Differences Between Aggressive and Non‐Aggressive Single Spore Lines of Leptosphaeria maculans in Cultural Characteristics and Phytotoxin Production
1989
Koch, E. | Badawy, H. M. A. | Hoppe, H. H.
Stems of oilseed rape (Brassica napus) bearing pseudothecia of Leptosphaeria maculans were collected in different parts of West Germany. From single ascospores of this material a total of 352 fungal lines were derived, tested on rape cotyledons and devided into 124 aggressive and 228 non‐aggressive pathotypes. The two groups could be distinguished by certain characteristics. On nutrient agar, aggressive strains grew more slowly. In liquid cultures, non‐aggressive types produced a yellow‐brown pigment whereas the culture filtrates of aggressive strains remained unpigmented. The culture filtrates of aggressive lines contained phytotoxic compounds which were identified as sirodesmins. These compounds were absent in culture filtrates of non‐aggressive pathotypes. The very close correlation between aggressiviness as a pathogen and the phytotoxin production indicates that phytotoxins of Leptosphaeria maculans could be involved in the disease development.
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