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

Abstract

A new disease of fennel is described from Sicily (southern Italy). Surveys of the disease and sampling were conducted during spring 2017 and 2018 in Adrano and Bronte municipalities (Catania province) where this crop is widely cultivated. Isolations from the margin of symptomatic tissues resulted in fungal colonies with the same morphology. Pathogenicity tests with one isolate of the fungus on 6-month-old plants of fennel reproduced similar symptoms to those observed in nature. Inoculation experiments to assess the susceptibility of six different fennel cultivars to infection by the pathogen showed that the cultivars ‘Narciso’, ‘Apollo’, and ‘Pompeo’ were more susceptible than ‘Aurelio’, ‘Archimede’, and ‘Pegaso’. Phylogenetic analyses based on a matrix of the internal transcribed spacer (ITS), the large subunit (LSU), and the small subunit (SSU) rDNA regions revealed that the isolates represent a new genus and species within the Leptosphaeriaceae, which is here described as Ochraceocephala foeniculi gen. et sp. nov. This study improves the understanding of this new fennel disease, but further studies are needed for planning effective disease management strategies. According to the results of the phylogenetic analyses, Subplenodomus iridicola is transferred to the genus Alloleptosphaeria and Acicuseptoria rumicis to Paraleptosphaeria.

The Plant Family Asteraceae Is a Cache for Novel Fungal Diversity: Novel Species and Genera With Remarkable Ascospores in Leptosphaeriaceae

“…Ochraceocephala foeniculi is only known from its hyphomycetous asexual morph, which is characterized by hyaline, loosely or densely branched conidiophores, phialidic conidiogenous cells, and hyaline to yellowish, globose to subglobose conidia, and isolated as plant pathogen from living Foeniculum vulgare ( Aiello et al, 2020 ). Praeclarispora artemisiae is reported herein from only its ascomycetous sexual morph, characterized by black ascomata, narrowly obovoid asci, and fusiform ascospores with a larger, brown, median cell, and isolated as saprobe from decaying twigs of Artemisia argyi .…”

Synopsis of Leptosphaeriaceae and Introduction of Three New Taxa and One New Record from China

“…Our study shows that the polyphyletic topology of the Plenodumus group is due to the rpb 2 gene ( Figures S2–S4 ). This could be due to a lack of rpb 2 barcodes in several related taxa, but the rpb 2 gene can be useful for delineation at the genus level [ 12 , 41 ]. In contrast, using the tub 2 gene provides a better resolution at the species level within the genera ( Figure 2 ).…”

“…[ 1 , 2 , 3 ]. This family is characterized by conical or globose ascomata, scleroplectenchymatous or plectenchymatous peridium cells, cylindrical to oblong pedicellate asci, and septate reddish-brown or yellowish-brown ascospores ( Figure 1 ) [ 2 , 4 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. Although Leptosphaeriaceae is similar to Phaeosphaeriaceae , the peridium structure is morphologically distinguishable [ 15 ].…”

“…Although Leptosphaeriaceae is similar to Phaeosphaeriaceae , the peridium structure is morphologically distinguishable [ 15 ]. Most Leptosphaeriaceae species occur abundantly on dicotyledons, and the asexual morph can be coelomycetous (coniothyrium-like or phoma-like) or hyphomycetous [ 12 , 16 , 17 ]. Members of Leptosphaeriaceae are saprobes, hemibiotrophs, and pathogens [ 18 , 19 , 20 , 21 , 22 ].…”

“…The family was revised based on morphological characteristics and phylogenetic evidence, and ten genera were accepted [ 4 ]. Several other genera have also been added to Leptosphaeriaceae , such as Heterosporicola , Ochraceocephala , Querciphoma , Sclerenchymomyces , and Praeclarispora [ 8 , 12 , 13 , 14 ].…”