Genome-Guided Reanalysis of Root-Knot Nematode Meloidogyne incognita Esophageal Gland Cell-Enriched Sequence Tag Libraries: A Resource for the Discovery of Novel Effectors

Abstract

Most plant-parasitic nematode species (PPNs) use a hollow, protrusible stylet to secrete effector proteins originating from three large, secretory esophageal gland cells (two subventral and one dorsal) to parasitize host plants (Hussey 1989). These stylet-secreted effector proteins are packaged into secretory granules within the gland cells, marking them for secretion from the nematode stylet (Mitchum et al. 2013). Sedentary endoparasitic nematodes such as root-knot nematodes (RKNs) (Meloidogyne spp.) secrete effector proteins to aid penetration and migration through root tissues and facilitate the establishment and maintenance of a permanent feeding site within the vascular cylinder of the root (Caillaud et al. 2008). The identification and functional characterization of stylet-secreted effectors, therefore, is not only critical for understanding the complex molecular interactions between the nematode and its host but also opens the door for devising novel strategies for nematode control by interfering with key steps in the infection process. Thus, identifying genes encoding stylet-secreted effector proteins has been an intense focus for researchers.