Neofabraea

H.S. Jacks., Rep. Oregon Exp. Sta. 1911–1912: 187. 1913.

• Classification: Leotiomycetes, Leotiomycetidae, Helotiales, Dermateaceae.
• Type species: Neofabraea malicorticis H.S. Jacks. Neotype and ex-neotype culture: CBS H-22219, CBS 122030 = OSC 100036.
• DNA barcodes (genus): LSU.
• DNA barcodes (species): ITS, tub2, rpb2.

Ascomata apothecial, erumpent from bark, sessile to short-stalked, solitary or in clusters on a basal stroma; disc often not well-delimited, circular, elliptical, or irregular and merged, greyish, flesh-coloured to pale reddish or brownish, drying darker, 0.5–2.0 mm diam. Paraphyses numerous, filiform, septate, obtuse, simple or branched, hyaline, smooth-walled, apical cells mostly slightly swollen. Asci inoperculate, cylindrical-clavate, apex rounded or truncate-rounded, attenuated into a stalk of variable length, crozier present, 8-spored; apical apparatus with a well-developed apical thickening, Lugol's + or -, blue in herbarium material, Melzer’s + or -. Ascospores inequilateral, elongated ellipsoid, ends rounded, straight or curved, aseptate, thin-walled, smooth, hyaline, with granular contents or small oil droplets; later septate, sometimes germinating or forming conidia from minute openings or phialides. Conidiomata erumpent from bark, stromatic, acervular, plane to pulvinate. Conidiophores simple or branched, smooth, hyaline, acrogenous or acropleurogenous. Conidiogenous cells discrete or integrated, determinate, phialidic, cylindrical to narrowly ampulliform, giving rise to macro- and/or microconidia. Macroconidia cylindrical-fusiform, allantoid to ellipsoid, straight or curved, rounded or somewhat pointed at apex, rounded or attenuated and with an indistinct, barely or non-protruding scar at base, smooth, aseptate, hyaline, and thin-walled when liberated, mostly filled with numerous oil droplets; later becoming septate and brown. Microconidia present or absent, cylindrical, rounded at apex, narrowly truncate at base, aseptate, hyaline, thin- and smooth-walled, with minute granular contents (adapted from Chen et al. 2016).

Culture characteristics:

Colonies on OA white, cottony. Colonies on PDA orange or red, slimy.

Optimal media and cultivation conditions:

OA at 25 °C under near-ultraviolet light (12 h light, 12 h dark); OA supplemented with sterile nettle stems (Anthriscus sylvestris) or direct inoculation into apple fruit (Malus domestica) can be used to induce sporulation.

Distribution:

Worldwide.

Hosts:

Pathogens or harmless saprobes of apples and pears, but also of several other hosts such as species of Prunus and Populus.

Disease symptoms:

Anthracnose canker, perennial canker and bull's-eye rot.

Notes:

Neofabraea was introduced by Jackson (1913) to accommodate the sexual morph Gloeosporium malicorticis. Subsequently, Nannfeldt (1932) synonymised this genus with Pezicula. However, Verkley (1999) revalidated it in a world monograph of Pezicula and observed that species of Neofabraea are more explicitly pathogenic than those of Pezicula. Neofabraea differs from Pezicula in that Neofabraea produces ascomata with excipular tissues less differentiated and macroconidia more strongly curved with the basal scar less distinct than in Pezicula. Moreover, Pezicula comprises species that have two types of conidiogenesis: conidiogenous cells are determinate and phialidic, or indeterminate and proliferating percurrently; while Neofabraea spp. only produces phialidic conidiogenous cells (Chen et al. 2016). Recently, Chen et al. (2016) carried out a revision of the genus by performing a phylogenetic study based on LSU, ITS, tub2 and rpb2 sequences of Neofabraea, Pezicula and related genera. Consequently, the genus Phlyctema was re-established to accommodate Neofabraea alba, which is the main pathogen causing bull's eye rot in continental Europe. Moreover, the new genera Parafabraea and Pseudofabraea were introduced in order to accommodate Neofabraea eucalypti and Neofabraea citricarpa, respectively (Chen et al. 2016).

References:

• Verkley 1999 (morphology and pathogenicity), Wang et al. 2015 (morphology and key of Neofabraea spp.), Chen et al. 2016 (phylogeny). 
• Chen C, Verkley GJM, Sun G, et al. (2016). Redefining common endophytes and plant pathogens in Neofabraea, Pezicula, and related genera. Fungal Biology 120: 1291–1322.
• Jackson HS (1913). Apple tree anthracnose. Oregon Agricultural Experiment Station Biennial Crop, Pest and Horticulture Report 1911–1912: 178–197.
• Nannfeldt JA (1932). Studien uber die morphologie und systematik der nicht-lichenisierten inoperculaten discomyceten. Nova Acta Regiae Societatis Scientiarum Upsaliensis, ser. 4 8: 1–368.
• Verkley GJM (1999). A monograph of the genus Pezicula and its anamorphs. Studies in Mycology 44: 1–180.
• Wang L, Sun X, Wei J-G, et al. (2015). A new endophytic fungus Neofabraea illicii isolated from Illicium verum. Mycoscience 56: 332–339.

Table 11. DNA barcodes of accepted Neofabraea spp.

¹CBS: Westerdijk Fungal Biodiversity Institute, Utrecht, the Netherlands; CNPUV: Centro Nacional de Pesquisa de Uva e Vinho, Bento Gonçalves, RS, Brazil. ^T and ^NT indicates ex-type and ex-neotype strains, respectively.

²ITS: internal transcribed spacers and intervening 5.8S nrDNA; rpb2: partial RNA polymerase II second largest subunit gene; tub2: partial β-tubulin gene.

•  
• Chen C, Verkley GJM, Sun G, et al. (2016). Redefining common endophytes and plant pathogens in Neofabraea, Pezicula, and related genera. Fungal Biology 120: 1291–1322.
• Crous PW, Wingfield MJ, le Roux JJ, et al. (2015). Fungal Planet description sheets: 371–399. Persoonia 35: 264–327.
• De Jong SN, Levesque CA, Verkley GJM, et al. (2001). Phylogenetic relationships among Neofabraea species causing tree cankers and bull’s-eye rot of apple based on DNA sequencing of ITS nuclear rDNA, mitochondrial rDNA, and the β-tubulin gene. Mycological Research 105: 658–669.