Functional genomics in sugarcane breeding: key challenges and strategies

Sugarcane, a leading source of sugar and bio-energy around the globe stands at the cross-road of genome complexity and agricultural innovation, offering the immense potential to fuel a sustainable future. Functional genomics with its precise identification and manipulation of genes could enable researchers unlock this potential and accelerate the breeding efforts. However, the polyploid genome of sugarcane with: high heterozygosity, high-repetitive DNA content, multiple copies of homo(eo)logous gene, epistatic interaction of alleles, etc., challenges the gene annotation, genome sequencing, genome editing, and phenotypic characterization. Similarly long breeding cycle, low transformation efficiency, time-consuming, and labor-intensive transformation methods further complicates the genome editing. Recent advances of functional genomics are transforming this scenario, such as current availability of reference genome "R570," has provided a significant insight of genome architect and function. Genome wide association studies (GWAS)/genome selection (GS) are enhancing trait-mapping and prediction of breeding values to accelerate the breeding cycles. The current era of smart breeding with integrative bio-informatics, advance genome editing tools, i.e., CRISPR/Cas-systems (Cas-proteins, Cas-RNPs, d-Cas-RNPs, and CRISPRa/i), and high-throughput phenomics offers a significant approach to: overcome transformation bottlenecks, explore complex trait architect and address polyploidy challenges. Therefore, this review summarizes the key challenges and focuses on elaborating recent advances and suggests optimized strategies for future improvement in functional genomics of sugarcane breeding.