An expansin-like candidate effector protein from Pratylenchus penetrans modulates immune responses in Nicotiana benthamiana

Authors: VIEIRA, PAULO - Virginia Tech; Nemchinov, Lev

Submitted to: Phytopathology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/31/2019
Publication Date: 11/4/2019
Citation: Vieira, P., Nemchinov, L.G. 2019. An expansin-like candidate effector protein from Pratylenchus penetrans modulates immune responses in Nicotiana benthamiana. Phytopathology. https://doi.org/10.1094/PHYTO-09-19-0336-R.
DOI: https://doi.org/10.1094/PHYTO-09-19-0336-R

Interpretive Summary: Worldwide crop losses due to plant-parasitic nematodes have been estimated at $118 billion annually, with root lesion nematodes (RLN), Pratylenchus spp., ranking third in terms of economic losses. RLN is a migratory species that attacks a broad range of plant species, including alfalfa, the third most widely grown crop in the US, planted on more than 23 million acres in all 50 states. P. penetrans causes a reduction in root growth after infection, accompanied by the formation of lesions, necrotic areas, browning and cell death. To gain biological insights into parasitism strategy of RLN, this study focused on some of the nematode’s virulence factors, or effectors, that are critical for a successful parasitism. As a result of this investigation, the biological roles of these proteins were proposed and molecular mechanisms of plant responses to the nematode-secreted protein identified. Results of this work will be of interest to the researchers in academia and government organizations working in the fields of nematology, plant pathology and plant molecular biology.

Technical Abstract: The root lesion nematode (RLN) Pratylenchus penetrans is a migratory species that attacks a broad range of crops. After initial attraction to host roots caused by root exudates and compounds, RLN releases its own secretions that are critical for a successful parasitism. Among those secretions are nematode virulence factors, or effectors, that facilitate entry and migration of nematodes through the roots and modulate plant immune defenses. Recognition of the effectors by host resistance proteins leads to the effector triggered immunity and incompatible plant-nematode interactions. Although many candidate effectors of RLN and other plant parasitic nematodes have been identified, detailed mechanisms of their functions and particularly their host targets remain largely unexplored. In this study, we sequenced and described genes encoding for expansin-like proteins, major candidate effectors of P. penetrans. One of the genes, Pp-EXPB1, which was the most highly expressed during the nematode infection of different plant species, was further functionally characterized by means of transient expression in a model plant Nicotiana benthamiana and global transcriptome profiling of gene expression changes, triggered by this candidate effector in plants. As a result of this investigation, we proposed biological roles of the Pp-EXPB1 in the parasitism of P. penetrans, its perspective cellular targets, and molecular mechanisms of plant responses to this nematode-secreted protein.