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

Abstract

Five genes were identified in Brassica crops which control the level of synthesis of the fatty acid, erucic, in their seed oils. These genes, designated e, Ea, Eb, Ec and Ed, 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, B. napus L., had erucic acid contents of 7-8% and a genotype of EdEdee; these plants were reciprocally crossed with selected plants that had erucic acid levels of .simeq. 10% and a genotype of Eaeee. Fatty acid analysis of F1 and backcross seed demonstrated that the genes Ed and Ea 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 B. campestris L. (genotype ee) to determine whether the genes, Ed and Ea, resided in the oleracea or the campestris genome of B. napus parents. Fatty acid analysis of F1 and backcross seed from these interspecific crosses suggest that the alleles of Ed and Ea are located on chromosomes of the oleracea genome.