Illumina based transcriptome sequencing of Wolbachia infected and Wolbachia cured Trichogramma pretiosum

Trichogramma is a parasitoid wasp widely used as a biological control agent against most of the lepidopteran insect pests and hence used as a potential biocontrol agent in a wide variety of crop ecosystem. The efficacy of the biocontrol depends on the number of females in the wasp population. Wolbachia an a-proteobacterium which is an endosymbiont of 20-70 per cent of insects induces femaleness in Trichogramma. Although several studies at molecular level have been carried out for characterization of the parasitoid wasp, little information is available on the molecular basis of Trichogramma – Wolbachia interaction. From the studies on other organisms it is evident that Wolbachia has a profound influence on the host gene expression and hence many of the genes are regulated by the bacterium. Since there is a lack of genetic information on Trichogramma, understanding the molecular mechanism behind their interaction is difficult. Techniques such as microarray need prior knowledge on the genetic sequences. Alternatively, revolution in sequencing technologies has made it feasible to obtain the sequences of an organism in less time in a comparatively low cost. The Illumina sequencing technology is proficient to generate high quality DNA sequences and can be effectively assembled and used for gene discovery and comparison of gene expressions. Hence, Trichogramma pretiosum was reared in lab for 12 generations and was split in to two. One was maintained as normal (hereafter referred as Wild) and the other was treated with 0.1mg/ml tetracycline antibiotic (hereafter referred as Control) to cure Wolbachia infection. Antibiotic treatment was done continuously for three generations or until the presence of Wolbachia was no more detected. Transcriptome library for sequencing was constructed according to the Illumina TruSeq RNA library protocol outlined in TruSeq RNA Sample preparation guide (Part # 15008136; Rev.A; Nov 2010). The prepared library was quantified using Nanodrop and validated for quality by running an aliquot on High Sensitivity Bioanalyzer Chip (Agilent). The library was proceeded for De novo sequencing in Illumina HiSeq1000 (Genotypic Technology Pvt Ltd, Bangalore, India) platform.