FaNES1 and Linalool Characterization in Diverse Strawberry Genotypes

An earlier report showed that a truncated form of the Nerolidol Synthase 1 (FaNES1) protein in cultivated, octoploid strawberry catalyzed the production of linalool, a consumer-favorable volatile (Aharoni et al., 2004).  The biochemical mechanism for this phenomenon showed that the truncated protein lacked a plastid signaling peptide and was therefore localized to the cytoplasm where it was hypothesized to interact with substrates for linalool and nerolidol.  The truncated, linalool-producing variant was present in all octoploid material tested and not in any of 12 apparent diploids used in the study.  In an attempt to identify the presence/absence of the allele in potential breeding materials, as well as to understand the origin of the variant, we expanded on this original report to include a more diverse collection of cultivated germplasm and all ploidy levels within Fragaria.  Our results show that the truncated FaNES allele is detectable in all 112 tested F. x ananassa genotypes representing cultivated material from both Europe and the United States.  The FaNES1 allele was absent from all diploid, tetraploid, and hexaploid genotypes in our study. Also investigated were 46 wild genotypes in the Fragaria supercore and all were positive for the truncated allele except for three F. virginiana genotypes.  These F. virginiana accessions were negative for the FaNES1 allele yet the two that produced berries under our growing conditions still produced linalool.  These findings suggest that there may be an alternative method to produce linalool in some F. virginiana genotypes, and that the variant with the linalool phenotype most likely arose recently after polyploidization in an ancestral octoploid.