Browsing by Author "Türkkan, Muharrem"

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Activity of nanosized copper-boron alloys against Phytophthora species
(Springer Science and Business Media Deutschland GmbH, 2023) Yiğit, Uğur; Türkkan, Muharrem; İlhan, Hasan; Şimşek, Tuncay; Güler, Ömer; Derviş, Sibel
This study aimed to evaluate the antifungal activity of copper-boron (Cu-B) nanoalloys against a range of Phytophthora species, including P. capsici, P. citrophthora, P. palmivora, P. cinnamomi, P. nicotianae, P. cactorum, P. plurivora, P. inundata, and P. megasperma. The nanoalloys were synthesized via mechanical alloying under an argon atmosphere, resulting in the formation of nanocrystalline Cu-B nanoalloys with irregular morphology and particle sizes ranging from 50 to 240 nm. At a concentration of 250 µg mL−1, the Cu-B nanoalloys demonstrated complete inhibition of mycelial growth, sporangium production, and zoospore germination in all tested Phytophthora species. The EC50 values for mycelial growth ranged from 28.02 to 120.17 µg mL−1, while for sporangium production and zoospore germination, they were below 10 µg mL−1. Furthermore, the nanoalloys exhibited fungicidal activity against specific Phytophthora species, such as P. capsici, P. citrophthora, P. inundata, and P. megasperma, at concentrations of 100, 250, 250, and 250 µg mL−1, respectively. Notably, the Cu-B nanoalloys displayed significant protective and curative effects on tuber rot severity in P. nicotianae-inoculated potatoes, resulting in reductions of 94.13% and 92.61% compared to the control, respectively, at a concentration of 10 µg mL−1 (P < 0.05). These findings highlight the potential of Cu-B nanoalloys as a promising fungicide for the management of plant diseases caused by Phytophthora spp.
Antifungal effect of boron compounds against Neoscytalidium dimiatum
(2023) Yildirim, Elif; Türkkan, Muharrem; Yiğit, Abdurrahman; Derviş, Sibel; Özer, Göksel; Erper, İsmail
Neoscytalidium dimidiatum has been recently identified as the agent responsible for canker, dieback, shoot blight, and root rot on different hosts in Türkiye. In this study, we evaluated the inhibitory effect of boric acid (H3BO3), three borates [disodium octaborate tetrahydrate (Na2B8O13.4H2O), disodium tetraborate decahydrate (Na2B4O7.10H2O) and disodium tetraborate (Na2B4O7)] on the mycelial growth, germ tube elongation and conidial germination of N. dimidiatum. The antifungal effects of the boron compounds were investigated at 0.125, 0.25, 0.5, 1.0 and 2.0% (w/v) concentrations. The differences observed between the inhibitory effects of boron compounds on the parameters were found to be significantly important at P < 0.05. The 0.5% concentration of disodium tetraborate decahydrate and disodium octaborate tetrahydrate completely inhibited the fungus, whereas other salts did not. Disodium tetraborate decahydrate and disodium octaborate tetrahydrate completely inhibited three parameters at 0.5% and higher concentrations. However, boric acid and disodium tetraborate were able to completely inhibit investigated factors of N. dimidiatum at 2.0% and 1.0% concentration, respectively. Disodium tetraborate and boric acid at 0.5% concentration decreased germ tube elongation and conidia germination of the fungus by 94.97%-63.57%, 59.33%-51.26%, respectively. The effectiveness of the 0.5% concentration on conidial germination was also similar in both salts at P < 0.05. However, disodium tetraborate inhibited germ tube elongation more effectively than boric acid. The minimum inhibition concentration (MIC) values of the four boron compounds also varied between 0.5% and 2.0% concentrations. The boron compounds in this study could be potential agents to manage N. dimidiatum.
Characterization and pathogenicity of Pythium-like species associated with root and collar rot of kiwifruit in Turkey
(In Plant Disease, 2021) Türkkan, Muharrem; Özer, Göksel; Karaca, Gürsel; Erper, İsmail; Derviş, Sibel
During the period of June to October in 2018, a widespread decline was observed on kiwifruit vines in the vineyards located in Altınordu, Fatsa, and Perşembe districts of Ordu province. The symptoms were associated with reddish-brown rots expanding from the root to the collar with sparse off-color foliage. Based on the percentage of the total infected samples across 18 vineyards, the most common oomycete species were Globisporangium intermedium (37.1%), Phytopythium vexans (34.3%), G. sylvaticum (14.3%), G. heterothallicum (11.4%), and Pythium dissotocum (2.9%). The morphological identification of isolates was confirmed based on partial DNA sequences containing the nuclear rDNA internal transcribed spacer region (rDNA ITS) and the mitochondrial cytochrome c oxidase subunit II (coxII) gene. The optimum growth temperature and the optimum pH of 5 species ranged from 22.98 to 28.25°C and 5.67 to 8.51, respectively. Pathogenicity tests on the seedlings of kiwifruit cv. Hayward revealed significant differences in virulence among isolates. Phytopythium vexans and G. sylvaticum isolates caused severe root and collar rot resulting in seedling death, while G. heterothallicum and G. intermedium isolates had relatively lower virulence. All Globisporangium spp. and P. vexans isolates significantly decreased plant growth parameters (plant height, shoot and root dry weights and root length); however, P. dissotocum caused very mild symptoms and did not affect these parameters of growth. To our knowledge, this is the first study reporting G. sylvaticum, G. heterothallicum, and G. intermedium causing root and collar rot on kiwifruit not only in Turkey but also in the world.
Evaluation of inhibitory effect some bicarbonate carbonate salts against Neoscytalidium dimiatum
(2023) Yildirim, Elif; Türkkan, Muharrem; Özer, Göksel; Derviş, Sibel; Erper, İsmail
Neoscytalidium dimidiatum, a member of the Botryosphaeriaceae family, has emerged as a significant pathogen causing canker and blight diseases in various fruit trees, field crops, park and forest trees, and other hosts. Neoscytalidium dimidiatum is the only recognized species within the genus, with the other two previously recognized species, N. novaehollandiae and N. orchidacearum. There is no suggested chemical control method against Neoscytalidium. In this study, we evaluated the inhibitory effect of some salts on the mycelial growth, germ tube elongation and conidial germination of the N. dimidiatum isolate phylogenetically clustered with the isolates previously recognized as N. novaehollandiae. The antifungal effects of the salts were determined at 0.125, 0.25, 0.5, 1.0 and 2.0% (w/v) concentrations of salts in vitro conditions. Statistically, differences were observed between the inhibitory effects of six salts on the parameters at P ≤ 0.05. The 0.25% and higher concentrations of the ammonium bicarbonate and ammonium carbonate salts completely inhibited mycelial growth, germ tube elongation and conidial germination. Potassium and sodium bicarbonate salts in the highest concentration (2.0%) were able to decrease the mycelial growth, germ tube elongation and conidial germination with the rates of 95.58%-95.58%, 95.05%-95.76% and 77.44%-82.91%, respectively. In addition, potassium and sodium carbonate were able to completely inhibit investigated factors of the pathogen at 2.0% and 1.0% concentrations, respectively. The minimum inhibition concentration values of the ammonium bicarbonate, potassium carbonate and sodium carbonate varied between 0.25% and 2.0%. The minimum fungicidal concentration values of the ammonium carbonate and bicarbonate also ranged between 0.25% and 1.0%. As a result, this study showed that salts of carbonate and bicarbonate could be recommended to manage diseases caused by N. dimidiatum.
Selenyumun Bazı Bitki Patojeni Funguslara Karşı In Vitro Değerlendirmesi
(2024) Özer, Göksel; Türkkan, Muharrem; Sönmez, Ferit; Kabakcı, Hüseyin; Alkan, Mehtap; Derviş, Sibel; Derviş, Sibel
Amaç: Selenyum (Se), tarımsal alanlarda fungal patojenlerini kontrol etmek için umut vaat eden çevre dostu bir element olarak ilgi çekmektedir. Bu çalışmada, sodyum selenit (selenit) ve sodyum selenat (selenat) formlarını içeren Se uygulamalarının 10 farklı bitki patojeni fungus türünün büyümesi üzerindeki etkisi değerlendirilmiştir. Materyal ve Yöntem: Selenyum uygulamalarının fungusların miselyal gelişmesi ve spor oluşumu üzerindeki etkisi in vitro koşullarda değerlendirilmiştir. Probit analizi, fungusların hem miselyal gelişme hem de spor oluşumunda %50 azalmaya (EC50) yol açan tuz konsantrasyonlarını belirlemek için kullanılmıştır. Araştırma Bulguları: En yüksek konsantrasyonda (120 ppm), selenit tüm türlerin miselyal gelişmesini %6.82 ile %62.46 arasında engellemiştir. Buna karşın, selenat daha geniş bir engelleme spektrumu göstermiş ve miselyum büyümesini %0 ile %87.14 arasında etkilemiştir. Farklı konsantrasyonlarda, Fusarium pseudograminearum selenit karşısında (EC50<24 ppm) en yüksek duyarlılığı gösterirken onu Bipolaris sorokiniana ve Verticillium dahliae izlemiştir. Benzer şekilde, Colletotrichum coccodes selenat uygulamasına karşı (EC50<24 ppm) en yüksek duyarlılığı gösterirken, onu B. sorokiniana, Botrytis cinerea, Sclerotinia sclerotiorum ve V. dahliae takip etmiştir. Her iki tuz da anlamlı bir farklılık gözlenmeksizin fungal türleri üzerinde spor oluşumunu etkili bir şekilde inhibe etmiştir. Colletotrichum coccodes, F. pseudograminearum, B. cinerea, F. culmorum, V. dahliae ve B. sorokiniana selenit tarafından anlamlı şekilde inhibe edilmiştir fakat F. oxysporum’a karşı daha düşük bir inhibisyon gözlenmiştir. Benzer şekilde, engelleme yüzdeleri arasında küçük farklar bulunmakla birlikte bu türler, V. dahliae ve F. oxysporum ile birlikte, selenat tarafından anlamlı şekilde inhibe edilmiştir. Colletotrichum coccodes, B. cinerea, F. culmorum, B. sorokiniana ve F. oxysporum için 24 ppm'nin altındaki EC50 değerleri, her iki tuzun da spor oluşumunu etkin bir şekilde inhibe ettiğini göstermiştir. Fusarium pseudograminearum’un %50 inhibisyonu için daha yüksek konsantrasyonların gerektiği anlaşılmıştır. Verticillium dahliae, selenit karşısında 33.16 ppm ve selenat karşısında 24 ppm'nin altında olan EC50 değerleri ile selenata karşı daha yüksek duyarlılık göstermiştir. Sonuç: Bu çalışmanın bulguları, Se'nin sürdürülebilir tarımda çeşitli bitki patojen fungus türleri üzerindeki antifungal potansiyeline ilişkin anlayışımıza katkıda bulunmaktadır. Hastalık yönetimi için elementin mekanizmalarını anlamak ve uygulama protokollerini optimize etmek için daha fazla araştırmaya ihtiyaç vardır.