Cytogenetic studies in Cochlearia L. (Cruciferae). The chromosomal constitution of C. danica L.

Genome analysis has been used to investigate the relationship of C. danica L. to the diploid and tetraploid species in the genus. The results of this analysis suggest that C. danica has the genomic constitution A¹ ₇ A¹ ₇ A² ₇ A² ₇ T₇ T₇. Both A₇ genomes in C. danica are segmentally differentiated from the A₇ genome in C. groenlandica L. and from the similar A₆ genomes in C. pyrenaica DC. and C. officinalis L. but, in hybrids, are capable of some pairing with these genomes. A² ₇ is more distantly related to A₇ and A₆ than is A¹ ₇ and in A₇ some of the differentiation has taken place by reciprocal translocations. A¹ ₇ and A² ₇ still retain enough homology for pairing between them. The T₇ genome has no homology with any of the A genomes but may be derived from an ancestral T₆ genome.