CYTOLOGICAL LOCALIZATION OF THE PGIP GENES IN THE EMBRYO SUSPENSOR CELLS OF PHASEOLUS-VULGARIS L

Polygalacturonase-inhibiting protein (PGIP) is a cell wall protein which inhibits fungal endopolygalacturonases. A small gene family encodes PGIP in the genome of common bean, as indicated by Southern-blot experiments performed at high-stringency conditions. Southern-blot analysis of DNA extracted from different cultivars of Phaseolus vulgaris and from Phaseolus coccineus showed length polymorphism of the hybridizing restriction fragments. The cytological localization of the PGIP genes was determined in polytene chromosomes of the P. vulgaris embryo suspensor cells. In-situ hybridization experiments using the cloned PGIP gene revealed labelling over a single region of the pericentromeric heterochromatin of chromosome pair X. next to the euchromatin, suggesting that PGIP gene family may be clustered in one chromosomal region.