1. Plant-Microbe Interactions Research Unit; National Institute of Agrobiological Sciences; 2-1-2 Kannondai Tsukuba Ibaraki 305-8602 Japan
2. Biomolecular Research Unit; National Institute of Agrobiological Sciences; 2-1-2 Kannondai Tsukuba Ibaraki 305-8602 Japan
3. Département de Microbiologie Fondamentale; Université de Lausanne; CH-1015 Lausanne Switzerland