Pathways for Introgression of Pest Resistance into Arachis hypogaea L.1

Four pathways for gene introgression into Arachis hypogaea L. were studied. Two “hexaploid routes” involved direct crosses of diploid Arachis species and diploid species hybrids with A. hypogaea (Pathways 1 and 2, respectively) and were followed by chromosome doubling with colchicine. A third pathway, a tetraploid route, involved chromosome doubling of a diploid hybrid before crossing with A. hypogaea. These first three routes involved only the A genome species, and all were unsuccessful because of lack of fertility. The fourth pathway, also a tetraploid route, utilized the B genome A. batizocoi Krap. et Greg. as a bridge species and brought about a successful (fertile) introgression. Genes from A. cardenasii Krap. et Greg. nom. nud. and A. chacoensis Krap et Greg. nom. nud. were combined into a hybrid and incorporated into A. hypogaea by using the B genome bridge species. Introgression of additional characters from these and other species through this pathway should be possible.