Scanning electron microscopy of Fusarium damaged kernels of spring wheat H. Jackowiak a , D. Packa b , M. Wiwart b, * , J. Perkowski c a Department of Animal Anatomy, Agriculture University in Poznan ´, 60-625 Poznan ´, ul. Wojska Polskiego 71c, Poland b Department of Plant Breeding and Seed Production, University of Warmia and Mazury in Olsztyn, 10-724 Olsztyn, Pl. £o ´dzki 3 Poland c Department of Chemistry, Agriculture University in Poznan ´, 60-625 Poznan ´, ul. Wojska Polskiego 75, Poland Received 13 February 2004; received in revised form 24 May 2004; accepted 26 May 2004 Abstract Kernels of five wheat cultivars (Triticum aestivum) of different bread-making quality were examined. Grown under field conditions, heads of wheat were inoculated in the flowering stage with an aqueous suspension of Fusarium culmorum conidia. Wheat heads were collected from the control and inoculated plots at full maturity. Control (non-inoculated) kernels without any symptoms of disease and Fusarium damaged kernels (FDK) were examined under scanning electron microscopy (SEM). Examination of the FDK fraction confirmed localisation of Fusarium hyphae on the surface and inside the tissues of kernels. Observations of the endosperm from Fusarium infected kernels revealed presence of fungal hyphae in the endosperm and some characteristic structural changes in many of its regions, such as partial or complete lack of the protein matrix, damage to large and small starch granules caused by fungal amylolytic enzymes, disappearance of small starch granules as the colonisation progressed, complete disappearance of the starchy endosperm under severe infection. Fungal colonisation of the endosperm and structural changes in its area were highly variable traits within the FDK fraction of a given cultivar. D 2004 Elsevier B.V. All rights reserved. Keywords: Fusarium culmorum; Kernel; Scanning electron microscopy; Wheat 1. Introduction Among the major diseases of cereal crops reducing grain yields in Central Europe, diseases caused by Fusarium species are third after rusts and powdery mildew. Pathogenic species of Fusarium invade plants in different stages of growth and development. Due to their parasitic and saprophytic mode of life, Fusaria are present in the natural soil environment, but can also be transmitted with seed material. Fusarium head blight (Fusarium ear blight, scab) occurs on wheat, barley, triticale, rye and oat (Parry et al., 1995). Although over 17 species of fungi responsible for generating symptoms of this disease in cereal grains have been identified, only 5 represent the most com- mon sources of head, panicle and grain infection. These are F. culmorum, F. graminearum, F. avena- ceum, F. poae and Microdochium nivale (F. nivale) (Parry et al., 1995). In Eastern Europe, head blight is mainly caused by F. culmorum, whereas in North America the disease is most often evoked by F. graminearum (£acicowa, 1989; McMullen et al., 0168-1605/$ - see front matter D 2004 Elsevier B.V. All rights reserved. doi:10.1016/j.ijfoodmicro.2004.05.014 * Corresponding author. Tel./fax: +48-89-5234880. E-mail address: marian.wiwart@uwm.edu.pl (M. Wiwart). www.elsevier.com/locate/ijfoodmicro International Journal of Food Microbiology 98 (2005) 113– 123