The metabolism of triacylgioycerols (TAG) and their conversion into new triglycerides
and polar lipids such as linolenlc acid take place during the first phase of development of
Helianthus annuus L. seed after seeding. Oléate desaturase and linoleate desaturase
are two major enzymes responsible for the synthesis of these compounds. To determine
whether enzymatic mechanisms function the same in catabolizing seed store lipids of
normal and mutant sunflower lines, modifications of fatty acids composition of seeds and
the initial stages of growth (seeding-VE) cultivated under conditions of controlled
temperature were assessed. The increase of linoleic acid content during all stages of
development in a mutant line revealed a higher activity of oleic acid desaturase
(∆12-desaturase) In transforming oleic acid to linoleic acid probably due to higher
availability of the substrate of this enzyme In this line: however, its amount increased
moderately In a normal line. The activity of FAD2-3 in developing sunflower seeds is
recognized even two days after seeding (DAS) in both lines; however, linolenic acid
accumulation starts seven DAS.
