GROWTH OF FOUR RACES OF PHYTOPHTHORA INFESTANS (MONT.) DE BARY IN SYNTHETIC MEDIA

Abstract

A basal medium is described containing three inorganic salts, dextrose, asparagine and thiamine, that supported the growth of races 1,2 and 1,2,3 of Phytophthora infestans, but not that of races 0 and 1. The medium supported growth of races 0 and 1 when peptone was added, but not when 24 other nitrogen sources were added singly. The addition of any one of 24 carbon sources failed to promote growth of race 1. None of 12 vitamins tested promoted the growth of all four races. However, one of the vitamins, ascorbic acid, and another reducing compound, sodium thioglycollate, promoted growth of races 0 and 1. A number of organic nitrogen compounds were utilized by races 1,2 and 1,2,3 but others, along with ammonium and nitrate salts, were not. Races 1,2 and 1,2,3 differed in their ability to utilize lysine and norleucine, and several nitrogen sources inhibited growth of both races. The best carbon sources for the growth of races 1,2 and 1,2,3 were dextrose, fructose, sucrose and glycerol.