Premium
Members of the acetohydroxyacid synthase multigene family of Brassica napus have divergent patterns of expression
Author(s) -
Ouellet Thérèse,
Rutledge Robert G.,
Miki Brian L.
Publication year - 1992
Publication title -
the plant journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.058
H-Index - 269
eISSN - 1365-313X
pISSN - 0960-7412
DOI - 10.1046/j.1365-313x.1992.t01-31-00999.x
Subject(s) - biology , gene , housekeeping gene , genetics , transcriptome , gene family , gene expression , ploidy , brassica , botany
Summary Brassica species possess the most complex acetohydroxyacid synthase (AHAS) multigene family reported for plants. The AHAS genes code for an essential enzyme in branched‐chain amino acid biosynthesis. In the allotetraploid species, B. napus , four ( AHAS1–4 ) of the five AHAS genes have been cloned and sequenced. The transcripts were examined by RNase protection assays using gene‐specific, antisense RNA probes. Only AHAS1, AHAS2 and AHAS3 were shown to be expressed in B. napus and one of the diploid progenitor species B. campestris or B. oleracea. AHAS1 and AHAS3 are highly conserved genes that presumably code for the essential AHAS housekeeping functions. They were expressed as low abundance mRNA in all somatic and reproductive tissues examined. AHAS2 , which is structurally distinct from all other plant AHAS genes, was only expressed in mature ovules and extra‐embryonic tissues of immature seeds. This study provides direct evidence for multiple AHAS isoforms in plants and for an AHAS gene which is developmentally regulated in a tissue‐specific manner. The discovery raises questions concerning the functional significance of AHAS in seed development.