Forest Pathology最新文献

The European beech (Fagus sylvatica) is threatened by the foliar nematode Litylenchus crenatae subsp. mccannii (Lcm), the causal agent of beech leaf disease (BLD). Thus far, the majority of studies regarding BLD have focused on American beech (F. grandifolia). To better determine the impact of Lcm in buds of European beech, a total of 54 buds were collected from naturally symptomatic trees. Here, we characterized for the first time the bud scale morphology of two different cultivars of F. sylvatica infected with Lcm. Detailed observations of asymptomatic and symptomatic bud scales provided insight into the physical changes and arrangements of cells in the bud scale, shedding light on the dynamic processes occurring during Lcm infection. In addition, we evaluated the suitability of using the bud scale morphology for the early detection of BLD and Lcm in naturally infected buds. The distinct cellular arrangement of symptomatic bud scales cells (i.e., asymmetric pattern of enlarged cells) provides a rapid and visual, user-friendly methodology to prematurely diagnose BLD symptoms within the buds, as well as the detection of associated nematodes.

The author affiliations in the published version were incorrect and the corrected version is as follows.

Valeh abbasi¹, Heshmatollah Rahimian¹, Mohammad Ali Tajick-Ghanbari¹ and Ali Barzegar².

¹Department of Plant Protection, Faculty of Agronomy Sciences, Sari Agricultural Sciences and Natural Resources University (SANRU), Iran.

²Department of Basic Sciences, Sari Agricultural Sciences and Natural Resources University (SANRU), Iran.

We apologize for this error.

Hyrcanian forests comprise a long strip along the southern coast of the Caspian Sea in northern Iran. Oriental beech (Fagus orientalis) is one of the most valuable forest tree species in the Hyrcanian forests. Bark necrosis and bleeding spots of oriental beech were observed in Savadkuh forests in Mazandaran province during summer 2021. Ten samples were collected from symptomatic oriental beech trees. The bark canker symptoms included stem tissue necrosis, dark brown to black spots on the trunk, bleeding with dark exudates and dark lesions in the inner bark. Twenty-six strains of culturable bacteria were isolated from the samples which in culture were predominantly round, convex, smooth with entire margins on nutrient agar and a metallic green sheen pigment on eosin-methylene blue (EMB) agar. Fourteen strains induced necrosis and browning of the tissues around the inoculation sites on acorns after 2 weeks. Five representative strains also caused dieback in twigs of oriental beech 3 weeks after inoculation. These bacteria were Gram-negative, catalase positive and oxidase negative. All strains produced colonies with a green metallic sheen on EMB agar. Strains were negative in tests for starch and gelatine hydrolysis or production of levan. A phylogenetic tree based on concatenated sequences of gyrB and infB genes, of representative strains well as in each of the single gene-based phylogenetic trees, indicated that these strains clustered with Brenneria alni NCPPB 3934^T with high bootstrap values. To the best of our knowledge, this is the first report of B. alni associated with bark necrosis and bleeding spots on oriental beech.

In December 2022, a leaf spot and blight disease was observed in Eucalyptus plantations in northern India. Morphological features coupled with phylogenetic analysis of combined internal transcribed spacer (ITS), translation elongation factor 1-alpha (tef1) and β-tubulin (tub2) regions confirmed the association of Pseudoplagiostoma eucalypti with the disease symptoms. The pathogenicity of P. eucalypti was first proved on detached leaves of Eucalyptus camaldulensis and reconfirmed in glasshouse inoculation experiments. Finally, Koch's postulates were fulfilled by re-isolating the pathogen from the inoculated leaves. This pathogen was first described in 1995 from the leaves of Eucalyptus spp. collected from southern India, and this study confirms its first serious occurrence after more than two decades in northern India. In addition, this is the first report on the polyphasic characterization of P. eucalypti from India.

Due to intense ash dieback, this research tested the bioactivity of Thymus vulgaris, Lavandula angustifolia, and Cupressus sempervirens essential oils (EO) against Hymenoscyphus fraxineus. In vitro testing showed that EOs had a pronounced fungitoxic effect on H. fraxineus. The most effective EO was extracted from T. vulgaris, while EOs obtained from L. angustifolia and C. sempervirens were less effective and showed the same effect. At a concentration of 1%, all tested EOs inhibited mycelial growth, while 0.01% and 0.1% concentrations of EO extracted from T. vulgaris also inhibited the growth of H. fraxineus. The in planta test of EO extracted from T. vulgaris conducted on three-year-old Fraxinus angustifolia seedlings showed a reduction in the size of necrotic lesions and a better crown condition compared to untreated seedlings. This research demonstrates, for the first time, the efficiency of EOs in suppressing ash dieback making a path for the development of new biological protection measures against H. fraxineus.

Introduction: The purpose of this study was to assess internet, social media, and related technology use in patients with serious mental disorders, and to examine their relationship with disease severity and functionality and gain insight about the thoughts of patients with severe mental disorders on benefits and risks of social media.

Methods: The study included 150 patients with bipolar disorder and 150 patients with schizophrenia spectrum disorder (82 with schizophrenia, 56 with psychotic disorders not otherwise specified and 12 with schizoaffective disorder) in remission. Information about demographics, clinical features, the use of social media and related technologies, and opinions on social media use were obtained via a data form prepared by the clinicians. Severity of disease and symptoms were measured using the Hamilton Rating Scale for Depression, the Young Mania Rating Scale, the Brief Psychiatric Rating Scale and, the Clinic Global Impression Scale. The Functioning Assessment Short Test was used to evaluate psychosocial functioning.

Results: Among the patients who participated in the current study, 65.3% (n=196) reported internet use and, 59.7% (n=179) reported social media use. The Functioning Assessment Short Test total scores and the Clinic Global Impression Scale scores were significantly higher in patients who did not use social media than in those who did. The use of social media, mobile phones, smartphones, short message services (SMS), e-mail was significantly higher in patients with bipolar disorder than in patients with schizophrenia spectrum disorder.

Conclusion: The use of social media, Internet and mobile devices cannot be underestimated among patients with serious mental disorders.

Endophytic fungi pass all or at least a part of their life cycle inside or between host cells in living plant tissues. These fungi are not capable of causing disease in the host plants, however, they are deemed to be associated with the production of some secondary metabolites in plants. Therefore, this study was laid out to shed light on how fungicides are involved in the formation of key metabolites of yew (Taxus baccata L.), especially taxol. Through the symbiotic fungal endophyte activities and population changes an experiment was conducted as a completely randomized block design using two foliar application treatments of Rovral-TS and Fosetyl aluminium fungicides. Plants sprayed with distilled water were used as a control. The findings revealed that the diversity of endophytic fungi declined with the application of systemic fungicides, leading to a decrease in the production of certain secondary metabolites. Specifically, the levels of paclitaxel decreased by 35%, while the photosynthetic pigments chlorophyll-a, chlorophyll-b and total chlorophyll decreased by 26%, 20.6% and 19.6%, respectively. Additionally, the levels of carotenoids, total phenol and total flavonoids decreased by 18%, 15% and 21.8%, respectively. The highest amount of these compounds was observed in the control treatment. An increase in antioxidant activity, soluble sugars and proline content was observed soon after fungicides application. The variation in the content of soluble sugars, proline and antioxidant activity was fungicide-dependent. Compared to Fosetyl aluminium fungicide, the numerical value of the above parameters in plants treated with Rovral-TS was 14.4%, 11.7% and 25.4% higher, respectively. The fungicide-mediated induction of Taxol production—key secondary metabolites in yew—was to a great extent associated with the change in endophytic fungi. This further establishes the role of fungal endophytes in the stimulation of secondary metabolite formation in yew plants.

Recently, a previously unseen Exobasidium leaf blister disease was observed on Rhododendron mucronulatum in its natural habitat in Korea. The fungus associated with the disease was identified as Exobasidium miyabei based on morphological characteristics and two-locus sequence analyses. To our knowledge, this is the first report of E. miyabei in Korea and of its novel association with the host species, R. mucronulatum.

Needle diseases caused by pathogens within Rhytismataceae are increasing in frequency globally where pines are either a predominate species or are grown commercially, and yet remain poorly understood. Here, we provide background information on the current knowledge and management strategies of needle pathogens in the Rhytismataceae and discuss research opportunities using molecular tools to fill knowledge gaps. Many of the aggressive needle pathogens within this group lack morphological features to delimit species and are difficult to grow in axenic cultures, which complicates scientific investigations. Molecular research has greatly advanced knowledge of this unique group of pathogens. Nucleotide sequences from multiple gene loci identified greater diversity within this group of pathogens than previously thought, as new and cryptic species are being discovered in broader geographic regions. High throughput sequencing and analyses revealed that an endophytic lifestyle is a common trait among fastidious if not obligate needle pathogens within Rhytismataceae. Further, molecular analyses showed the impact these pathogens have on the diversity of endophytic microbiota is underestimated. Early detection in healthy-looking needles using PCR-based markers greatly improves capabilities for disease diagnosis and monitoring. Despite growing number of molecular studies on Rhytismataceae needle pathogens, fundamental questions on the taxonomy, phylogeny, ecology and pathology of many Rhytismataceae needle pathogens remain unanswered. Nonetheless, with the projected changes in the occurrence and severity of Rhytismataceae pathogens, increased accessibility to molecular tools vastly expands the potential to gain more insights into understudied needle pathosystems to help define and address its impact under changing environments and consequently inform forest disease management more effectively.

Sydowia polyspora is a common fungal species living on conifers, often occurring as an epiphyte or endophyte on asymptomatic plants and in seeds. The fungus may become pathogenic under abiotic or biotic stress conditions. It is often associated with current season needle necrosis and shoot dieback on conifer species, especially Abies spp. and Pinus spp. throughout Europe and North America. The conifer Pinus brutia is common and widely distributed in Türkiye and is frequently used in reforestation. The work described here aimed to investigate the S. polyspora associated with needle necrosis and shoot dieback in five different Pinus brutia stands located in Denizli-Türkiye, to determine the severity of the disease and to reveal the pathogenicity of this agent in P. brutia seedlings. For this purpose, fungal isolations from symptomatic P. brutia needles were carried out in five different stands. In total, 68 S. polyspora isolates were obtained, each from a different tree from which macroscopic-microscopic morphological characterization was made and molecular characterization was done using the internal transcribed spacer (ITS) region. BLAST analysis of the ITS sequences confirmed the identification of the isolates, with 99–100% similarity to previously reported sequences of S. polyspora. Disease incidence and severity were assessed in five P. brutia stands. The disease incidence ranged between 38% and 62% (mean = 47%) while disease severity varied among sites. Pathogenicity studies were carried out on 2-year-old P. brutia seedlings using obtained isolates. Infection frequency in inoculated shoots was 90%. The pathogenicity tests, followed by re-isolation of the fungus from symptomatic shoots clearly demonstrated that S. polyspora played a role in the development of needle necrosis and shoot dieback in P. brutia stands. To the best of our knowledge, this is the first report of current season needle necrosis and shoot dieback on P. brutia caused by S. polyspora in Türkiye.