Browsing by Author "Derviş, S."

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Assessment Of Genetic Diversity Among Fusarium Species Isolated from Wheat Using SCoT Markers
(Namik Kemal University - Agricultural Faculty, 2026) Özer, G.; Yeken, M.; Derviş, S.; Palacıoğlu, G.
Fusarium species pose significant threats to wheat cultivation by inducing root rot, crown rot, and head blight. Understanding the genetic variations within these species is pivotal for effective disease management strategies. This investigation aimed to evaluate the genetic variation among isolates of Fusarium culmorum, F. graminearum, and F. pseudograminearum following their identification via cultural and species-specific PCR assays. The application of species-specific PCR facilitated the precise identification of these species by generating bands of distinct sizes (F. culmorum: 570 bp, F. pseudograminearum: 520 bp; F. graminearum: 420 bp), aligning with morphological classifications. A total of 36 Start Codon Targeted (SCoT) markers were employed to characterize the genetic variability among Fusarium isolates. Among the selected SCoT primers, 181 bands were amplified, with 131 exhibiting polymorphism (72.37%). The percentages of polymorphic bands in primers varied between 61.54 and 89.29. The highest polymorphism locus was observed in Fusarium culmorum with 12.71%, followed by F. pseudograminearum and F. graminearum. The average polymorphism information content and resolving power for the SCoT markers were calculated as 0.26 and 10.04, respectively. Utilizing the unweighted pair group method with arithmetic mean (UPGMA) clustering analysis employing Dice's method, the SCoT data delineated the Fusarium isolates into three distinct clusters corresponding to species. The study which focused on specifically evaluating the genetic diversity of Fusarium culmorum, F. graminearum and F. pseudograminearum, recognized as primary threats to global wheat cultivation, with SCoT markers, substantial genetic variations were revealed among Fusarium isolates at both inter-and intra-species levels. This investigation represents the initial endeavor to elucidate the genetic diversity of Fusarium isolates obtained from wheat utilizing SCoT markers. © 2026, Namik Kemal University - Agricultural Faculty. All rights reserved.
Comparative Aggressiveness and Fungicide Sensitivity of Phytopythium Vexans and P. Litorale Associated With Kiwifruit Vine Decline in Türkiye
(John Wiley and Sons Ltd, 2025) Polat, Z.; Gültekin, M.A.; Özer, G.; Türkkan, M.; Derviş, S.
BACKGROUND: Kiwifruit vine decline syndrome (KVDS) is an economically critical disease threatening production in Türkiye. The oomycetes Phytopythium vexans and P. litorale are increasingly implicated, but their comparative roles and effective management remain poorly understood, creating an urgent need for sustainable control strategies. This study aimed to (i) compare the virulence of these two species and (ii) evaluate the in vitro versus in vivo efficacy of key fungicides to identify reliable control strategies. RESULTS: Pathogenicity assays revealed that P. litorale was significantly more aggressive, causing severe disease (Disease Severity Index, DSI > 70%), whereas P. vexans induced only moderate symptoms (DSI < 42%). A critical disconnect was observed between laboratory and greenhouse fungicide performance. For instance, oxathiapiprolin, which was highly potent in vitro (EC50 = 0.001169–0.006158 μg mL−1), provided only moderate disease control in vivo. Conversely, pyraclostrobin-based fungicides delivered superior protection against the highly aggressive P. litorale, reducing the DSI to a range of 20.83–21.88% and significantly enhancing root biomass. CONCLUSION: This study establishes P. litorale as a highly aggressive pathogen in KVDS etiology and demonstrates that in vitro data alone are misleading for predicting fungicide field performance. Pyraclostrobin-based fungicides are identified as the most effective candidates for managing KVDS caused by P. litorale. These findings underscore the necessity of integrating in vivo validation in screening protocols and adopting species-specific management approaches, providing a critical roadmap for developing sustainable solutions against this devastating disease. © 2025 Society of Chemical Industry. © 2025 Elsevier B.V., All rights reserved.
Emergence of Severe Stemphylium Leaf Blight on Leek (Allium Porrum) During Seed Production in Türkiye
(John Wiley and Sons Inc, 2026) Polat, Z.; Beşirli, G.; Gültekin, M.A.; Derviş, S.; Özer, G.
A severe leaf blight epidemic caused by Stemphylium vesicarium was observed on cultivated leek (Allium porrum L.) in a commercial seed production field in Türkiye. The disease occurred in early summer 2025 during the second year of a biennial seed production cycle, where incidence reached 50%–75%. The extended cultivation period characteristic of seed production (12–18 months) likely served as a key epidemiological driver, enabling pathogen overwintering and extensive inoculum accumulation, in contrast to the shorter cropping period of annual vegetable production systems. The pathogen was identified as S. vesicarium based on morphological features and confirmed by maximum likelihood phylogenetic analysis of combined internal transcribed spacer (ITS) and glyceraldehyde-3-phosphate dehydrogenase (gapdh) gene sequences. Pathogenicity was verified through fulfilment of Koch's postulates using two representative isolates on healthy leek plants. This report constitutes the first confirmed occurrence of S. vesicarium on leek in Türkiye and demonstrates a shift in its epidemiological importance from a minor foliar pathogen in annual systems to the causal agent of a severe epidemic under biennial seed production conditions, highlighting the need for targeted surveillance and management strategies to mitigate disease risk in both seed and commercial leek production. © 2026 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.
First Report of Fomitopsis Marianiae as a Causal Agent of Brown Wood Rot in Hazelnut (Corylus Avellana) Worldwide
(John Wiley and Sons Inc, 2026) Türkkan, M.; Özer, G.; Bozoglu, T.; Erper, İ.; Derviş, S.
Hazelnut (Corylus avellana L.) is a cornerstone of Türkiye's agricultural economy, accounting for over 60% of global production. In 2022, a wood decay disease was observed in orchards of Samsun Province, affecting 3% (15 of 500) of surveyed trees. Symptoms included branch dieback and canopy chlorosis, while internal inspection revealed extensive brown rot of the xylem. Fungal isolates consistently produced white, fast-growing colonies with clamp connections. Multilocus sequencing of the internal transcribed spacer (ITS), large subunit (LSU) and small subunit (SSU) ribosomal DNA regions, and the partial translation elongation factor 1-alpha (tef1) gene identified the pathogen as Fomitopsis marianiae. Phylogenetic analysis of ITS + tef1 datasets placed the Turkish isolate within the F. marianiae clade. Pathogenicity was confirmed by inoculating 1-year-old hazelnut seedlings, which developed necrotic lesions averaging 3.88 ± 0.22 cm within 3.5 months; the fungus was successfully reisolated, fulfilling Koch's postulates. This study represents the first report of F. marianiae as a pathogen of hazelnut and, more broadly, its first documentation in any agricultural system. These findings identify F. marianiae as an emerging threat to a globally important nut crop and highlight the need for targeted disease surveillance and management strategies. © 2026 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.
Citation - Scopus: 5
First Report of Phytopythium Litorale Causing Root Rot of Apple in Turkey
(Springer Science and Business Media Deutschland GmbH, 2020) Türkölmez, Ş.; Özer, G.; Derviş, S.; Çiftçi, O.; Mert, F.
Citation - Scopus: 1
A new host for Fusarium algeriense causing crown and root rot on barley in Kyrgyzstan
(Wiley Online Library, 2022) Zholdoshbekova S; Bozoğlu T.; Erper I.; Derviş, S.; Özer, G.
After maize, wheat and rice, barley is the most widely planted and economically important cereal crop in the Kyrgyzstan’s highlands (Usubaliev et al., 2013) and worldwide. In two barley fields in the Manas district of Bishkek, Kyrgyzstan, diseased plants exhibiting crown and root rot, stunting and brown discolouration on internodes were observed in 2020. Disease incidence was approximately 5% in the two fields.
Nonlinear Modeling of Temperature-Driven Mycelial Growth Reveals Divergent Thermal Niches in Multinucleate and Binucleate Rhizoctonia Isolates
(American Chemical Society, 2025) Türkkan, M.; Özer, G.; Derviş, S.
Temperature fundamentally governs fungal growth and pathogenic potential, yet conventional polynomial approaches often produce biologically unrealistic cardinal temperature estimates. Robust thermal performance characterization is crucial for disease risk prediction and elucidating the ecological adaptations of Rhizoctonia spp., a soilborne pathogen of substantial economic and ecological significance. We conducted a systematic comparison of 11 nonlinear regression frameworks to describe temperature-dependent mycelial growth dynamics across 17 isolates, encompassing 11 binucleate (BN) Rhizoctonia and six multinucleate (MN) R. solani anastomosis groups (AGs). We evaluated model performance using a multicriteria approach that combined goodness-of-fit statistics (adjusted R2, RMSE, SE) with information-theoretic measures (AICc, Akaike weights ωi). No single model proved universally superior. However, asymmetric models consistently outperformed symmetric ones in capturing nonlinear thermal responses. Thermal characterization using the best-fit models revealed divergent ecological strategies: BN Rhizoctonia isolates showed broad thermal tolerance ranges (base temperature, Tb: 5.43–13.86 °C; optimal temperature, Topt: 19.42–31.03 °C), indicative of generalist adaptation. Conversely, MN R. solani isolates exhibited restricted, elevated-temperature preferences (Tb: 7.18–15.47 °C; Topt: 24.70–28.39 °C), reflecting a specialized, highly aggressive pathogenic phenotype. Bootstrap resampling (n = 1,000) confirmed overwhelming statistical significance for all cardinal parameters (p < 10–9), with optimal temperatures exhibiting the highest precision (median SE = 0.28 °C). Our findings highlight the value of nonlinear, biologically grounded models─notably Segmented and Weibull formulations─for resolving thermal growth kinetics in Rhizoctonia spp. The multicriteria model selection strategy we present has wide-ranging applicability to ecophysiological investigations and facilitates climate-adaptive approaches to disease forecasting and integrated management. © 2025 American Chemical Society
Occurrence of Fusarium Ananatum on Marketed Pineapples: First Report of Fruitlet Core Rot and Crown Rot in Türkiye
(John Wiley and Sons Inc, 2026) Türkkan, M.; Bozoglu, T.; Özer, G.; Alkan, M.; Derviş, S.
Pineapple is an increasingly important tropical fruit crop in Türkiye; however, its quality is threatened by significant postharvest diseases. In June 2025, symptomatic pineapples were observed in central retail markets in Ordu Province, Türkiye. To identify the causal agent of the observed fruit and crown decay, affected fruits displaying distinct crown necrosis, bract browning, and cottony white to cream mycelial growth were collected. A fungus was consistently isolated from these tissues, producing floccose white colonies and fusiform macroconidia typical of the Fusarium fujikuroi species complex (FFSC). For molecular identification, partial sequences of the translation elongation factor 1-alpha (tef1) and RNA polymerase II second-largest subunit (rpb2) genes were analysed. The results confirmed that the Turkish isolates clustered with Fusarium ananatum isolates with high bootstrap support. Pathogenicity was confirmed using the toothpick inoculation method on fruits and detached crown leaves. These assays successfully reproduced the characteristic symptoms of fruitlet core rot and crown rot, and the pathogen was re-isolated, fulfilling Koch's postulates. This study constitutes the first report of F. ananatum in Türkiye. These findings highlight the emergence of this pathogen in the Mediterranean region and emphasise the urgent need for stringent phytosanitary monitoring to safeguard fruit quality and prevent postharvest losses in the domestic market. © 2026 Wiley-VCH GmbH. Published by John Wiley & Sons Ltd.
Citation - Scopus: 2
Sustainable Use of Chlorides Against Biotic and Abiotic Stresses
(Elsevier, 2025) Türkkan, M.; Özer, G.; Taheri, P.; Derviş, S.
This chapter explores the multifaceted role of chloride salts in sustainable agriculture, moving beyond their traditional association with salinity stress to reveal their potential in mitigating various biotic and abiotic challenges. The review analyzes the effectiveness of diverse chloride salts, including NaCl, KCl, CaCl2, and MgCl2, demonstrating their efficacy in suppressing a broad spectrum of plant pathogens, with a primary focus on fungal diseases. Chloride salts achieve this through diverse mechanisms including cell wall reinforcement, osmotic regulation, and induced systemic resistance. For example, calcium chloride treatments have shown remarkable success in controlling postharvest diseases, in some cases reducing losses by up to 90%. Similarly, potassium chloride has demonstrated promising results in managing diseases such as take-all root rot in wheat, indirectly enhancing plant health and resilience. For bacterial diseases, chloride salts such as copper chloride offer direct antibacterial activity, while others such as calcium chloride can enhance plant defenses and reduce disease severity. Chloride-based disinfectants such as sodium hypochlorite have proven effective against various plant viruses. Beyond direct pathogen suppression, the chapter also explores the use of chloride salts for insect control, highlighting their potential against aphids, stable fly larvae, and termites by disrupting various aspects of their biology, from feeding behavior to social interactions. The review also addresses the role of chlorides in mitigating abiotic stressors such as drought and heat, notably the use of calcium chloride to alleviate heat stress through enhanced antioxidant activity and flavonoid biosynthesis. Furthermore, the potential of integrating chloride salts with other sustainable practices, such as combining them with beneficial microorganisms for enhanced disease control, is discussed. While acknowledging potential phytotoxic effects and the need for careful management of sodium chloride due to salinity risks, this review emphasizes the importance of optimized application strategies tailored to specific pathosystems and environmental conditions. This integrated approach, combined with the relative cost-effectiveness and lower environmental impact of chloride salts compared with many synthetic pesticides, offers promising avenues for developing sustainable and resilient agricultural practices. © 2025 Elsevier B.V., All rights reserved.