General characteristics of Pinus spp. seed fatty acid compositions, and importance of Delta 5-olefinic acids in the taxonomy and phylogeny of the genus

The Delta 5-unsaturated polymethylene-interrupted fatty acid (Delta 5-UPIFA ) contents and profiles of gymnosperm seeds are useful chemometric data for the taxonomy and phylogeny of that division, and these acids may also have some biomedical or nutritional applications. We recapitulate here all data available on pine (Pinus; the largest genus in the family Pinaceae) seed f atty acid (SFA) compositions, including 28 unpublished compositions. This o verview encompasses 76 species, subspecies, and varieties, which is approxi mately one-half of all extant pines officially recognized at these taxon le vels; Qualitatively, the SFA from all pine species analyzed so far are iden tical. The genus Pinus is coherently united-but this qualitative feature ca n be extended to the whole family Pinaceae-by the presence of Delta 5-UPIFA with C-18 [taxoleic (5,9-18:2) and pinolenic (5,9,12-18:3) acids] and C-20 chains [5,11-20.2, and sciadonic 15,11,14-20:3) acids]. Not a single pine species was found so far with any of these acids missing. Linoleic acid is almost always, except in a few cases, the prominent SFA, in the range 40-60 % of total fatty acids. The second habitual SFA is oleic acid, from 12 to 3 0%. Exceptions, however, occur, particularly in the Cembroides subsection, where oleic acid reaches ca. 45%, a value higher than that of linoleic acid . alpha-Linolenic acid, on the other hand, is a minor constituent of pine S FA, almost always less than 1%, but that would reach 2.7% in one species (P . merkusii). The sum of saturated acids [16:0 (major) and 18:0 (minor) acid s principally] is most often less than 10% of total SFA, and anteiso-17:0 a cid is present in all species in:amounts up to 0.3%. Regarding C18 Delta 5- UPIFA, taxoleic acid reaches a maximum of 4.5% of total SFA, whereas pinole nic acid varies from 0.1 to 25.3%. The very minor coniferonic (5,9,12,15-18 :4) acid is less than 0.2% in all species. The C20 elongation product of pi nolenic acid, bishomo-pinolenic (7,11,14-20:3) acid, is a frequent though m inor SFA constituent (maximum, 0.7%). When considering C20 Delta 5-UPIFA, a difference is noted between the subgenera Strobus and Pinus. In the former subgenus, 5,11-20:2 and sciadonic acids are less than or equal to 0.3 and less than or equal to 1.9%, respectively, whereas in the latter subgenus, t hey are most often greater than or equal to 0.3 and greater than or equal t o 2.0%, respectively. The highest values for 5,11-20:2 and sciadonic acids are 0.5% (many species) and 7.0% (P. pinaster). The 5,11,14,17-20:4 (junipe ronic) acid is present occasionally in trace amounts. The highest level of total Delta 5-UPIFA is 30-31% (P. sylvestris), and the lowest level is 0.6% (P. monophylla). Uniting as well as discriminating features that may compl ement the knowledge about the taxonomy and phylogeny of pines are emphasize d.