Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 5/30/2013
Publication Date: 5/30/2013
Citation: Susca, A., Proctor, R., Logrieco, A., Stea, G., Mule, G., Moretti, A. 2013. Characterization of the fumonisin B2 biosynthetic gene cluster in Aspergillus niger and A. awamori [abstract]. Mycored International Conference. Interpretive Summary:
Technical Abstract: Aspergillus niger and A. awamori strains isolated from grapes cultivated in Mediterranean basin were examined for fumonisin B2 (FB2) production and presence/absence of sequences within the fumonisin biosynthetic gene (fum) cluster. Presence of 13 regions in the fum cluster was evaluated by PCR assays, and confirmed for some strains by Southern hybridization analysis. The results of our study indicate that some strains of both species produce FB2 while other strains do not. In A. awamori, all FB2-nonproducing strains appear to have a large deletion within the fum cluster between fum15 and fum6; the putative deleted region includes eight fum genes. In contrast, in FB2-nonproducing strains of A. niger, there is no evidence for such a lesion, suggesting that the lack of production in strains of this species is caused by a small lesion in one or more cluster genes or by a lesion in a regulatory gene(s) outside the cluster. Maximum Parsimony analysis using DNA sequence of the calmodulin gene indicates that the phylogenetic relationships of A. awamori and A. niger strains do not correlate with the deletion between fum15 and fum6. The phylogenetic data also indicate that relationships between fum-gene sequences are not correlated with the ability or inability to produce FB2. The results of this study suggest that both A. awamori and A. niger are being maintained as mixed populations of FB2-producing and nonproducing individuals on grape in the Mediterranean basin. However, the genetic basis of FB2 nonproduction appears to differ in these two closely related aspergilli suggesting that nonproduction has arisen independently in each species.