Inheritance of oleic acid content in F2 and a population of recombinant inbred lines segregating for the high oleic trait in sunflower

Abstract

Pervenets is a sunflower mutant having a seed oil oleic acid content greater than 65%. All lines derived from the mutant Pervenets population display seed oil with a high oleic acid content [HOAC], over 80%. Linoleic (LO) and [HOAC] genotypes carry specific RFLP markers, oleLOR and oleHOS, revealed by oleate-desaturase cDNA used as a probe. Linkage disequilibria between the OleHOS allele and Pervenets mutation, and oleLOR and [LO] were without any exception. We studied the inheritance of [HOAC] in F2 progenies from a cross [LO] x [HOAC]. This study has shown one dominant allele for [HOAC] that cosegregated with the oleate-desaturase oleHOS, [HOAC]-specific RFLP. Variance analyses revealed almost complete dominance and that oleHOS marker explained 86% of the OAC variation. F6 recombinant inbred lines segregating for [HOAC] / [LO] showed that all [HOAC] RI lines carried oleHOS, but half of the RI lines carrying oleHOS were [LO]. Conversely, the absence of [HOAC] RI lines carrying oleLOR is evidence against recombination having taken place between the oleHOS locus and the Pervenets mutation locus. The [HOAC] trait is therefore due to 2 independent loci: the locus carrying the oleHOS allele and another locus. One allele, supole, at this second locus may suppress the effect of the oleHOS allele on the [HOAC] trait. Preliminary results with SSR (170 microsatellites, 500 cM) indicated that the oleHL and the supole loci are independent and explained 47.14 and 32.2% of the OAC variation respectively. The existence of the Pervenets mutation, supole and epistatic combinations for modifier alleles leading to [HOAC] trait has never been suggested. It may explain the discordant results found in our segregating populations and literature.