Meloidogyne arenaria candidate effector MaMsp4 interacts with maize (Zea mays L.) proteins involved in host defense response and cell wall modifications

Abstract

Abstract Background and aims Meloidogyne arenaria is an economically important root-knot nematode species. Successful plant infection by nematode is facilitated by parasite effectors. This study aimed to characterize a candidate M. arenaria effector, indicate its molecular partners from maize, and analyze its role during infection. Material and methods At first, we performed EST database mining to find candidate effector protein from M. arenaria. The expression of its coding gene in nematode developmental stages was assessed using digital droplet PCR. Candidate effector molecular partners were determined using yeast two-hybrid screening of maize cDNA library and interactions were confirmed by co-immunoprecipitation after co-expression in Nicotiana benthamiana. Candidate effector and its molecular partners were GFP-fused and localization in N. benthamiana leaves was observed under confocal microscope. Then, expression level of genes encoding interacting proteins from maize was measured. Results MaMsp4 protein was evaluated as candidate effector in M. arenaria and the highest expression level of its coding gene was observed in stage J2. MaMsp4 maize molecular partners were indicated, interactions with beta-galactosidase 11, pectinesterase, S-adenosyl methionine decarboxylase 2, and ethanolamine-phosphate cytidylyltransferase were confirmed, and all proteins fused with GFP were detected in the apoplast and/or cytoplasm. Genes of beta-galactosidase 11 and pectinesterase, playing role in cell wall modifications, were overexpressed at 24 hpi followed by down-regulation at 7 dpi, while S-adenosyl methionine decarboxylase 2 and ethanolamine-phosphate cytidylyltransferase, involved in plant defense response, were suppressed at 7 dpi, without preceding up-regulation. Conclusions We have found that MaMsp4 interacts with plant proteins involved in plant cell wall modifications and defense mechanisms related to polyamines biosynthesis.