Wingless gene cloning and its role in manipulating the wing dimorphism in the white-backed planthopper, Sogatella furcifera.

Ju-Long Yu,Xiang-Dong Liu,Zhi-Fang An

doi:10.1186/1471-2199-15-20

Abstract

BackgroundWingless gene (Wg) plays a fundamental role in regulating the segment polarity and wing imaginal discs of insects. The rice planthoppers have an obvious wing dimorphism, and the long- and short-winged forms exist normally in natural populations. However, the molecular characteristics and functions of Wg in rice planthoppers are poorly understood, and the relationship between expression level of Wg and wing dimorphism has not been clarified.ResultsIn this study, wingless gene (Wg) was cloned from three species of rice planthopper, Sogatella furcifera, Laodelphgax striatellus and Nilaparvata lugens, and its characteristics and role in determining the wing dimorphism of S. furcifera were explored. The results showed that only three different amino acid residuals encoded by Wg were found between S. furcifera and L. striatellus, but more than 10 residuals in N. lugens were different with L. striatellus and S. furcifera. The sequences of amino acids encoded by Wg showed a high degree of identity between these three species of rice planthopper that belong to the same family, Delphacidae. The macropterous and brachypterous lineages of S. furcifera were established by selection experiment. The Wg mRNA expression levels in nymphs were significantly higher in the macropterous lineage than in the brachypterous lineage of S. furcifera. In macropterous adults, the Wg was expressed mainly in wings and legs, and less in body segments. Ingestion of 100 ng/μL double-stranded RNA of Wg from second instar nymphs led to a significant decrease of expression level of Wg during nymphal stage and of body weight of subsequent adults. Moreover, RNAi of Wg resulted in significantly shorter and deformative wings, including shrunken and unfolded wings.ConclusionWg has high degree of identity among three species of rice planthopper. Wg is involved in the development and growth of wings in S. furcifera. Expression level of Wg during the nymphal stage manipulates the size and pattern of wings in S. furcifera.

Highlights

Wingless gene (Wg) plays a fundamental role in regulating the segment polarity and wing imaginal discs of insects
Characteristics of wingless gene (Wg) from three species of rice planthoppers The full-length Complementary DNA (cDNA) clone encoding Wg was isolated from S. furcifera and L. striatellus by the 3′ and 5′ Rapid-amplification of cDNA ends (RACE), as well as the open reading frame (ORF) of Wg from N. lugens
Nilaparvata lugens Wg had ten and eleven different amino acid residues compared to S. furcifera and L. striatellus, respectively

Summary

Introduction

Wingless gene (Wg) plays a fundamental role in regulating the segment polarity and wing imaginal discs of insects. Different concentrations of Wg protein lead to different cell reactions It can stimulate some specific target genes when its concentration reaches a threshold gradient [10,11]. Wg gene is expressed in a narrow stripe along the dorsal/ ventral (D/V) boundary during the development of wing disc of Drosophila [15], and it has been considered as one of important signal transduction pathways in the formation of wing pattern [16]. During the formation of wings, Wg regulates the expression of downstream target genes through changing its own concentration, and results in the morphological differentiation of wing imaginal disc cells [9]. When the expression level of Wg was reduced in the fifth instar larvae by RNA interference method, the resulting adults showed a partial or even complete loss of wings [18]

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Results

Conclusion