Constitutive Expression of the Xylanase Inhibitor TAXI-III Delays Fusarium Head Blight Symptoms in Durum Wheat Transgenic Plants

• DOI: 10.1094/mpmi-04-13-0121-r
• Publication Date: 2013-08-14T14:29:41Z
• Authors: Ilaria Moscetti; Silvio Tundo; Michela Janni; Luca Sella; Katia Gazzetti; Alexandra Tauzin; Thierry Giardina; Stefania Masci; Francesco Favaron; Renato D'Ovidio
• Keywords: 0301 basic medicine; 0303 health sciences; Endo-1,4-beta Xylanases; Time Factors; Botany; Plants, Genetically Modified; Microbiology; QR1-502; Fungal Proteins; Plant Leaves; 03 medical and health sciences; Ascomycota; Fusarium; Gene Expression Regulation, Plant; QK1-989; Ascomycota; Disease Resistance; Edible Grain; Endo-1,4-beta Xylanases; Enzyme Inhibitors; Fungal Proteins; Fusarium; Gene Expression Regulation, Plant; Plant Diseases; Plant Leaves; Plant Proteins; Plants, Genetically Modified; Time Factors; Triticum; Physiology; Agronomy and Crop Science; Enzyme Inhibitors; Edible Grain; Triticum; Disease Resistance; Plant Diseases; Plant Proteins

Cereals contain xylanase inhibitor (XI) proteins which inhibit microbial xylanases and are considered part of the defense mechanisms to counteract microbial pathogens. Nevertheless, in planta evidence for this role has not been reported yet. Therefore, we produced a number of transgenic plants constitutively overexpressing TAXI-III, a member of the TAXI type XI that is induced by pathogen infection. Results showed that TAXI-III endows the transgenic wheat with new inhibition capacities. We also showed that TAXI-III is correctly secreted into the apoplast and possesses the expected inhibition parameters against microbial xylanases. The new inhibition properties of the transgenic plants correlate with a significant delay of Fusarium head blight disease symptoms caused by Fusarium graminearum but do not significantly influence leaf spot symptoms caused by Bipolaris sorokiniana. We showed that this contrasting result can be due to the different capacity of TAXI-III to inhibit the xylanase activity of these two fungal pathogens. These results provide, for the first time, clear evidence in planta that XI are involved in plant defense against fungal pathogens and show the potential to manipulate TAXI-III accumulation to improve wheat resistance against F. graminearum.