Taxonomy, phylogeny, and divergence time estimation for Apiosphaeria guaranitica, a Neotropical parasite on bignoniaceous hosts

ABSTRACT

Apiosphaeria guaranitica, the causal agent of brown crust disease of several bignoniaceous hosts, among them Handroanthus and Tabebuia species, has been traditionally placed in Phyllachoraceae, based exclusively on morphological studies, without supporting molecular evidence. Here, we provide molecular data for the link between sexual and asexual states of the fungus and elucidate the phylogeny of A. guaranitica. The multilocus phylogenetic analyses employed sequences from the 18S subunit (18S), 28S subunit (28S), and nuclear internal transcribed spacers (ITS1-5.8S-ITS2 = ITS) of the nuc rDNA, second-largest subunit of RNA polymerase II (RPB2), and translation elongation factor 1-α (TEF1) genetic loci. Estimates of the divergence time of this lineage were supported by fossil calibration (FC) and secondary calibration (SC) strategies. Our results indicate a natural placement of Apiosphaeria within Diaporthaceae (Diaporthales), where it represents an ancient lineage of the crown group of Diaporthaceae, diverging during the late Paleocene at 61.15 (FC) and 60.63 (SC) million years ago. This divergence time estimate within Diaporthales is based on Spataporthe taylori, a diaporthaceous fossil.

KEYWORDS:

• Ascomycete
• Bignoniaceae
• brown crust disease
• Cerrado
• fossil calibration
• molecular clock
• multilocus phylogeny
• Neotropica

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Additional information

Funding

We thank Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) for a PhD fellowship to Debora C. Guerres, a research grant to Prof. Robert N. G. Miller; and also specially thank the CNPq Research Program on Biodiversity - PPBIO-Cerrado, for a grant to Prof. José C. Dianese.