De novo transcriptome analyses of host-fungal interactions in oil palm (Elaeis guineensis Jacq.)

Abstract

BackgroundBasal stem rot (BSR) is a fungal disease in oil palm (Elaeis guineensis Jacq.) which is caused by hemibiotrophic white rot fungi belonging to the Ganoderma genus. Molecular responses of oil palm to these pathogens are not well known although this information is crucial to strategize effective measures to eradicate BSR. In order to elucidate the molecular interactions between oil palm and G. boninense and its biocontrol fungus Trichoderma harzianum, we compared the root transcriptomes of untreated oil palm seedlings with those inoculated with G. boninense and T. harzianum, respectively.ResultsDifferential gene expression analyses revealed that jasmonate (JA) and salicylate (SA) may act in an antagonistic manner in affecting the hormone biosynthesis, signaling, and downstream defense responses in G. boninense-treated oil palm roots. In addition, G. boninense may compete with the host to control disease symptom through the transcriptional regulation of ethylene (ET) biosynthesis, reactive oxygen species (ROS) production and scavenging. The strengthening of host cell walls and production of pathogenesis-related proteins as well as antifungal secondary metabolites in host plants, are among the important defense mechanisms deployed by oil palm against G. boninense. Meanwhile, endophytic T. harzianum was shown to improve the of nutrition status and nutrient transportation in host plants.ConclusionThe findings of this analysis have enhanced our understanding on the molecular interactions of G. boninense and oil palm, and also the biocontrol mechanisms involving T. harzianum, thus contributing to future formulations of better strategies for prevention and treatment of BSR.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-016-2368-0) contains supplementary material, which is available to authorized users.

Peer Review #1 of "Insight into plant cell wall degradation and pathogenesis of Ganoderma boninense via comparative genome analysis (v0.1)"

“…Importantly, PG is one of the first enzymes secreted by pathogenic fungi upon contact with plant cell wall and these pectinases have been widely studied for their role in plant pathogenesis especially necrosis and rotting in the infected plants (De Lorenzo & Ferrari, 2002;Kubicek, Starr & Glass, 2014). This finding corroborated with the reported polygalacturonase activities from the transcriptome profile of G. boninenseinfected oil palm (Elaeis guineensis) whereby PG transcript was shown to be elevated as compared to none observed in control unaffected oil palm (Ho et al, 2016). It can be postulated that pectin-acting PG work synergistically with hemicellulases for Ganoderma infection in similar fashion to necrotrophic infection and virulence of many phytopathogens including Fusarium spp., the main causative agents of vascular wilt and head blight diseases in important crops (Gómez-Gómez et al, 2002;Chen et al, 2012b;Paccanaro et al, 2017).…”

“…Combined actions of ligninolytic and cellulolytic enzymes including laccase and endoglucanase were previously shown to be directly involved in the wood decaying and infection processes of wheat and cacao by necrotrophic F. graminearum and Moniliophthora roreri, respectively (Zhang et al, 2012;Meinhardt et al, 2014). Transcriptome analysis of Ganoderma infected-oil palm seedling demonstrated the presence of multiple copies of laccase transcripts as compared to none observed in the sample of beneficial fungus, T. harzianum, indicating the important role of cell wall degradation in oil palm infection (Ho et al, 2016(Ho et al, , 2018. The identification of these cell wall degrading PHI genes further supported the hemibiotrophic mode of infection of G. boninense conferred by fungal genotypic capabilities to produce a plethora of carbohydrateacting enzymes.…”

Transcription Profiling Analysis of Mango–Fusarium mangiferae Interaction

“…cubense (Li et al, 2013 ), tomato and Xanthomonas perforans race T3 (Du et al, 2015 ), oil palm and Ganoderma spp. (Ho et al, 2016 ), pea and Phytophthora pisi (Hosseini et al, 2015 ), wheat and Heterodera avenae (Kong et al, 2015 ), and soybean and F. oxysporum (Lanubile et al, 2015 ). Many genes were revealed to be involved in defense mechanism and resistance-associated signal transduction in plants.…”

Integrated Translatome and Proteome: Approach for Accurate Portraying of Widespread Multifunctional Aspects of Trichoderma

“…The significance and global impact of this beneficial microbe in reprogramming the molecular physiology of host plant to stress responses through the regulation of transcription, signal transduction pathways has been reported in different studies ( Morán-Diez et al, 2012 ; Lamdan et al, 2015 ). Further host specific response of Trichoderma strain with plants representing monocot and dicot hosts under the same conditions have also been explored to identify signature transcriptome repertoires and answer the widely prevalent questions of specificity of responses and role of secreted proteins in mutualistic interaction, root colonization, and induction of immune responses ( Morán-Diez et al, 2015 ; Ho et al, 2016 ; Sharma et al, 2017b ). These studies indicate the limitations of transcriptome based studies in precise estimation of ribosome loaded active mRNA population involved in complex mycoparasitic behavior of Trichoderma species as BCAs.…”