2 Synthetic Hexaploids: Harnessing Species of the Primary Gene Pool for Wheat Improvement Francis C. Ogbonnaya and Osman Abdalla International Center for Agricultural Research in the Dry Areas (ICARDA) P.O. Box 5466 Aleppo, Syria Abdul Mujeeb-Kazi and Alvina G. Kazi National Institute of Biotechnology and Genetic Engineering (NIBGE) Faisalabad National University of Science and Technology (NUST) Islamabad, Pakistan Steven S. Xu USDA-ARS, Northern Crop Science Laboratory 1605 Albrecht Blvd. Fargo, ND 58102-2765, USA Nick Gosman The National Institute of Agricultural Botany (NIAB) Huntington Road Cambridge CB3 0LE, UK Evans S. Lagudah CSIRO Plant Industry GPO Box 1600, Canberra Australian Capital Territory 2601, Australia 35 Plant Breeding Reviews, Volume 37, First Edition. Edited by Jules Janick. Ó 2013 Wiley-Blackwell. Published 2013 by John Wiley & Sons, Inc.