Pre-Breeding for Genetic Enhancement of Cultivated Peanut.

Peanut (Arachis hypogaea L.) is an important self-pollinated tetraploid (AABB; 2n=4x=40) legume grown for high quality edible oil and easily digestible protein in its seeds. Enormous genetic variability is present in genus Arachis comprising 80 wild species and cultivated peanut. Wild Arachis species offer significant variability particularly for biotic and abiotic stresses and can be utilized to develop cultivars having enhanced levels of resistance to key stresses and broaden the existing narrow genetic base of cultivated peanut. However, utilization of these species requires use of ploidy manipulations, bridge crosses, and embryo/ovule rescue, thus making it a time-consuming and resources-demanding research endeavor. To overcome this, pre-breeding provides a unique opportunity to the breeders through the introgression of desirable genes from wild germplasm into genetic backgrounds readily used by the breeders with minimum linkage drag. At ICRISAT, wild Arachis accessions possessing high levels of resistance to multiple stresses have been identified. Further, for efficient utilization of diploid wild species from section Arachis, several synthetics (amphidiploids and autotetraploids) have been developed by using various A- and B- genome species. These synthetics are being utilized in crossing programs with cultigens to develop pre-breeding populations/introgressions lines (ILs) having high frequency of useful genes/alleles and good agronomic background. Evaluation of two such populations derived from ICGV 91114 x ISATGR 1212 (a synthetic derived from A. duranensis × A. ipaensis) and ICGV 87846 x ISATGR 265 (A. kempf-mercadoi × A. hoehnei) has led to the identification of ILs having high levels of late leaf spot (LLS) and rust resistance and sufficient genetic variability for morpho-agronomic traits. These ILs are being genotyped using linked-markers for LLS and rust resistance to identify novel alleles from different wild species other than commonly used A. cardenasiifor further use in peanut improvement programs.