| dc.description | The expression of the regenerative trait in red clover is sporadic. A regenerative somaclonal variant, F49R capable of regeneration from somatic cells and transmission of this trait to progeny, was obtained from a diploid cultivar Florex (2n = 24) (MacLean 1997). In this study DNA rearrangements in "the hot spot" of F49R genome were detected by DNA fingerprinting with Jeffreys' probe 33.6. These rearrangements seem to be linked to regeneration trait. This highly mutable DNA region was stable in non-regenerative callus of F49M, explant source for F49R. A common RFLP band linked to proline analogue (Azc) tolerance was also identified in this mutational "hot spot". The substantial changes in quantity of repetitive DNA associated with differentiation (amplifications) and de-differentiation (de-amplifications) of plant cell in tissue culture were detected by dot hybridization of genomic DNA using as probes repetitive DNA sequences isolated from a red clover lambda genomic library. These changes in repetitive DNAs during red clover regeneration took place independently of each other in different families of repetitive DNA sequences resulting in alternation in their relative proportion in the genome. This study showed that expression of multigene family, MsCOR A (Laberge et al. 1993), can vary in regenerative somaclonal variants, even though genomic organization of the gene is unchanged. Northern and Western analysis showed that cold-acclimated F49R and its regenerative progeny had induced expression (2-5 fold) of gene associated with improved cold-tolerance compared to cold-acclimated F49M and non-regenerative progeny of F49R. Genomic organization of the MsCOR A gene, revealed by Southern blotting, was the same for F49R and F49M. | en_US |
