Ayşe Gülden Aday Kaya

Dünya nüfus artışının tarımsal üretime etkileri ile bitki hastalıklarının bu üretim üzerindeki olumsuz etkileri, günümüzde giderek daha fazla önem kazanmaktadır. Her yıl, küresel ürün kayıplarının %20-40’ı hastalıklardan meydana gelmektedir. Tarımsal üretimde verim ve kaliteyi artırmak için hastalık etmenlerinin hızlı ve doğru bir şekilde tanısı gereklidir. Özellikle Pythium cinsi oomiset’ler, bitkilerin köklerinde ve farklı dokularında önemli zararlara yol açarak ekonomik kayıplara neden olmaktadır. Morfolojik tanı yöntemleri zaman alıcı ve araştırmacılar için zorluklar içerirken, moleküler teknikler (örneğin, Real-time PCR, LAMP) duyarlılık ve özgüllük sunarak kısmen daha etkili çözümler sağlamaktadır. Sonuç olarak, tarımsal üretim için ciddi sorunlara neden olan Pythium türlerinin etkilerini azaltmak, erken teşhis ve mücadele yöntemlerinin geliştirilmesiyle mümkün olacaktır. Bunun için hem moleküler hem de immünolojik yöntemlerin entegre bir şekilde kullanılması, bitki hastalıklarının kontrolünde daha etkili yöntemler geliştirilmesine yardımcı olacaktır.

In this study, the distribution, life cycle and associations with fungi of the alien invasive species Leptoglossus occidentalis Heidemann, 1910 (Hemiptera: Coreidae) in Türkiye were investigated. During the study, conducted between 2019 and 2021, the pest was found to have spread across 35 provinces in Türkiye. The biological data obtained in the study were divided into ecologically similar sub-regions (Ankara-Çankırı-Kırşehir, Artvin, Isparta-Burdur, Izmir-Aydın-Manisa-Muğla-Antalya) in order to reveal the life cycle of the species. Additionally, host plant and insect samples were examined for the presence of Diplodia sapinea (Fr.) Fuckel (pine shoot blight agent) and entomopathogenic fungi species through morphological and molecular identification methods. Consequently, it was found that Leptoglossus occidentalis has two generations in Türkiye. The timing of the first flight was in early May-mid June and the second generation was from mid-July to late August. Although Diplodia sapinea was detected in some of the sampled host plant tissues, it could not be isolated from Leptoglossus occidentalis individuals. Accordingly, it did not find any evidence that Leptoglossus occidentalis vectors Diplodia sapinea although the insect and the fungus cooccurs in sampling areas. Although it was detected 25 fungal species isolated from Leptoglossus occidentalis adults, none of them were entomopathogenic fungal species. It has been revealed that the pest has spread almost all over Türkiye and has become an important risk factor affecting seed yield and quality in coniferous species.

The endophytic fungi present in needles of Pinus sylvestris, Pinus pinaster, Pinus nigra, Pinus taeda and Pinus radiata were investigated in Kerpe Research Forest, İzmit in 2016. Ten trees of each pine species were sampled systematically. Previous years green needles were sampled from the lower part of the canopy, from two equally spaced positions around the tree. Each needle was surface sterilized and cut into 0.5 cm sections then individually placed onto malt extract agar plates. DNA was ex-tracted from reprensentative seven isolates and amplified using primers ITS1 and ITS4 targeting the nuclear 5.8S rDNA gene and the two ITS regions flanked between 18S and 28S rDNA genes. Amplicons sequenced in both directions using the univer-sal fungal primers ITS1 and ITS4. Isolations from a total of 1000 needles (200 from each pine species) yielded 750 fungal isolates. Pestalotiopsis funerea (Desm.) Steyaert was isolated at the highest frequency followed by Acremonium sp., Cladio-sporum sp. and Cyclaneusma minus.

Heterobasidion species are the most important pathogens causing root and stem rot on conifers in northern hemisphere forests. The host list of this complex is very wide and includes over 200 species of trees and shrubs. Among the members of this complex, Heterobasidion annosum s. s. has the largest host range. In this study, young plants of Pinus sylvestris, Picea orientalis, Abies nordmanniana, Cedrus libani and Pinus brutia (three different origins) were inoculated on the lower stem with known genets of Heterobasidion annosum s.s. collected from Pinus brutia stands in south‐western Türkiye. Infection frequency, assessed as presence of the conidial stage in stem discs following incubation, in the inoculated seedlings was 100%. The Heterobasidion annosum s. s. isolates were re‐isolated from all inoculated host species. Control seedlings showed no symptoms of disease. Mortality in inoculated plants was 11.5% of the 735 inoculated plants, which died over an 8‐weeks incubation period. The isolates showed greater growth on Cedrus libani, Pinus sylvestris and Picea orientalis seedlings compared to other species tested. On the other hand, it was found that the least affected seedlings were Pinus brutia TB12 and Abies nordmanniana. This study proved that differences occur in aggressiveness of Heterobasidion annosum s. s. to host species. A striking point in the results is that, despite being the host species from which the isolates were obtained, Pinus brutia seedlings showed lower sensitivity to Heterobasidion annosum s. s. than the other conifer species tested. Inoculations of three different Pinus brutia provenances suggested there was no significant difference in mean lesion lengths and fungal growth values in Pinus brutia plants, except in Pinus brutia TB14, which was more susceptible to extension growth of the pathogen.

Species of Heterobasidion are amongst the most destructive disease agents on conifers in the Northern hemisphere. The area examined in the present work was the first example of typical disease centres and symptoms of H. annosum root rot observed on pines in Turkey. Twenty disease centres were identified in a Pinus brutia regeneration area, and a total of 182 isolates were obtained from the centres. All isolates from the regeneration area mated almost perfectly with H. annosum s.s. isolates from Europe, giving a clear identification. Based on a combination of morphological and molecular methods, the genetic variation of H. annosum was determined in the study site. The variation amongst and within isolates amounted to, respectively, 49% and 51% of total variation. The population structure of the isolates is discussed. It was concluded that H. annosum was well‐established in the regeneration area and was probably not caused by recent infections and spread.

The occurrence of Phytophthora species in Alnus glutinosa stands in the Karacabey and Iğneada floodplain forests was investigated. Twenty‐seven soil samples taken from the rhizosphere of declining trees (without bark symptoms) were baited for Phytophthora. In total, 311 Phytophthora isolates were obtained following culturing on selective medium. On the basis of the morphological characteristics and the ITS sequences of the rDNA, Phytophthora plurivora accounted for 83% of the rhizosphere isolates. In addition to P. plurivora, P. gonapodyides (9%), P. chlamydospora (3.8%), P. lacustris (2.5%) and P. aff. cactorum (2%) were isolated from the surveyed areas. No P. × alni was detected in the present work. This paper is the first to report the isolation of P. plurivora and P. aff. cactorum from the rhizosphere of Alnus species in Turkey.

Summary: Dothistroma needle blight (DNB) is among the most serious foliar diseases affecting Pinus spp. globally. Infected needles were collected from potential host species in four locations in western Ukraine and in four locations in eastern Georgia during spring–summer 2015 to update the knowledge on pathogen distribution in these countries. Dothistroma spp. were detected using isolation, sequencing and species‐specific priming (SSPP) PCR. Two new hosts for Dothistroma spp. were recorded in western Ukraine: D. septosporum on Pinus nigra var. australica and D. pini on P. nigra var. mollet. D. septosporum was found on 15‐year‐old P. strobus in western Ukraine. New hosts for D. septosporum were recorded in Georgia on 5‐ to 10‐year‐old naturally regenerated P. sylvestris var. hamata and on 40‐ to 50‐year‐old P. ponderosa trees. D. pini was found for the first time in Georgia on 30‐ to 40‐year‐old P. nigra trees. The work confirmed the presence of both D. septosporum and D. pini in western Ukraine and Georgia, and demonstrated new hosts for both Dothistroma species.

Summary: Ceratocystis platani was detected at several locations in the European side of Istanbul, causing severe dieback and mortality, mainly on Platanus × acerifolia imported from Italy approximately 160 years ago, but also on Platanus orientalis. In the work reported here, the causal agent of the dieback and mortality was identified based on morphological characteristics in culture and internal transcribed spacer (ITS) sequencing, confirming the presence of C. platani in Turkey. All analysed C. platani isolates from Istanbul shared the same ITS sequence with European C. platani strains available in the NCBI, but differed from other species previously ascribed to the Ceratocystis fimbriata species complex. Pathogenicity of C. platani was proven by inoculation onto 25‐cm‐long and 4–9 mm diam. P. orientalis twigs and the causal agent reisolated from symptomatic tissues. In a survey of 976 Platanus in streets and parks of Istanbul, 26.5% of trees showed symptoms of C. platani infections, whilst 5.6% were dead. The proportion of symptomatic trees was higher where management interventions, such as topping or pruning and felling infected trees had been carried out.