Lesion Nematode Pratylenchus Thornei Research Articles

COMPARATIVE STUDIES OF DIFFERENT ORGANIC SOURCES ON GROWTH OF LESION NEMATODE ON CHICKPEA

The chickpea (Cicer arietinum) is an annual legume of the family Fabaceae sub family Papilionoideae. Its different types are variously known as gram or Bengal gram, Garbanzo or Garbanzo bean, or Egyptian pea. Chickpea seeds are high in protein. The lesion nematode Pratylenchus thornei is described as a major limiting factor in chickpea. In this taking experiment we have taken 10 treatments i.e. T1 - Compost, T2 - Glomus etunicatium, T3 Rhizobium, T4 - Oil seed cake, T5 - Acaulospora scrobiculata, T6 - Compost + Glomus etunicatium + Acaulospora scrobiculata, T7 - Compost + Rhizobium + Acaulospora scrobiculata, T8 - Oil seed cake + Glomus etunicatium + Acaulospora Scrobiculata, T9 - Oil seed cake + Rhizobium + Acaulospora scrobiculata) and used T0 - Control as a check. We have analyzed it statistically on the basis of observation made in this research. The observations include pot and eld experiments having growth parameters [Days owering initiation, Branches (No.), Shoot length (cm), Flower (no.)]. In this research paper we have compiled the all above information and study the studies of different organic sources on growth of lesion nematode on chickpea.

Pratylenchus thornei: The Relationship Between Presowing Nematode Density and Yield Loss in Wheat and Barley.

The root lesion nematode Pratylenchus thornei causes economic losses in wheat and barley internationally through both reduced grain yield and grain quality. This study investigated the relationships between the presowing P. thornei density and grain yield and the postharvest nematode densities. Four field experiments were conducted at the same site between 2010 and 2014. A range of presowing P. thornei densities was established in the first year by growing three cereal cultivars that ranged from resistant to susceptible. In the following year, plots were sown with the five same cereal cultivars. A linear relationship was observed between the natural log of the presowing P. thornei density and grain yield across all seasons. The results showed that grain yield losses varied between cultivars and seasons. The importance of season was significant, with this study conducted over several seasons, and it highlighted the variability in yield losses between seasons, which will need further investigation. The greatest yield losses observed were 25 to 28% when the maximum presowing P. thornei densities ranged between 150 and 250 P. thornei g of soil-1. An analysis of the relationship between the presowing and postharvest nematode densities revealed that increased presowing nematode densities resulted in decreased multiplication rates in all seasons and in all cultivars. Nematode multiplication rates also varied between seasons. These results explain why it is difficult to predict nematode levels based on cropping history, and additionally, they highlight the importance of growing resistant cultivars to maintain low levels of P. thornei to minimize risk of yield losses.

Resistance to the root lesion nematodes Pratylenchus thornei and P. neglectus in cereals: Improved assessments in the field

The root lesion nematodes (RLN) Pratylenchus thornei and P. neglectus cause yield losses in intolerant field crops, internationally. They both have wide host ranges, invading grass and broadleaf grain crops, pasture species and weeds. Plant resistance, the ability of the plant to prevent nematode reproduction, is the main method of control, but requires accurate information on varietal resistance rankings to plan effective management strategies. This study used a multi environment trial (MET) analysis to examine the effect of cereal varieties (wheat, durum, barley and triticale) on the multiplication of P. thornei and P. neglectus when grown in a range of field environments at high and low pre-sowing nematode densities across a range of growing years. The study measured multiplication of P. thornei (68 varieties) and P. neglectus (62 varieties) in six and seven field experiments, respectively, each with high and low pre-sowing nematode densities, conducted during the years 2011–2014. This study showed genetic variation in the resistance ranking between cereal types and varieties for both P. thornei and P. neglectus. This provides management options to growers and information to breeding programs, which can be used to improve the resistance of future varieties. The consistent rankings across the field experiments and observed high genetic correlation between environments was unexpected given experiments were conducted across a range of years, soil types, geographic locations and different pre-sowing nematode densities. These high correlations suggested that varietal resistance can be determined with small numbers of field experiments, thus reducing the costs and time taken to determine varietal resistance. Finally, it was found that a lower pre-sowing nematode density resulted in a higher nematode multiplication rate compared to the high pre-sowing nematode density. This highlights the need to select resistant varieties to avoid large increases in nematode densities in fields with low nematode densities. This analysis of field experimental data for nematodes is novel and indicates that field data can be used to accurately assess varietal resistance (nematode multiplication) across environments. Therefore, accurate data on varietal resistance that is applicable over wide area can be produced with fewer experiments, resulting in varieties with increased resistance being planted, thus reducing grain yield losses due to root lesion nematodes.

Diploid and tetraploid progenitors of wheat are valuable sources of resistance to the root lesion nematode Pratylenchus thornei

The root lesion nematode Pratylenchusthornei is widely distributed in Australian wheat (Triticumaestivum) producing regions and can reduce yield by more than 50%, costing the industry AU$50 M/year. Genetic resistance is the most effective form of management but no commercial cultivars are resistant (R) and the best parental lines are only moderately R. The wild relatives of wheat have evolved in P. thornei-infested soil for millennia and may have superior levels of resistance that can be transferred to commercial wheats. To evaluate this hypothesis, a collection of 251 accessions of wheat and related species was tested for resistance to P. thornei under controlled conditions in glasshouse pot experiments over two consecutive years. Diploid accessions were more R than tetraploid accessions which proved more R than hexaploid accessions. Of the diploid accessions, 11 (52%) Aegilopsspeltoides (S-[B]-genome), 10 (43%) Triticummonococcum (Am-genome) and 5 (24%) Triticumurartu (Au-genome) accessions were R. One tetraploid accession (Triticumdicoccoides) was R. This establishes for the first time that P. thornei resistance is located on the A-genome and confirms resistance on the B-genome. Since previous research has shown that the moderate levels of P. thornei resistance in hexaploid wheat are dose-dependent, additive and located on the B and D-genomes, it would seem efficient to target A-genome resistance for introduction to hexaploid lines through direct crossing, using durum wheat as a bridging species and/or through the development of amphiploids. This would allow resistances from each genome to be combined to generate a higher level of resistance than is currently available in hexaploid wheat.

De novo analysis and functional classification of the transcriptome of the root lesion nematode, Pratylenchus thornei, after 454 GS FLX sequencing

The migratory endoparasitic root lesion nematode Pratylenchus thornei is a major pest of the cereals wheat and barley. In what we believe to be the first global transcriptome analysis for P. thornei, using Roche GS FLX sequencing, 787,275 reads were assembled into 34,312 contigs using two assembly programs, to yield 6,989 contigs common to both. These contigs were annotated, resulting in functional assignments for 3,048. Specific transcripts studied in more detail included carbohydrate active enzymes potentially involved in cell wall degradation, neuropeptides, putative plant nematode parasitism genes, and transcripts that could be secreted by the nematode. Transcripts for cell wall degrading enzymes were similar to bacterial genes, suggesting that they were acquired by horizontal gene transfer. Contigs matching 14 parasitism genes found in sedentary endoparasitic nematodes were identified. These genes are thought to function in suppression of host defenses and in feeding site development, but their function in P. thornei may differ. Comparison of the common contigs from P. thornei with other nematodes showed that 2,039 were common to sequences of the Heteroderidae, 1,947 to the Meloidogynidae, 1,218 to Radopholus similis, 1,209 matched expressed sequence tags (ESTs) of Pratylenchus penetrans and Pratylenchus vulnus, and 2,940 to contigs of Pratylenchus coffeae. There were 2,014 contigs common to Caenarhabditis elegans, with 15.9% being common to all three groups. Twelve percent of contigs with matches to the Heteroderidae and the Meloidogynidae had no homology to any C. elegans protein. Fifty-seven percent of the contigs did not match known sequences and some could be unique to P. thornei. These data provide substantial new information on the transcriptome of P. thornei, those genes common to migratory and sedentary endoparasitic nematodes, and provide additional understanding of genes required for different forms of parasitism. The data can also be used to identify potential genes to study host interactions and for crop protection.

Rather than by direct acquisition via lateral gene transfer, GHF5 cellulases were passed on from early Pratylenchidae to root-knot and cyst nematodes

BackgroundPlant parasitic nematodes are unusual Metazoans as they are equipped with genes that allow for symbiont-independent degradation of plant cell walls. Among the cell wall-degrading enzymes, glycoside hydrolase family 5 (GHF5) cellulases are relatively well characterized, especially for high impact parasites such as root-knot and cyst nematodes. Interestingly, ancestors of extant nematodes most likely acquired these GHF5 cellulases from a prokaryote donor by one or multiple lateral gene transfer events. To obtain insight into the origin of GHF5 cellulases among evolutionary advanced members of the order Tylenchida, cellulase biodiversity data from less distal family members were collected and analyzed.ResultsSingle nematodes were used to obtain (partial) genomic sequences of cellulases from representatives of the genera Meloidogyne, Pratylenchus, Hirschmanniella and Globodera. Combined Bayesian analysis of ≈ 100 cellulase sequences revealed three types of catalytic domains (A, B, and C). Represented by 84 sequences, type B is numerically dominant, and the overall topology of the catalytic domain type shows remarkable resemblance with trees based on neutral (= pathogenicity-unrelated) small subunit ribosomal DNA sequences. Bayesian analysis further suggested a sister relationship between the lesion nematode Pratylenchus thornei and all type B cellulases from root-knot nematodes. Yet, the relationship between the three catalytic domain types remained unclear. Superposition of intron data onto the cellulase tree suggests that types B and C are related, and together distinct from type A that is characterized by two unique introns.ConclusionsAll Tylenchida members investigated here harbored one or multiple GHF5 cellulases. Three types of catalytic domains are distinguished, and the presence of at least two types is relatively common among plant parasitic Tylenchida. Analysis of coding sequences of cellulases suggests that root-knot and cyst nematodes did not acquire this gene directly by lateral genes transfer. More likely, these genes were passed on by ancestors of a family nowadays known as the Pratylenchidae.

Effect of oat (Avena sativa) on the population density of Pratylenchus thornei in the field

The effect of eight oat cultivars on the end-of-season population density of the root lesion nematode Pratylenchus thornei was determined in the field in two seasons in the Wimmera region of Victoria. There was no difference among the oat cultivars tested on their effect on final population density of P. thornei. The oat cultivars tested were all found to result in significantly lower population densities of P. thornei than the susceptible wheat but population densities were similar to, or slightly higher than, the resistant barley and bare fallow treatments. Oat was regarded as a crop with useful resistance that can be grown in paddocks to reduce the population density of P. thornei.

Evidence for the involvement of the root lesion nematode Pratylenchus thornei in wheat yield decline in northern New South Wales

Factors responsible for a decline in wheat yields in some paddocks in the Gunnedah (northern New South Wales) area were investigated in a series of field experiments. Yield decline is not apparent on soils cultivated for less than 10 years, and barley and sorghum crops are not affected. Plant nutrition apparently is not a major factor in the decline, because, although there was a small response to zinc application in 1 experiment, wheat yields were not significantly increased by the application of N, P, K, Cu, Mg, B, Mn, Mo or S in a paddock where the yield of wheat was half that of the surrounding barley crop. Fumigation of the soil with methyl bromide increased wheat cv. Timgalen yield by 78% to equal that of barley cv. Clipper in a second experiment. Large numbers of root lesion nematodes (Pratylenchus thornei) were associated with unfumigated wheat plots, with smaller numbers present on barley plots. In a third experiment, the grain yields of all of the 9 cereal genotypes tested were increased when sown with 4 kg/ha of aldicarb. The relative yield increase associated with aldicarb showed good correlation with the reputed tolerance of the genotypes to P. thornei. Pratylenchus thornei occurred to a depth of 120 cm. Aldicarb did not affect P. thornei numbers below 15 cm, while methyl bromide controlled P. thornei to depths of 30-90 cm. Aldicarb virtually eliminated P. thornei from the surface 10 cm of soil, but had no effect on the incidence of the fungal diseases common root rot (Bipolaris sorokiniana) or crown rot (Fusarium graminearum). Soil fumigation with methyl bromide controlled B. sorokiniana and F. graminearum as well as P. thornei and gave yields 9% higher than did treatment with aldicarb. In another experiment, ethylene dibromide (2.7-10.8 L/ha) had no consistent effect on the yield of wheat or numbers of P. thornei while terbufos (0.6 and 1.2 kg/ha) gave a small reduction in P. thornei numbers and a small increase in yield. These data indicate that P. thornei is at least partially responsible for wheat yield decline in parts of northern New South Wales.