Biotechnological Interventions in Unravelling the Genetic Treasure of an Orphan Crop, Cluster Bean (Cyamopsis tetragonoloba L.)

Cluster bean [Cyamopsis tetragonoloba (L.) Taub.], also known as guar, is an underutilized crop grown in arid and semi-arid areas. It is mainly grown for vegetable and guar gum production. Guar gum is a natural, non-toxic polymer with great industrial potential. The foremost industrial targets are mining, oil and gas well fracturing, paper, food, pharmaceuticals, textiles, cosmetics, and explosives. Despite having significant industrial importance, guar research has received less attention than other major legumes. However, with the increase in industrial demand in recent years, progress has been made in better understanding of cluster bean genetics. This review summarizes the recent progress in molecular marker development, quantitative trait locus mapping, omics-based approaches, and functional genomics in cluster bean. Although large numbers of simple sequence repeats and single-nucleotide polymorphisms have been identified, their application remains largely restricted to diversity analysis, with limited integration into breeding programs. Genome-wide association studies and quantitative trait locus mapping efforts are still scarce, and many reported associations lack validation across populations, constraining the identification of stable loci for key traits such as gum content, stress tolerance, and yield. Omics studies have provided insights into galactomannan biosynthesis and stress-responsive pathways; however, most findings lack functional validation and practical deployment. Recent developments in RNA interference and CRISPR/Cas9-based genome editing provide new opportunities for precise functional validation and targeted crop improvement. Therefore, bridging the gap between the genomic discoveries and their implementation into breeding strategies is key to developing improved cluster bean cultivars that can meet the industry demands.