Cytogenetical studies in the genus Persea (lauraceae). III. Electrophoretical studies on peroxidase isozymes.

Abstract

Comparison of the peroxidase zymograms of the avocado, Persea americana between states from which a large number of strains were collected indicated that the strains from Michoacan, Mexico, Morelos, Puebla and Veracruz have 15, 13, 10, 12 and 12 active regions in the zymograms, respectively. The form having activities at more regions of zymograms would be regarded as more advanced ones than those possessing lower number of active regions. The percentage of strains in which statistically significant variation of zymograms within strains were found was high in Puebla (60.0%), Michoacan (43.1%) and Veracruz (37.4%). Also these states are the major places where avocado is cultivated more abundantly. Considering the higher frequencies of strains having significant differences of peroxidase zymograms within strains and lower number of active regions in the zymograms, the Puebla-Veracruz region was postulated as the possible center of the origin of the Mexican type of avocado. Archeological evidences found in the Valley of Tehuacan in Puebla, and the fact that P. schiedeana and P. floccosa, semicultivated and wild relatives of P. americana, respectively, grow in the Puebla-Veracruz area support this postulation.Differences of peroxidase zymograms between Mexican, Guatemalan and West Indian types were also found to be highly significant. From the frequency of strains which showed significant variations within strains (62.5%, 50.0% and 39.1% in Guatemalan, West Indian and Mexican types, respectively), it was presumed that Guatemalan type is the most ancient form.