frequency and distribution, chromosome pairing, as well as the occurrence of B-chromosomes and their effects on chiasma frequency. Such cytogenetic pairing, along with agronomic characteristics, may be used in planning hybridization among the B. napus cultivars. All the cultivars studied possessed n=19 chromosome number (4x) and showed a deviant course of prophase-I meiosis with a synezetic knot and post pachytene diffuse stage. Chromosome stickiness occurred in most of the cultivars from early prophase to late telophase-II leading to the formation of laggard chromosomes and micronuclei. The cultivars studied differed significantly in chiasma frequency and distribution as well as bivalent formation, indicating their genomic differences. Cluster analysis and ordination based on principal components analysis grouped those cultivars showing meiotic similarities. Some of the cultivars showed the occurrence of B-chromosomes.