Identification of candidate effector genes of Pratylenchus penetrans

Abstract

Pratylenchus penetrans is one of the most important species of root lesion nematodes (RLNs) because of its detrimental and economic impact in a wide range of crops. Similar to other plant-parasitic nematodes (PPNs), P. penetrans harbours a significant number of secreted proteins that play key roles during parasitism. Here, we combined spatially and temporally resolved next-generation sequencing datasets of P. penetrans to select a list of candidate genes aimed at the identification of a panel of effector genes for this species. We determined the spatial expression of transcripts of 22 candidate effectors within the oesophageal glands of P. penetrans by in situ hybridization. These comprised homologues of known effectors of other PPNs with diverse putative functions, as well as novel pioneer effectors specific to RLNs. It is noteworthy that five of the pioneer effectors encode extremely proline-rich proteins. We then combined in situ localization of effectors with available genomic data to identify a non-coding motif enriched in promoter regions of a subset of P. penetrans effectors, and thus a putative hallmark of spatial expression. Expression profiling analyses of a subset of candidate effectors confirmed their expression during plant infection. Our current results provide the most comprehensive panel of effectors found for RLNs. Considering the damage caused by P. penetrans, this information provides valuable data to elucidate the mode of parasitism of this nematode and offers useful suggestions regarding the potential use of P. penetrans-specific target effector genes to control this important pathogen.

Current Insights into Migratory Endoparasitism: Deciphering the Biology, Parasitism Mechanisms, and Management Strategies of Key Migratory Endoparasitic Phytonematodes

“…However, parasitism proteins involved in disparate stages of host interaction can also be released by other tissues such as the amphids and hypodermis [10]. Cellulases have also been characterized in the molecular and transcriptomic studies of the lesion nematode P. penetrans, P. thornei (Sher and Allen), P. vulnus (Allen and Jensen, 1951), and P. zeae Graham, 1951 [15,16,37,44,45]. The P. penetrans GHF5 cellulases have shown similarity to those in cyst and root-knot nematodes, enforcing a previous finding that some of the early members of the Pratylenchidae family could be gene donors to the root-knot and cyst nematodes [16,43].…”

“…In P. penetrans, numerous effectors have been identified and their putative role in parasitism has been deciphered [16,45]. Some of the significant effectors discovered in the P. penetrans transcriptome include catalases (with N-terminal signal peptide) and glutathione peroxidase that play role in shielding the nematode against host induced reactive oxygen species (ROS) molecules.…”

“…Moreover, notable effectors identified in the transcriptome dataset include the venom allergen-like proteins (VAPs) that have also been identified in B. xylophilus and have been hypothesized to be involved in movement within the host plant [ 67 ]. Furthermore, effectors such as transthyretin-like proteins (TTLs) and fatty-acid and retinol-binding proteins (FARs) were also identified in the P. penetrans transcriptome dataset [ 45 ]. TTLs have been implicated to play an important role in the nervous system of R. similis and FARs from the cyst, and root-knot nematodes have been shown to bind precursor molecules involved in the defense related jasmonic acid signaling pathway [ 68 , 69 , 70 ].…”

Multi-copy alpha-amylase genes are crucial for Ditylenchus destructor to parasitize the plant host

“…The exogenous double-stranded RNA (dsRNA) and small interfering RNA (siRNA) ingested by nematodes can cause the silencing of homology-dependent endogenous genes through the conserved RNAi pathway in nematodes [ 14 ]. Therefore, expressing dsRNA or siRNA targeting nematode pathogenesis-related genes in plant cells can improve plant resistance against plant-parasitic nematodes [ 15 ]. Currently, most studies on pathogenesis-related genes are focused on the sedentary root-knot nematode ( Meloidogyne spp.)…”

Assessment of the pest status of Pratylenchus curvicauda and ultrastructural changes in roots of infected wheat and barley

“…is still not fully understood. The recent increase in the availability of data on genomes and transcriptomes of root-lesion nematodes is paving the way for such detailed assessment to be made (Haegeman et al, 2011;Nicol et al, 2012;Vieira et al, 2015;Vieira et al, 2018).…”