Occurrence and characterization of oils rich in gamma-linolenic acid (III): the taxonomical value of the fatty acids in Echium (Boraginaceae)

Fourteen species of the genus Echium (Fain. Boraginaceae) collected in the Macaronesia were surveyed in a search for high levels of gamma -linolenic a cid (GLA, 18:3 omega6) in the seed oil. High amounts of this fatty acid wer e found in all of them, ranging from 18.85% (E. pitardii var. pitardii) to 27.42% (E. gentianoides) on total seed fatty acids. The GLA content related to total seed weight was also significant, ranging from 1.26% (E. handiens e) to 8.22% (E. gentianoides). In addition, considerable amounts of stearid onic acid (SA, 18:4 omega3) were detected, ranging from 3.78% (E. bonnetii var. bonnetii) to 8.81% (E. pininana) on total fatty acids. Besides all the perennial species, the four herbaceous Echium taxa endemic to the Macarone sia also showed high GLA percentages. This is in contrast to the low GLA le vel found in continental Echium species, all of them bearing an herbaceous habit. These results are in good agreement with the available genetic data and show the ability of GLA to discriminate between Macaronesian and contin ental Echium species. The analysis of five other Macaronesian species belon ging to plant families rich in GLA are also reported. (C) 2001 Elsevier Sci ence Ltd. All rights reserved.