Differential Sensitivity of Wheat Embryos against Extracts Containing Toxins of Septoria nodorum: First Steps towards in vitro Selection

Abstract

AbstractAs a first step towards the development of an in vitro‐selection system for septoria nodorum blotch resistance, wheat embryo culture on media containing extracts from Septoria nodorum was established. Extracts prepared from inoculated wheat grains had a toxic activity. Control extracts from uninoculated grains showed at least a 10‐fold lower toxic activity. Two wheat breeding lines susceptible to Septoria nodorum showed reduced growth in the presence of the fungal extract whencompared to a breeding line known to have good resistance in the field. A test with seven additional wheat lines showed a good agreement between field resistance of the ear and embryo resistance. Mellein is one of the toxins produced by Septoria nodorum and was used in pure form for in vitro‐selection. It showed toxic effects at 50 μg/ml, a concentration which is about 200‐fold higher than the mellein concentration in the diluted extract with embryotoxic activity. This indicates the importance of additional toxic compounds in the crude extract. Mellein acted non‐selectively on embryos of the different cultivars.