Organik Tarım Bölümü Koleksiyonu

Permanent URI for this collectionhttps://hdl.handle.net/20.500.12514/109

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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.
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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Browsing Organik Tarım Bölümü Koleksiyonu by Author "Dervis, Sibel"