Spot blotch in bread wheat: virulence, resistance, and breeding perspectives

Abstract Spot blotch caused by Cochliobolus sativus is an important foliar disease of wheat (Triticum aestivum L.), leading to significant reductions in grain yield and quality. In this chapter, the losses caused by spot blotch as well as epidemiological insights and biochemical mechanisms of the pathogenesis are considered. Chronological strives toward production of resistant stocks for spot blotch have also been highlighted in this chapter. It has been observed that additive genetic resistance against biotic and abiotic stresses in wheat has been achieved through alien genetic resources. Studies at the molecular level regarding quantitative trait locus identification and application of markers for precise identification of genotypes as well as marker trait associations have been outlined. Finally, we discuss the importance of recently evolving techniques such as next-generation sequencing approaches, single nucleotide polymorphism chip, and genotyping-by-sequencing for genetic dissection and better understanding of complex diseases such as spot blotch. The importance of spot blotch resistance genes (sb1, sb2, and sb3) mapped to 5BL, 7DS, and 3BS chromosomal arms with closely linked SSR marker is explained. It is imperative to screen diverse germplasm with high-throughput genotyping platforms and validate these genes and discover new tightly linked markers for better resolution and screening against spot blotch. Advances in genome editing and phenomic technologies allowing rapid discovery of genes and molecular markers have enabled systematic examination of the complex wheat genome and generating new opportunities for wheat improvement and resistance against important diseases such as spot blotch.