Host lipid alterations afterMacrophomina phaseolinainfection contribute to charcoal rot disease susceptibility in grain sorghum: Evidence from transcriptomic and lipidomic data

Abstract

SUMMARYLipids are involved in central metabolic processes and confer basic configuration to cellular and subcellular membranes. Lipids also play a role in determining the outcome of plant-pathogen interactions. Lipid based links that delineate either host resistance or susceptibility against necrotrophic microorganisms are poorly investigated and described.Macrophomina phaseolina(MP) is an important necrotrophic fungus which causes diseases in over 500 plant species including charcoal rot in sorghum.We used RNA sequencing and automated direct infusion electrospray ionization-triple quadrupole mass spectrometry (ESI-MS/MS) to quantitatively profile the transcriptomes and lipidomes of a known charcoal rot resistant (SC599) and susceptible (Tx7000) sorghum genotype in response to MP inoculation.We found that MP is capable of significantly decreasing the phosphatidylserine, phytosterol, and ox-lipid contents in the susceptible genotype while significantly increasing its stigmasterol:sitosterol and monogalactosyldiacylglycerol: digalactosyldiacylglycerol ratios. None of the above was significantly affected in the resistant genotype, except for the significantly increased ox-lipid content.Our transcriptome and functional lipidome findings suggested the lethal impacts of MP inoculation on plastid- and cell- membrane integrity and the lipid based signaling capacity of the charcoal rot susceptible sorghum genotype, Tx7000. Findings also suggested the strong oxidative stress experienced by Tx7000 under MP inoculation and shed light on the potential lipid classes involved in induced charcoal rot disease susceptibility.