ABSTRACT

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.

ABSTRACT. Malate dehydrogenase (MDH) isozymes were used as biochemical markers to discriminate and cluster cladophylls of plants of one clonal population of the prickly pear, Opuntia ficus-indica (Cactaceae). The isozyme electrophoretic patterns obtained with MDH provided 8 isozymes and 5 different electrophoretic phenotypes. Similarity in cladophylls was estimated using Jaccard's coefficient. This clonal population studied was founded by only one propagule, and after 50 years, it is likely to have been formed by asexual and sexual propagules. Since that differential expression of MDH isozymes could play a significant role in overall plant cell metabolism, we suggest that the cladophylls of prickly pear that were clustered together showing identity or higher similarity are specially a suitable source for industrial procedures of industrial extraction of commercial interest compounds because a same extraction protocols can be most quickly and easily standardized using genetically uniform materials. Electrophoretic patterns of MDH isozymes can be used as an effective tool for previously determine the genetic similarity in the cladophylls of O. ficus-indica plants.Key words: isozymes, malate dehydrogenase, prickly pear, polymorphism, genetic similarity.RESUMO. Padrões de isozimas de malato desidrogenase em população clonal nos cladófilos de Opuntia ficus-indica Mill (Cactaceae). Isozimas de malato desidrogenase (MDH) foram usadas como marcadores moleculares para discriminar e agrupar cladófilos de plantas de uma população clonal de cactus da espécie Opuntia ficus-indica (Cactaceae), conhecida como palma. O padrão eletroforético obtido revelou 8 isozimas MDH e 5 fenótipos eletroforéticos diferentes. A similaridade entre os cladófilos foi estimada usando o coeficiente de similaridade de Jaccard. Essa população clonal estudada foi fundada por somente um propágulo e, após 50 anos, parece ser formada por propágulos assexuais e sexuais. Uma vez que a expressão diferencial de isozimas MDH pode ter um papel significante no metabolismo das células da planta, sugerimos que os cladófilos de palma que foram agrupados com os mais altos valores de similaridade são os mais adequados para serem utilizados em procedimentos de extração industrial de compostos de interesse comercial, porque um mesmo protocolo de extração pode ser mais rapidamente e facilmente padronizado quando se utiliza material geneticamente uniforme. O padrão eletroforético das isozimas MDH pode ser usado como uma ferramenta efetiva para uma análise prévia da similaridade genética entre os cladófilos das plantas de O. ficusindica.Palavras-chave: isozimas, malato desidrogenase, palma, polimorfismo, similaridade genética.