Comparative analyses of salivary proteins from the facultative symbiont-infected and uninfected Tetranychus truncatus

Abstract

Salivary proteins of herbivorous insects play a central role in plant-insect interactions. Spider mite Tetranychus truncatus is a polyphagous agricultural pest harboring various bacterial symbionts. However, whether endosymbionts infection in spider mite alters the host saliva protein remains largely unknown. Here, by using shotgun LC-MS/MS analysis, we identified and characterized the components of saliva in Wolbachia-Spiroplasma infected and uninfected T. truncatus. In total, 177 putative salivary proteins were identified. The function of many proteins remains unknown, while in numerous cases belong to catalytic activity and binding proteins. The saliva enzymes included oxidoreductase, hydratase, isomerase, transferase, protease, esterase, ribonuclease, kinase, lyase and phosphorylase. Other proteins, such as ATP-binding, actin, heat shock proteins and vitellogenin were also detected in the T. truncatus saliva. In addition, we found some of the saliva proteins are mite strain-specific salivary proteins—14 proteins were only found in Wolbachia-Spiroplasma infected spider mite, and 6 proteins were only found in Wolbachia-Spiroplasma uninfected spider mite. Overall, this is the first research to identify and characterize the proteins in saliva of facultative symbionts-infected and uninfected spider mites, T. truncatus. Our novel findings revealed that the presence of bacterial symbionts affected the saliva components of spider mites, opening the path for future studies.

How does saliva function in planthopper–host interactions?

“…Recently, the influence of microorganisms on saliva secretions has attracted increasing attention (Chaudhary et al, ; Zhu et al, ). Planthoppers harbor many endosymbionts and are an important vector in viral transmission (Xue et al, ).…”

Tetranins: new putative spider mite elicitors of host plant defense

“…Although previous proteome studies on spider mites identified about 90 and 177 putative SGPs from T. urticae and Tetranychus truncates (Jonckheere et al ., ; Zhu et al ., ), neither Tet1 nor Tet2 was listed among them. However, we observed that Tet1 is expressed predominantly in the anterior podocephalic salivary glands, possibly together with the silk glands, of T. urticae , implying that Tet1 is secreted outside of the body.…”

Planthopper-Secreted Salivary Disulfide Isomerase Activates Immune Responses in Plants

“…After transient overexpression, PDI1 orthologs strongly induce ROS burst and plant cell death. Classical PDIs have also been detected in saliva proteomes of other piercing-sucking insects such as aphids ( Carolan et al, 2011 ; Van Bel and Will, 2016 ) and spider mites ( Zhu et al, 2018 ). For this reason, PDIs may have a common interaction mechanism between various herbivorous insects and their plant hosts and may be able to induce broad-spectrum insect resistance.…”