1. Department of Organic Chemistry; The Weizmann Institute of Science; Rehovot 7610001 Israel
2. Faculty of Chemistry; University of Wrocław; F. Joliot-Curie 14 50-383 Wrocław Poland
3. Department of Plant Pathology and Microbiology; The R.H. Smith Faculty of Agriculture Food and Environment; The Hebrew University of Jerusalem; Rehovot 7610001 Israel