First Report of Fruit Canker Caused by Nothophoma quercina on Chinese quince in South Korea.

The Chinese quince (Pseudocydonia sinensis (Thouin) CK Schneid.) is a tree that is commonly distributed in all regions of South Korea and other Asian countries. The ripened yellow fruit contains medically active compounds (Hamauzu et al. 2005). It has been consumed as tea and candies and used in traditional medicine for treating asthma, cough, influenza, harsh throat, and tuberculosis and for liver protection (Chun et al. 2012). In the Kyungpook National University campus (Daegu, South Korea), fruit canker on the Chinese quince was ubiquitously observed during May-August 2020. The average disease incidence was around 30%-40%, which caused significant yield loss. Initially, minute, brown-to-rust-colored, unbroken, circular, necrotic areas appear, and in the advanced stage of infection, the epidermis tears open and tube- or aecia-like white structures are formed. Successively, the affected areas become necrotic and gradually enlarge to reach 3-5 cm in diameter. To isolate the causative pathogen, symptomatic tissues obtained from diseased fruits were surface-sterilized for 1 min with 70% ethanol, rinsed in sterile distilled water, and plated onto potato dextrose agar (PDA). The inoculated plates were incubated for 7 days at 25°C. Successively, pure cultures were obtained by transferring hyphal tips to new PDA plates. A total of 15 isolates were obtained across 20 fruit trees investigated. The colonies on the PDA plates reached a diameter of 60-70 mm after 7 days at 25°C, spreading with a regular margin, aerial mycelium covering the entire colony, compact, white to pale gray in color, and solitary and globose pycnidia were produced after ten days. Conidiogenous cells were phialidic, hyaline, simple, smooth, doliiform to ampulliform, 3-5 × 3-4 µm; conidia were subglobose to oval or obtuse, thin-walled, smooth, aseptate, minute guttules, brown, 5.5-8 × 4-7 µm. These morphologies corresponded to those of phoma-like species. Sequence data for the 28S nrDNA, the internal transcribed spacer, ß-tubulin, and RNA polymerase II subunit (White et al. 1990, Liu et al. 1999, Aveskamp et al. 2009) were obtained randomly for one of the pure isolates (EAH 2), which resulted in the GenBank accession numbers MW325675, MW325676, MW330391, and MW330390, respectively. The RAxML analysis (Stamatakis 2014) was run on the CIPRES Science Gateway portal of the combined sequence data of the isolate EAH 2 and the reference sequences obtained from GenBank. Analyses for the combined datasets were conducted with RAxML-HPC2 on XSEDE v. 8.2.10 using a GTR+GAMMA substitution model with 1000 bootstrap iterations. Results demonstrated that the isolate EAH2 formed a strongly support clade with the type isolates of Nothophoma quercina (Syd.) Q. Chen & L. Cai (basionym: Ampelomyces quercinus), which has been found on Quercus sp. in Ukraine (Chen et al. 2015). The procedure for Koch's postulates was followed to confirm fungal pathogenicity using 3-day-old mycelial disks. A total of 15 same-aged healthy fruits were divided into three groups, and each group received a different treatment. Artificial wounds were created on one group of fruits using a sterile pin, and a 5-mm mycelial plug of the fungus was placed on the injured tissues. Mycelial plugs were also placed on the surfaces of the sets of unwounded fruits. The remaining fruits were maintained as control and inoculated with sterile PDA plugs. The test was repeated three times. The wounded fruits exhibited symptoms after 8-10 identical to those observed in the field. The control group remained asymptomatic, and the morphology of the fungus reisolated from the inoculated fruits was similar to that of N. quercina. The phylogeny, together with morphological identification and inoculation results, confirmed the identity of the fungus as N. quercina (Chen et al. 2015). A previous study had also reported shoot canker caused by N. quercina in the Chinese quince (Yun and Oh 2016). However, to our knowledge, this is the first report of fruit canker caused by N. quercina in the Chinese quince.

First Report of Didymosphaeria rubi-ulmifolii Brown Spot infection of Chinese quince fruit in South Korea.

Chinese quince (Pseudocydonia sinensis (Thouin) CK Schneid.), a deciduous tree in the family Rosaceae, is native to China, Japan, and South Korea; the fruit is known as mogwa in South Korea. The ripened yellow fruit has been used as a traditional therapeutic for respiratory ailments and as an additive in health products such as syrups, tea, and candies (Sawai et al. 2008). From May to August 2020, Chinese quince trees showing symptoms of brown spots were observed on the Kyungpook National University premises, Daegu, South Korea, with an incidence of 30%-40%. The disease first appeared as small, round, yellow specks on the fruits, which necrotized over time and gradually enlarged to 0.7-2.7 cm in diameter. To isolate the pathogen, symptomatic tissues obtained from disease fruit were surface sterilized for 1 min with 70% ethanol, rinsed in sterile distilled water, and plated onto potato dextrose agar (PDA). The inoculated plates were incubated at 25°C for 7 days. Successively, pure cultures were obtained by transferring hyphal tips to new PDA plates. Twenty isolates were obtained from 25 fruit. Colonies on PDA reached a diameter of 30-40 mm. After incubation for 7 days at 25°C, spreading with an even, colorless-to-buff glabrous margin, a submarginal ring of conidiomata developed from day 5 to 12 and was visible as scattered dots on either side of the plate. Conidiogenous cells were discrete (3.5-6 × 3.5-5 µm); conidia were ellipsoid to short-cylindrical [3-5 × 2.1-3.5 µm (n = 60)] and olivaceous in color. These conidial dimensions corresponded to those of Didymosphaeria rubi-ulmifolii Ariyaw., Camporesi & K.D. Hyde (basionym: Paraconiothyrium brasiliense), which has been found on Rubus ulmifolius in Italy (Ariyawansa et al. 2014). Sequence data for the rDNA internal transcribed spacer (ITS), large subunit ribosomal RNA (LSU), and partial translation elongation factor 1-α (TEF) (White et al. 1990, Rehner and Buckley 2005) were obtained for one of the pure culture isolate (BT1) with GenBank accession numbers MW020087, MW020060 and MW027220, respectively. The sequences of BT1 isolate using a BLASTn analysis showed 100% identity with the ex-type MFLUCC 14-0023 of D. rubi-ulmifolii in ITS, and LSU portions (accession nos. MT310602, and MT214555, respectively) and 99% identity in TEF portion (accession no. MT394734). The procedure for Koch's postulates was followed to confirm fungal pathogenicity using 3-day-old mycelial discs. Fifteen healthy fruit were divided into three groups of five fruit each, with each group receiving a different treatment. One group of fruit was wounded by puncturing with a sterile pin and inoculated using 5-mm agar discs with mycelium on the wounds. Mycelium covered agar discs were also placed on the surfaces of five unwounded fruits. The remaining five fruit were maintained as a control and inoculated with sterile PDA plugs. The pathogenicity test was replicated thrice. The wounded fruits showed symptoms similar to those observed in the field. The control group remained asymptomatic and the morphology of the fungus re-isolated from the inoculated fruit was the same as that of D. rubi-ulmifolii. The phylogeny, together with the morphological identification and inoculation results, confirmed the identity of the fungus as D. rubi-ulmifolii (Ariyawansa et al. 2014). To the best of our knowledge, this is the first report of D. rubi-ulmifolii causing brown spot in Chinese quince.

Brunneosporopsis yunnanensis gen. et sp. nov. and Allocryptovalsa xishuangbanica sp. nov., New Terrestrial Sordariomycetes from Southwest China.

Three fungal taxa were collected on dead branches of wood during fieldwork in Sichuan and Yunnan Provinces, China. The new generic name Brunneosporopsis gen. nov. and species B. yunnanensis sp. nov. are introduced for a novel taxon characterized by globose to subglobose and dark olivacous-brown conidia. Phylogenetic analyses based on combined LSU, SSU and tef1-α loci strongly support the monophyly of this taxon and place it in the subclass Diaporthomycetidae. It could not be assigned to any currently recognized families in the subclass and was, therefore, placed in the Diaporthomycetidae genera incertae sedis. A second taxon represents a new species in Allocryptovalsa based on an analysis of the sequence datasets of ITS and btub loci of the novel, brown-spored sexual morphic species. This taxon is described here as A. xishuangbanica sp. nov. An interesting hypocrealean fungus producing synnemata, Stilbocrea gracilipes, was collected from dead wood of an unknown host from Sichuan Province and is reported here, with asexual morph from both the host and culture as well as LSU, ITS, tef1-α, rpb2 and rpb1 sequence data.

Illumina-MiSeq analysis of fungi in acid lime roots reveals dominance of Fusarium and variation in fungal taxa.

A study was conducted to analyze fungal diversity in the roots of acid lime (Citrus aurantifolia) collected from Oman, a semi-arid country located in the South Eastern part of the Arabian Peninsula. MiSeq analysis showed the Ascomycota and Sordariomycetes were the most abundant phylum and class in acid lime roots, respectively. Glomeromycota, Basidiomycota and Microsporidia were the other fungal phyla, while Glomeromycetes and some other classes belonging to Ascomycota and Basidiomycota were detected at lower frequencies. The genus Fusarium was the most abundant in all samples, making up 46 to 95% of the total reads. Some fungal genera of Arbuscular mycorrhizae and nematophagous fungi were detected in some of the acid lime roots. Analysis of the level of fungal diversity showed that no significant differences exist among groups of root samples (from different locations) in their Chao richness and Shannon diversity levels (P < 0.05). Principle component analysis of fungal communities significantly separated samples according to their locations. This is the first study to evaluate fungal diversity in acid lime roots using high throughput sequencing analysis. The study reveals the presence of various fungal taxa in the roots, dominated by Fusarium species and including some mycorrhizae and nematophagous fungi.

Fungal Diversity in Tomato Rhizosphere Soil under Conventional and Desert Farming Systems.

This study examined fungal diversity and composition in conventional (CM) and desert farming (DE) systems in Oman. Fungal diversity in the rhizosphere of tomato was assessed using 454-pyrosequencing and culture-based techniques. Both techniques produced variable results in terms of fungal diversity, with 25% of the fungal classes shared between the two techniques. In addition, pyrosequencing recovered more taxa compared to direct plating. These findings could be attributed to the ability of pyrosequencing to recover taxa that cannot grow or are slow growing on culture media. Both techniques showed that fungal diversity in the conventional farm was comparable to that in the desert farm. However, the composition of fungal classes and taxa in the two farming systems were different. Pyrosequencing revealed that Microsporidetes and Dothideomycetes are the two most common fungal classes in CM and DE, respectively. However, the culture-based technique revealed that Eurotiomycetes was the most abundant class in both farming systems and some classes, such as Microsporidetes, were not detected by the culture-based technique. Although some plant pathogens (e.g., Pythium or Fusarium) were detected in the rhizosphere of tomato, the majority of fungal species in the rhizosphere of tomato were saprophytes. Our study shows that the cultivation system may have an impact on fungal diversity. The factors which affected fungal diversity in both farms are discussed.

Population genetic analysis reveals a low level of genetic diversity of 'Candidatus Phytoplasma aurantifolia' causing witches' broom disease in lime.

Witches' broom disease of lime (WBDL) is a serious phytoplasma disease of acid lime in Oman, the UAE and Iran. Despite efforts to study it, no systemic study attempted to characterize the relationship among the associated phytoplasma, 'Candidatus Phytoplasma aurantifolia', from the three countries. This study utilized sequences of the 16S rRNA, imp and secA genes to characterize 57 strains collected from Oman (38), the UAE (9) and Iran (10). Phylogenetic analysis based on the 16S rRNA gene showed that the 57 strains shared 98.5-100 % nucleotide similarity to each other and to strains of 'Ca. P. aurantifolia' available in GenBank. The level of genetic diversity was low based on the 16S rRNA (0-0.011), imp (0-0.002) and secA genes (0-0.015). The presence of low level of diversity among phytoplasma strains from Oman, the UAE and Iran can be explained by the movement of infected lime seedlings from one country to another through trading and exchange of infected plants. The study discusses implication of the findings on WBDL spread and management.