Microarray analysis of gene expression and diapause in Glassy-winged Sharpshooter (Homalodisca vitripennis: Hemiptera: Cicadellidae)

Authors: Hunter, Wayne; SINISTERRA, X - USAID; NORTHFIELD, T - UNIV OF FLORIDA; MIZELL, R - UNIV OF FLORIDA

Submitted to: CDFA Pierce's Disease Control Program Research Symposium
Publication Type: Proceedings
Publication Acceptance Date: 10/23/2007
Publication Date: 12/10/2007
Citation: Hunter, W.B., Sinisterra, X., Northfield, T., Mizell, R. 2007. Microarray analysis of gene expression and diapause in Glassy-winged Sharpshooter (Homalodisca vitripennis: Hemiptera: Cicadellidae). In: Proceedings of the 2007 Pierce's Disease Symposium Annual Meeting, December 12-14, 2007, San Diego, California, p. 22-24.

Interpretive Summary: The condition of diapause in the glassy-winged sharpshooter, GWSS, Homalodisca vitripennis, is poorly understood. Diapause is better known from other, non hemipteran insects. We used oligonucleotide microarrays to address the specificities of transcriptional responses of adult female GWSS, which were in ‘diapause’, to different lighting regimes. Two of these lighting regimes were known to induce oviposition in diapause females under greenhouse conditions during winter months. Thus we examined female GWSS gene expression during diapause and during the ‘breaking’ of diapause induced by light. Upon ‘breaking’ diapause, the females’ ovaries became active, produced eggs and females oviposited similar to springtime conditions. The mRNA from 22 individual GWSS adult females was compared. Each individual was hybridized to a single chip. There were 6 individuals in the control group, and 8 individuals in each treatment. Using strict criteria (a twofold change in expression), we determined that a definable number of genes was differentially expressed between the diapause females within the three lighting regimes. Of the 2,126 genes surveyed, 5 genes showed an increase in expression and 2 showed a decrease in expression (at least a 2.2-fold change) when comparing the control adult female GWSS to the GWSS exposed to the light treatments. Identification of the genetic basis of diapause will provide genetic targets which may be subjected to ‘silencing’ or ‘down-regulation’ by emerging technologies in plant improvement, or through virus delivery, or endophytic bacterial expression systems.

Technical Abstract: The condition of diapause in the glassy-winged sharpshooter, GWSS, Homalodisca vitripennis, is poorly understood. Diapause is better known from other, non hemipteran insects. We used oligonucleotide microarrays to address the specificities of transcriptional responses of adult female GWSS, which were in ‘diapause’, to different lighting regimes. Two of these lighting regimes were known to induce oviposition in diapause females under greenhouse conditions during winter months. Thus we examined female GWSS gene expression during diapause and during the ‘breaking’ of diapause induced by light. Upon ‘breaking’ diapause, the females’ ovaries became active, produced eggs and females oviposited similar to springtime conditions. The mRNA from 22 individual GWSS adult females was compared. Each individual was hybridized to a single chip. There were 6 individuals in the control group, and 8 individuals in each treatment. Using strict criteria (a twofold change in expression), we determined that a definable number of genes was differentially expressed between the diapause females within the three lighting regimes. Of the 2,126 genes surveyed, 5 genes showed an increase in expression and 2 showed a decrease in expression (at least a 2.2-fold change) when comparing the control adult female GWSS to the GWSS exposed to the light treatments. Identification of the genetic basis of diapause will provide genetic targets which may be subjected to ‘silencing’ or ‘down-regulation’ by emerging technologies in plant improvement, or through virus delivery, or endophytic bacterial expression systems.