Challenges and Opportunities with CRISPR-Based Genome Editing in Legume Crops.

Over the last couple of decades, tremendous progress has been made in legume genomics. Genomics information generated for legume crops is being explored through molecular breeding and transgenic approaches. However, the gap between knowledge generation and its utilization is increasing. In this regard, recent developments in genome editing techniques provide an excellent opportunity to utilize the available knowledge for the improvement of legume crops. This review highlights recent developments with Clustered Regularly Interspaced Short Palindromic Repeats/CRISPR-associated protein 9 (CRISPR/Cas9)-based genome-editing approaches, including Cas variants/orthologs and Protospacer adjacent motif-less (PAMless) Genome Editing, multiplex genome editing, base editing, prime editing, transcriptional regulation, methylome editing, and DNA-free editing methods. Furthermore, the applications of non-homologous end joining (NHEJ) and homology-directed repair (HDR)- based editing, are addressed which enable targeted and precise genomic modifications. Moreover, virus-mediated genome editing, in planta transformation, and mobile guide RNAs are increasingly being leveraged to enhance the efficiency and heritability of genome editing. Additionally, the role of artificial intelligence in guide RNA design, off-target prediction, and the development of novel Cas variants is also discussed, which can speed up the legume improvement. This article highlights the successful examples of efforts utilizing CRISPR/Cas9 for the development of legume crops with biotic and abiotic stress tolerance, desirable plant architecture, improved nutrient uptake, and enhanced yield and quality. The biggest limitation in the genome editing of legume crops is their recalcitrance to both transformation and tissue culture. This article discusses how this particular limitation can be addressed in the context of genome editing of legume crops. Finally, the possibilities of integrating these recently developed tools with translational breeding have also been discussed, which will facilitate the legume production for sustainable agriculture and food security.