%0 Journal Article
%T Screening of Fusarium graminearum Isolates for Enzymes Extracellular and Deoxynivalenol Production
%A Leonel M. Ortega
%A Gisele E. Kikot
%A Andrea L. Astoreca
%A Teresa M. Alconada
%J Journal of Mycology
%D 2013
%I Hindawi Publishing Corporation
%R 10.1155/2013/358140
%X Fusarium graminearum, the main etiological agent of Fusarium head bligh, has high intraspecific genetic diversity, which is related to the variability in the aggressiveness among isolates against wheat. The aggressiveness involves different mechanisms as the production and liberation of extracellular enzymes and mycotoxins. In the present paper, several F. graminearum isolates obtained from wheat spikes from Pampas region, Argentina, were screened for polygalacturonase (pectinase), proteolytic, and lipase extracellular enzymatic activities production, as well as for the capacity to produce deoxynivalenol. The enzymatic production in terms of magnitude was varied among isolates, which could be related to a differential capacity to infect wheat. Both polygalacturonase as proteolytic activities had a maximum activity in the first days of incubation. Instead, the lipase activity reached its maximum activity after advanced incubation time. Deoxynivalenol production was delayed over time with respect to the first enzymatic activities, which would infer its relation to the progress of the disease in the host, more than with the early stages of infection. The characterization carried out in this research would allow us to apply a selection criterion among isolates for further research. 1. Introduction Fusarium head blight (FHB) is one of the most devastating diseases of small-grain cereals. Severe epidemics have occurred all over the world, affecting wheat in all cropping areas around the world, including those in Argentina, altering the yield and quality of grains, as manifest in their weight, carbohydrate and protein composition, and the mycotoxins presence such as deoxynivalenol (DON) [1¨C3]. Fusarium graminearum is the main etiologic agent of this disease in South America. The aggressiveness of F. graminearum involves different mechanisms or components, as the production and release of extracellular enzymes that degrade the cell wall (CWDEs) which are crucial in the processes of colonization and establishment of the disease [4¨C6]. Therefore, a reduced secretion of enzymes might retard both the fungal growth on the host surface and the infective process, thus giving the host more time to muster a defensive response [7¨C9]. Once the infection is established, mycotoxins are released and they interfere with the metabolism, physiologic processes and structural integrity of the host cell [10]. The CWDEs participation in the infection process, by Fusarium spp. has been analyzed through diverse methodologies, which include cytological, ultrastructural, immunological,
%U http://www.hindawi.com/journals/jmy/2013/358140/