Phenotypic variation in isoprenoid content among Arabidopsis accessions
A set of 116 natural Arabidopsis accessions, originating from various geographical locations, was carefully selected for a detailed analysis of seven isoprenoid compounds (carotenoids, chlorophylls, Dols, phytosterols, plastoquinone, Prens, and tocopherols). Levels of seven selected isoprenoids were quantified in 3-week-old seedlings grown on solid Murashige-Skoog medium. For all analyzed accessions, the same profiles of isoprenoids were observed, however, their level differed remarkably. Thus, for all accessions, one ‘family’ of Prens composed of 9 to 12 isoprene units (Pren-9 to -12, Pren-10 dominating) and one ‘family’ of Dols (Dol-15 to -18, Dol-16 dominating) were detected (HPLC/UV, Figure S1A); however, the content of Prens and Dols revealed remarkable variation between accessions (Figure 1A). The highest difference in Pren content was observed for the accessions Est-1 and Uod-7 (20-fold), while in Dol content ‒ for LL-0 and Bur-0 (4-fold). Similar observations were noted for the remaining isoprenoids – although the profile was the same for all accessions (Figure S1B-D), their content revealed substantial differences (Figure S2A-E). For phytosterols – 5-fold (Sav-0 vs. Est-1), for plastoquinone – 25-fold (Mr-0 vs. Er-0), for tocopherols – 8-fold (Lip -0 vs. Edi-0), for carotenoids – 4-fold (Est-1 vs. CS22491) and for chlorophylls – 5-fold (Br-0 vs. CS22491). Detailed analyses revealed considerable differences in the content of 5 out of 7 analyzed compounds (i.e., Prens, Dols, phytosterols, carotenoids, and plastoquinone) between Est-1 and Col-0 (Figure 1A, Figure S2A-E).
Moreover, Est-1 and Col-0 are the parents of the advanced intercross recombinant inbred lines (AI-RILs) mapping population (EstC), which is an excellent resource for QTL analyses due to a large number of fixed recombination events and the density of polymorphisms (Balasubramanian et al., 2009). For these reasons, the EstC population was selected for further analyses in addition to the analysis of the natural accessions.