Peanut (Arachis hypogaea l.) breeding

Abstract

Cultivated peanut (Arachis hypogaea L.), a vital source of proteins and nutrient-rich fodder for livestock, is considered globally as a major oilseed crop. Being a segmental allopolyploid with AABB genome conformation, the cultivated peanut is considered to have evolved through single interspecific hybridization amid two diploid species. A number of biotic and abiotic forces restrict the production and productivity of peanut. Intensive attempts to develop superior peanut varieties with inherent tolerance/resistance and enriched nutritional components were executed to combat stress factors in fulfilling the requirements of farmers and consumers. Breeding objectives in the past were achieved mainly through mass and pure-line selections. Subsequently to accomplish breeding objectives, peanut breeders employed backcross and pedigree approaches followed by inter- and intra-specific hybridization in a considerable way. Simultaneously, peanut breeding through the mutagenic approach played a noteworthy part during the development of multiple propitious high-yielding varieties. Traditional breeding approaches helped in identification and advancement of cultivars with inherent resistant traits, but such resistance traits are tightly linked with inferior pod and kernel characteristics that are extremely challenging to break. Under non-conventional approaches, several molecular breeding techniques were successfully attempted to break this barrier. Marker-assisted selection (MAS) and transformation of genes coding the traits of interest, overlaying the way of gene insertion, assisted significantly in establishing superior varieties of peanut with inherent resistance and enhanced pod and kernel features. Among all efficient markers, microsatellite markers were extensively employed in constructing linkage maps, genotyping as well as MAS, owing to the distinguishable and co-dominance nature of these markers. A number of reproducible molecular markers were developed that are associated with salinity and drought tolerance, as well as resistance to biotic stresses like rust, and leaf spots, and to a certain extent Sclerotinia blight etc. Agrobacterium-mediated genetic transformations, via in planta or particle-bombardment approaches, have resulted in development of transgenic peanuts with enhanced yield attributes and inherent resistance against a few biotic and abiotic stresses. Such genetically transformed peanut populations could also be employed as donor parents in traditional breeding system to develop fungal and a few virus disease tolerant varieties. Nevertheless, it could be suggested that a combination of breeding and biotechnological tools and approaches, might deliver an inherent, cost-effective, as well as eco-friendly solutions in developing better peanut varieties globally.