Molecular and Pathogenic Characteristics of Paecilomyces formosus, a New Causal Agent of Oak Tree Dieback in Iran

Abstract

Oak dieback is one of the most important diseases that presently affects the Kermanshah oak forests (West Iran). During the period from 2013 to 2015, oak trees exhibiting branch dieback were sampled, and fungal colonies resembling those of the Paecilomyces sp. were obtained from diseased tissues. Based on morphology, physiology, and phylogeny of the internal transcribed spacer rDNA, all isolates were identified as Paecilomyces formosus. Pathogenicity tests in vivo were made on 2-year-old seedlings, potted Q. brantii plants, and excised branch sections under controlled conditions. Inoculated seedlings produced characteristic symptoms, and subsequent pathogen recovery confirmed pathogenicity. We determined these to be thermophilic fungi, which may be related to warming and drought. This is the first report of Paecilomyces formosus as the causal agent of Q. brantii dieback in Iran and the world.

Living in the dark: Bat caves as hotspots of fungal diversity

“…Species of Paecilomyces were found in acidic habitats and can tolerate microaerophilic conditions; however, P . formosus can also be found causing plant diseases and as an opportunistic pathogen in humans [ 76 – 78 ]. Basidiomycota taxa needs substrates rich in nutrients (such as wood and dung) to grow in cave environments, and species included in Rigidoporus are mainly found as plant pathogens [ 5 , 72 , 79 ].…”

“…Species identified in Aspergillus section Polypaecilum are mainly treated as xerotolerant/xerophilic and halotolerant/halophilic and found in built environments [74], although a species was recently described from marine sediments in Mexico [75]. Species of Paecilomyces were found in acidic habitats and can tolerate microaerophilic conditions; however, P. formosus can also be found causing plant diseases and as an opportunistic pathogen in humans [76][77][78]. Basidiomycota taxa needs substrates rich in nutrients (such as wood and dung) to grow in cave environments, and species included in Rigidoporus are mainly found as plant pathogens [5,72,79].…”

Transcontinental Dispersal of Nonendemic Fungal Pathogens through Wooden Handicraft Imports

“…4 ) ( A. alternata ( 28 ), A. flavus (postharvest) ( 29 , 30 ), B. austrostipae ( 31 ), Chaetomium globosum ( 32 ), C. cladosporioides ( 33 ), C. lunata ( 34 ), Curvularia sp. ( 34 ), P. formosus ( 35 , 36 ), P. albobadia ( 37 ), Periconia macrospinosa ( 38 ), R. oryzae ( 39 ), R. kalkhoffii ( 40 ), S. commune ( 40 ), and X. badia (decay fungus) ( 41 , 42 ), with three of these not previously reported in the United States: B. austrostipae , P. formosus , and X. badia . These pathogens represent disease agents of cereal crops, fruits/vegetables, trees, and postharvest pathogens, as well as decayers ( 29 , 33 , 40 , 42 ).…”

Morphological and molecular features of stain fungi infecting rubberwood (Hevea brasiliensis)

“…Microscopically, it was observed that the conidiophores had verticillate branches, septate hyphae, hyaline, 3 to 6 phialids, and conidia chains that were fusiform or ellipsoidal in shape with a smaller size, i.e 1.8-2.1 X 2.3-2.8 µm. Sabernasab et al (2019) also showed that the growth of Paecilomyces colonies reached 2.5 cm with a yellow colony surface after being grown in PDA media for seven days. Microscopically, this study found branching conidiophores with one or more phialids, and chain conidia with cylindrical to ellipsoidal shapes were seen measuring 3.53-6.58 (16.3) X 2.01-3.80 (2.75) µm.…”