Comparative transcriptomic analyses revealed divergences of two agriculturally important aphid species.

Dahai Wang,Qi Liu,Huw D Jones,Toby Bruce,Lanqin Xia

doi:10.1186/1471-2164-15-1023

Abstract

BackgroundGrain aphid (Sitobion avenae F) and pea aphid (Acyrthosiphon pisum) are two agriculturally important pest species, which cause significant yield losses to crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring debilitating plant viruses. Although a close phylogenetic relationship between grain aphid and pea aphid was proposed, the biological variations between these two aphid species are obvious. While the host ranges of grain aphid is restricted to cereal crops and in particular wheat, that of pea aphid is wider, mainly colonizing leguminous plant species. Until now, the genetic factors underlying the divergence between grain aphid and pea aphid still remain unclear due to the limited genomic data of grain aphid available in public databases.ResultsBased on a set of transcriptome data of grain aphid generated by using Roche 454 GS-FLX pyrosequencing, comparative analysis between this set of transcriptome data of grain aphid and mRNA sequences of pea aphid available in the public databases was performed. Compared with mRNA sequences of pea aphid, 4,857 unigenes were found to be specifically presented in the transcriptome of grain aphid under the rearing conditions described in this study. Furthermore, 3,368 orthologous pairs which could be calculated with both nonsynonymous (Ka) and synonymous (Ks) substitutions were used to infer their sequence divergences. The average differences in the coding, 5′ and 3′ untranslated regions of these orthologs were 10.53%, 21.29% and 18.96%, respectively. Moreover, of 340 orthologs which were identified to have evolved in response to positive selection based on the rates of Ka and Ks substitutions, 186 were predicted to be involved in secondary metabolism and xenobiotic metabolisms which might contribute to the divergence of these two aphid species.ConclusionsThe comprehensive transcriptome divergent sequence analysis between grain aphid and pea aphid provides an invaluable resource for the investigation of genes involved in host plant adaptation and evolution. Moreover, the demonstration of divergent transcriptome sequences between grain aphid and pea aphid pave the way for the investigation of the molecular mechanisms underpinning the biological variations of these two agriculturally important aphid species.Electronic supplementary materialThe online version of this article (doi:10.1186/1471-2164-15-1023) contains supplementary material, which is available to authorized users.

Highlights

Grain aphid (Sitobion avenae F) and pea aphid (Acyrthosiphon pisum) are two agriculturally important pest species, which cause significant yield losses to crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring debilitating plant viruses
In order to reveal the genetic factors underlying the divergence between the grain and pea aphids, comparative analysis between the transcriptome data of grain aphid generated in our lab by Roche 454 GS-FLX pyrosequencing and mRNA sequences of pea aphid available in the public databases was performed
The demonstration of divergent transcriptome sequences between grain aphid and pea aphid pave the way for the investigation of the molecular mechanisms underpinning the biological variations of these two destructive aphid species

Summary

Introduction

Grain aphid (Sitobion avenae F) and pea aphid (Acyrthosiphon pisum) are two agriculturally important pest species, which cause significant yield losses to crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring debilitating plant viruses. While the host ranges of grain aphid is restricted to cereal crops and in particular wheat, that of pea aphid is wider, mainly colonizing leguminous plant species. Aphids are major agricultural pests which cause significant yield losses to crop plants each year by inflicting damage both through the direct effects of feeding and by vectoring debilitating plant viruses [1]. In some wheat production areas, it has damaging infestations every year, causing the wide-spread use of chemicals and as much as 15 to 60% of severe reduction in wheat yield [6]. Due to the complexity of plant-aphid interactions and the rapid development of resistant pest biotypes, outbreak of aphids causing substantial losses of wheat are reported regularly [5,6]

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