Heredity of seventeen isozyme loci in cassava (Manihot esculenta Crantz)

Abstract

Starch gel electrophoresis was used to assess isozyme polymorphism in two Manihot species. Crude extracts were obtained from leaves and pollen. Ten enzymes were examined for their polymorphism in a germplasm collection of 365 cultivated plus 109 wild accessions, mainly from Africa. The inheritance of these enzymes was examined using 13 intra and interspecific progenies. Seventeen polymorphic loci were found for the ten enzyme systems, with 59 alleles. All the markers showed disomic heredity and three linkage groups were identified.

Isoenzymatic variability of cassava accessions from different regions in Brazil

“…The ACP enzyme in plants is mentioned by various authors as either dimeric or monomeric. The results obtained for this enzyme differed from those of Borsoi Filho (1995) and Faraldo (1999), who reported two monomeric loci, and by Lefèvre & Charrier (1993a), who also observed two loci: one monomorphic and the other dimeric and polymorphic. Our results are similar to those presented by Silva (2000), who reported one monomeric locus with the heterozygotes showing two bands.…”

“…The SKDH system showed only one monomeric locus (Skdh-1) with four alleles (Figure 2), similar to the results observed by Lefèvre & Charrier (1993a), Faraldo (1999), Silva (2000) and Peroni (1998). The latter author also found four bands, which were separated in two groups, A and B, because of the inconsistency of band number 4 resolution in some individuals, which the author related to the different ages of the plants analyzed.…”

“…Faraldo (1999) found three loci, with two monomorphic loci and one dimeric, polymorphic locus with three bands for the heterozygotes. Lefèvre & Charrier (1993a) observed for this system three to eight bands with three migration levels and three loci, A, B and C: two polymorphic (A and B) and one monomorphic (C) with two bands. Borsoi Filho (1995) found two activity zones, the first showing a monomorphic locus with three bands, the second one with more than one locus, showing enzymatic polymorphism.…”

“…The author did not observe any polymorphism probably because only six cultivars were evaluated and the two bands detected were probably out of a monomeric locus A (A 1 and A 2 ). Lefèvre & Charrier (1993a), studying the inheritance of 17 loci in M. esculenta, found a locus with one to three alleles for LAP system, and considered locus B as part of locus A.…”

A molecular genetic map of cassava (Manihot esculenta Crantz)

“…Normal chromosome pairing at meiosis occurs in hybrids of Manihot species that are morphologically very different and belong to separate primary phylogenetic lineages according to cpDNA studies (Fregene et al 1994). This combined with the lack of a strong interspecies boundaries in the genus has led to the theory that a polyploidization event occurred before species differentiation (Lefevre and Charrier 1993;Bryne 1984).…”