Gene Editing for Improving Biotic Stress Resistance in Pigeonpea

Gene-editing technologies, such as clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9, present promising strategies for enhancing resistance to a variety of stresses in crops including cereals and legumes. Among legumes, pigeonpea production is significantly impacted by various biotic stresses, including Fusarium wilt, sterility mosaic disease, Phytophthora blight, pod borer and pod fly, leading to substantial yield losses. Conventional breeding efforts and genomics-assisted breeding (GAB) approaches have identified candidate gene(s) and quantitative trait loci (QTLs) for traits imparting resistance against the biotic stresses, which could accelerate selection decisions in breeding programs. In recent years, precise and accurate genetic changes in the genome induced by programmable nuclease enzymes have provided an opportunity to understand the complex mechanisms underlying stress resistance/tolerance and rapidly modify the target genes to improve stress response. A key challenge in this context is the transformation and regeneration of pigeonpea, which has remained a major stumbling block due to the recalcitrant nature of the crop. This book chapter reviews the status of gene-editing in pigeonpea with respect to biotic stresses besides discussing the future prospects and challenges of developing a gene-edited pigeonpea crop. Regulatory guidelines in India currently allow SDN1- and SDN2-edited crops, yet the excision of the exogenous DNA including the Cas protein and selection markers during selection remains necessary. With growing refinements, gene-editing systems have a significant potential for targeted modification of deference-related genes in pigeonpea; however, overcoming transformation and regeneration challenges would be crucial in this to promote widespread applications of gene-editing in this recalcitrant legume crop.