DETECTION OF FUSARIUM POAE ISOLATES WITH THE POTENTIAL TO PRODUCE NIVALENOL

DINOLFO M.I., BARROS G.G., STENGLEIN S.A.

Congreso; VIII Congreso de Microbiología General; 2012

Fusarium Head Blight, also known as scab, is an economically devastating fungal disease able to affect the quality and quantity of cereals such as wheat, barley, oat and corn, not only by producing yield reduction but also by the capacity to produce certain mycotoxins. Within Fusarium species responsible to produce this important disease, Fusarium poae has increased in importance in some countries like Argentina, Canada, Japan, Hungary, Ireland, Slovakia, Wales, England, and Poland. Moreover, F. poae has been reported to produce some mycotoxins that include type A and type B trichothecenes, beauvericins, enniatins and moniliformin. An important type B trichothecene is nivalenol, a toxic secondary metabolite whose effects have been well studied showing stronger cytotoxic effect that could be ascribed to an acceleration of apoptotic pathway on murine macrophages. Moreover, nivalenol inhibits the proliferation of human lymphocytes. In the trichothecene biosynthesis, 12 genes are involved, which tri13 and tri7 genes produce the acetylation and oxygenation of the oxygen at C-4 to produce nivalenol and 4-acetyl nivalenol, respectively. The objective of this work was to develop a primer set based on the tri7 gene to detect potential nivalenol producing F. poae isolates. Seventeen Argentinean Fusarium poae isolates from different regions and hosts selected at random were analyzed by HPLC/FD to test NIV production to use as positive controls. Different combinations of nivalenol-Fusarium primers were used, and one of them amplified three different fragments with different sizes in three of 25 F. poae isolates tested. These fragments were sequenced and a nivalenol-F. poae primer set was developed by aligning the F. poae sequences and the tri7 region of the F. graminearum 88-1. The primer set was tested in a total of 125 F. poae isolates, 4 F.cerealis (NIV producers), 2 F. culmorum (NIV producers), 1 F. langsethiae, 1 F. sporotrichioides and 7 F. graminearum (NIV-DON producers). The expected fragment of 296 bp only was present in F. poae isolates showing that the primer set is F. poae-specific. Moreover, the primer set was tested from cereal seed samples where F. poae and other Fusarium species with a negative result for the specific reaction (F. graminearum, F. oxysporum, F. chlamydosporum, F. sporotrichioides, F. equiseti and F. acuminatum) were isolated, and the expected fragment was amplified. To confirm that the amplified fragment corresponds to a part of tri7 gene sequence, the specific fragment of isolates of F. poae isolated from different hosts and countries were sequenced and compared with those of the NCBI webpage. In conclusion, we developed an effective and quick PCR assay to detect potential nivalenol producing F. poae isolates.