Regulation of the host Spodoptera frugiperda (J.E.Smith) (Lepidoptera: Noctuidae) by the parasitoid Campoletis flavicincta (Ashmead) (Hymenoptera: Ichneumonidae): transcriptomic and proteomic approach

Author(s)

Bruna Laís Merlin

• Document type: Master's Dissertation
• Press: Piracicaba.
• Institution: Universidade de São Paulo (USP). Escola Superior de Agricultura Luiz de Queiroz (ESALA/BC)
• Defense date: 2014-01-24

Examining board members

Fernando Luis Cônsoli; Odair Aparecido Fernandes; Celso Omoto

• Advisor: Fernando Luis Cônsoli

Abstract

Koinobiont parasitoids regulate the growth and development of their hosts in order to colonize and adequate their host to their own nutritional needs. Parasitoids interfere with several physiological processes at the molecular and cellular levels to regulate their hosts. Thus, this project evaluated the effects of the parasitization by Campoletis flavicincta (Ashmead) (Hymenoptera: Ichneumonidae) on gene expression and protein availability at different stages of parasitization of larvae of the host Spodoptera frugiperda (J.E. Smith) (Lepidoptera: Noctuidae). Comparative gene expression was carried out by RNA-Seq analysis using next-generation sequencing tools (Illumina), with data validation by quantitative real time PCR (qPCR). Protein availability in the host hemolymph was checked by colorimetric and SDS-PAGE assays. Protein changes in the hemolymph were verified throughout parasitoid development at 1, 3, 5, 7 and 9 days after parasitization. The parasitoid induced an increase in the total concentration of proteins from day 3 to 9, and induced the precocious synthesis of two proteins (180 kDa and 75 kDa) and their maintenance in the hemolymph until the end of parasitoid development. No parasitism specific proteins were detected. Differential gene expression analysis was concentrated at early parasitization (06, 24 and 72 h), and allowed the identification of 1.189 differentially expressed transcripts. The majority of these transcripts (72.7%) were down-regulated in parasitized larvae as compared to the nonparasitized. Analysis of the differentially expressed transcripts led to the identification of functionally important transcripts for the parasitoid development, belonging to i) sugar metabolism, ii) storage proteins, iii) hormone synthesis and degradation, and iv) immune response. qPCR experiments using selected transcripts validated the differential expression observed in RNA-Seq experiments. Additional analysis using the de novo transcriptome assembly also led to the identification of 22 transcripts associated with the genome of the polydnavirus of C. flavicincta distributed in four gene families: vankyrin, repeated-element, cysteine-motif and N-family. These transcripts had specific temporal patterns of expression, with the transcripts from vankyrins and cysteine-motif being the most abundant. (AU)

• FAPESP's process: 12/13703-7 - Regulation of genes related with the metabolism of Spodoptera frugiperda parasitized by Campoletis falvicincta: a transcriptomic and proteomic approach
• Grantee: Bruna Laís Merlin
• Support Opportunities: Scholarships in Brazil - Master