Reniform Nematode Rotylenchulus Reniformis Research Articles

Distribution of Rotylenchulus reniformis (Tylenchida, Hoplolaimidae) reproductive types in Kyushu, Japan

The reniform nematode Rotylenchulus reniformis Linford and Oliveira (Tylenchida, Hoplolaimidae) is a serious pest of a number of crops worldwide. Although different reproductive types of R. reniformis populations have been reported in Japan, there is no information regarding the difference in their pathogenicity. In this study, we investigated the distribution of R. reniformis reproductive types primarily in sweet potato fields in Kyushu for a further study on their pathogenicity. Rotylenchulus reniformis was widely detected in sweet potato fields, but there were variations in its density and male frequency. DNA amplification conducted using primers designed to distinguish the male-absent type from the male-numerous type revealed that male-rare populations in Kumamoto were the male-absent type, but a population from Saito, Miyazaki, was a mixture of both types. Although R. reniformis density was high in some fields at the harvest time in Kumamoto and Saga, there was no apparent damage to sweet potato.

SUSCEPTIBILITY OF NINE GRAPE CULTIVARS TO THE ROOT-KNOT NEMATODE, Meloidogyne incognita AND RENIFORM NEMATODE, Rotylenchulus reniformis

The susceptibility of nine grape cultivars (Bez Alanza, Early Sweet, Flame Seedless, Mangawy, Queen, Red Globe, Romy Red, Sperior and Thompson Seedless) were tested for the two nematode species (root-knot nematode, Meloidogyne incognita and reniform nematode Rotylenchulus reniformis) under greenhouse conditions. The results indicated that both nematode species reproduced well on all tested grape cultivars, also grape cultivars were different in their susceptibility to both nematode species. The cultivars were ranked for their susceptibility against M. incognita as follows: two cultivars, Mangawy and Queen were categorized as very resistant to the nematode. Red Globe and Thompson Seedless cultivars were considered as slightly resistant. On the other hand, five cultivars Bez Alanza, Early Sweet, Flame Seedless, Romy Red and Sperior were graded as susceptible. As for the response of these grape cultivars to the R. reniformis Bez Alanza, Mangawy, Queen and Romy Red were categorized as highly resistant. Only Sperior was rated as resistant. Early Sweet, Red Globe and Thompson Seedless were considered as less susceptible. In contrast, one cultivar Flame Seedless was ranged as highly susceptible. Plant growth parameters of tested grape cultivars were also discussed.

Top 10 plant‐parasitic nematodes in molecular plant pathology

The aim of this review was to undertake a survey of researchers working with plant-parasitic nematodes in order to determine a 'top 10' list of these pathogens based on scientific and economic importance. Any such list will not be definitive as economic importance will vary depending on the region of the world in which a researcher is based. However, care was taken to include researchers from as many parts of the world as possible when carrying out the survey. The top 10 list emerging from the survey is composed of: (1) root-knot nematodes (Meloidogyne spp.); (2) cyst nematodes (Heterodera and Globodera spp.); (3) root lesion nematodes (Pratylenchus spp.); (4) the burrowing nematode Radopholus similis; (5) Ditylenchus dipsaci; (6) the pine wilt nematode Bursaphelenchus xylophilus; (7) the reniform nematode Rotylenchulus reniformis; (8) Xiphinema index (the only virus vector nematode to make the list); (9) Nacobbus aberrans; and (10) Aphelenchoides besseyi. The biology of each nematode (or nematode group) is reviewed briefly.

Field Efficacy of Biocontrol Agents for the Management of Root Knot Nematode Meloidogyne incognita (Kofoid&White) Chitw. and Reniform Nematode Rotylenchulus reniformis (Linford&Oliviera) in Tomato

Two field experiments were conducted with tomato Hybrid 5005 at Kuttathottam and Theethipalayam villages of Coimbatore district to investigate the potential of two promising native isolates of plant growth promoting rhizobacteria (PGPR), viz., Pseudomonas fluorescens (Pfbv22) and Bacillus subtilis (Bbv57) for the management of root knot nematode Meloidogyne incognita and reniform nematode Rotylenchulus reniformis in tomato. The biocontrol agents were compared with the standard chemical viz., carbofuran. Consortium application of P. fluorescens (Pfbv22) and B. subtilis (Bbv57) as seed treatment each @ 5 g kg -1 seeds and soil application (SA) @ 1.25 kg ha -1 significantly reduced the nematode infestation in soil and root. The microbial consortium treatment also significantly enhanced the plant growth parameters such as plant height, shoot weight, root length, root weight and fruit yield.

Response of cucurbit species to Rotylenchulus reniformis

The state of Rio Grande do Norte is the major melon (Cucumis melo) producer in Brazil and the reniform nematode Rotylenchulus reniformis has become increasingly important due to damages to that crop and the lack of resistant cultivars and effective control measures. Under these circumstances, eight cucurbit genotypes were screened for resistance or tolerance to a population of R. reniformis in naturally infested field soil, under greenhouse conditions. A high reduction in shoot mass was found in all infected genotypes. Watermelon (Citrullus lanatus) cv. Sugar Baby showed the lowest rate of nematode reproduction.

An efficient method for the purification and characterization of nematicidal azadirachtins A, B, and H, using MPLC and ESIMS.

Azadirachtin A enriched concentrate containing 60% active ingredient (a.i.) was prepared from the methanolic extract of the de-fatted neem (Azadirachta indica A. Juss) seed kernels. Azadirachtins A, B, and H, the three major bioactive constituents of neem seed kernel, were purified from this methanolic concentrate by employing reverse phase medium-pressure liquid chromatography (MPLC), using methanol-water solvent system as an eluant. The three pure azadirachtin congeners thus obtained were characterized by their unique mass spectral fragmentation, using electrospray probe in positive ion mode (ESI). All three azadirachtins exhibited nematicidal and antifungal activities. Azadirachtin B was the most effective against the reniform nematode Rotylenchulus reniformis (EC(50) 96.6 ppm), followed by Azadirachtin A (119.1 ppm) and H (141.2 ppm). At 200-ppm concentration, the test compounds caused 50-65% mortality of Caenorhabditis elegans nematode. Azadirachtin H showed the highest activity against the phytophagous fungi Rhizoctonia solani (EC(50) 63.7 ppm) and Sclerotium rolfsii (EC(50) 43.9 ppm), followed by B and A. The isolation of pure azadirachtins A, B, and H directly by MPLC purification from its concentrate and their characterization by ESIMS are unique and less time-consuming.

Transgenic resistance to the nematode Rotylenchulus reniformis conferred by Arabidopsis thaliana plants expressing proteinase inhibitors.

The level of resistance to the reniform nematode Rotylenchulus reniformis conferred on Arabidopsis thaliana by transgenic expression of proteinase inhibitors (PI) was studied over 40 days of infection. A cysteine PI differing from Oc-I expressed in rice seed by one amino acid (Oc-IΔD86) had a considerable effect. It reduced parasite density and fecundity to 65±4% and 31±8% respectively, relative to values for untransformed plants when expressed at ca. 0.4% total soluble protein. The overall reproductive success was only 19±5% relative to the controls. Similar expression levels of cowpea trypsin inhibitor, a serine PI, reduced the density of the females on the plants to 77±3% of control values but did not reduce their fecundity. There was no evidence for additive effects when both PIs were expressed as a fusion protein using a peptide linker. Both PIs in the fusion PI protein are known to be functional from our previous work. When developing on A. thaliana plants expressing the transgenic proteins the intact PI fusion protein of 22 kDa was detected in nematodes by western blot analysis. Similarly, R. reniformis females were observed to have ingested Green Fluorescent Protein (28 kDa). Demonstrating the ingestion of the fusion protein, which has been associated with additive effects of the two PIs against other nematodes, supports the observation that serine PIs are of less value than cysteine PIs for R. reniformis control. The effect of Oc-IΔD86 on R. reniformis was dependent on the level of expression of different A. thaliana lines in the range of 0.1–0.4% total soluble protein indicating that the upper level of expression is required for an effective defence. Virtual northern analysis with cysteine and serine proteinase gene probes from Heterodera glycines showed high transcript abundance of a serine proteinase in both pre-parasitic and parasitic stages whereas expression of the cysteine proteinase was more abundant in the feeding adult female. This study provides further evidence that cystatins represent a valuable source of control against a range of economic nematodes including Globodera, Heterodera and Meloidogyne and now including R. reniformis. Preliminary screening in A. thaliana provides a convenient guide for selection of transgenes against nematode pathogens of crops such as pineapple that have a prolonged regeneration period.

Effect of root-knot and reniform nematodes on plant growth and bulk-density of plant residues of pigeonpea

Different varieties of pigeonpea showed varied reactions to the root-knot nematode Meloidogyne incognita and reniform nematode Rotylenchulus reniformis. Loss in plant weight, number of pods per plant, chlorophyll content of leaves and bulk density of stem parts was directly correlated with the multiplication of the nematodes, the highest being in susceptible varieties with minimal or no change in resistant varieties. Variety ICPL 8562 showed resistance to M. incognita and variety ICPL 87 to R. reniformis.