The plant apoplasm is an important recipient compartment for nematode secreted proteins

Abstract

Similarly to microbial pathogens, plant-parasitic nematodes secrete into their host plants proteins that are essential to establish a functional interaction. Identifying the destination of nematode secreted proteins within plant cell compartment(s) will provide compelling clues on their molecular functions. Here the fine localization of five nematode secreted proteins was analysed throughout parasitism in Arabidopsis thaliana. An immunocytochemical method was developed that preserves both the host and the pathogen tissues, allowing the localization of nematode secreted proteins within both organisms. One secreted protein from the amphids and three secreted proteins from the subventral oesophageal glands involved in protein degradation and cell wall modification were secreted in the apoplasm during intercellular migration and to a lower extent by early sedentary stages during giant cell formation. Conversely, another protein produced by both subventral and dorsal oesophageal glands in parasitic stages accumulated profusely at the cell wall of young and mature giant cells. In addition, secretion of cell wall-modifying proteins by the vulva of adult females suggested a role in egg laying. The study shows that the plant apoplasm acts as an important destination compartment for proteins secreted during migration and during sedentary stages of the nematode.

Functional roles of effectors of plant-parasitic nematodes

“…Although nematodes in general posses hundreds of protease encoding genes (Castagnone-Sereno et al, 2011), only a fraction of these proteins are secreted into the plant tissue. A protein similar to aspartyl proteases was shown to be secreted from Meloidogyne incognita into plant tissues during migration and apparently also accumulates at the wall of the giant cells during the sedentary phase (Vieira et al, 2011). Additional proteases were identified in the M. incognita secretome including aminopeptidases and a cysteine protease (Bellafiore et al, 2008).…”

The Plant Cell Cycle Machinery: Usurped and Modulated by Plant-Parasitic Nematodes

“…encountered in A. thaliana allowed us to functionally analyze genes and proteins during plant development and nematode infection. An adapted BM method has been effectively employed for the localization of a number of nematode-secreted proteins (Vieira, Youssef, et al, 2012), for example a Mi-CRT (Jaubert et al, 2005), Mi-CBM2-bearing proteins (Figure 4(A)) Mi-MAP-1 (Figure 4(B)), Mi-PEL3 (Figure 4(C)), Mi-6D4 (Figure 4(D)) and Mi-EFF1 (Danchin et al, 2010;Jaouannet et al, 2012;Vieira et al, 2011;Vieira, Youssef, et al, 2012). The protocol permits the simultaneous detection of nematode-secreted proteins, previously localized within nematode secretory glands, and plant cytoskeletal proteins such as actins, tubulins and an actin-binding protein (de Almeida Engler et al, 2004;Clément et al, 2009;Youssef Banora et al, 2011).…”

Cellular Signaling Pathways and Posttranslational Modifications Mediated by Nematode Effector Proteins

“…Effectors with strong similarity to proteases have been identified from both cyst and root-knot nematodes. The aspartyl protease-like effector from M. incognita (MiASP2) was secreted into the apoplasm during the intercellular migration of infective juveniles as well as during the early sedentary stages of giant cell formation (Vieira et al, 2011). While the proteolytic activity of MiASP2 has not been demonstrated, it may contribute to host range (GrCLE1), and proteolysis (VAP1).…”