International Center for Agricultural Research in the Dry Areas (ICARDA), P.O. Box 5466, Aleppo, Syria, and Root and Tuber Program, IRAD, B.P. 2123 Messa, Yaoundé, Cameroon. German Collection of Microorganisms and Cell Cultures (DSMZ) c/o BBA, Messeweg 11/12, D-38104 Braunschweig, Germany. Virginia State University, Agricultural Research Station, Box 9061 Petersburg, VA 23806, USA ADAS Arthur Rickwood, Mepal, Ely, Cambs, CB6 2BA, UK. International Institute of Tropical Agriculture (IITA), Oyo Road, PMB 5320 Ibadan, Nigeria.