PRELIMINARY RESULTS ON FUSARIUM CULMORUM-SOFT WHEAT INTERACTIONS IN STEM BASES AND ROOTS

• Published in: Journal of plant pathology 2009-12, Vol.91 (4), p.S4.48-S4.49
• Main Authors: Beccari, G, Covarelli, L, Thomsett, MA, Nicholson, P
• Format: Article
• Language: English
• Subjects: Fusarium; Triticum aestivum
• ISSN: 1125-4653

An isolate of F. culmorum expressing the green fluorescent protein (GFP) was used to examine the infection process and host response during the early stages of the infection of the stem base and roots of wheat (cv. Genio). Following inoculation of seedlings, disease progress in leaf sheaths and roots was assessed macroscopically by visual symptom observations, microscopically by confocal laser scanning microscopy (CLSM) and by gene expression analysis of fungal and wheat genes by real time RT-PCR. The fungus sequentially penetrated though the first, second and third basal leaf sheaths and produced trichothecenes (expression of TR15) very early in infection. Expression of TR15 decreased later in colonisation. CLSM observations revealed a host response in uninfected areas on the internal leaf sheaths in advance of fungal infection. Differential expression of the wheat genes Wheatwin 1-2, PR1, Chitinase, PAL, LOXC, W1R1 and OPR1 was recorded in the stem base tissues depending on infection stage and leaf position. Interestingly, most of these genes were expressed in tissues ahead of fungal colonisation. In the roots, F. culmorum consistently expressed TR15 (24, 48 and 96 h post-inoculation). CLSM investigations showed an initial intercellular and a subsequent intracellular colonisation by fungal hyphae, epidermal layer and cortex invasion and the absence of the fungus in the stele. Expression of the host defence-associated genes increased early in infection and decreased in later stages.