Sorghum Biology Klaus Ammann, [email protected], Version April 20, 2010 and July 2011 With a contribution on a gene flow experiment on Sorghum in Africa from Mary Mgonja, Nairobi Fig. 1 Oklahoma Farm Bureau, Galleries Grain Sorghum http://www.okfarmbureau.org/press_pass/galleries/grainSorghum/Sorghum2.jpg 2 Fig. 2 Schools in West Africa: Students threshing and winnowing sorghum earlier harvested from the school farm. http://wassumbee.blogspot.com/2006/01/schools-in-west-africa-1.html Fig. 3 Lysine Biosynthesis in Sorghum bicolor: GenomeNet Database Service, from KEGG: Kyoto Encyclopedia of Genes and Genomes http://www.genome.jp/dbget-bin/get_pathway?org_name=esbi&mapno=00300 3 Sorghum Biology ............................................................................................................... 1 1. Preface ........................................................................................................................... 20 2a. Executive Summary ................................................................................................... 22 2a.1. General Remarks ..................................................................................................................................................................................22 2a.2. Taxonomy ...............................................................................................................................................................................................22 2a.3. Evolutionary dynamics and Landraces of Sorghum bicolor .............................................................................................................23 2a.4. Sorghum Breeding Activities ................................................................................................................................................................23 2a.5. Gene flow in Sorghum and related species .......................................................................................................................................24 2a.6. Mitigation of Gene Flow in Sorghum and related species................................................................................................................24 2b. Extended summary Report Sorghum Biology ....................................................... 27 2b.1. General Remarks ..................................................................................................................................................................................27 2b.2. Taxonomy of Sorghum, the wider picture ..........................................................................................................................................27 2b.3. Sorghum species ...................................................................................................................................................................................28 2b.4. Sorghum halepense, Johnsongrass ...................................................................................................................................................28 2b.5. Sorghum propinquum ...........................................................................................................................................................................29 2b.6. Sorghum bicolor (L.) Moench ..............................................................................................................................................................29 2b.7. Numerical taxonomy of Sorghum ........................................................................................................................................................32 2b.8. Molecular taxonomy of Sorghum.........................................................................................................................................................32 2b.9. Distribution of Sorghum ........................................................................................................................................................................32 2b.10. Centers of crop origin .........................................................................................................................................................................32 2b.11. Earliest evidence of Sorghum cultivation in Africa 8000 years ago ..............................................................................................32 2b.12. Centers of biodiversity generally more robust against alien invasions ........................................................................................33 2b.13. Preservation of landraces through participative breeding programs ............................................................................................33 2b.14. Development of Sorghum breeding ..................................................................................................................................................34 2b.15. Evolutionary dynamics of cultivated Sorghums ...............................................................................................................................35 2b.16. Gene flow from Sorghum cultivars to wild and feral species .........................................................................................................35 2b.17. Gene flow in Sorghum from crop to crop .........................................................................................................................................36 2b.18. Gene flow from weedy to cultivated Sorghums ...............................................................................................................................37 2b.19. Assessment of gene flow of cultivated Sorghums in Africa ...........................................................................................................37 2b.20. The agricultural reality ........................................................................................................................................................................39 2b.21. A summary of gene flow in Sorghum cultivars and its wild relatives ............................................................................................39 2b.22. Consequences and mitigation of gene flow in African Sorghum ..................................................................................................41 2b.23. Coexistence rules to be followed ......................................................................................................................................................41 2b.24. How to avoid gene flow in cultivated Sorghums .............................................................................................................................42 3. Taxonomy of Sorghum ................................................................................................ 46 3.1. Wider taxonomic range of the genus Sorghum .................................................................................. 46 3.1.1. The position of the Andropogoneae and Sorghum within the system of the Poaceae ..............................................................46 3.1.2. The genetic comparison between Maize, Sugarcane and Sorghum .............................................................................................47 3.2. The genus Sorghum Moench ................................................................................................................. 58 3.2.1. Genetics within the genus Sorghum ..................................................................................................................................................58 3.2.1. Section Sorghum within the genus ....................................................................................................................................................64 3.2.2. Summary taxonomy and systematics of Sorghum ..........................................................................................................................68 3.2.3. Bibliographic references taxonomy and systematics of Sorghum .................................................................................................69 3.3. Sorghum halepense (L.) Pers. ................................................................................................................ 70 3.3.1. Taxonomic description .........................................................................................................................................................................70 3.3.2. Evolution of Sorghum halepense .......................................................................................................................................................72 3.3.3. Distribution of Sorghum halepense ....................................................................................................................................................76 4 3.3.4. Summary Sorghum halepense ...........................................................................................................................................................76 3.3.5. Bibliographic References Sorghum halepense ................................................................................................................................77 3.4. Sorghum propinquum (Kunth) Hitchc. Ling. Sci. J. 7: 249, 1929. .................................................... 77 3.4.1. Taxonomic description .........................................................................................................................................................................77