In various aspects, the invention provides Brassica juncea plants, seeds, cells, nucleic acid sequences and oils. Edible oil derived from plants of the invention may have significantly higher oleic acid content than other B. juncea plants. In one embodiment, the B. juncea line MJ02-357-3 contains a mutant allele MJ02-313-1/BjFAD2-a at the BjFAD2-a gene locus, having a single base-pair change (a G to A substitution in the ORF at position 281 in reference to the first ATG start codon) relative to the wild type sequence. The change is predicted to encode a Glycine-94 Aspartic acid mutation in the sequence of the predicted BjFAD2-a protein. In another embodiment, the B. juncea line MJ02-357-3 contains a mutant allele MJ02-357-3/BjFAD2-a at the BjFAD2-a gene locus, having a single base-pair change (a C to T substitution in the ORF at position 647 in reference to the first ATG start codon) relative to the wild type sequence. The change is predicted to encode a Proline-216 Leucine mutation in the sequence of the predicted BjFAD2-a protein. As a result of these mutations, it can be predicted that the function of the BjFAD2-a proteins are negatively affected in Brassica juncea lines MJ02-313-1 and MJ357-3 as reflected in the increased levels of oleic acid in seed oil in comparison with the wild-type line J96D-4830. Seeds from MJ02-313-1 and MJ02-357-3 plants may for example yield an oil having oleic acid content of greater than 70% by weight.