VARIABILITY FOR THE FATTY-ACID COMPOSITION OF THE SEED OIL IN A GERMPLASM COLLECTION OF THE GENUS BRASSICA

A germplasm collection consisting of 1475 entries from 21 species of B rassica, including 36 lower taxa, was evaluated for the fatty acid com position of the seed oil. A total of 358 entries representing the taxo nomic variability in the collection were selected and analysed by gas- liquid chromatography (GLC). The remaining 1117 entries were analysed by near-infrared reflectance spectroscopy (NIRS), after developing mul ti-species calibration equations. The results demonstrated that NIRS i s an effective technique to assess variability for oleic, linoleic, li nolenic and erucic acid in intact-seed samples of multiple Brassica sp ecies, provided that calibration equations be developed from sets cont aining large taxonomic and chemical variability. Some fatty acid ratio s were used to estimate the efficiency of the different biosynthetic p athways. Two well-defined patterns were observed. The first one was ch aracterised by high elongation efficiency and accumulation of high lev els of erucic acid. The highest erucic acid content (>55% of the total fatty acids) was found in the cultivated species B. napus L., B. oler acea L., and B. rapa L., and in the wild species B. incana Tenore, B. rupestris Raf., and B. villosa Bivona-Bernardi, the three latter belon ging to the B. oleracea group (n=9). The second pattern was characteri sed by high desaturation efficiency, resulting in the accumulation of high levels of the polyunsaturated linoleic and linolenic acid (up to more than 55%). The highest levels of these fatty acids were found in samples of B. elongata Ehrh., especially of the var. integrifolia Bois s. The utility of the reported variability for plant breeding is discu ssed.