The homosporous pteridophytes have been largely uninvestigated by electrophoresis, despite the fact that they offer many exciting research possibilities (Soltis et al., 1980). The paucity of electrophoretic studies of ferns and fern allies may be due in large part to the high concentrations of condensed tannins that many species contain (Cooper-Driver, 1976 and pers. comm.). These compounds render enzymes inactive by binding with them following cellular disruption, thereby frustrating researchers who have attempted electrophoretic analysis utilizing standard methods of sample preparation.The method of sample preparation developed by Kelley and Adams (1977a, b) in their analysis of enzyme variation in Jimiperus was an important procedural breakthrough in overcoming the difficulties that result from the liberation of large amounts of phenolic compounds during tissue preparation. Recently, a simplified version of that method was applied by Soltis et al. (1980) to fern leaf tissue, facilitating rapid preparation of active enzyme samples and thereby making electrophoretic analyses of large numbers of individuals more feasible.In an attempt to improve methods of analysis of fern enzymes in starch gel electrophoresis, we have experimented with modifications of the method of sample We M Werth fern tissue. Finally, during the course of our electrophoretic investigations of ferns we found that standard gel and electrode buffers and staining schedules, such as those of Brewer (1970) and Shaw and Prasad (1970), often provided unsatisfactory results when applied to ferns. We have determined gel and electrode buffers, as well as staining schedules, that provide clear starch gel enzyme banding for 22 enzyme systems in ferns. Requests for advice resulting from the recent surge of interest in fern enzyme electrophoresis have prompted us to compile our procedural data so that other researchers can take advantage of our experimentation. We hope that these data will stimulate more extensive electrophoretic investigation of pteridophytes and other electrophoretically difficult taxa. Gottlieb (1981b) recently reviewed aspects of enzyme electrophoresis primarily in gymnosperms and angiosperms. His discussion is equally relevant to understanding the potential applications and limitations of electrophoretic evidence in pteridophytes. Since homosporous pteridophytes have high chromosome numbers, it is tempting to invoke polyploidy in interpreting their enzyme band patterns. It is well
Intact chloroplasts isolated from mature leaf tissue of the homosporous fern Athyrium filixfemina were osmotically ruptured and subjected to starch gel electrophoresis in side by side comparisons with whole leaf extracts. The single enzyme activities of reportedly cytosolic [NADP]IDH and [NADP]ME were not expressed in the chloroplast fraction, and these were used as controls ensuring the cytosol‐free quality of the chloroplast preparations. Isozymes F1,6DP‐1, PGI‐1, PGM‐1, 6PGDH‐1, ALDO‐1, TPI‐2, [NAD(P)]G3PDH‐1, and [NAD(P)]G3PDH‐2 are active in the chloroplast fraction, whereas Fl,6DP‐2, PGI‐2, PGM‐2, 6PGDH‐2, ALDO‐2, and TPI‐1 were lacking from the chloroplast fraction and are considered cytosolic. The single enzyme activities observed for AAT and SkDH, are chloroplastic. These data indicate that the two isozymes of certain enzymes in Athyrium filix‐femina are not the products of duplicated loci resulting from polyploidy, but are distinct and subcellularly compartmentalized as demonstrated in heterosporous plants. Thus A. filix‐femina is functionally diploid in spite of its high chromosome number of 2n = 80.
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