Transcriptomic analysis of Dubas bug (Ommatissus lybicus Bergevin) infestation to Date Palm

Date palm (Phoenix dactylifera L.) and its fruit possess sociocultural, health and economic importance in Middle East. The date palm plantations are prone to Dubas bug (DB; Ommatissus lybicus DeBergevin; Homoptera: Tropiduchidae) attacks that severely damages the tree's growth and reduces fruit production. However, the transcriptome related datasets are not known to understand how DB activates physiological and gene regulatory mechanisms during infestation. Hence, we performed RNA-Seq of leaf infected with or without DB to understand the molecular responses of date palm seedlings. Before doing that, we noticed that DB infestation significantly increase superoxide anion and malondialdehyde production to two-folds as compared to healthy control. Stress-responsive genes such as proline transporter 2, NADP-dependent glyceraldehyde and superoxide dismutase were found significantly upregulated in infected seedlings. The infection repercussions were also revealed by significantly higher contents of endogenous phytohormonal signaling of jasmonic acid (JA) and salicylic acid (SA) compared with control. These findings persuaded to dig out intrinsic mechanisms and gene regulatory networks behind DB infestation to date palm by RNA-Seq analysis. Transcriptome analysis revealed upregulation of 6,919 genes and down-regulation of 2,695 genes in leaf during the infection process. The differentially expressed genes were mostly belongs to cellular functions (calcium and MAPK), phytohormones (auxin, gibberellins, abscisic acid, JA and SA), and secondary metabolites (especially coumarinates and gossypol). The data showed that defense responses were aggravated by gene networks involved in hypersensitive responses (PAR1, RIN4, PBS1 etc.). In conclusion, the results revealed that date palm's leaf up-regulates both cellular and phytohormonal determinants, followed by intrinsic hypersensitive responses to counter infestation process by Dubas bug.