Dataset Information

Incorporating Molecular Identification of Meloidogyne spp. into a Large-scale Regional Nematode Survey.

ABSTRACT: A regional nematode survey of potato fields was conducted in the central United States during 2002 and 2003. The survey encompassed seven states and included a morphological and molecular examination of nematodes of regulatory concern from 1,929 soil samples. No regulated pest species were recovered during this survey. Meloidogyne juveniles extracted from soil were identified by mitochondrial and 18S ribosomal molecular markers. Eighty-two DNA sequences representing the two marker regions for Meloidogyne species were submitted to GenBank to facilitate evaluation of marker variability. Sufficient 18S variation was observed among some Meloidogyne species to aid in identification; however, nucleotide sequence from this highly conserved region of 18S did not discriminate among M. arenaria, M. incognita, and M. javanica. The mitochondrial gene region provided greater species discrimination and revealed intraspecific variation among many isolates. One nucleotide substitution found in a subset of M. hapla isolates from west Texas and New Mexico affected a DraI restriction site used in the PCR/RFLP diagnostic protocol. None of the mitochondrial sequence variants observed in this study compromised the PCR/RFLP identification protocol for M. chitwoodi. Additional sequence analysis is recommended for validation and evaluation of genetic markers used in diagnostic decisions.

SUBMITTER: Powers TO

PROVIDER: S-EPMC2620951 | biostudies-other | 2005 Jun

REPOSITORIES: biostudies-other

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Incorporating Molecular Identification of Meloidogyne spp. into a Large-scale Regional Nematode Survey.

Powers T O TO Mullin P G PG Harris T S TS Sutton L A LA Higgins R S RS

Journal of nematology 20050601 2

A regional nematode survey of potato fields was conducted in the central United States during 2002 and 2003. The survey encompassed seven states and included a morphological and molecular examination of nematodes of regulatory concern from 1,929 soil samples. No regulated pest species were recovered during this survey. Meloidogyne juveniles extracted from soil were identified by mitochondrial and 18S ribosomal molecular markers. Eighty-two DNA sequences representing the two marker regions for Me ...[more]

PMID: 19262865

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Project description:BACKGROUND:Cereal cyst nematode Heterodera avenae, an important soil-borne pathogen in wheat, causes numerous annual yield losses worldwide, and use of resistant cultivars is the best strategy for control. However, target genes are not readily available for breeding resistant cultivars. Therefore, comparative transcriptomic analyses were performed to identify more applicable resistance genes for cultivar breeding. METHODS:The developing nematodes within roots were stained with acid fuchsin solution. Transcriptome assemblies and redundancy filteration were obtained by Trinity, TGI Clustering Tool and BLASTN, respectively. Gene Ontology annotation was yielded by Blast2GO program, and metabolic pathways of transcripts were analyzed by Path_finder. The ROS levels were determined by luminol-chemiluminescence assay. The transcriptional gene expression profiles were obtained by quantitative RT-PCR. RESULTS:The RNA-sequencing was performed using an incompatible wheat cultivar VP1620 and a compatible control cultivar WEN19 infected with H. avenae at 24 h, 3 d and 8 d. Infection assays showed that VP1620 failed to block penetration of H. avenae but disturbed the transition of developmental stages, leading to a significant reduction in cyst formation. Two types of expression profiles were established to predict candidate resistance genes after developing a novel strategy to generate clean RNA-seq data by removing the transcripts of H. avenae within the raw data before assembly. Using the uncoordinated expression profiles with transcript abundance as a standard, 424 candidate resistance genes were identified, including 302 overlapping genes and 122 VP1620-specific genes. Genes with similar expression patterns were further classified according to the scales of changed transcript abundances, and 182 genes were rescued as supplementary candidate resistance genes. Functional characterizations revealed that diverse defense-related pathways were responsible for wheat resistance against H. avenae. Moreover, phospholipase was involved in many defense-related pathways and localized in the connection position. Furthermore, strong bursts of reactive oxygen species (ROS) within VP1620 roots infected with H. avenae were induced at 24 h and 3 d, and eight ROS-producing genes were significantly upregulated, including three class III peroxidase and five lipoxygenase genes. CONCLUSIONS:Large-scale identification of wheat resistance genes were processed by comparative transcriptomic analysis. Functional characterization showed that phospholipases associated with ROS production played vital roles in early defense responses to H. avenae via involvement in diverse defense-related pathways as a hub switch. This study is the first to investigate the early defense responses of wheat against H. avenae, not only provides applicable candidate resistance genes for breeding novel wheat cultivars, but also enables a better understanding of the defense mechanisms of wheat against H. avenae.

Dataset Information

Incorporating Molecular Identification of Meloidogyne spp. into a Large-scale Regional Nematode Survey.

Publications

Incorporating Molecular Identification of Meloidogyne spp. into a Large-scale Regional Nematode Survey.

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