Isozyme diversity in cassava cultivars (Manihot esculenta Crantz).

Isoenzyme electrophoresis was used as a method to determine genetic diversity in various M. esculenta cultivars collected in the Southwestern (SW) and Northwestern (NW) regions of the State of Parana, in the South region of Brazil, and in cultivars produced at the Agronomic Institute of Campinas (IAC), São Paulo State, Southeastern region of Brazil. The cultivars have been maintained by vegetative propagation for 5 years and are useful in production programs. A total of 28 loci in the acid phosphatase (ACP; EC 3.1.3.2), esterases (EST; EC 3.1.1.1), malate dehydrogenase (MDH; EC 1.1.1.37), and shikimate dehydrogenase (SKDH; EC 1.1.1.15) isozymes was analyzed. The proportion of polymorphic loci for NW, SW, and IAC cultivars was 57.14, 50.0, and 53.6% respectively. Genetic diversity calculated by Nei's genetic identity (I) showed high I values for the three M. esculenta subpopulations. The high degree of polymorphism expressed by cassava cultivars is highly relevant to stimulate breeding programs with M. esculenta species.