Fatty acid composition of edible pine seeds with emphasis on North American and Mexican pines of the Cembroides subsection

The fatty acid compositions of the edible seeds from six Pinus species (P, monophylla, P. nelsonii, P. maximartinezii, P. flexilis, P. sabiniana, and P, gerardiana) have been established. The dehulled seeds are generally rich in oil, up to ca. 65 % by weight, and are characterized by high levels of both oleic and linoleic acids, generally with less than 12 % of saturated a cids. Delta 5-olefinic acids are low as compared to most other conifer spec ies: 5,9-18:2 acid, 0.03-0.43 % 5,9,12-18:3 acid, 0.13- 1.60 % 5, 11-20:2 a cid, trace-0.13 %; and 5, 11,14-20:3 acid, 0.23-0.78 %. Their sum is less t han 2.5 % of total fatty acids. Pinus monophylla, P. nelsonii, P. maximarti nezii, and I? edulis, from the same subsection Cembroides, and which grow i n semi-arid regions in the Southwest of the United States and in Mexico, ar e united by their low content of Delta 5-olefinic acids (1 % at most). When considering P. gerardiana, an Himalayan species, this observation can appa rently be extended to the section Parrya. Owing to the recognized antiquity of this section, the reduction in the activities of the enzymes responsibl e for the biosynthesis of Delta 5-olefinic acids appears an early event in the history of pine evolution, more precisely in the Strobus subgenus. Howe ver, a similar reduction also occurred independently in species from other sections of the same subgenus leg: P. flexilis) or from the other genetical ly distinct pine subgenus Pinus leg, P. pinea and P. sabiniana), It is hypo thesized that such reductions might be linked to some climatic adaptation.