Resistance to rust (Puccinia arachidis Speg.) identified in nascent allotetraploids cross-compatible with cultivated peanut (Arachis hypogaea L.)

Authors: LEVINSON, CHANDLER - University Of Georgia; ANTEPENKO, ERIC - University Of Georgia; LEAL-BERTIOLI, SORAYA - University Of Georgia; CHU, YE - University Of Georgia; CULBREATH, ALBERT - University Of Georgia; STALKER, THOMAS - University Of Georgia; Gao, Dongying; OZIAS-AKINS, PEGGY - University Of Georgia

Submitted to: Peanut Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2021
Publication Date: 8/25/2021
Citation: Levinson, C.M., Antepenko, E., Leal-Bertioli, S.C., Chu, Y., Culbreath, A.K., Stalker, T., Gao, D., Ozias-Akins, P. 2021. Resistance to rust (Puccinia arachidis Speg.) identified in nascent allotetraploids cross-compatible with cultivated peanut (Arachis hypogaea L.). Peanut Science. 48(2):123-130. https://doi.org/10.3146/PS21-4.1.
DOI: https://doi.org/10.3146/PS21-4.1

Interpretive Summary: Peanut rust is a serious disease in the United States and other countries which can cause significant yield loss in some cases. Utilization of host resistance is one of the most efficient ways to control the disease, however, no good resistance resources for peanut rust were identified in cultivated peanut materials. We investigated peanut rust resistance in 32 wild peanut genotypes including diploid wild peanut species and their synthetic allotetraploid interspecific hybrids. We found that all wild peanut species tested were very highly resistant to rust, except for A. ipaënsis, and some wild species showed no symptoms for rust. Several wild species we identified as resistance resources to peanut rust in the present study can be used for developing rust resistant cultivars and mapping the genes/QTLs associated with peanut rust resistance.

Technical Abstract: Peanut rust, caused by Puccinia arachidis Speg., is a foliar disease that plagues peanut production along with early and late leaf spots, Passalora arachidicola (Hori) U. Braun and Nothopassalora personata (Berk. & M.A. Curtis) U. Braun, C. Nakash, Videira & Crous, respectively. Rust can cause up to 80% yield losses without control and is widespread in tropical countries but is also a sporadic problem in the United States. An integrative plant management strategy with rust resistant peanut cultivars is needed to decrease dependence on costly fungicides and increase yields for farmers who cannot afford or do not have access to fungicides. Only moderate levels of rust resistance have been found in cultivated peanut germplasm, but fortunately, high resistance to rust has been identified in wild Arachis species that can be introgressed into peanut cultivars. In this study, 16 diploid, wild Arachis species, five diploid, interspecific hybrids, 11 unique, allotetraploid interspecific hybrids, and two cultivated peanut controls were tested for resistance to rust. Resistance was evaluated in vitro by incubation time, susceptibility index (calculated based on the number of lesions of different diameters)/ leaf area, total number of lesions/ leaf area, and total number of sporulating lesions/ leaf area. All wild Arachis species tested were very highly resistant to rust, except for A. ipaënsis, the B-genome progenitor of cultivated peanut. Additionally, all interspecific hybrids and synthetic allotetraploids not produced with A. ipaënsis as a parent did not show symptoms for rust. Any of these nine synthetic allotetraploids, BatCor, BatDur1, BatDur2, BatSten1, GregSten, MagCard, MagDio, MagDur, and ValSten1 are recommended for progression to QTL mapping of rust resistance. These resistance QTLs can be pyramided into peanut cultivars to protect yields in the United States and to increase yields in tropical, developing countries for farmers that cannot afford, or do not have access to, costly fungicides.