Rapeseed Mutants with Reduced Levels of Polyunsaturated Fatty Acids and Increased Levels of Oleic Acid

Abstract

Development of cultivars of both tetraploid ( Brassica napus L.) and diploid ( B. rapa L.) rapeseed with reduced levels of polyunsaturated fatty acids and increased levels of oleic acid could increase both the utility and value of the oil. The objective of this experiment was to use chemcical mutagenesis to induce mutations for these traits in rapeseed. Imbibed seed of ‘R‐500’ ( B. rapa ) and ‘Cascade’ ( B. napus ) were treated with 5% v/v of ethyl methanesulfonate. The M 2 generations of these populations were screened to identify mutants with low levels of polyunsaturated fatty acids (PUFA) using a modified thiobarbituric acid procedure. Putative mutants and their derived progeny were increased in the greenhouse and the seed analyzed for fatty acid composition using gas chromatography. The most promising mutant identified from 4 734 M 2 seeds of B. rapa , was M‐30, which had 2.1% linoleic acid and 3.0% linolenic acid, vs. 11.9% linoleic and 8.6% linolenic acid in the original cultivar. This mutant was crossed with ‘Tobin’ to derive F 4 lines having <6% total PUFA and oleic acid concentrations >87%. The most promising mutant identified from 39 504 M 2 seeds of B. napus was X‐82, which had 6.6% PUFA, vs. 27.4% PUFA in Cascade. Several M 3 and M 4 lines derived from X‐82 had <6% total PUFA and >88% oleic acid. The development of commercial cultivars with reduced levels of polunsaturated fatty acid in both B. rapa and B. napus could develop new markets for both industrial rapeseed and edible canola oil.