Multi-Omics Approaches to Understand Biotic Stress Response in Pigeonpea

Pigeonpea ( Cajanus cajan L.) is an important legume crop, particularly in semiarid tropical regions, renowned for its resilience to various environmental stresses. Despite its hardiness, its growth and productivity are significantly impacted by both abiotic and biotic stresses. The biotic stresses are primarily caused by a range of pathogens, including insects (e.g., Helicoverpa armigera , Maruca vitrata ), fungi ( Fusarium udum , Phytophthora drechsleri sp. cajani , Cercospora cajani ), and viruses, notably the sterility mosaic virus. These biotic factors can disrupt plant systems at the molecular, cellular, and developmental levels. To better understand and address these challenges, multi-omics approaches spanning genomics, epigenomics, transcriptomics, proteomics, lipidomics and metabolomics provide a holistic view of plant stress responses. These integrated techniques enable researchers to explore the complex interactions within the plant’s cellular systems and its various pathogens, offering a multilayered perspective that reveals real-time cellular activities. Such approaches are essential for uncovering the intricate molecular mechanisms, along with causal genes/alleles underlying biotic stress tolerance. Furthermore, combining multi-omics data with genome-assisted breeding holds promise for improving pigeonpea’s resilience. This chapter reviews the application of multi-omics strategies to dissect the pigeonpea genome and its pathogen interactions. It covers the complexities of the genome, transcriptome, and metabolome in response to pathogens, with the aim of identifying candidate genes and pathways involved in biotic stress tolerance. Additionally, the chapter highlights the role of recent gene editing technologies in advancing our understanding of biotic stress responses in pigeonpea.