Intraspecifïc variation in gel electrophoresis patterns of soluble mycelial proteins of Phytophthora megasperma isolated from alfalfa

Abstract

The electrophoretic patterns of the buffer-soluble proteins of 26 isolates of Phytophthora megasperma f. sp. medicaginis from diseased alfalfa plants and soil were studied. On the basis of the protein patterns, the isolates were divided into two groups which correlated with cardinal temperatures for growth, pathogenicity, and oogonia size. Group 1 (seven isolates) has minimum growth at 5 °C, optimum at 25–30 °C, and maximum at 35 °C, and is a highly pathogenic pathotype with small oogonia. Group 2 (19 isolates) has minimum growth at less than 5 °C, optimum at 20 °C, and maximum at 30 °C, and is a less pathogenic pathotype with large oogonia. The electrophoresis technique was useful in identifying differences among the Phytophthora isolates.