Molecular divergence of alfalfa somaclones.

Plantlets were regenerated from alfalfa callus following passage through a tissue culture medium which contained gibberellic acid. A proportion of these plantlets showed obvious morphological variations. Leaflet, stem and petiole tissue of these plants were extracted to yield a soluble protein homogenate which was characterized by polyacrylamide gel electrophoresis. Over 18 individual protein bands were resolved and visualized by staining with coomassie blue G250. Electrophoretic gels from regenerated plantlets and from the parent plant were scanned spectrophotometrically and analyzed. The relative quantity of each of the proteins resolved from plants was correlated with proteins of other plants via the Pearson's product-moment correlation. Cluster analysis was then performed using these correlation coefficients to judge relatedness among somaclones and the parent plant. Two of 22 somaclones (9.1%) differed significantly from the parent and from the other somaclones judged by quantitative protein pattern variations. Three distinctive lineages through tissue culture produced plantlets. Using a discriminant analysis strategy somaclones could be grouped according to lineage with 80.8% accuracy based upon distinctions between protein electrophoretic patterns. Two of the somaclone lineage groupings showed no overlap with the parental grouping which indicated significant molecular divergence of these plantlets as judged by quantitative protein differences.