Fusarium graminearumforms mycotoxin producing infection structures on wheat

BMC Plant Biology

Research Article

Marike J Boenisch¹  Wilhelm Schäfer¹ 

[1] Biocenter Klein Flottbek, Molecular Phytopathology and Genetics, University of Hamburg, Ohnhorststrasse 18, 22609, Hamburg, Germany;

关键词: Green Fluorescent Protein;    Graminearum;    Fusarium Head Blight;    Trichothecene;    Green Fluorescence Protein Fluorescence;   

DOI  :  10.1186/1471-2229-11-110

 received in 2010-08-09, accepted in 2011-07-28,  发布年份 2011

来源: Springer

【 摘 要 】

BackgroundThe mycotoxin producing fungal pathogen Fusarium graminearum is the causal agent of Fusarium head blight (FHB) of small grain cereals in fields worldwide. Although F. graminearum is highly investigated by means of molecular genetics, detailed studies about hyphal development during initial infection stages are rare. In addition, the role of mycotoxins during initial infection stages of FHB is still unknown. Therefore, we investigated the infection strategy of the fungus on different floral organs of wheat (Triticum aestivum L.) under real time conditions by constitutive expression of the dsRed reporter gene in a TRI5prom::GFP mutant. Additionally, trichothecene induction during infection was visualised with a green fluorescent protein (GFP) coupled TRI5 promoter. A tissue specific infection pattern and TRI5 induction were tested by using different floral organs of wheat. Through combination of bioimaging and electron microscopy infection structures were identified and characterised. In addition, the role of trichothecene production for initial infection was elucidated by a ΔTRI5-GFP reporter strain.ResultsThe present investigation demonstrates the formation of foot structures and compound appressoria by F. graminearum. All infection structures developed from epiphytic runner hyphae. Compound appressoria including lobate appressoria and infection cushions were observed on inoculated caryopses, paleas, lemmas, and glumes of susceptible and resistant wheat cultivars. A specific trichothecene induction in infection structures was demonstrated by different imaging techniques. Interestingly, a ΔTRI5-GFP mutant formed the same infection structures and exhibited a similar symptom development compared to the wild type and the TRI5prom::GFP mutant.ConclusionsThe different specialised infection structures of F. graminearum on wheat florets, as described in this study, indicate that the penetration strategy of this fungus is far more complex than postulated to date. We show that trichothecene biosynthesis is specifically induced in infection structures, but is neither necessary for their development nor for formation of primary symptoms on wheat.

【 授权许可】

CC BY   
© Boenisch and Schäfer; licensee BioMed Central Ltd. 2011