Integrated omics approach to understand Pistacia - aphid gall development

Abstract

Background: Pistacia chinensis subsp. integerrima (J. L. Stewart ex Brandis) Rech. f. belongs to family Anacardiaceae, is well known for usage of galls in traditional medicine. The galls in the apical meristem of plants are induced by aphid Baizongia pistaciae L infestation. The Pistacia galls are used in Ayurvedic formulations for the treatment of cough and respiratory diseases, loss of appetite, dyspeptic vomiting and dysentery. The drastic decrease in the gall formation in recent decades is possibly due to climate change or human interventions, making it an important species from conservation point of view. There is not much work carried out at molecular level to understand the gall development. In this study, we obtained molecular insight on insect and plant through genomic, transcriptomic and proteomic approaches. Results: We sequenced the whole genome of Pistacia genome using Illumina sequencing platform. The assembly genome size of Pistacia was 549 Mb with 80688 scaffolds at N50 = 12607 nts. A total of 51290 genes were from Pistacia genome annotation. The transcriptome analysis revealed of 76186 and 46327 transcripts from gall and leaf, respectively. The ethylene responsive transcription factor families were induced abundantly in galls including GATA, bHLH, MYB, BZIP, Trihelix, MADS, B3 domain. In addition, we have also obtained highly expressed genes in gall for biosynthesis of secondary metabolites, plant-aphid interactions, stress responses, phytohormone signal transduction and terpene biosynthesis. We have identified 21 proteins against Cajanus cajan , 10 proteins against Arabidopsis thaliana and 14 proteins against Drosophila melanogaster . We also identified abundant peptides for actin and tubulin of aphid in the gall tissue. Conclusion: This study provides a basis for the understanding of the genes expressed in gall when compared to leaf and also genes required for gall induction and development. We hypothesed that actin and microtubule proteins are from aphids origin as we found that transcript TRINITY_DN180182_c0_g1_i1 mapped to Acyrthosiphon pisum tubulin beta-1 (Tub1), mRNA with 75 % homology.