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.