Meloidogyne incognita Fatty Acid- and Retinol- Binding Protein (Mi-FAR-1) Affects Nematode Infection of Plant Roots and the Attachment of Pasteuria penetrans Endospores.

Victor Phani,Uma Rao,Keith G Davies,Tagginahalli N Shivakumara

doi:10.3389/fmicb.2017.02122

Abstract

Root-knot nematode (RKN) Meloidogyne incognita is an economically important pest of crops. Pasteuria penetrans, is a nematode hyperparasitic bacterium capable of suppressing the reproduction of RKN and thereby useful for its management. Secreted fatty acid and retinol-binding proteins are unique in nematodes and are engaged in nutrient acquisition, development and reproduction; they are also a component of the nematode cuticle and thought to be involved in the interface between hosts and parasites. Attachment of endospores to the cuticle of second stage juveniles of RKN is the primary step of infection and several factors have been identified to facilitate attachment. In this study, the full length of Mi-far-1 (573 bp) was cloned from M. incognita and characterized. Analysis revealed that the Mi-far-1 was rich in α-helix structure, contained a predicted consensus casein kinase II phosphorylation site and a glycosylation site. Quantitative PCR showed the highest expression in the fourth stage juveniles and in situ hybridization revealed the presence of Mi-far-1 mRNA in the hypodermis below the cuticle. Single copy insertion pattern of Mi-far-1 in M. incognita genome was detected by Southern blotting. Knockdown of Mi-far-1 showed significantly increased attachment of P. penetrans’ endospores on juvenile cuticle surface and also affected host finding, root infection and nematode fecundity.

Highlights

Plant-parasitic nematodes are important crop pests and have a major impact on global food production system
This study is the first to demonstrate that the fatty acid and retinol binding proteins (FARs) protein in M. incognita plays a key role in modulating the attachment of Pasteuria endospores to the cuticle of infective juveniles and was found to interfere with host finding, nematode growth, development and fecundity
Present investigation illustrates that FAR protein plays an important role in microbial adhesion to nematode cuticle, and corroborates earlier studies showing its involvement in other basic biological activities like development, reproduction and host infection process (Prior et al, 2001; Garofalo et al, 2003; Kuang et al, 2009)

Summary

Introduction

Plant-parasitic nematodes are important crop pests and have a major impact on global food production system. Around 4,100 species of plant-parasitic nematodes have been identified (Decraemer and Hunt, 2006) and the total crop loss has been estimated to be $173 billion every year (Elling, 2013). Root-knot nematodes (RKN) Meloidogyne spp. are widely regarded as the most economically important group as they are polyphagus attacking the majority of crops and inflicting serious yield and quality losses (Jones et al, 2013). Nematicides have been used to control these pests but they are highly toxic to humans, domestic animals and the environment and recently. Biological control promises to be a good and effective alternative where a suitable biological agent is used to reduce the nematode population density (Hallman et al, 2009; Collange et al, 2011) and is a compatible component of integrated nematode management system

Methods

Results

Conclusion