Cloning and sequencing of 5' flanking sequence from the gene encoding 2S storage protein, from two Brassica species

Using oligodeoxyribonucleotide primers and the polymerase chain reaction, we have cloned and sequenced about 1.2 kb of upstream sequences from two members of the 2S seed storage protein-encoding gene family from Brassica juncea and B. oleracea. The two sequences bear more than 90% homology and have characteristic seed-specific promoter motifs. The high degree of sequence conservation indicates that this napin-encoding gene family evolved earlier than the divergence of the three primary Brassica species and their amphidiploids, and the sequences have been conserved due to some metabolic constraints in seed development.