Liberomyces pistaciae sp. nov., the causal agent of pistachio cankers and decline in Italy

Abstract

A new canker and decline disease of pistachio (Pistaciavera) is described from Sicily (Italy). Observations of the disease and sampling of the causal agent started in spring 2010, in the area where this crop is typically cultivated, Bronte and Adrano (Catania province) and later extended to the Agrigento and Caltanissetta provinces. Isolations from the margins of twig, branch and stem cankers of declining plants resulted in fungal colonies with the same morphology. Pathogenicity tests on 5-year-old potted plants of Pistaciavera grafted on P.terebinthus reproduced similar symptoms to those observed in nature and the pathogen was confirmed to be a coloniser of woody plant tissue. Comparison of our isolates with the type of the apparently similar Asteromellapistaciarum showed that our isolates are morphologically and ecologically different from A.pistaciarum, the latter being a typical member of Mycosphaerellaceae. Asteromellapistaciarum is lectotypified, described and illustrated and it is considered to represent a spermatial morph of Septoriapistaciarum. Multi-locus phylogenies based on two (ITS and LSU rDNA) and three (ITS, rpb2 and tub2) genomic loci revealed isolates of the canker pathogen to represent a new species of Liberomyces within the Delonicicolaceae (Xylariales), which is here described as Liberomycespistaciaesp. nov. (Delonicicolaceae, Xylariales). The presence of this fungus in asymptomatic plants with apparently healthy woody tissues indicates that it also has a latent growth phase. This study improves the understanding of pistachio decline, but further studies are needed for planning effective disease management strategies and ensuring that the pathogen is not introduced into new areas with apparently healthy, but infected plants.

Didymella corylicola sp. nov., a new fungus associated with hazelnut fruit development in Italy

“…Its abundance in the early stages of fruit development may be facilitated by the psychrophilic nature of this fungus which is able to grow at 5°C. In addition, it seems to be associated only with hazelnut, since it has never been isolated from other common nut species such as walnut and pistachio, which were intensely surveyed in the past years by the authors (Belisario et al 2002;Vitale et al 2007Vitale et al , 2018Scotton et al 2015), and it has never been reported from almond. Although weak pathogenicity was revealed in the inoculation experiments, the impact of D. corylicola on the development of hazelnut fruit is yet unclear.…”

“…The extraction of genomic DNA from pure cultures was performed as reported in previous studies (Voglmayr and Jaklitsch 2011;Vitale et al 2018) by using the DNeasy Plant Mini Kit (QIAgen GmbH, Hilden, Germany) or the Wizard Genomic DNA Purification Kit (Promega Corporation, WI, USA). For the ex-holotype strain of the new species, the complete internal transcribed spacer region (ITS1-5.8S-ITS2) and a ca.…”

Lichens or endophytes? The enigmatic genus Leptosillia in the Leptosilliaceae fam. nov. (Xylariales), and Furfurella gen. nov. (Delonicicolaceae)

“…Therefore, this indicates that the Leptosilliaceae comprise widespread and important components of the endophyte communities of woody hosts, and they may harbour numerous undescribed species especially in understudied tropical and subtropical areas. It is interesting that Leptosillia pistaciae , a recently described canker pathogen of Pistacia vera (Vitale et al 2018), is also embedded within the Leptosillia clade, which indicates that pathogenicity may have secondarily evolved from an endophytic lifestyle. However, it also cannot be excluded that some of the strains isolated as endophytes may actually represent latent pathogens.…”

“…So far, no sexual morph is known for this species. For morphological description, illustrations and pathogenicity, see Vitale et al (2018).…”

Potential Role of Biocontrol Agents for Sustainable Management of Fungal Pathogens Causing Canker and Fruit Rot of Pistachio in Italy

“…Regarding diseases affecting this crop, only a few outdated studies were available until recently. Recent studies conducted in Italy updated the knowledge of fungal diseases of pistachio, specifically canker and dieback caused by Cytospora pistaciae , Eutypa lata and Leptosillia pistaciae (ex Liberomyces pistaciae ) [ 5 , 6 , 7 ]. Among fruit and foliar diseases Arthrinium xenocordella and Tuberculina persicina were reported attacking fruit nuts [ 8 , 9 ] and molecular investigation confirmed the species Septoria pistaciarum as the main foliar pathogen of pistachio in Italy [ 10 ].…”