Genome‐wide expression profiling of the host response to root‐knot nematode infection in Arabidopsis^a

Abstract

SummaryDuring a compatible interaction, root-knot nematodes (Meloidogyne spp.) induce the redifferentiation of root cells into multinucleate nematode feeding cells (giant cells). Hyperplasia and hypertrophy of the surrounding cells leads to the formation of a root gall. We investigated the plant response to root-knot nematodes by carrying out a global analysis of gene expression during gall formation in Arabidopsis, using giant cell-enriched root tissues. Among 22 089 genes monitored with the complete Arabidopsis transcriptome microarray genespecific tag, we identified 3373 genes that display significant differential expression between uninfected root tissues and galls at different developmental stages. Quantitative PCR analysis and the use of promoter GUS fusions confirmed the changes in mRNA levels observed in our microarray analysis. We showed that a comparable number of genes were found to be up-and downregulated, indicating that gene downregulation might be essential to allow proper gall formation. Moreover, many genes belonging to the same family are differently regulated in feeding cells. This genome-wide overview of gene expression during plant-nematode interaction provides new insights into nematode feeding-cell formation, and highlights that the suppression of plant defence is associated with nematode feeding-site development.

Comprehensive Transcriptome Profiling in Tomato Reveals a Role for Glycosyltransferase in Mi-Mediated Nematode Resistance

“…A similar conclusion was made by Jammes et al (2005), who examined differential gene expression in RKN-infected Arabidopsis roots at weekly intervals postinfection. Collectively, this suggests that the nematode might manipulate multiple pathways to coordinate feeding site formation, protect from host defense responses, and maintain GCs.…”

“…Based on the hypothesis that GCs are transfer cells (Jones and Northcote, 1972), Hammes et al (2005) examined expression of transporter genes in RKN-infected and healthy root tissue at weekly intervals and established that multiple transport processes are regulated, some in GCs and others in uninfected areas of the root. Another study (Jammes et al, 2005) interrogated GCenriched root tissue, establishing that as many genes are repressed as are up-regulated upon nematode infection. They further substantiated that successful RKN infection is associated with suppression of a number of plant defenses.…”

Not to be suppressed? Rethinking the host response at a root-parasite interface

“…A microarray analysis of Arabidopsis thaliana galls at 7 days post inoculation identified a similar number of defense-and cell rescue-related genes that had reduced or increased transcript accumulation compared to non-infested root fragments that had the meristems removed [27]. By 14 days, a large proportion of genes in this functional category were either repressed or were not significantly different in transcript accumulation.…”

Shared Peptides in Mass Spectrometry Based Protein Quantification

“…Inside, they manipulate the cellular machinery to create specialized feeding cells, which grow and multi-nucleate, but do not divide, eventually forming giant cells that provide nutrients to the parasite [3,10]. As the nematodes exploit the Arabidopsis cellular machinery to create the giant cell phenotype, an analysis of proteins that are differentially expressed in infected versus non-infected host cells can help elucidate the underlying mechanism [4]. As the Arabidopsis genome is sequenced, with extensive annotation on the known genes and pathways, it is an appropriate model for the host.…”

“…However, the actual value is hard to interpret, as it depends upon a number of poorly understood factors, including instrument types, energetics of the process, and physico-chemical properties of the peptide itself. Consequently, it is often the relative-abundance of a peptide, measured as the ratio of intensities of a peptide across samples, that is investigated [4,8]. By the same token, intensity values of different peptides are usually not comparable.…”