Occurrence Of Fusarium Verticillioides In Symptomatic And Symptomless Seed/Grain Maize And Its Relation With Fumonisin Content

M. LILA GENTILI; JESSICA AGOSTINI; ISMAEL MALBRÁN; CECILIA A. MOURELOS; GLADYS A. LORI

Mendoza

Conferencia; ISM Conference 2011 "Strategies to reduce the impact of mycotoxins in Latin America in a global context"; 2011

"Fusarium ear rot" and "Gibberella ear rot" are diseases of maize caused by Fusarium verticillioides and F. graminearum, both affect the quality of seed, as well as the grain due to the production of mycotoxins. F. verticillioides invades maize plant in two ways: a) horizontal infection (via the silks) causing ear rot and producing symptomatic grains, and b) vertical transmission (entering by the seed during germination) colonizing the seedling trough endophytic pathway and producing symptomless grains. In order to measure the presence of F. verticillioides and its relationship to fumonisins contamination of symptomatic and symptomless grains, 38 samples of commercial maize hybrids were collected prior to storage during 2010. The samples were categorized macroscopically as symptomatic or symptomless and grains were plated on potato dextrose agar medium (PDA) 2% (w/v) supplemented with 250 mg L-1 of chloramphenicol and 600 mgL-1 of pentachloronitrobenzene (PCNB 75% wettable powder) to evaluate the presence of Fusarium spp. and its effect on germination. Concentration of fumonisins in grains from the 38 samples was assessed using a commercially available enzyme immunoassay (enzyme-linked immunosorbent assay [ELISA]) (RIDASCREEN FAST DON; R-Biopharm GmbH, Darmstadt, Germany). Fusarium verticillioides (MP A) was highly present in all samples (98 to 100% of seeds) but only 21% of the samples were categorized as symptomatic based on the presence of rot symptoms. For these samples a decrease of germination was detected (germination power [GP]: 98 to 41%). Although the symptomless samples (30/38) shown a high presence of F. verticillioides, they did not showed a decrease in the GP. F. graminearum was isolated in 63% of the samples in 2 to 18% of the seeds plated. The presence of this pathogen was always associated with a decrease in GP. Fumonisins were detected in 8 samples correponding to the symptomatic group, with concentrations that ranged from 4.0 to 1.1 ppm. Within the symptomless samples, the presence of fumonisins was verified in only 3 samples with values below 1 ppm. A significant correlation between the decrease of the germination and fumonisins content in samples was found (r = 0.8, p