Heterodera Filipjevi Research Articles

Molecular characterization of cereal cyst nematodes from the South Anatolian Region in Turkey using ITS-rDNA sequences

Summary The Heterodera avenae group includes 12 species feeding on roots of cereals. Three species, Heterodera avenae Wollenweber, 1924, Heterodera filipjevi (Madzhidov, 1981) Stelter, 1984 and Heterodera latipons Franklin, 1969 are among the most economically important cyst nematode pests of cereals cultivated in different parts of Turkey. In this study, forty seven cereal cyst nematode isolates collected from cereal growing areas of the South

Effective Resources in Wheat and Wheat–Thinopyrum Derivatives for Resistance to Heterodera filipjevi in China

ABSTRACTCereal cyst nematode (CCN) is becoming one of the important soil‐borne pathogens in wheat (Triticum aestivum L.) monocropping or wheat–maize (Zea mays L.)–wheat cropping systems of central China. Heterodera filipjevi (Madzhidov, 1981) Stelter, 1984 was recently recognized as a causal agent of CCN in China, but little information is available on sources of resistance against this nematode species. The present study was initiated to determine the current status of resistance in wheat cultivars against H. filipjevi and to identify effective resources for improvement of CCN resistance in China. A 3‐yr field study of CCN resistance that involved 174 wheat cultivars or wheat–Thinopyrum derivatives was conducted in a wheat field in Xuchang, Henan Province, China, where H. filipjevi had been present for years. Greenhouse experiments were conducted with representative resistant entries from each group of accessions. None of the 78 wheat cultivars and breeding lines from China was resistant in field tests. Wheat cultivar Madsen from Washington State was most resistant among the entries tested both in field and under controlled environment. New sources of resistance to H. filipjevi were identified in some wheat–intermediate wheatgrass [Thinopyrum intermedium (Host) Barkworth & D. R. Dewey] and wheat–tall wheatgrass [Thinopyrum ponticum (Podp.) Barkworth & D. R. Dewey] partial amphiploids, which will diversify resistance resources in enhancing resistance of wheat against CCN.

Screening for resistance to Heterodera filipjevi and Pratylenchus thornei in sister lines of spring wheat

Screening for resistance to Heterodera filipjevi and Pratylenchus thornei in sister lines of spring wheat

Distribution, frequency and occurrence of cereal nematodes on the Central Anatolian Plateau in Turkey and their relationship with soil physicochemical properties

The distribution of important plant-parasitic and free-living nematodes in the cereal production areas of the Central Anatolian Plateau (CAP) of Turkey was investigated with systematic surveys. Two important plant-parasitic nematode groups were found widely distributed; cereal-cyst nematodes (78.3%) and root-lesion nematodes (42.6%). Cereal cyst nematodes (CCN) were identified as Heterodera filipjevi in 18 provinces. Heterodera latipons was found in only one province. Pratylenchus thornei and P. neglectus were the most widely distributed species of root-lesion nematodes. Other frequently recorded plant-parasitic nematodes belonged to the genera Geocenamus (52.4%), Pratylenchoides (35.6%), Helicotylenchus (29.7%) and Paratylenchus (19.2%). Konya on the southern CAP had a significantly high incidence of P. neglectus as well as free-living nematodes. The incidence of CCN was greatest in areas of sandy soils on the CAP, with densities of up to 95 cysts (100 g soil)−1. Population densities of Geocenamus, Pratylenchus and Pratylenchoides were high in some locations. Soil physicochemical properties were investigated for their relationship to nematode distribution. There was a slight positive correlation of P. thornei and clay content; conversely, there was a significant negative correlation of P. neglectus with clay and a positive correlation with sand. Electrical conductivity (EC) was positively correlated with P. neglectus. Nematodes in the genera Helicotylenchus, Paratylenchus, Trophurus and Tylenchorhynchus were only recorded at low population densities in the sampled area. By contrast, nematodes in the genera Aphelenchus, Aphelenchoides, Ditylenchus, Dorylaimus, Tylenchus and bacterivorous genera had relatively high populations. Total free-living nematodes were positively correlated with EC and zinc (Zn) concentration. The Zn content of soil was generally at a level deficient for plant growth.

Resistance of CIMMYT Wheat Germplasm to Heterodera filipjevi Xuchang Population from Henan Province, China

The cereal cyst nematode (CCN) of wheat has become a severe disease in recent years. Heterodera filipjevi is a new pathogenic nematode in China. For screening resistant resources to H. filipjevi, the resistance of 75 wheat cultivars or lines from the International Maize and Wheat Improvement Center (CIMMYT) was evaluated in greenhouse and field conditions using relative resistance index (RRI) and Pf/Pi ratios, with the nematode from Xuchang population, Henan Province, China. No cultivar was immune to H. filipjevi. However, line 6R(6D) was highly resistant in both test conditions. Lines CROC_1/AE.SQUARROSA(224)//OPATA*1, CROC_1/AE.SQUARROSA (224)//OPATA*2, MACKELLER, CPI 133842, CPI 133814, and TRIDENT were moderately resistant to H. filipjevi in the greenhouse test. In the field test, CPI 133842, CPI 133814, DURATI, and TURCAN#39 showed a high resistant reaction with RRI values ranging from 0.90 to 0.96. Fourteen lines including ID-2150, BAXTER, and MACKELLER were moderately resistant to H. filipjevi. The disease severity was heavier in the greenhouse test than in the field test, and resistance identification in the greenhouse is much easier and reliable. The results indicated that relative resistance index (RRI) is an efficient index for evaluating the resistance of wheat cultivars to CCN.

Molecular characterisation of cereal cyst nematodes in winter wheat on the Huang-Huai floodplain of China using RFLP and rDNA-ITS sequence analyses

In response to the recent discovery of Heterodera filipjevi central Henan and the uncertain taxonomic status of Heterodera avenae more widely in China, heteroderid specimens from winter wheat at 21 locations in Henan and adjacent provinces were subjected to RFLP and rDNA-ITS sequence analysis. H. filipjevi was found in six locations in Henan, including two mixed with H. avenae; H. avenae being found at all other locations. A new RFLP profile type was found for H. filipjevi, three new types for H. avenae and the Australian type (Heterodera australis) were found for the first time in China (at two locations). Otherwise, H. avenae and H. filipjevi were of RFLP types previously reported in China. Phylogenic analysis of the rDNA sequences showed H. filipjevi in China was less diverse than H. avenae, with greatest similarity to specimens from Italy and the USA, which is consistent with a more recent introduction. In contrast, H. avenae in China was clearly distinct from H. avenae found elsewhere, except for the discovery of the Australian types. Although the Australian types clustered together, this fell within the variation found for the remainder of the specimens from China, which may represent a single species. These data reveal additional genetic diversity within the two cereal cyst nematode species in China, which is likely to have implications for the development of their control by host resistance.

Indirect selection of Cre1 gene in winter wheat populations

The nematodes are important biotic constraint in rain-fed wheat production systems. In Turkey, they is found in 75.0% of soil samples in Central Anatolia with the dominant species being Heterodera filipjevi. Yield losses for winter wheat in rain-fed environments are documented between 27.0-46.0%. A single dominant gene for resistance to H. avenae, designated as Cre1, was assessed in Turkey. It was also found to be effective to Heterodera filipjevi. In this research, a STS based Cre1 marker was applied in a number of segregating wheat populations from F1 to F4 to discriminate Cre1-positive lines among the wheat populations. Results clearly indicated that Marker Assisted Selection (MAS) is functioning effectively, with recovery of Cre1 positive lines up to 88.0 % depending on the cross in early stage of breeding.

Tahıl kist nematodu, Heterodera filipjevi (Madzhidov, 1981) Stelter’nin patotipinin belirlenmesi ve buğday genotiplerinin, H. filipjevi populasyonlarına karşı dayanıklılıklarının araştırılması

*Summary Determination of the pathotype group of Heterodera filipjevi (Madzhidov, 1981) population and resistance of H. populations against wheat genotypes The international pathotype differential lines were used to determine the pathotype group of Heterodera filipjevi (Madzhidov, 1981) Stelter population collected from Yozgat province, Turkey. The reaction of H. filipjevi Yozgat population on the differential lines indicated they were different than the other 5 known H. filipjevi pathotypes. Futherwork was conducted with these H. filipjevi populations to assess the usabilitiy of known published Cereal Cyst Nematode (CCN) resistance genes against a closely related species and pathotypes of Heterodera avenae Wollenweber, 1924. Several of these wheat lines known to possess resistance against H. avenae pathotypes and also the Haymana H. filipjevi populations did not exhibit resistance against H. filipjevi Yozgat populations.

Distinguishing Heterodera filipjevi and H. avenae Using Polymerase Chain Reaction-Restriction Fragment Length Polymorphism and Cyst Morphology

The cereal cyst nematodes Heterodera filipjevi and H. avenae impede wheat production in the Pacific Northwest (PNW). Accurate identification of cyst nematode species and awareness of high population density in affected fields are essential for designing effective control measures. Morphological methods for differentiating these species are laborious. These species were differentiated using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) of internal transcribed spacer (ITS)-ribosomal (r)DNA with up to six restriction endonucleases (TaqI, HinfI, PstI, HaeIII, RsaI, and AluI). The method was validated by inspecting underbridge structures of cyst vulval cones. Grid soil sampling of an Oregon field infested by both species revealed that H. filipjevi was present at most of the infested grid sites but mixtures of H. avenae and H. filipjevi also occurred. These procedures also detected and differentiated H. filipjevi and H. avenae in soil samples from nearby fields in Oregon and H. avenae in samples from Idaho and Washington. Intraspecific polymorphism was not observed within H. filipjevi or PNW H. avenae populations based on the ITS-rDNA. However, intraspecific variation was observed between H. avenae populations occurring in the PNW and France. Methods described here will improve detection and identification efficiencies for cereal cyst nematodes in wheat fields.

Hatching of Heterodera filipjevi in controlled and natural temperature conditions in Turkey

Abstract The effect of different temperatures under both in vitro and in vivo conditions on the hatching behaviour of second-stage juveniles (J2) of the cereal cyst nematode, Heterodera filipjevi, was studied. Cumulative percent hatching was affected significantly by temperature after 290 days of incubation. Hatching was significantly greater at lower temperatures (5, 10 and 15°C) compared with that at the higher temperatures of 20 and 25°C, ranging between 75 and 94% vs 19 and 22%, respectively. The highest cumulative hatch of 94% was obtained at a constant temperature of 15°C at 290 days. However, the lowest cumulative hatch of 33% was obtained after initial exposure to 5°C followed by transfer to 25°C at day 290. In general, incubating the cysts at lower initial temperatures of 10 or 15°C for 58 days gave the highest initial hatching rates 1 week after exposure to the final temperatures. Under natural temperature conditions in the field, J2 emergence started at 17°C in October and continued until the end of April in the temperature range of 2-17°C. A total hatch of 94% was recorded under field temperature conditions over the course of 1 year. Hatch of most J2 occurred in two peaks; the first in October and the second in February, and, accordingly, the greatest invasion by H. filipjevi is most likely to occur just after these two peaks. Heterodera filipjevi does not seem to have a diapause and could hatch anytime when wheat plants are available.

Effect of the cereal cyst nematode, Heterodera filipjevi, on wheat in microplot trials

AbstractThe cereal cyst nematodes, Heterodera avenae, H. filipjevi and H. latipons, are considered to be the most economically important species of cyst-forming nematodes on wheat. Two trials were conducted in 2006 and 2007 to determine the impact of different initial population levels of H. filipjevi (0, 2.5, 5, 10 and 20 eggs and second-stage juveniles (J2) (g soil)−1) on wheat cv. Sardari in microplots under natural field conditions in Iran. The results showed that increasing the initial populations of H. filipjevi significantly reduced several growth parameters of wheat (plant height, root dry weight, aerial shoot dry weight and grain yield) compared with the untreated controls. The final population of H. filipjevi increased with increasing initial population, while the reproduction factor (Rf) declined as the initial population increased but was greater than 1 in all treatments. Regression analysis showed a significant negative relationship between the initial populations and grain yield. The modelling clearly demonstrated that H. filipjevi is economically important on winter wheat in Iran. Grain yield loss was demonstrated even at the lowest population density and reached a maximum loss of 48% with an initial population density of 20 eggs and J2 (g soil)−1. The aerial shoot yield loss was as great as 40% in both years.

Molecular characterization of Cereal Cyst Nematode diagnostic markers Cre1 and Cre3 in some winter wheat germplasm and their potential use against Heterodera filipjevi

Two PCR based markers tightly linked to Cre1 and Cre3 resistant genes against the Cereal Cyst Nematode (CCN, causal agent Heterodera avenae) were used to characterize a number of diploid, tetraploid and hexaploid wheat germplasm consisting of obsolete, advanced lines and new cultivars from the Turkish National Breeding Program and the joint TURKEY CIMMYT ICARDA International Winter Wheat Improvement Program. In addition a number of landraces and wild relatives of wheat collected from the Turkish side of the Fertile Crescent, the centre of origin of cereals, were included. None of the genetic material tested positive for either marker except the land race Sardari which originated from neighboring Iran was found positive for Cre1 gene. Combining both of these molecular markers in one assay for fast and cost-effective screening of the germplasm was not effective, so marker genotyping with germplasm was realized using each primer alone. Most work that has been reported is on the CCN species H. avenae, however the predominant species in Turkey is the closely related H. filipjevi. In vitro resistance assaying for this species indicates that Cre1 is a moderate source of resistance against the H. filipjevi population, however Cre3 gene appears ineffective. It is suggested that a larger pool of a range of germplasm should be screened for Cre1 in Turkey. Furthermore, the landrace Sardari could be used as a parent to deploy CCN resistance in to genetic background of Turkish bread wheat cultivars with a targeted Marker Assisted Selection Backcrossing approach.

Genetic and phenotypic diversity in the graminaceous cyst nematode complex, inferred from PCR-RFLP of ribosomal DNA and morphometric analysis

Graminaceous cyst nematodes form a group of eleven valid species including Heterodera avenae, Heterodera filipjevi and Heterodera latipons and constitute major pests to cereals. They are widely spread in circum-mediterranean areas where they are presumed to cause yield losses on bread and durum wheat. The objective was to document the diversity of these cereal cyst nematodes, in particular samples from Mediterranean regions, in comparison to species which develop on cultivated or wild grasses (H. arenaria, H. hordecalis, H. mani) and on rice or sugarcane (H. sacchari). Studies involved PCR-RFLP of ITS and morphometrics of the juvenile and cyst characters. UPGMA analysis of molecular data showed that the isolates segregated in two main clusters which seem to represent different evolutionary lineages. The H. avenae sensu lato cluster (I) contained H. arenaria, H. avenae, H. filipjevi and H. mani. The second cluster (II) contained isolates of H. hordecalis and H. latipons. Within H. avenae sensu lato, H. filipjevi was separated from the other related species with significant bootstrap value. The differentiation of H. arenaria, recognized for the first time based on molecular data, and H. mani with few restriction enzymes were the least significant. Intraspecific polymorphism allowed differentiation of isolates originating from Australia within H. avenae sensu stricto. The group H. hordecalis–H. latipons showed the greatest genetic variability between and within isolates. Two representatives of Heterodera sacchari, taxonomically included in the ‘schachtii’ group, were genetically as distant to this group as to the other graminaceous species belonging to either H. avenae sensu lato or H. hordecalis–H. latipons group. Results inferred from multivariate analysis applied on morphometrics of the cysts and juveniles showed agreement between genetic and phenotypic classifications. This study demonstrates the utility of combined molecular and classical methods to enhance our knowledge about the diversity within the complex of graminaceous cyst nematodes and to establish robust techniques to identify a wider set of nematode species.