Overexpression of Wild Arachis Lipocalin Enhances Root-Knot Nematode Resistance in Peanut Hairy Roots

Abstract

Plant parasitic root-knot nematodes (RKN) have evolved sophisticated strategies for exploiting plants, and they cause devastating yield losses in many susceptible crops. The RKN Meloidogyne arenaria is the most predominant pathogenic nematode affecting cultivated peanut (Arachis hypogaea L.). Resistance against the M. arenaria has been identified in the wild peanut relative, Arachis stenosperma. Transcriptome studies on A. stenosperma–M. arenaria interaction revealed candidate genes potentially involved in the first stages of this resistance response, including a temperature-induced lipocalin (TIL) protein. Plant TILs have a protective role against harmful molecules produced in response to a number of stresses. In this study, the characterization of the RKN-responsive TIL from A. stenosperma (AsTIL) provides new insights into the role of plant lipocalins in nematode resistance. The AsTIL gene has a 2-exon/1-intron structure and encodes a 21.4 kDa polypeptide. It contains three structurally conserved regions, which are a signature for plant lipocalins. Overexpression of AsTIL in transgenic hairy roots from a susceptible peanut cultivar led to the reduction of M. arenaria galls and egg masses 60 days after inoculation. This is the first report of a possible involvement of plant lipocalins in RKN resistance. It also reveals a promising candidate gene for peanut breeding to produce cultivars resistant to M. arenaria.