Transcriptome analysis, using RNA‐Seq of Lomandra longifolia roots infected with Phytophthora cinnamomi reveals the complexity of the resistance response

Abstract

The plant pathogen Phytophthora cinnamon the causal agent of disease in numerous species, is a major threat to natural vegetation and has economic impacts in agriculture. The pathogen principally invades the root system, which, in susceptible species, is rapidly colonised and functionally destroyed. Few species are resistant, however, where resistance is expressed the pathogen is restricted to small, localised lesions. The molecular mechanisms that underpin this response in resistant species are not well understood. Lomandra longifolia, an Australian native species, is highly resistant to P. cinnamomi. In an earlier study, we showed induction of resistance-related components such as callose, lignin and hydrogen peroxide (H O ) in L. longifolia roots that had been inoculated with P. cinnamomi. Here, in order to further identify, during the very early stages of infection, the molecular components and regulatory networks that may trigger resistance, a comprehensive root transcriptome analysis was performed using next generation sequencing. Overall, 18 cDNA libraries were produced generating 52.8 GB 126 base pair reads, which were de novo assembled into contigs. Differentially expressed genes (DEGs) were identified allowing the identification of infection-responsive candidate genes that were putatively related to resistance, and from this set ten were selected for qRT-PCR to validate the RNA-Seq expression value. Further analysis of individual candidates revealed that many were involved in PAMP-triggered immunity (PTI; pattern recognition receptors, glutathione S-transferase, callose synthases, pathogenesis-related protein-1, mitogen activated protein kinases) and effector-triggered immunity (ETI) (NBS-LRR, signalling genes, transcription factors and anti-pathogenic compound synthase genes). As these candidate genes or mediated components activate different defence signalling systems, they may have potential for investigation of novel approaches to disease control and in transgenic approaches for improvement, in susceptible species, of resistance to P. cinnamomi.

Endophytic Fungi Activated Similar Defense Strategies of Achnatherum sibiricum Host to Different Trophic Types of Pathogens

“…Jasmonic acid is also an important signaling molecule in plant disease resistance responses. Many studies have shown that plants initiate JA−dependent responses upon exposure to necrotrophs (Mengiste, 2012;Qi et al, 2012;Pandey et al, 2016;Islam et al, 2018). In the present study, the content of JA in E+ and E− leaves was not affected by the biotrophic pathogen Erysiphales species but was increased by the necrotrophic pathogen C. lunata, which was consistent with the conclusions of previous research.…”

Comparative transcriptome analysis reveals resistant and susceptible genes in tobacco cultivars in response to infection by Phytophthora nicotianae

“…The transcriptome has been widely used to study the defense response in plants and to identify specific genes that interact with pathogens. In Lomandra longifolia roots, callose synthase genes, MAPK 15, 2 PR genes, and 5 receptor-like protein genes were found to be significantly expressed when infected by Phytophthora cinnamomi 18 . In N. benthamiana leaves, expression of 13 b-1,3-glucanases from the PR-2 family, and 16 chitinases from the PR-3, PR-4, PR-8, and PR-11 families were induced following infection with P. parasitica 19 .…”

Phaeophyceaean (Brown Algal) Extracts Activate Plant Defense Systems in Arabidopsis thaliana Challenged With Phytophthora cinnamomi

“…Equally importantly, each seaweed extract was found to exert its effect through different subsets of genes. A number of studies explored plant transcriptomes following abiotic and biotic stress (see for example: Tommasini et al, 2008;Allardyce et al, 2013;GonñI et al, 2016;Islam et al, 2018;Jithesh et al, 2019), however, the present study is the first report of a comprehensive transcriptome analysis, following treatment of plants with seaweed extracts, root pathogen infection and analysis over multiple time points.…”