Genomic Designing for Biotic Stress Resistance in Sorghum

Sorghum (Sorghum bicolor (L.) Moench) is an immensely valuable staple cereal crop across semi-arid tropical regions of the world and is regarded as a nutritionally potential crop compared to other cereals with high fibre content, minerals and slow digestibility. A multitude of bacterial, fungal and viral pathogens and several insect pests cause significant losses in yield and quality of sorghum. Management of these biotic stresses using chemicals is quite expensive and environmentally not sustainable. Developing host-plant resistance and use of resistant cultivars has great promise in this direction. Repository of genetic resources and the wild gene pool in sorghum that harbor many biotic resistant genes serve as a rich source to develop resistant cultivars. Crossing programs involving several resistance sources resulted in many resistant varieties, hybrids and parents. The genetic barriers between wild and cultivated sorghum species are still challenging to transfer resistant genes. However, with the recent advances in genomic tools, next generation sequencing/re-sequencing technologies, genetic engineering, more genomic data is being utilized in the sorghum breeding programs. These advanced molecular tools have helped to unravel the genetic architecture and provide a deeper understanding of the marker-trait associations. A maximum number of individuals in the mapping population coupled with large-scale genotyping with markers like SNPs would capture more recombination events, leading to high resolution of QTL mapping. Marker-assisted selection can now be efficiently used for pyramiding multiple resistance genes/QTLs which can accelerate the varietal development process, resulting in durable resistance with great impact on the sorghum yield stability and sustainability. This chapter provides an overview of biotic stresses in sorghum, their impact, various breeding strategies and genomics assisted tools in prospecting sorghum biotic stress resistance besides highlighting the recent concepts and future perspectives for genomic designing.