TRANSCRIPTION OF GENES FOR CONGLUTIN-GAMMA AND A LEGINSULIN-LIKE PROTEIN IN NARROW-LEAFED LUPIN

The expression of genes encoding conglutin gamma and a leginsulin-like protein has been examined in narrow-leafed lupin, Lupinus angustifoli us L. Conglutin gamma is a homologue of basic 7S globulin (Bg), the in sulin and leginsulin binding protein from soybean. Accumulation of con glutin gamma mRNA, as assessed by northern assays and reverse-transcri ption PCR, was tightly regulated both spatially and temporally in lupi n plants and was detected almost exclusively in developing seeds. Simi lar tissue and temporal specificity was demonstrated when 1.8 kb of th e promoter region from the conglutin gamma gene was used to drive the expression of a beta-glucuronidase reporter gene in transgenic plants. In stably transformed tobacco the conglutin gamma promoter produced s trong, temporally regulated and seed-specific expression of the report er gene which was localised to the embryo tissues and to a layer of ce lls adjacent to the seed coat. A truncated 0.29 kb promoter fragment p roduced much reduced levels of expression and a loss of embryo specifi city. Leginsulin-like mRNA was similarly detected in lupins only in de veloping seeds. The leginsulin-like gene detected in L. angustifolius showed 96% sequence identity to leginsulin from soybean within the 280 bp region amplified from lupin by PCR. The results demonstrate that b oth components of a Bg-leginsulin putative signal transduction pathway are present in the seeds of lupin.