Development and characterization of new allohexaploid resistant to web blotch in peanut

Abstract Peanut diseases seriously threaten peanut production, creating disease-resistant materials via interspecific hybridization is an effective way to deal with this problem. In this study, the embryo of an interspecific F1 hybrid was obtained by crossing the Silihong (Slh) cultivar with Arachis duranensis (ZW55), a diploid wild species. Seedlings were generated by embryo rescue and tissue culture. A true interspecific hybrid was then confirmed by cytological methods and molecular markers. After treating seedlings with colchicine during in vitro multiplication, the established interspecific F1 hybrid produced seeds which were named as Am1210. With oligonucleotide fluorescence in situ hybridization (Oligo FISH), molecular marker evaluations, morphological and web blotch resistance characterization, we found that: 1) Am1210 was an allohexaploid between Slh and ZW55; 2) the traits of spreading lateral branches, single-seeded or double-seeded pods and red seed coats were observed to be dominant compared to the erect type, multiple-seeded pods and brown seed coats; 3) the web blotch resistance of Am1210 was significantly improved than that of Slh, indicating the contribution of the web blotch resistance from the wild parent A. duranensis. In addition, 69 dominant and co-dominant molecular markers were developed which could be both used to verify the hybrid in this study and to identify translocation or introgression lines with A. duranensis chromosome fragments in future studies as well.