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Abstract
Nodulisporic acid, a novel indole terpene with insecticidal properties, was first isolated from a fermentation broth of an endophytic Nodulisporium sp. Following an extensive culture screening effort, fermentations of 12 other strains of Nodulisporium also yielded nodulisporic acid. These strains came from a variety of environmental substrata collected from seven tropical regions in four continents. Cultural characteristics and microscopic features show that all the nodulisporic acid-producing Nodulisporium strains are morphologically very similar. AP-PCR and sequencing of the rDNA region consisting of the two internal transcribed spacers and the 5.8S gene revealed that the isolates were distributed into three groups, according to the length of the ITS1. The two groups with the longest sequences were not distinguishable, based on nucleotide divergence data calculated from the common region of ITS1. The group of isolates with shorter sequences showed lower homology with the other groups in the ITS1 region, but those strains could not be distinguished from the other groups, according to ITS2 sequences. These data suggest that the nodulisporic acid producing isolates are very closely related and may constitute a single species, although divided into populations showing some degree of genetic differentiation. Comparison of the sequences obtained in this work with sequences from other xylariaceous fungi with Nodulisporium-type anamorphs failed in determining the teleomorph of the nodulisporic acid-producing Nodulisporium species. However, it revealed that these isolates constitute a monophyletic group, clearly different from other tropical and temperate isolates of Nodulisporium not able to produce nodulisporic acid.