Tissue specific expression of PvPGIP2 to improve wheat resistance against Fusarium graminearum

Fusarium Head Blight (FHB) is one of the most important wheat diseases caused by Fusarium spp.. The pathogen infects the spike at flowering time and causes severe yield losses and deterioration of grain quality due to the secretion of mycotoxins during infection. The understanding of the precise mode of pathogen entering and the subsequent floral tissue colonize is a crucial point to control FHB. Polygalacturonase inhibiting proteins (PGIPs) are cell wall proteins that inhibit the pectin-depolymerizing activity of polygalacturonases (PGs) secreted by pathogens. The constitutive expression of the bean PvPGIP2 limits FHB symptoms and reduces mycotoxin accumulation in wheat. To better understand which spike tissues plays a role in limiting Fusarium infection, we have produced transgenic wheat plants expressing PvPGIP2 in the endosperm or simultaneously in lemma, palea, anthers and rachis. This latter approach reduced FHB symptoms, whereas the expression of PvPGIP2 only in the endosperm did not affect FHB development, indicating that when the pathogen has reached the endosperm, inhibition of pathogen PGs ineffective to prevent fungal spread.