Overexpression of the grapevine PGIP1 in tobacco is associated with leaf cell wall pectin modification and glycoprotein changes following Botrytis cinerea infection

Introduction Grapevine PGIP1 (polygalacturonase inhibiting protein 1) expressed in tobacco produces plants with enhanced resistance against B. cinerea infection. Grapevine PGIP1 has been shown to remodel leaf cell walls in transgenic tobacco in the absence of fungal infection. The associated dynamic cell wall changes linked to the mechanism of resistance have not been investigated in the context of fungal infection. Methods Scanning electron microscopy was used to evaluate infection progression. Monosaccharide composition analysis was used to evaluate cell wall changes as infection progressed. Comprehensive microarray polymer profiling tracked polysaccharide and glycoprotein changes. Results No difference was observed for lesions between wild-type and transgenic PGIP1 during the first 72 hpi. Rhamnogalacturonan I (RG-I) levels increased at the infection site. The cell wall glycoproteins, arabinogalactan proteins and extensin proteins, show higher signals in the lesion and adjacent tissue in response to Botrytis cinerea infection. Discussion RG-I and cell wall protein reorganisation in grapevine PGIP1-expressing tobacco lines upon infection with Botrytis cinerea suggest cell wall remodelling enhances fungal resistance.