Identification and Characterization of a Fatty Acid- and Retinoid-Binding Protein Gene (Ar-far-1) from the Chrysanthemum Foliar Nematode, Aphelenchoides ritzemabosi

Abstract

The chrysanthemum foliar nematode (CFN), Aphelenchoides ritzemabosi, is a migratory, plant-parasitic nematode that is widely distributed and infects the aboveground parts of many plants. The fatty acid- and retinoid-binding proteins (FAR) are nematode-specific proteins that are involved in the development, reproduction, and infection of nematodes and are secreted into the tissues to disrupt the plant defense reaction. In this study, we obtained the full-length sequence of the FAR gene (Ar-far-1) from CFN, which is 727 bp and includes a 546 bp ORF that encodes 181 amino acids. Ar-FAR-1 from CFN has the highest sequence similarity to Ab-FAR-1 from A. besseyi, and they are located within the same branch of the phylogenetic tree. Fluorescence-based ligand-binding analysis confirmed that recombinant Ar-FAR-1 was bound to fatty acids and retinol. Ar-far-1 mRNA was expressed in the muscle layer, intestine, female genital system, and egg of CFN, and more highly expressed in females than in males among the four developmental stages of CFN. We demonstrated that the reproduction number and infection capacity of CFN decreased significantly when Ar-far-1 was effectively silenced by in vitro RNAi. Ar-far-1 plays an important role in the development, reproduction, infectivity, and pathogenesis of CFN and may be used as an effective target gene for the control of CFN. The results provide meaningful data about the parasitic and pathogenic genes of CFN to study the interaction mechanism between plant-parasitic nematodes and hosts.

Fatty acid- and retinol-binding protein 6 does not control worm fatty acid content in Caenorhabditis elegans but might play a role in Haemonchus contortus parasitism

“…However, either free fatty acids or free retinoids are relatively insoluble in water, susceptible to oxidation, and potentially toxic to nematodes [ 19 , 44 ]. FARs represent one of the approaches evolved by nematodes to acquire and transport free fatty acids and retinol [ 19 , 26 , 44 , 57 , 58 ]. Therefore, FAR protein-coding genes (e.g.…”

Novel Functions of the Fatty Acid and Retinol Binding Protein (FAR) Gene Family Revealed by Fungus-Mediated RNAi in the Parasitic Nematode, Aphelenchoides besseyi

“…Preliminary progress has been made in the study of the sequence characteristics, basic functional properties, and binding activity with FAR proteins [ 9 , 13 , 27 ]. However, to date, there are still no reports on their specific functions in nematodes.…”

“…Fatty acids and retinols play important roles in physiological processes, such as gene activation, cell signaling pathways, tissue differentiation, and repair, and may inhibit or interfere with the host’s defensive immune response [ 8 , 9 ]. As a unique protein in nematodes, more than 70 FAR sequences and functions have been identified in different species of nematodes [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 ]. The function of the FAR protein gene ( far ) in five species of plant nematodes has been studied and verified by RNA interference (RNAi) [ 8 , 12 , 15 , 18 , 19 , 20 ].…”

Aphelenchoides besseyi Ab-FAR-1 Interacts with Arabidopsis thaliana AtADF3 to Interfere with Actin Cytoskeleton, and Promotes Nematode Parasitism and Pathogenicity

“…Fatty acid and retinol-binding proteins (FAR) are among the most widely studied proteins secreted by the body wall of nematodes, and have been widely reported in free-living nematodes, animal-parasitic nematodes, and plant-parasitic nematodes [ 24 , 25 , 26 , 27 , 28 , 29 , 30 , 31 , 32 , 33 , 34 , 35 , 36 , 37 ]. At present, the structures and functions of FAR are mainly explained as follows: (1) FAR are unique to nematodes and do not exist in other biological groups [ 38 ]; (2) their function in obtaining fatty acids and retinols from hosts and the environment is necessary for nematode lipid biosynthesis and assembly of macromolecular structures to complete the growth and development of nematodes [ 31 , 32 ]; (3) most of them are located on the nematode body wall, which is the host–parasite interface, and, therefore, they play important roles in promoting nematode parasitism and regulating host defences [ 30 ]; and (4) there is evidence that FAR can influence the fecundity and pathogenicity of nematodes [ 32 , 33 , 39 ]. In previous studies, we found eight FAR proteins with significantly different mRNA localisations and diverse functions in RWTNs [ 32 , 33 , 39 ].…”

“…At present, the structures and functions of FAR are mainly explained as follows: (1) FAR are unique to nematodes and do not exist in other biological groups [ 38 ]; (2) their function in obtaining fatty acids and retinols from hosts and the environment is necessary for nematode lipid biosynthesis and assembly of macromolecular structures to complete the growth and development of nematodes [ 31 , 32 ]; (3) most of them are located on the nematode body wall, which is the host–parasite interface, and, therefore, they play important roles in promoting nematode parasitism and regulating host defences [ 30 ]; and (4) there is evidence that FAR can influence the fecundity and pathogenicity of nematodes [ 32 , 33 , 39 ]. In previous studies, we found eight FAR proteins with significantly different mRNA localisations and diverse functions in RWTNs [ 32 , 33 , 39 ]. The expression level of Ab-far-1 was significantly higher than that of other FAR genes in RWTNs.…”