Transcriptomic and Expression Analysis of the Salivary Glands in White-Backed Planthoppers, Sogatella furcifera.

Zhen Li,Mao-Lin Hou,Yu-Di Liu,Xing-Kui An,Youjun Zhang

doi:10.1371/journal.pone.0159393

Zhen Li, Mao-Lin Hou + Show 3 more

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https://doi.org/10.1371/journal.pone.0159393

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Abstract

The white-backed planthopper (WBPH), Sogatella furcifera (Horváth), is one of the serious rice pests because of its destructive feeding. The salivary glands of the WBPH play an important role in the feeding behaviour. Currently, however, very little is known about the salivary glands at the molecular level. We sequenced the salivary gland transcriptome (sialotranscripome) of adult WBPHs using the Illumina sequencing. A total of 65,595 transcripts and 51,842 unigenes were obtained from salivary glands. According to annotations against the Nr database, many of the unigenes identified were associated with the most studied enzymes in hemipteran saliva. In the present study, we identified 32 salivary protein genes from the WBPH sialotranscripome, which were categorized as those involved in sugar metabolism, detoxification, suppression of plant defense responses, immunity-related responses, general digestion, and other phytophagy processes. Tissue expression profiles analysis revealed that four of 32 salivary protein genes (multicopper oxidase 4, multicopper oxidase 6, carboxylesterase and uridine phosphorylase 1 isform X2) were primarily expressed in the salivary gland, suggesting that they played putative role in insect-rice interactions. 13 of 32 salivary protein genes were primarily expressed in gut, which might play putative role in digestive and detoxify mechanism. Development expression profiles analysis revealed that the expression level of 26 of 32 salivary protein genes had no significant difference, suggesting that they may play roles in every developmental stages of salivary gland of WBPH. The other six genes have a high expression level in the salivary gland of adult. 31 of 32 genes (except putative acetylcholinesterase 1) have no significant difference in male and female adult, suggesting that their expression level have no difference between sexes. This report analysis of the sialotranscripome for the WBPH, and the transcriptome provides a foundational list of the genes involved in feeding. Our data will be useful to investigate the mechanisms of interaction between the WBPH and the host plant.

Highlights

The saliva of insect herbivores contains a diversity of digestive enzymes and components, which either induce or inhibit plant defence [1]
Different tissues including salivary gland (SG), head, gut, malpighian tubule (MT), and remaining body (RB) of adult white-backed planthopper (WBPH) and salivary gland at different developmental stages (2nd-3rd instar, 4th-5th instar, female and male adult) of WBPHs were collected for realtime quantitative PCR test
We identified 32 putative salivary protein genes in the WBPH Illumina HiSeq sialotranscripome data (Table 2). 24 of 32 putative salivary protein genes have intact open reading frame (ORF) with lengths ranging from 1050 bp to 2805 bp

Summary

Introduction

The saliva of insect herbivores contains a diversity of digestive enzymes and components, which either induce or inhibit plant defence [1]. Hemipterans are phloem feeders with piercing-sucking mouthparts. The salivary organs of hemipterans are a pair of primary and accessory salivary glands, which produce two primary types of saliva: coagulable and watery [3, 4]. During feeding, they discharge the gelling and watery saliva into the rice plant tissues. Most hemipteran vectors secrete and inoculate pathogens into healthy plants through the proteins of saliva [5, 6]. The saliva of phloem feeders is a mediator of plant-(pathogen)-insect interactions [5, 6]

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