Frequency of a loss-of-function mutation in oleoyl-PC desaturase (ahFAD2A) in the mini-core of the US peanut germplasm collection

High oleic acid to linoleic acid ratios (high O/L) in tetraploid peanut (Arachis hypogaea L.) are controlled by the activity of oleoyl-PC desaturase, which is encoded by two homeologous genes (ahFAD2A and ahFAD2B). In a naturally occurring high O/L peanut, a spontaneous mutation (G-to-A at position 448 resulting in a D150N amino acid substitution) has been found in ahFAD2A, which resulted in a dysfunctional desaturase. In normal x high O/L crosses, segregation ratios for high:normal O/L are either 1:3 or 1:15 suggesting that one gene in some normal O/L lines may be mutated. We designed a cleaved amplified polymorphic sequence (CAPS) marker to differentiate the mutant and wild-type ahFAD2A alleles at the critical point mutation. The mutant allele was present in 31.6% of the accessions from the mini-core collection of peanut germplasm and was confirmed by DNA sequence analysis. The mutant allele was frequent among subspecies hypogaea accessions but absent from subspecies fastigiata accessions and the putative diploid, A-genome progenitor of peanut, Arachis duranensis. These data will be useful to breeders who would like to transfer disease resistance traits from mini-core accessions to high oleic acid cultivars.