Serine proteinase inhibitors in common bean (Phaseolus vulgaris L.): preliminary investigation on genome organisation

In order, to explore this hypothesis we started with the isolation and sequencing of the promoter region of trypsin inhibitor, using our BAC library from Phaseolus vulgaris accession G12949, (CIAT, Cali, Colombia). To identify all BAC clones containing BBI genes, the entire library (consisting of 30,720 clones), was gridded onto two high-density filters double-spotted in a 4 x 4 array and probed with a previously isolated trypsin inhibitor gene (Piergiovanni and Galasso, 2004). After filter hybridisation a second screening was carried out by PCR, using specific BBI-primers. Three positive BAC clones were identified after filter hybridisation and PCR. Southern profiles obtained after digestion with selective restriction enzymes of positive BAC clones probed with labelled-BBI, suggest a complex genome organisation. Results confirmed that BBI are coded by a multigene family constituted by at least three types of double-headed inhibitors.