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) [1–3]. 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 [4–6]. 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 [7–9]. 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,
References
[1]
F. A. Lazzari, “Control integrado de plagas, manejo de hongos e insectos,” Granos y Post-Cosecha Latinoamericana, vol. 6, no. 23, 2000.
[2]
S. R. Pirgozliev, S. G. Edwards, M. C. Hare, and P. Jenkinson, “Strategies for the control of Fusarium head blight in cereals,” European Journal of Plant Pathology, vol. 109, no. 7, pp. 731–742, 2003.
[3]
I. Malbrán, C. A. Mourelos, J. R. Girotti, M. B. Aulicino, P. A. Balatti, and G. A. Lori, “Aggressiveness variation of Fusarium graminearum isolates from Argentina following point inoculation of field grown wheat spikes,” Crop Protection, vol. 42, pp. 234–243, 2012.
[4]
á. Mesterházy, T. Bartók, C. G. Mirocha, and R. Komoróczy, “Nature of wheat resistance to Fusarium head blight and the role of deoxynivalenol for breeding,” Plant Breeding, vol. 118, no. 2, pp. 97–110, 1999.
[5]
G. E. Kikot, R. A. Hours, and T. M. Alconada, “Contribution of cell wall degrading enzymes to pathogenesis of Fusarium graminearum: a review,” Journal of Basic Microbiology, vol. 49, no. 3, pp. 231–241, 2009.
[6]
G. E. Kikot, R. A. Hours, and T. M. Alconada, “Extracellular enzymes of Fusarium graminearum isolates,” Brazilian Archives of Biology and Technology, vol. 53, no. 4, pp. 779–783, 2010.
[7]
Z. Kang and H. Buchenauer, “Ultrastructural and cytochemical studies on cellulose, xylan and pectin degradation in wheat spikes infected by Fusarium culmorum,” Journal of Phytopathology, vol. 148, no. 5, pp. 263–275, 2000.
[8]
Z. Kang and H. Buchenauer, “Cytology and ultrastructure of the infection of wheat spikes by Fusarium culmorum,” Mycological Research, vol. 104, no. 9, pp. 1083–1093, 2000.
[9]
N. J. Jenczmionka and W. Sch？fer, “The Gpmk1 MAP kinase of Fusarium graminearum regulates the induction of specific secreted enzymes,” Current Genetics, vol. 47, no. 1, pp. 29–36, 2005.
[10]
J. M. Wagacha and J. W. Muthomi, “Fusarium culmorum: infection process, mechanisms of mycotoxin production and their role in pathogenesis in wheat,” Crop Protection, vol. 26, no. 7, pp. 877–885, 2007.
[11]
H. Jackowiak, D. Packa, M. Wiwart, J. Perkowski, M. Busko, and A. Borusiewicz, “Scanning electron microscopy of mature wheat kernels infected with Fusarium culmorum,” Journal of Applied Genetic, vol. 43, pp. 167–176, 2002.
[12]
W. M. Wanjiru, K. Zhensheng, and H. Buchenauer, “Importance of cell wall degrading enzymes produced by Fusarium graminearum during infection of wheat heads,” European Journal of Plant Pathology, vol. 108, no. 8, pp. 803–810, 2002.
[13]
C. Jansen, D. von Wettstein, W. Sch？fer, K. Kogel, A. Felk, and F. J. Maier, “Infection pattern in barley and wheat spikes inoculated with wild-type and trichodiene synthase gene disrupted Fusarium graminearum,” Proceedings of the National Academy of Sciences of the United States of America, vol. 102, no. 46, pp. 16892–16897, 2005.
[14]
V. Phalip, F. Delalande, C. Carapito et al., “Diversity of the exoproteome of Fusarium graminearum grown on plant cell wall,” Current Genetics, vol. 48, no. 6, pp. 366–379, 2005.
[15]
A. T. Have, W. Mulder, J. Visser, and J. A. L. van kan, “The endopolygalacturonase gene Bcpg1 is required to full virulence of Botrytis cinerea,” Molecular Plant-Microbe Interactions, vol. 11, no. 10, pp. 1009–1016, 1998.
[16]
F. I. García-Maceira, A. Di Pietro, M. D. Huertas-González, M. C. Ruiz-Roldán, and M. I. G. Roncero, “Molecular characterization of an endopolygalacturonase from Fusarium oxysporum expressed during early stages of infection,” Applied and Environmental Microbiology, vol. 67, no. 5, pp. 2191–2196, 2001.
[17]
O. Valette-Collet, A. Cimerman, P. Reignault, C. Levis, and M. Boccara, “Disruption of Botrytis cinerea pectin methylesterase gene Bcpme1 reduces virulence on several host plants,” Molecular Plant-Microbe Interactions, vol. 16, no. 4, pp. 360–367, 2003.
[18]
M. I. G. Roncero, C. Hera, M. Ruiz-Rubio et al., “Fusarium as a model for studying virulence in soilborne plant pathogens,” Physiological and Molecular Plant Pathology, vol. 62, no. 2, pp. 87–98, 2003.
[19]
M. J. Nightingale, B. A. Marchylo, R. M. Clear, J. E. Dexter, and K. R. Preston, “Fusarium head blight: effect of fungal proteases on wheat storage proteins,” Cereal Chemistry, vol. 76, no. 1, pp. 150–158, 1999.
[20]
A. J. Barneix, “Physiology and biochemistry of source-regulated protein accumulation in the wheat grain,” Journal of Plant Physiology, vol. 164, no. 5, pp. 581–590, 2007.
[21]
B. Brzozowski, K. Dawidziuk, and W. Bednarski, “Gliadin degradation by proteases of Fusarium genus fungi in different in vivo and in vitro conditions,” Polish Journal of Natural Sciences, vol. 23, pp. 188–206, 2008.
[22]
J. Feng, G. Liu, G. Selvaraj, G. R. Hughes, and Y. Wei, “A secreted lipase encoded by LIP1 is necessary for efficient use of saturated triglyceride lipids in Fusarium graminearum,” Microbiology, vol. 151, no. 12, pp. 3911–3921, 2005.
[23]
C. Pritsch, G. J. Muehlbauer, W. R. Bushnell, D. A. Somers, and C. P. Vance, “Fungal development and induction of defense response genes during early infection of wheat spikes by Fusarium graminearum,” Molecular Plant-Microbe Interactions, vol. 13, no. 2, pp. 159–169, 2000.
[24]
R. H. Proctor, T. M. Hohn, and S. P. McCormick, “Reduced virulence of Gibberella zeae caused by disruption of a trichothecene toxin biosynthetic gene,” Molecular Plant-Microbe Interactions, vol. 8, no. 4, pp. 593–601, 1995.
[25]
S. D. Harris, “Morphogenesis in germinating Fusarium graminearum macroconidia,” Mycologia, vol. 97, no. 4, pp. 880–887, 2005.
[26]
P. B. Schwarz, R. D. Horsley, B. J. Steffenson, B. Salas, and J. M. Barr, “Quality risks associated with the utilization of Fusarium head blight infected malting barley,” Journal of the American Society of Brewing Chemists, vol. 64, no. 1, pp. 1–7, 2006.
[27]
M. J. Martínez, M. T. Alconada, F. Guillén, C. Vázquez, and F. Reyes, “Pectic activities from Fusarium oxysporum f. sp. melonis: purification and characterization of an exopolygalacturonase,” FEMS Microbiology Letters, vol. 81, no. 2, pp. 145–150, 1991.
[28]
M. Somogyi, “Notes on sugar determination,” The Journal of Biological Chemistry, vol. 195, no. 1, pp. 19–23, 1952.
[29]
M. M. Bradford, “A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein dye binding,” Analytical Biochemistry, vol. 72, no. 1-2, pp. 248–254, 1976.
[30]
M. Hellweg, Molecular biological and biochemical studies of proteolytic enzymes of the cereal pathogen Fusarium graminearum [Inaugural Dissertation der Westf？lischen Wilhelms], Universit？t Münster, 2003.
[31]
C. Sequeiros, L. M. I. López, N. O. Caffini, and C. L. Natalucci, “Proteolytic activity in some Patagonian plants from Argentina,” Fitoterapia, vol. 74, no. 6, pp. 570–577, 2003.
[32]
M. L. Ramirez, S. Chulze, and N. Magan, “Temperature and water activity effects on growth and temporal deoxynivalenol production by two Argentinean strains of Fusarium graminearum on irradiated wheat grain,” International Journal of Food Microbiology, vol. 106, no. 3, pp. 291–296, 2006.
[33]
M. Schmidt-Heydt, R. Parra, R. Geisen, and N. Magan, “Modelling the relationship between environmental factors, transcriptional genes and deoxynivalenol mycotoxin production by strains of two Fusarium species,” Journal of the Royal Society Interface, vol. 8, no. 54, pp. 117–126, 2011.
[34]
J. M. Cooney, D. R. Lauren, and M. E. Di Menna, “Impact of competitive fungi on trichothecene production by Fusarium graminearum,” Journal of Agricultural and Food Chemistry, vol. 49, no. 1, pp. 522–526, 2001.
[35]
G. H. Bai, A. E. Desjardins, and R. D. Plattner, “Deoxynivalenol-nonproducing Fusarium graminearum causes initial infection, but does not cause disease spread in wheat spikes,” Mycopathologia, vol. 153, no. 2, pp. 91–98, 2002.
[36]
Z. Kang, H. Buchenauer, L. Huang, Q. Han, and H. Zhang, “Cytological and immunocytochemical studies on responses of wheat spikes of the resistant Chinese cv. Sumai 3 and the susceptible cv. Xiaoyan 22 to infection by Fusarium graminearum,” European Journal of Plant Pathology, vol. 120, no. 4, pp. 383–396, 2008.
[37]
Z. Kang, I. Zingen-Sell, and H. Buchenauer, “Infection of wheat spikes by Fusarium avenaceum and alterations of cell wall components in the infected tissue,” European Journal of Plant Pathology, vol. 111, no. 1, pp. 19–28, 2005.
[38]
P. B. Schwarz, B. L. Jones, and B. J. Steffenson, “Enzymes associated with Fusarium infection of barley,” Journal of the American Society of Brewing Chemists, vol. 60, no. 3, pp. 130–134, 2002.
