Groundnut Bud Necrosis Virus Modulates the Expression of Innate Immune, Endocytosis, and Cuticle Development-Associated Genes to Circulate and Propagate in Its Vector, Thrips palmi

Abstract

Thrips palmi (Thysanoptera: Thripidae) is the predominant tospovirus vector in Asia-Pacific region. It transmits economically damaging groundnut bud necrosis virus (GBNV, family Tospoviridae) in a persistent propagative manner. Thrips serve as the alternate host, and virus reservoirs making tospovirus management very challenging. Insecticides and host plant resistance remain ineffective in managing thrips–tospoviruses. Recent genomic approaches have led to understanding the molecular interactions of thrips–tospoviruses and identifying novel genetic targets. However, most of the studies are limited to Frankliniella species and tomato spotted wilt virus (TSWV). Amidst the limited information available on T. palmi–tospovirus relationships, the present study is the first report of the transcriptome-wide response of T. palmi associated with GBNV infection. The differential expression analyses of the triplicate transcriptome of viruliferous vs. nonviruliferous adult T. palmi identified a total of 2,363 (1,383 upregulated and 980 downregulated) significant transcripts. The Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses showed the abundance of differentially expressed genes (DEGs) involved in innate immune response, endocytosis, cuticle development, and receptor binding and signaling that mediate the virus invasion and multiplication in the vector system. Also, the gene regulatory network (GRN) of most significant DEGs showed the genes like ABC transporter, cytochrome P450, endocuticle structural glycoprotein, gamma-aminobutyric acid (GABA) receptor, heat shock protein 70, larval and pupal cuticle proteins, nephrin, proline-rich protein, sperm-associated antigen, UHRF1-binding protein, serpin, tyrosine–protein kinase receptor, etc., were enriched with higher degrees of interactions. Further, the expression of the candidate genes in response to GBNV infection was validated in reverse transcriptase-quantitative real-time PCR (RT-qPCR). This study leads to an understanding of molecular interactions between T. palmi and GBNV and suggests potential genetic targets for generic pest control.

Development of a Polymerase Spiral Reaction-Based Isothermal Assay for Rapid Identification of Thrips palmi

“…T. palmi is known to infest more than 200 plant species including important crops such as beans, cucumber, eggplant, gourds, groundnut, melons, peppers, potatoes, tomatoes, and ornamentals ( MacLeod et al, 2004 ; Jangra et al, 2020b ; Dhall et al, 2021 ; Mahanta et al, 2022 ). Under changing climatic conditions, outbreaks of T. palmi have become more frequent and severe ( Stuart et al, 2011 ; Seal et al, 2013 ; Hong et al, 2019 ; Ghosh et al, 2020 ), posing a threat to international biosecurity.…”

Rna Interference in Thrips Vectors: A Step Forward Toward Sustainable Management

“…More recently, the investigation of the transcriptomewide response of T. palmi to GBNV infection found 2,363 significant transcripts (1,383 upregulated and 980 downregulated). These differentially expressed genes (DEGs) are involved in innate immune response, endocytosis, cuticle formation, receptor binding, and signalling, which all contribute to viral invasion and replication in the vector system (Mahanta et al, 2022). These studies shed light on potential genetic targets for thrips-tospovirus management.…”

“…A series of transplastomic tobacco plants that expressed dsRNAs and hairpin RNAs were developed that targeted four critical F. occidentalis genes (ACT, TUB, VAT, and SNF), resulting in target gene suppression and high mortality (Wu et al, 2022). The expression of T. palmi Btk29A and COL3A1 genes are highly abundant in response to the infection of tospoviruses (Widana Gamage et al, 2018;Mahanta et al, 2022). The fitness of T. palmi was significantly altered post-exposure to Btk29A and COL3A1 dsRNA under controlled laboratory conditions (Vavilapalli Rajesh, 2022).…”

“…Genetic host plant resistance is not available for all the crop species that are infected by thrips-tospoviruses. The use of transgenic plants is not feasible considering the broad host range and ethical issues related to GM crops (Mahanta et al, 2022). RNA interference (RNAi) represents an attractive avenue for pest control.…”

Effect of silencing Thrips palmi Btk29A and COL3A1 on fitness and virus acquisition

“…Little attempts were made to study the gene functions of T. palmi . In our previous study, T. palmi transcripts related to innate immune response, receptor binding, cell signaling, cellular trafficking, viral replication, and apoptosis were responsive to the acquisition of GBNV ( Mahanta et al, 2022 ). Silencing of T. palmi UHRF1BP1 and PFAS using modified anti-sense oligos showed a decline in GBNV titer in T. palmi ( Priti et al, 2022 ).…”