Transcriptome Analyses of Pre-parasitic and Parasitic Meloidogyne Chitwoodi Race 1 to Identify Putative Effector Genes

Abstract

Meloidogyne chitwoodi is a root-knot nematode that is a major pest of potato in the northwestern United States. Due to the lack of resistance against root-knot nematodes in potato, research has been undertaken to understand the M. chitwoodi-potato interaction at the molecular level. To identify the nematode genes that are playing roles in parasitism, we have performed transcriptome analyses on pre-parasitic and parasitic M. chitwoodi juveniles in susceptible potato. We compared gene expression profiles and identified genes that were significantly up-or down-regulated during nematode parasitism. Because parasitism proteins are typically secreted by the nematode to facilitate infection of host roots, we focused on the genes that encoded proteins that were predicted to be secreted. We found that approximately 34% (43/127) of the genes in the predicted secretome encoded proteins with no significant homology in the public genome databases, and 12% (15/127) encoded either a known effector, putative effectors or putative esophageal gland cell proteins. The transcriptome analyses of M. chitwoodi at the preparasitic and parasitic life stages shed light on the genes involved in nematode parasitism.

Understanding Molecular Plant–Nematode Interactions to Develop Alternative Approaches for Nematode Control

“…There are some molecular methods that should be dealt with carefully because they are based on materials that may be suitable for controlling a specific nematode genus but not others. Therefore, more studies with adequate tools and updated methods may be preferably directed towards nature, and structure of PPN-feeding tubes, the nematode-derived compounds, and consequent plant responses involved in such plantnematode interactions for determining the molecular efficacy against the target nematode genus/species [9,10,12,16,27,61]. In this respect, as PPNs have a stylet orifice while feeding; it acts as a molecular sieve to uptake certain molecules and exclude others while feeding on tomato roots that express a nematicidal Bacillus thuringiensis crystal protein.…”

“…This technique also considerably reduced the large list of genes in the M. chitwoodi secretome reported by the former method [70], isolating the nematodes from the roots led to recording genes not related to parasitism. While it is really difficult to functionally characterize ≥ 300 genes via a traditional method [70], dual RNA-seq could analyze the expression of fewer genes specifically at the early parasitic life stages of M. chitwoodi too [61].…”

Appraising the natural root-knot nematode resistance inSolanum sisymbriifolium, a wild relative of potato

“…To prepare the sterile nematodes juveniles for potato and S. sisymbriifolium tissue culture inoculation, M. hapla eggs were surface sterilized three times with 0.6% sodium hypochlorite and rinsed liberally with DI water. Afterwards, eggs were placed in a modified Baermann funnel apparatus with hatching solution (0.1% Plant Preservative Mixture (PPM), 0.01% DDT in sterile DI water) (Zhang and Gleason, 2021). After 4 days of hatching, the sterile M. hapla J2 were collected.…”