Comparative RNA-Seq Analyses of Solenopsis japonica (Hymenoptera: Formicidae) Reveal Gene in Response to Cold Stress.

Mohammad Vatanparast,Youngjin Park

doi:10.3390/genes12101610

Abstract

Solenopsis japonica, as a fire ant species, shows some predatory behavior towards earthworms and woodlice, and preys on the larvae of other ant species by tunneling into a neighboring colony’s brood chamber. This study focused on the molecular response process and gene expression profiles of S. japonica to low (9 °C)-temperature stress in comparison with normal temperature (25 °C) conditions. A total of 89,657 unigenes (the clustered non-redundant transcripts that are filtered from the longest assembled contigs) were obtained, of which 32,782 were annotated in the NR (nonredundant protein) database with gene ontology (GO) terms, gene descriptions, and metabolic pathways. The results were 81 GO subgroups and 18 EggNOG (evolutionary genealogy of genes: Non-supervised Orthologous Groups) keywords. Differentially expressed genes (DEGs) with log2fold change (FC) > 1 and log2FC < −1 with p-value ≤ 0.05 were screened for cold stress temperature. We found 215 unigenes up-regulated and 115 unigenes down-regulated. Comparing transcriptome profiles for differential gene expression resulted in various DE proteins and genes, including fatty acid synthases and lipid metabolism, which have previously been reported to be involved in cold resistance. We verified the RNA-seq data by qPCR on 20 up- and down-regulated DEGs. These findings facilitate the basis for the future understanding of the adaptation mechanisms of S. japonica and the molecular mechanisms underlying the response to low temperatures.

Highlights

Fire ants is the common name for the ant genus Solenopsis Westwood (Hymenoptera: Formicidae: Myrmicinae) that is represented in South America by 16 native species [1].While, in general, these ants cause occasional local problems in their homeland, some species, such as Solenopsis japonica, are not reported pests
We aimed to provide a basis for the adaptive mechanism and a rich resource for the discovery and identification of novel genes involved in the cold stress response in S. japonica, a rare underground-dwelling invertebrate predator
Illumina raw data was qualified by filtering to reveal the transcriptome responses to cold stress in S. japonica (Supplementary Tables S3 and S4)

Summary

Introduction

Fire ants is the common name for the ant genus Solenopsis Westwood (Hymenoptera: Formicidae: Myrmicinae) that is represented in South America by 16 native species [1]. While, in general, these ants cause occasional local problems in their homeland, some species, such as Solenopsis japonica, are not reported pests. It is supposed that it preys on the larvae of other ant species by tunneling into a neighboring colony’s brood chamber [2]. S. japonica can move through gaps in the soil or make tunnel systems to detect and attack prey [2]. Species interactions underground cannot be observed directly, they are suspected to occur as frequently as those above ground

Objectives

Methods

Results

Discussion

Conclusion