Sorghum breeding for biotic stress tolerance Ramasamy Perumal, Agricultural Research Center – Hays, USA; Clint W. Magill, Texas A&M University, USA; Gary C. Peterson, Texas A&M AgriLife Research and Extension Center, USA; Louis K. Prom, USDA-ARS, USA; and Elfadil M. Bashir, Tesfaye T. Tesso, Desalegn D. Serba and Christopher R. Little, Kansas State University, USA

1 Introduction

2 Fungal diseases of sorghum

3 Sorghum pests

4 Other threats: bacterial diseases, Potyvirus spp., Striga and nematodes

5 Resistance genes

6 Summary

7 Where to look for further information

8 Acknowledgements

9 References

Biotic and abiotic constraints can play a major role in limiting productivity and grain quality in sorghum. Host plant resistance should be the most effective way to reduce losses incurred by biotic stresses. However, classical breeding approaches for the development of resistant cultivars have been complicated by the fact that the disease and pest interaction often involves: a) complex polygenic inheritance, b) continuous development of new races or biotypes and c) enormous environmental interactions that affect pest/ disease incidence and severity. These complications when combined with tedious and time-consuming inoculation procedures for sorghum diseases or insects that mimic natural conditions have presented challenges to screening genotypes under field conditions and, hence, the development of new germplasm tolerant/resistant to biotic stresses is critical for a thriving sorghum industry. Molecular diagnostics offers a more reliable method to screen large numbers of germplasm to identify potential resistance sources in a short time, but useful markers must be identified and verified before the technology can be applied.