Isoenzymatic variability of cassava accessions from different regions in Brazil

Abstract

Cassava (Manihot esculenta Crantz) belongs to the Euphorbiaceae family, and is widely cultivated in Brazil. The objective of this study was to evaluate the isoenzymatic variability of 200 cassava accessions from the germplasm bank of Embrapa Amazonia Oriental. Seven groups were formed according to their origin: 1-Amazonas, 2-Amapa, 3-Bahia, 4-Para, 5-Rondonia, 6-Various, for accessions with a maximum of three individuals per place of origin, and 7 - Accessions of indefinite origin. The accessions were also evaluated as a whole. For the electrophoretic analyses, samples of young leaves were used in a 12% starch gel. Eight isoenzymatic systems were evaluated: acid phosphatase (ACP), leucine aminopeptidase (LAP), glucose-6-phosphate dehydrogenase (G6PDH), malate dehydrogenase (MDH), shikimate dehydrogenase (SKDH), malic enzyme (ME), glutamate dehydrogenase (GTDH) and isocitrate dehydrogenase (IDH). Analysis revealed a polymorphic locus for each system and high isoenzymatic variability among accessions. The average number of alleles per locus varied from 2.3 to 2.5. Average observed heterozigosity varied from 0.381 to 0.615 and the diversity index varied from 0.479 to 0.559. Genetic variability within groups was greater than among groups, suggesting a distribution pattern similar to what can be expected for natural populations of outcrossing plants.