Characterization of peanut lines with interspecific introgressions conferring late leaf spot resistance

Authors: LAMON, SAMUELE - University Of Georgia; CHU, YE - University Of Georgia; GUIMARAES, LARISSA - University Of Georgia; BERTIOLI, DAVID - University Of Georgia; LEAL-BERTIOLI, SORAYA C.M. - University Of Georgia; CULBREATH, ALBERT - University Of Georgia; Holbrook, Carl - Corley; OZIAS-AKINS, P - University Of Georgia

Submitted to: Crop Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/20/2020
Publication Date: 3/14/2021
Citation: Lamon, S., Chu, Y., Guimaraes, L.A., Bertioli, D., Leal-Bertioli, S., Culbreath, A.K., Holbrook Jr, C.C., Ozias-Akins, P. 2021. Characterization of peanut lines with interspecific introgressions conferring late leaf spot resistance. Crop Science. 61:1724–1738. https://www.doi.org/10.1002/csc2.20414.
DOI: https://doi.org/10.1002/csc2.20414

Interpretive Summary: Late leaf spot (LLS) disease is one of the most costly diseases of U.S. grown peanut. IAC 322 is a breeding line that contains three introgressed chromosome segments from a wild species that provides a very high level of resistance to LLS. Although this line has excellent resistance to leaf spot, it does not have acceptable agronomic performance in Georgia. Genetic markers are available for these genomic regions, so marker assisted selection (MAS) to combine resistance with acceptable agronomic performance is feasible. The goal of this study was to identify the genomic regions or combinations of genomic regions that provide the highest level of resistance. The variety TifNV-High O/L was crossed with IAC 322, and 400 resulting progeny were genotyped. Individuals with single introgressions, individuals with all pairwise combinations, and individuals with all three introgressions were identified. This material was then evaluated for resistance in field and lab studies. Results indicated that major genes for resistance are contained on the introgressions from the bottom of chromosome A03 and the top of chromosome A02. The third introgressed region was from the bottom of chromosome A02 and did not add significantly to the levels of resistance to LLS. These results will allow breeders to use MAS to more effectively and efficiently develop peanut varieties with resistance to leaf spot.

Technical Abstract: Late leaf spot (LLS) disease caused by Nothopassalora personata (Berk. & M.A. Curtis) U. Braun, C. Nakash, Videira & Crous is a ubiquitous pathogen of peanut (Arachis hypogaea L.). Chemical control is expensive, sometimes inaccessible, and can be difficult to apply. One effective solution to control this disease is the employment of resistant cultivars. IAC 322 is a breeding line with alien introgressions from A. cardenasii Krapov. & W.C. Gregory, a wild diploid relative of peanut. Three major introgressed segments have been identified on the top and bottom segments of chromosome A02 and the bottom part of chromosome A03. The objective of this study was to determine the level of LLS resistance conferrred by the three introgressed segments in progenies from TifNV-High O/L x IAC 322 that were selected based on their genotype. These lines were phenotyped for LLS resistance under both in vitro and field conditions and were found to have varied levels of LLS resistance depending on the combination of segments. The introgressed segments on the top part of A02 combined with the bottom part of A03 accounted for the majority of LLS resistance. High correlations of LLS resistance between in vitro and field experiments were found. In addition, field disease ratings at late season were found to correlate with the entire LLS infection progression under both field and in vitro conditions. Among the parameters collected for in vitro experiments, number of LLS lesions and sporulating LLS lesions at late stages of LLS infection and incubation period can be used to predict LLS resistance under field conditions.