Acknowledgement
This study was financially supported by the Vavilov-Frankel Fellowship to the first author under grant CONT/08/136/RF and the Leibniz Institute of Plant Genetics and Crop Plant Research (IPK). We acknowledge contribution and technical support from Christina Koch, Petra Oswald, Birgit Wohlbier, R.S. Vodouhe, and Adam Ahanchede. We thank Augustin Ganse for assistant in map making and Hanno Schaefer for useful comments on the manuscript.