Reappraisal of the genus <I>Alternariaster</I> (<I>Dothideomycetes</I>)

Abstract

Alternariaster was erected in 2007 to accommodate Alternaria helianthi, a fungal species known to cause leaf spots on Helianthus annuus (sunflower). It was segregated from Alternaria based on conidial morphology. Recently an unknown alternaria-like dematiaceous fungus was found associated with leaf spots on Bidens sulphurea (yellow cosmos) in Brazil. Based on a multi-gene phylogeny of parts of the ITS and LSU genes, this fungus was placed within the Leptosphaeriaceae with Alternariaster helianthi as its closest neighbour. Additional genes sequenced, RPB2 and GAPDH, confirmed this close relationship. The fungus on B. sulphurea has smaller conidia, 50–97.5 × 12.5–20 μm, compared to Al. helianthi, 80–160 × 18–30 μm, and lacks oblique or transverse septa which can be present in Al. helianthi. Pathogenicity studies on 18 plant species belonging to the Compositae showed that the B. sulphurea fungus only infected B. sulphurea, whereas Al. helianthi infected H. annuus and Galinsoga quadriradiata, a yet unreported host of Al. helianthi. The fungus causing disease on B. sulphurea is hence closely related but phylogenetically, morphologically and pathologically distinct from Al. helianthi, and therefore newly described as Alternariaster bidentis. The collection of a second species in the genus Alternariaster and the multigene phylogenetic analysis of these two species, confirmed Alternariaster to be a well-delimited genus in the Leptosphaeriaceae rather than the Pleosporaceae, to which Alternaria belongs.

Alternaria redefined

“…Our study showed that this genus is clearly not part of the Alternaria complex and belongs to the Leptosphaeriaceae (Fig. 2) (Alves et al 2013). …”

Ochraceocephala foeniculi gen. et sp. nov., a new pathogen causing crown rot of fennel in Italy

“…Further studies are needed to examine the life cycle of O. foeniculi and to ascertain the cardinal temperatures of the fungus for successful infection since this pathogen is well established in this representative fennel production area. This information is required for the setup and timing of sustainable approaches for soil disinfection, including solarization and/or fumigation at low rates, to reduce the level of the primary inoculum in the soil and hence the disease amount, like successfully applied for other soilborne plant pathogens (Vitale et al 2013;Aiello et al 2018).…”

Naming and outline of Dothideomycetes–2014 including proposals for the protection or suppression of generic names

“…Simmons. Simmons (2007) considered Alternariaster to be related to Alternaria , however, Alves et al (2013) and Woudenberg et al (2013) clealy showed Alternariaster ( Leptosphaeriaceae ) to have a distinct phylogenetic affinity in Pleosporales and removed it from Alternaria sensu stricto ( Pleosporaceae ).…”