Polygalacturonase-inhibiting proteins (PGIPs) are plant defence glicoproteins associated with the cell wall of both monocot and dicot species. They interact with fungal endopolygalacturonases (PGs) and modulate their activity favouring the accumulation of oligogalacturonides active as elicitors of plant defence responses. A number of pgip genes and of their encoded products have been characterized from dicot species, whereas only a few data are available for PGIPs from monocots. In this work we report the structural and functional characterization of PGIPs and of their encoding genes from wheat and rice and the effect of the over expression of a bean PGIP in wheat. Deduced amino acid sequences of PGIP from both rice and wheat show the typical LRR organization and a conserved distribution of cysteines. Nevertheless, the overall amino acid sequence similarity with PGIPs from dicots never exceeds 40%. To determine their recognition specificities, wheat and rice pgip genes have been expressed in Nicotiana benthamiana using the potato virus X (PVX) as vector. Only rice OsPGIP1, and to a lesser extent the wheat TaPGIP1, are active against the fungal pathogen PGs tested, whilst OsPGIP2 and OsPGIP3 show none inhibition. We have also found that the lack of an entire LRR repeat in rice OsPGIP1 does not affect the ability of recognizing fungal PGs. To verify the involvement of PGIP in protecting wheat from fungal pathogens producing PG, such as Fusarium graminearum, we have performed quantitative RT-PCR (qRT-PCR) analysis in infected wheat tissue and produced transgenic wheat with a bean PGIP possessing a wide spectrum of recognition towards fungal PGs. qRT-PCR showed induction of Tapgip1 following infection with F. graminearum and preliminary infection experiments with the same pathogen indicate that the transgene-encoded protein is active and endows the transgenic wheats with new PG recognition capabilities.
Structural and function features of wheat and rice polygalacturonase inhibiting proteins (PGIPs) and addition of novel PGIP recognition capabilities in wheat
FAVARON, FRANCESCO;SELLA, LUCA;
2004
Abstract
Polygalacturonase-inhibiting proteins (PGIPs) are plant defence glicoproteins associated with the cell wall of both monocot and dicot species. They interact with fungal endopolygalacturonases (PGs) and modulate their activity favouring the accumulation of oligogalacturonides active as elicitors of plant defence responses. A number of pgip genes and of their encoded products have been characterized from dicot species, whereas only a few data are available for PGIPs from monocots. In this work we report the structural and functional characterization of PGIPs and of their encoding genes from wheat and rice and the effect of the over expression of a bean PGIP in wheat. Deduced amino acid sequences of PGIP from both rice and wheat show the typical LRR organization and a conserved distribution of cysteines. Nevertheless, the overall amino acid sequence similarity with PGIPs from dicots never exceeds 40%. To determine their recognition specificities, wheat and rice pgip genes have been expressed in Nicotiana benthamiana using the potato virus X (PVX) as vector. Only rice OsPGIP1, and to a lesser extent the wheat TaPGIP1, are active against the fungal pathogen PGs tested, whilst OsPGIP2 and OsPGIP3 show none inhibition. We have also found that the lack of an entire LRR repeat in rice OsPGIP1 does not affect the ability of recognizing fungal PGs. To verify the involvement of PGIP in protecting wheat from fungal pathogens producing PG, such as Fusarium graminearum, we have performed quantitative RT-PCR (qRT-PCR) analysis in infected wheat tissue and produced transgenic wheat with a bean PGIP possessing a wide spectrum of recognition towards fungal PGs. qRT-PCR showed induction of Tapgip1 following infection with F. graminearum and preliminary infection experiments with the same pathogen indicate that the transgene-encoded protein is active and endows the transgenic wheats with new PG recognition capabilities.
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