Canadian Forest Service Publications
DNA sequence relationships and origins of acetohydroxy acid synthase genes of Brassica napus. 1992. Hattori, J.; Rutledge, R.G.; Miki, B.L.; Baum, B.R. Canadian Journal of Botany 70: 1957-1963.
Issued by: National Capital Region
Catalog ID: 10781
Availability: PDF (request by e-mail)
The allotetraploid Brassica napus has been shown to contain a five-member multigene family (AHAS1-5) of the nuclear-encoded chloroplastic enzine acetohydroxy acid synthase, three members of which are expreessed. AHAS1 and AHAS3 are constitutively expressed while AHAS2 expression is ovule- and seed-specific. By sequence and phylogenetic analyses we show that AHAS1 and AHS3 genes are 96-98% similar in the coding region and the adjacent 5' and 3' noncoding regions and were derived from a common ancestral crucifer gene. In contrast, the AHAS2 gene shares only about 80% sequence similarity with the AHAS1 and AHAS3 genes, limited to the region coding for the mature peptide and in a short region of the presumptive transit peptide. The AHAS2 gene likely arose by gene duplication of a housekeeping AHAS gene and has acquired characteristics different from other plant housekeeping AHAS genes, perhaps owing to different functional constraints.