Peltaster cerophilus is a new species of the apple sooty blotch complex from Europe

Abstract

Adopting the currently used concept for the genus Peltaster, the sooty blotch fungus Peltaster cerophilus is newly described from the cuticle of ripening or ripe apples. It forms a punctate phenotype consisting of superficially formed pycnothyria and a superficial mycelial mat consisting of a net of brown or brownish black hyphae. The pycnothyria are olivaceous brown to brown but have a spot in the center that is less strongly pigmented. Pycnothyria on the holotype of P. fructicola are homogeneously pigmented. On synthetic nutrient-poor agar, P. cerophilus is largely indistinguishable from P. fructicola. It forms delicate, spreading hyphae and intercalary conidiogenous cells with short, lateral, apically thick-walled conidiogenous necks forming blastic, unpigmented, one-celled conidia in basipetal succession. Conidia can swell and become one-septate. The species has microcyclical conidiation in proximate parts of colonies. DNA sequence analyses based on the ITS and the partial nuclear small and large subunit ribosomal RNA genes, the partial mitochondrial small subunit rRNA gene and the partial translation elongation factor 1-α gene support the distinction of the European P. cerophilus from P. fructicola, which is known from North America and Europe. The nuclear small ribosomal RNA subunit gene sequences of P. cerophilus contain two group I introns at locations known to accommodate introns in certain other, unrelated taxa. One of these, for which the code "SSU-1506 intron" was adopted, is 1459 base pairs long and located between the universal primer sites ITS5 and ITS1. Similar or positional-differing introns were encountered also in three currently undescribed Peltaster species. Representative strains of Peltaster fructicola did not accommodate introns in the nuclear small subunit ribosomal RNA gene.

Peltaster fructicola genome reveals evolution from an invasive phytopathogen to an ectophytic parasite

“…It also causes SBFS signs on fruit of pawpaw ( Asimina triloba ) in Iowa, USA 6 and crabapple ( Malus × micromalus ) and hawthorn ( Crataegus pinnatifida ) in China 7 . Although P. fructicola was classified within the Capnodiales along with most other SBFS species, the genus Peltaster , including another recently established species P. cerophilus , seems to be an isolated lineage 2 8 9 . Research on P. fructicola has focused mainly on its taxonomy, biogeography, pathogenicity, control by fungicides, and responses to temperature, humidity, and nutrients 10 11 12 13 14 15 .…”

Control of sooty blotch and black rot of apple through removal of fruit mummies

“…The recently described species Peltaster cerophilus (Medjedović et al 2014) has been demonstrated to be the most important sooty-blotch fungus affecting organic orchards within the two largest German production areas of the Lower Elbe region in the north and the Lake Constance area in the south (R.W.S. Weber, unpublished).…”