Direct nematicidal effects of methyl jasmonate and acibenzolar-S-methyl against Meloidogyne incognita.

The aim of this study was to examine the nematicidal properties of two defence inducers against the root-knot nematode Meloidogyne incognita. A direct-contact bioassay was applied to evaluate the nematicidal effects of acibenzolar-S-methyl (ASM) and methyl jasmonate (MEJA) on second-stage juveniles (J2). Nematodes were incubated in different concentrations of these compounds, and the numbers of immobile nematodes were counted after 24 and 48 h post incubation.

Transcriptional changes of the root-knot nematode Meloidogyne incognita in response to Arabidopsis thaliana root signals.

Root-knot nematodes are obligate parasites that invade roots and induce the formation of specialized feeding structures. Although physiological and molecular changes inside the root leading to feeding site formation have been studied, very little is known about the molecular events preceding root penetration by nematodes. In order to investigate the influence of root exudates on nematode gene expression before plant invasion and to identify new genes potentially involved in parasitism, sterile root exudates from the model plant Arabidopsis thaliana were produced and used to treat Meloidogyne incognita pre-parasitic second-stage juveniles.

The Arabidopsis F-box/Kelch-repeat protein At2g44130 is upregulated in giant cells and promotes nematode susceptibility.

We report that the F-box/Kelch-repeat protein At2g44130 is specifically induced by the root-knot nematode Meloidogyne incognita during the initial stages of the initiation and maintenance of the feeding site. In addition, we show that the expression of this gene promotes susceptibility of infection because knocking down the F-box gene (At2g44130) drastically reduces nematode attraction to and infection of roots. In contrast, F-box overexpressing (OE) lines had a hypersusceptible phenotype, with an increase of 34% in nematode attraction and 67% in nematode infection when grown in soil.

Biometrical, Biochemical, and Molecular Diagnosis of Portuguese Meloidogyne hispanica Isolates.

Meloidogyne hispanica infects many economically important crops worldwide. The accurate identification of this pathogen is essential for the establishment of efficient and sustainable integrated pest management programs. Portuguese M.

Cuticle surface coat of plant-parasitic nematodes.

The surface coat (SC) of the plant-parasitic nematode cuticle is an understudied area of current research, even though it likely plays key roles in both nematode-plant and nematode-microbe interactions. Although in several ways Caenorhabditis elegans is a poor model for plant-parasitic nematodes, it is a useful starting point for investigations of the cuticle and its SC, especially in the light of recent work using this species as a model for innate immunity and the generic biology underpinning much host-parasite biology. We review the research focused on the involvement of the SC of plant-parasitic nematodes.

Chemotaxis can take plant-parasitic nematodes to the source of a chemo-attractant via the shortest possible routes.

It has long been recognized that chemotaxis is the primary means by which nematodes locate host plants. Nonetheless, chemotaxis has received scant attention. We show that chemotaxis is predicted to take nematodes to a source of a chemo-attractant via the shortest possible routes through the labyrinth of air-filled or water-filled channels within a soil through which the attractant diffuses.

Plant parasitic nematode proteins and the host parasite interaction.

This review focuses on the proteins and secretions of sedentary plant parasitic nematodes potentially important for plant-nematode interactions. These nematodes are well equipped for parasitism of plants. Having acquired the ability to manipulate fundamental aspects of plant biology, they are able to hijack host-cell development to make their feeding site.

Fused RolA protein enhances beta-glucoronidase activity 50-fold: implication for RolA mechanism of action.

We report that the plant oncoprotein RolA from Agrobacterium rhizogenes acts to stabilize beta-glucoronidase (Gus) when the two proteins are expressed as a fusion protein in transformed tobacco. The observed 50-fold increase of Gus activity was shown to be related to protein accumulation, with no significant changes in mRNA abundance, kinetic properties of the enzyme and thermostability. The entire RolA sequence is essential to achieve the full effect since both the N-terminal region, spanning a putative reverse signal-anchor and nuclear targeting sequences, or the contiguous C-terminal portion were shown to increase Gus activity only 10-fold.

A genomics approach to crop pest and disease research.

Genome-wide analyses of gene function and gene expression are beginning to yield valuable information in many areas of biological research, and these genomic tools are now being applied to crop pest and disease research. DNA sequencing of cDNA libraries to generate sets of expressed sequence tags (ESTs) are allowing gene compendiums for crop diseases to be compiled. Annotation of such data collections is also providing a wealth of functional information about gene products through similarities to proteins with known function.