Mustafa Imren

The importance and management strategies of cereal cyst nematodes, Heterodera spp., in Turkey

AbstractCereal cyst nematodes (CCNs) can cause significant economic yield losses alone or in combination with other biotic and abiotic factors. The damage caused by these nematodes can be enormous when they occur in a disease complex, particularly in areas subject to water stress. Of the 12 valid CCN species, Heterodera avenae, H. filipjevi, and H. latipons are considered the most economically important in different parts of the world. This paper reviews current approaches to managing CCNs via genetic resistance, biological agents, cultural practices, and chemical strategies. Recent research within the soil borne pathogen program of the International Maize and Wheat Improvement Center has focused on germplasm screening, the potential of this germplasm as sources of resistance, and how to incorporate new sources of resistance into breeding programs. Breeding for resistance is particularly complicated and difficult when different species and pathotypes coexist in nature. A lack of expertise and recognition of CCNs as a factor limiting wheat production potential, combined with inappropriate breeding strategies and slow screening processes limit genetic gains for resistance to CCNs.

Association analysis of resistance to cereal cyst nematodes (Heterodera avenae) and root lesion nematodes (Pratylenchus neglectus and P. thornei) in CIMMYT advanced spring wheat lines for semi-arid conditions

To identify loci linked to nematode resistance genes, a total of 126 of CIMMYT advanced spring wheat lines adapted to semi-arid conditions were screened for resistance to Heterodera avenae, Pratylenchus neglectus, and P. thornei, of which 107 lines were genotyped with 1,310 DArT. Association of DArT markers with nematode response was analyzed using the general linear model. Results showed that 11 markers were associated with resistance to H. avenae (pathotype Ha21), 25 markers with resistance to P. neglectus, and 9 significant markers were identified to be linked with resistance to P. thornei. In this work we confirmed that chromosome 4A (~90–105 cM) can be a source of resistance to P. thornei as has been recently reported. Other significant markers were also identified on chromosomal regions where no resistant genes have been reported for both nematodes species. These novel QTL were mapped to chromosomes 5A, 6A, and 7A for H. avenae; on chromosomes 1A, 1B, 3A, 3B, 6B, 7AS, and 7D for P. neglectus; and on chromosomes 1D, 2A, and 5B for P. thornei and represent potentially new loci linked to resistance that may be useful for selecting parents and deploying resistance into elite germplasm adapted to regions where nematodes are causing problem.

The Complex Cell Wall Composition of Syncytia Induced by Plant Parasitic Cyst Nematodes Reflects Both Function and Host Plant.

Plant–parasitic cyst nematodes induce the formation of specialized feeding structures, syncytia, within their host roots. These unique plant organs serve as the sole nutrient resource for development and reproduction throughout the biotrophic interaction. The multinucleate syncytium, which arises through local dissolution of cell walls and protoplast fusion of multiple adjacent cells, has dense cytoplasm containing numerous organelles, surrounded by thickened outer cell walls that must withstand high turgor pressure. However, little is known about how the constituents of the syncytial cell wall and their conformation support its role during nematode parasitism. We used a set of monoclonal antibodies, targeted to a range of plant cell wall components, to reveal the microstructures of syncytial cell walls induced by four of the most economically important cyst nematode species, Globodera pallida, Heterodera glycines, Heterodera avenae and Heterodera filipjevi, in their respective potato, soybean, and spring wheat host roots. In situ fluorescence analysis revealed highly similar cell wall composition of syncytia induced by G. pallida and H. glycines. Both consisted of abundant xyloglucan, methyl-esterified homogalacturonan and pectic arabinan. In contrast, the walls of syncytia induced in wheat roots by H. avenae and H. filipjevi contain little xyloglucan but are rich in feruloylated xylan and arabinan residues, with variable levels of mixed-linkage glucan. The overall chemical composition of syncytial cell walls reflected the general features of root cell walls of the different host plants. We relate specific components of syncytial cell walls, such as abundant arabinan, methyl-esterification status of pectic homogalacturonan and feruloylation of xylan, to their potential roles in forming a network to support both the strength and flexibility required for syncytium function.

Genetic variation and population dynamics of the cereal cyst nematode, Heterodera filipjevi in wheat areas of Bolu, Turkey

The cereal cyst nematode, Heterodera filipjevi (Madzhidov) Stelter, was detected in Turkey in 1996 and since then it has been increasingly reported to cause losses in wheat yields. Cereal cyst nematode populations have a wide genetic diversity which makes it difficult to be managed. The objectives of this research were to investigate the genetic variation of 23 cyst nematode populations collected from wheat growing areas of Bolu Province, utilising sequenced ITS-rDNA regions, and monitoring main nematode isolate population dynamics in field conditions. The results of ribosomal DNA sequencing revealed that all cyst populations were H. filipjevi and that little genetic variation was present among populations. The highest number of second-stage juveniles was observed between April and beginning of May in a field experiment; white females were visible on the roots in late May. The hatching process was positively correlated with low temperatures, but there were inverse correlations between reproductive factors and initial nematode population densities.

Occurrence, identification and phylogenetic analyses of cereal cyst nematodes (Heterodera spp.) in Turkey

Abstract Plant-parasitic nematodes are very common on cereal crops and cause economic losses via reduction in grain quality and quantity. During 2014, 83 soil samples were collected from wheat and barley fields in 21 districts of 13 provinces across five regions (Central Anatolia, Marmara, Aegean, Southeast Anatolia, and Black Sea Region) of Turkey. Cyst-forming nematodes were found in 66 samples (80%), and the internal transcribed spacer (ITS) sequencing and species-specific PCR identified the species in 64 samples as Heterodera filipjevi, Heterodera latipons, and Heterodera avenae. The predominant pathogenic cereal cyst nematode was H. filipjevi, which was found in all five regions surveyed. H. avenae was only detected in Southeast Anatolia whereas H. latipons was detected in Southeast Anatolia and Central Anatolia. ITS-rDNA phylogenetic analyses showed that H. avenae isolates from China clustered with H. australis, and Turkish isolates were closely related to European and USA isolates of this species. H. filipjevi from Turkey and China were clustered closely with those from the UK, Germany, Russia, and the USA. The density of many of these populations exceeded or approached the maximum threshold level for economic loss. To our knowledge, this is the first report of H. filipjevi in Diyarbakir, Edirne, and Kutahya provinces, and the first report of H. avenae in Diyarbakir Province. These results exhibit the most rigorous analysis to date on the occurrence and distribution of Heterodera spp. in Turkeys major wheat-producing areas, thus providing a basis for more specific resistance breeding, as well as other management practices.

Yumurta Parazitoiti, Trichogramma brassicae Bezdenko (Hymenoptera: Trichogrammatidae)’nin Düzce İlindeki Popülasyonları İçerisindeki Genetik Varyasyonların Belirlenmesi

Members of Trichogramma genus are the most widely used as natural enemies in biological control programs. Choice of natural enemies is known to have a critical important for the succession of biological control. Their morphologic identification has some bottlenecks as laborious, time-consuming and mostly based on very small structures of the bodies. Molecular techniques have been widely used for detection, discrimination, phylogenetic analysis, identification and characterization in biological control agents belong to Trichogramma spp. In this study, the efficacy of the direct sequencing analysis of internal transcribed spacer locus of rDNA was investigated for analyzing the genetic variation within nine Trichogramma brassicae population from corn growing areas in Duzce province. The comparison of the sequences was performed with other ITS2 locus of Trichogramma species available in GenBank database. The result of analyses indicated that no genetic variation was determined in the Duzce population.*Corresponding author a.samikoca@yahoo.com.tr Abstract. Members of Trichogramma genus are the most widely used as natural enemies in biological control programs. Choice of natural enemies is known to have a critical important for the succession of biological control. Their morphologic identification has some bottlenecks as laborious, time-consuming and mostly based on very small structures of the bodies. Molecular techniques have been widely used for detection, discrimination, phylogenetic analysis, identification and characterization in biological control agents belong to Trichogramma spp. In this study, the efficacy of the direct sequencing analysis of internal transcribed spacer locus of rDNA was investigated for analyzing the genetic variation within nine Trichogramma brassicae population from corn growing areas in Düzce province. The comparison of the sequences was performed with other ITS2 locus of Trichogramma species available in GenBank database. The result of analyses indicated that no genetic variation was determined in the Düzce population.

Effect of Purpureocillium lilacinum on Root Lesion Nematode, Pratylenchus thornei

Wheat (Triticum spp.) is highly susceptible to the root lesion nematode, Pratylenchus thornei, which causes excessive amounts of crop losses each year. In this research, we investigated the cumulative effect of the biocontrol agent Purpureocillium lilacinum (syn: Paecilomyces lilacinus) against P. thornei. Three doses of P. lilacinum (106, 107 and 108 conidia cultures mL-1) with one dose of 400 P. thornei individuals (adults and juveniles) mL-1 were applied in 100 cm3 soil under greenhouse conditions. The number of nematodes in the soil and root in addition to total nematode in soil+root were determined. Moreover, different plant parameters such as the plant height, plant fresh and dry weight, root fresh and dry weight were evaluated. Applications with the higher dose of bio-agents (100 cm3 P. thornei infested soil with 108 conidia culture of P. lilacinum mL-1) exhibited maximal enhancement in dry and fresh weight of shoot and reduced P. thornei population. As a consequence, P. lilacinum individually was highly effective in enhancing different plant parameters and suppressing P. thornei reproduction. Overall, present findings suggest that the exploitation of the biocontrol agent P. lilacinum could be helpful for effective management of the root lesion nematode P. thornei.

Determining the Optimal Meloidogyne Incognita Inoculum Level, Inoculation Time, Pathogencity and Gall Development on Tomato Roots for Resistance Experiments in Breeding Programs

Determining the Optimal Meloidogyne Incognita Inoculum Level, Inoculation Time, Pathogencity and Gall Development on Tomato Roots for Resistance Experiments in Breeding Programs. Root knot nematodes (RKN) cause a significant damage to many cultivated crops and present study was conducted to determine the most appropriate inoculum levels of a ubiquitous RKN nematode in warm climate, Meloidogynev incognita, inoculation time and plant age for the screening of nematode resistance studies on plant breeding programs under controlled conditions. The inoculum level experiment was conducted to investigate the effect of four M. incognita inoculum levels (1000, 1500, 2000, 2500 juveniles/ 1000 gram soil mix) on three different age of susceptible tomato plants. Gall development was observed at 3 different ages susceptible tomato plants with 7 different time points. The highest gall numbers were observed on nematode infected 3 day old plant roots and the least number of galls were detected on the roots of 5 day old plants. First galls were observed at 1 dpi and the highest gall number was observed on the 21st gall counting day on three day old tomato roots. Thus the inoculation of 2000- 2500 second stage juveniles /1000 gram soil mix to 3 days old tomato plants was the best to reach high gall numbers which are suitable for screening of nematode resistance studies on plant breeding programs5

Biber seralarında kök-ur nematodlarına karşı farklı sulama sistemleri ile alternatif mücadele yöntemlerinin belirlenmesi

Root-knot nematodes possess a wide group of hosts and cause significant yield losses in many economically important plant species. Restrictions on the use of nematicides in Turkey have increased; hence it is needed to discover new control methods for managing Root-knot nematodes. Therefore, establishing alternative control programme to combat root-knot nematodes in pepper greenhouse in Turkey remarkably is significant. In this study, soil solarization with two diverse chemicals and soil fumigants combined with two and four drip irrigation pipe in both side of systems for using availability against nematode was investigated. Solarization + metham sodium + iprodione application with four lateral drip irrigation pipes in both side of system were found to be effective on yield and nematode galls on the roots. Solarization + iprodione with four drip irrigation pipe in both sides of systems were found to have the highest impact on plant height and nematode reproduction rate.