A STUDY OF ERUCIC ACID ALLELES IN DIGENOMIC RAPESEED (Brassica napus L.)

Five genes have been identified in Brassica crops which control the level of synthesis of the fatty acid, erucic, in their seed oils. These genes, designated e, E a , E b , E c , and E d , act in an additive manner and result in erucic acid levels of < 1, 10, 15, 30 and 3.5, respectively. No direct evidence has yet been obtained to show that these genes are true alleles. Selected plants of the amphidiploid species Brassica napus L. with erucic acid contents of 7–8% and a genotype of E d E d ee were reciprocally crossed with selected plants with erucic acid levels of [Formula: see text] and a genotype of E a eee. Fatty acid analysis of F 1 and backcross seed demonstrated that the genes E d and E a in the parents used were in the same genome and were truly allelic. Interspecific crosses were made between these B. napus parents and selected zero erucic acid plants of Brassica campestris L. (genotype "ee") to determine whether the genes E d and E a resided in the oleracea or the campestris genome of B. napus parents. Fatty acid analysis of F 1 and backcross seed from these interspecific crosses suggest that the alleles of E d and E a are located on chromosomes of the oleracea genome.