Project description:Biological control is a promising approach to control diseases caused by Pythium species. Unusually for a single genus, the Pythium genus also includes species that can antagonise Pythium plant pathogens, such as Pythium oligandrum. These Pythium plant pathogens are commonly found in the soil such as the broad host-range pathogen Pythium myriotylum and cause various diseases of important crops. While P. oligandrum genes expressed in the interaction with oomycete plant pathogens have been identified previously, the transcriptional response of an oomycete plant pathogen to P. oligandrum has not been investigated. An isolate of P. oligandrum, GAQ1, recovered from soil could antagonise P. myriotylum in a plate-based confrontation assay. The P. oligandrum isolate had a strong disease control effect on soft-rot of ginger caused by P. myriotylum. We investigated the transcriptional interaction between P. myriotylum and P. oligandrum. As part of the transcriptional response of P. myriotylum to the presence of P. oligandrum, putative effector genes such as a sub-set of Kazal-type protease inhibitors were strongly upregulated. P. myriotylum cellulases and elicitin-like putative effectors were also upregulated. In P. oligandrum, cellulases, peroxidases, proteases and NLP effectors were upregulated. The transcriptional response of P. myriotylum suggests clear features of a counter-attacking strategy that may contribute to the variable success and durability of biological attempts to control diseases caused by Pythium species. Whether aspects of this counter-attack could inhibit aspects of this virulence of P. myriotylum is another interesting aspect for future studies.
Project description:Oomycetes, such as the broad host-range necrotrophic plant pathogen Pythium myriotylum, cause devastating crop losses. We have previously identified P. myriotylum as the major pathogen infecting ginger (Zingiber officinale) rhizomes in China with symptoms of Pythium soft rot (PSR) disease. Ginger is an important crop with global production estimated at approximately three million metric tonnes with about 20% of this production in China. To better understand how P. myriotylum infects ginger, transcriptomic analysis was performed on two P. myriotylum isolates (SWQ7 and SL2) infecting ginger leaves. From both of the isolates, there was a clear separation between the transcriptome replicates from the mycelial control condition and those from the infection of the ginger leaf. In SWQ7 and SL2, there were 2,110 and 2,513 genes upregulated during infection of ginger, respectively. Of the putative effectors, a subset of the NEP1-like toxin protein (NLP) effectors were highly induced during the infection of ginger leaves. Insights from the transcriptome highlight the important role of a subset of plant cell wall degrading enzymes (PCWDEs) and effectors in the pathogenicity of P. myriotylum towards ginger. The surprisingly large numbers of P. myriotylum PCWDEs and effectors within the genome may be due to the broad host-range of P. myriotylum whereby particular subsets of the PCWDEs and effectors are required for pathogenicity towards particular hosts.
