Japanese species of Alternaria and their species boundaries based on host range

Abstract

To clarify the diversity of plant-parasitic Alternaria species in Japan, diseased samples were collected, and fungal isolates established in culture. We examined 85 isolates representing 23 species distributed in 14 known sections based on conidial morphology and DNA phylogeny. Three species were found to be new, A. cylindrica, A. paragomphrenae and A. triangularis. Furthermore, a lectotype was designated for A. gomphrenae, and epitypes for A. cinerariae, A. gomphrenae, A. iridicola, and A. japonica. Species boundaries of isolates were also clarified by studying phenotypes and determining host ranges. Alternaria gomphrenae and related species in sect. Alternantherae were recognized as distinct species owing to their host specificity. Among the species infecting Apiaceae, the pathogenicity of A. cumini and a novel species, A. triangularis ex Bupleurum, were confirmed as host specific. Another novel species, A. cylindrica, proved to be host specific to Petunia. Alternaria iridicola was recognized as a large-spored species in sect. Alternaria, being host specific to Iris spp. On the other hand, the experimental host ranges of three morphologically and phylogenetically distinct species infecting Brassicaceae (A. brassicae, A. brassicicola, and A. japonica) showed almost no differences. Alternaria brassicicola and A. porri were even found on non-host plants. In general, host ranges of Alternaria species correlated with morphology and molecular phylogeny, and combining these datasets resulted in clearer species boundaries.

Leaf spots of calibrachoa caused by Nigrospora oryzae

“…Although calibrachoa is popular as a potted plant crop in many regions, little is known about the diseases these plants may develop, maybe because it is a relatively new crop. Among the pathogens previously reported on calibrachoa, only A. porri causes leaf spots (Nishikawa and Nakashima, 2020). The symptoms were not described but Alternaria leaf spots on many plants are clearly distinct from the ones we found associated with N. oryzae in calibrachoa.…”

“…To date, Calibrachoa mottle virus (CbMV) (Liu et al, 2003), Tobacco mild green mosaic virus (TMGMV) (Sabanadzovic et al, 2009), Podosphaera xanthii (Brielmaier-Liebetanz et al, 2015), Phytophthora nicotianae (Lin et al, 2018), Potato virus Y (PVY) (Tombion et al, 2019), Alternaria porri (Nishikawa and Nakashima, 2020), and Sclerotinia sclerotiorum (Borrelli et al, 2020), have been reported to infect calibrachoa plants in different countries. The development of new cultivars includes disease surveys.…”

Alternaria Genus and the Diseases Caused to Agricultural and Horticultural Plants

“…The year 1933 was a decisive one, because the researchers came to the conclusion that the genus Macrosporium should be called "nomen ambiguum" (Singh et al, 2016;Lawrence et al, 2016Lawrence et al, , 2013. This decision was based on the fact that problems occurred because of the numerous taxons that were superficially investigated, and more than 400 fake species were described (Nishikawa and Nakishima, 2020 The fifth stage was between 2003-2015, when the reclassification of the genus Alternaria and other related species, through DNA analysis was elaborated. The first approach of this was performed on the genus Stemphylium and Ulocladium.…”

Caliciopsis moriondi, a new species for a fungus long confused with the pine pathogen C. pinea

“…Caliciopsis arceuthobii infects the flowers of several species of dwarf mistletoe in the genus Arceuthobium (Ramsfield et al 2009), Caliciopsis rhoina is associated with bark and trunk cankers on Toona sinensis (Rikkinen 2000), while Caliciopsis brevipes was reported on needles and bark of Araucaria araucana and C. cochlearia on needles and twigs of A. araucana, Fitzroya cupressoides, Austrocedrus chilensis, Pilgerodendron uviferum and Podocarpus nubigenus (Butin 1970). More recently, Caliciopsis pleomorpha [now recombined in Hypsotheca as H. pleomorpha (Crous et al 2019)] has been reported as the causal agent of a canker disease on various Eucalyptus species in Australia (Pascoe et al 2018).…”