Differential accumulation of PGIP (polygalacturonase-inhibiting protein) mRNA in two near-isogenic lines of Phaseolus vulgaris L upon infection with Colletotrichum lindemuthianum

Polygalacturonase-inhibiting protein (PGIP) is an extracellular leucine-rich repeat (LRR) protein that binds to and inhibits the activity of fungal endopolygalacturonases. Accumulation of PGIP mRNA in near-isogenic lines of Phaseolus vulgaris differing only for a single gene (Are) which confers resistance to the race gamma of Colletotrichum lindemuthianum was followed by Northern blot analysis. In the incompatible interaction, approximately 40 h after inoculation and 4 h before the observed hypersensitive response, PGIP mRNA reached a level 20-fold higher than the basal level and returned to basal levels by 68 h. In the compatible interaction, PGIP mRNA did not significantly increase during the first 68 h. An eight-fold induction over the basal level was observed 84 h after inoculation. Transcripts returned to basal levels by 100 h. These data indicate that an early and rapid pgip transcript accumulation is associated with the hypersensitive response in bean C. lindemuthianum race gamma interactions. (C) 1996 Academic Press Limited