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    Ganoderma butt rot of hazelnut (Corylus avellana) caused by Ganoderma adspersum in Türkiye
    (Wiley, 2024) Turkkan, Muharrem; Dervis, Sibel; Ozgumus, Oezlem; Ozer, Goeksel
    In September 2022, hazelnut trees in six orchards in the & Ccedil;ar & scedil;amba district of Samsun province, a major hazelnut production area in the Black Sea region of T & uuml;rkiye, showed symptoms of leaf yellowing, shoot dieback, decline, basal stem rot and the presence of brown bracket-like sessile basidiocarps. Approximately 5%-10% of hazelnut trees were affected, highlighting the significant impact of the disease. A comprehensive morphological analysis was conducted to characterize fungal isolates obtained from symptomatic tissues as G. adspersum. This analysis incorporated features observed in basidiomata from declining trees and those reproduced after isolates were cultivated on wheat grain for spawn production and grown on an oak sawdust-based substrate. Confirmation of identification was achieved through the utilization of the internal transcribed spacer (ITS), large subunit (LSU) and small subunit (SSU) loci, along with sequencing and subsequent phylogenetic analysis. The G. adspersum isolates generally exhibited no significant growth differences at similar temperatures but demonstrated enhanced growth at 30 degrees C, while growth was completely inhibited at 40 degrees C. Incompatible reactions between isolates confirmed that distinct genotypes were present, highlighting genetic diversity within the species. In the pathogenicity trials, employing a single infested wheat grain per inoculation at the wounded site, hazelnut suckers exhibited distinct brown discolouration surrounding the inoculation site following a 2.5-month incubation period. Significantly, lesions exceeding 3 cm in length were observed, providing clear evidence of vigorous pathogenic activity by G. adspersum. This study is the first report of G. adspersum causing butt rot in hazelnuts, underscoring the significance of this finding for hazelnut cultivation and providing a foundation for future research and disease management strategies.
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    Morphological, physiological, molecular, and pathogenic insights into the characterization of Phytophthora polonica from a novel host, hazelnut (Corylus avellana)
    (Academic Press Ltd- Elsevier Science Ltd, 2024) Turkkan, Muharrem; Ozer, Goksel; Dervis, Sibel
    Hazelnuts, constituting a significant global crop, hold paramount importance in Turkiye, contributing to approximately 71.14 % of the world's hazelnut cultivation area. In the summer of 2023, hazelnut trees in two orchards situated in the Altinordu district of Ordu province, within the Black Sea region of Turkiye, the largest producer and exporter of hazelnuts, exhibited symptoms of decline associated with root rot. Phytophthora sp. was consistently isolated from necrotic taproots, initiating an in-depth study to discern the causal agent behind the observed hazelnut decline. The species was identified as P. polonica by its distinctive morphological traits, including homothallic characteristics, amphigynous or paragynous antheridia, long nonbranching sporangiophores, and nonpapillate sporangia with internal proliferation. Multiple genetic markers (ITS, tub2, and COI) facilitated a clear differentiation of P. polonica from other Phytophthora species within Clade 9, supporting its classification within Subclade 9b. This investigation also evaluated the impact of diverse nutrient media (CA, V8A, and CMA), temperatures, and pH levels on the mycelial growth of P. polonica HPp-1 and HPp-2 isolates. The optimal conditions for maximal mycelial growth were determined through the D-optimal design of the Response Surface Method, revealing the significant influence of all factors on mycelial growth. The identified optimal conditions were at 26.09 degrees C, pH 5.12, with CMA as the nutrient medium. Validation experiments conducted under these optimal conditions unveiled mycelial growth of 7.24 +/- 0.15 mm day(-1) and 6.81 +/- 0.09 mm day(-1) for P. polonica HPp-1 and HPp-2 isolates, respectively, with an error of less than 5 %. Pathogenicity assessments confirmed P. polonica's virulence on hazelnuts, with distinct lesion development observed in twig inoculation, cut stem segments, and foliar tests. While no statistically significant difference was noted in lesion areas between HPp-1 and HPp-2 isolates in twig and stem segment assays, a statistical difference in leaf lesion areas (19.96 +/- 2.04 cm(2) and 9.16 +/- 3.43 cm(2)) emerged in foliar tests after only a 5-day incubation period, indicating their high susceptibility to the pathogen. This study is the first to report P. polonica as a hazelnut pathogen in Turkiye and around the world, highlighting the previously non-existent threat of Phytophthora root rot in hazelnuts, given the substantial lack of scientifically documented cases related to hazelnut root rot diseases. The quadratic model design employed in physiological analyses is reliable for optimizing mycelial growth and can serve as a guiding framework for similar investigations.
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    Neoscytalidium dimidiatum: A newly identified postharvest pathogen of pears and its implications for pome fruits
    (Wiley, 2024) Dervis, Sibel; Zholdoshbekova, Sezim; Guney, Inci Guler; Ozer, Goksel
    T & uuml;rkiye is a prominent contributor to pear and diverse pome fruit production. Pear fruit with unusual brown to black spots and rot symptoms observed in public marketplaces in Mardin province have raised concerns regarding postharvest fruit health. The consistent isolation of a fungus from these fruits revealed morphological features indicative of Neoscytalidium dimidiatum. Phylogenetic confirmation of its identity ensued through BLASTn searches targeting, the internal transcribed spacer (ITS) of ribosomal DNA, the partial translation elongation factor 1-alpha gene (tef1), and the partial beta-tubulin gene (tub2). Pathogenicity evaluations were conducted on common pome fruits, namely pears, apples, and quinces, unveiling the susceptibility of all examined fruits to postharvest infection by this emergent pathogen. Furthermore, an investigation was carried out to discern the pathogen's response to varying temperature ranges on pear fruits, revealing that the most pronounced lesions occurred at 30 degrees C, followed by 25 degrees C, 35 degrees C, and 20 degrees C. Conversely, no lesion development was observed at 10 degrees C, 15 degrees C, or 40 degrees C. To the best of our knowledge, this study represents the first report of N. dimidiatum as the etiological agent responsible for postharvest rot in pear fruit. The implications of these findings highlight the potential threat posed by this pathogen to pome fruits postharvest, especially in regions where cold storage facilities are not widely utilized, warranting increased vigilance and preventive measures.
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    New Detection Methods for Cryphonectria Hypovirus 1 (CHV1) through SYBR Green-Based Real-Time PCR and Loop-Mediated Isothermal Amplification (LAMP)
    (Mdpi, 2024) Celik, Ali; Cakar, Deniz; Dervis, Sibel; Morca, Ali Ferhan; Simsek, Secil Akilli; Romon-Ochoa, Pedro; Ozer, Goksel
    Some mycoviruses can be considered as effective biocontrol agents, mitigating the impact of phytopathogenic fungi and consequently reducing disease outbreaks while promoting plant health. Cryphonectria parasitica, the causal agent of chestnut blight and a highly destructive pathogen, experienced a notable decrease in its virulence with the identification of cryphonectria hypovirus 1 (CHV1), a naturally occurring biocontrol agent. In this study, two innovative diagnostic protocols designed for the accurate and efficient detection of CHV1 are introduced. The ORF A and ORF B regions of CHV1 are targeted by these techniques, which employ colorimetric loop-mediated isothermal amplification (LAMP) with 2 Colorimetric LAMP Master Mix and real-time quantitative PCR (qPCR) with SYBR Green chemistry, respectively. The LAMP assay presents a discernible color transition, changing from pink to yellow after a 35 min incubation period. Comparative analysis, when assessed against two established reverse transcription-PCR (RT-PCR) techniques, reveals a significant enhancement in sensitivity for both the LAMP approach, which offers a tenfold increase, and the qPCR method, which showcases a remarkable 100-fold sensitivity improvement. Throughout the comparison phase, it was evident that the RT-PCR, LAMP, and qPCR procedures displayed superior performance compared to the Bavendamm test, relying on phenol oxidase activity, effectively distinguishing hypovirulent strains. Consequently, this study introduces two pioneer diagnostic assays for highly sensitive CHV1 detection, representing a substantial advancement in the realm of CHV1 surveillance techniques. These methodologies hold significant promise for enhancing research endeavors in the domain of the biological control of C. parasitica.