Role of conventional and biotechnological approaches for genetic improvement of cluster bean

Cluster bean [Cyamopsis tetragonoloba (L.) Taub. (Syn. C. psoraliodes)], commonly known as guar and an important crop from family Leguminaceae, is grown under resource constrained situations for use as seed, vegetable and forage in arid and semi-arid regions. The seed of this drought-resilient legume contains galactomannan polysaccharide, used in wide range of industries, which has made this orphan crop a high-valued cash crop. Cluster bean shows limited variability for morphological and agronomic traits. Narrow genetic base of cultivated cluster bean varieties and yield losses due to both biotic and abiotic stresses has hampered the intensive breeding efforts in cluster bean. Conventional breeding methods viz. induced mutations, wide-hybridization and induce male sterility have been employed to broaden the limited genetic base and for genetic improvement of cluster bean. Due to its pivotal role in rainfed agriculture, research efforts using biotechnological interventions like molecular markers, tissue culture and transformation have been initiated to boost the varietal improvement but development of these tools are still at early stage in cluster bean. This article attempts to summarize and discuss the recent progress made in mutation breeding, distant hybridization, DNA marker studies, development of in-vitro propagation system and genetic transformation protocols.