Comparative Transcriptomics Reveals Features and Possible Mechanisms of Glucose-Mediated Soil Fungistasis Relief in Arthrobotrys oligospora

Abstract

Soil-borne pest diseases result in large annual agricultural losses globally. Fungal biocontrol agents are an alternative means of controlling pest diseases; however, soil fungistasis limits the effect of fungal agents. Nutrients can relieve soil fungistasis, but the mechanisms behind this process remain poorly understood. In this study, we determined and quantified the transcriptomes of Arthrobotrys oligospora, a nematodetrapping fungus, derived from samples of fresh conidia, germinated conidia, soil fungistatic conidia, and glucose-relieved conidia. The transcriptomes of fungistatic and glucose-relieved conidia were significantly different from those of the other two conidia samples. KEGG pathway analyses showed that those genes upregulated in fungistatic and glucose-relieved conidia were mainly involved in translation and substance metabolism, and the downregulated genes were mainly involved in MAPK pathway, autophagy, mitophagy, and endocytosis. As being different from the transcriptome of fungistatic conidia, upregulated genes in the transcriptome of glucose-relieved conidia are also related to replication and repair, spliceosome, oxidative phosphorylation, autophagy, and degradation pathway (lysosome, proteasome, and RNA degradation). And the upregulated genes resulted from comparison of glucose-relieved conidia and fungistatic conidia were enriched in metabolic pathways, cycle, DNA replication, and repair. The differentially splicing events in the transcriptome of glucose-relieved conidia are far more than that of other two transcriptomes, and genes regulated by differentially splicing were analyzed through KEGG pathway analysis. Furthermore, autophagy genes were proved to play important role in resisting soil fungistasis and glucose-mediated soil fungistasis relief. These data indicate that, in addition to being a carbon and energy source for conidia germination, glucose may also help to relieve soil fungistasis by activating many cellular processes, including autophagy, DNA replication and repair, RNA alternative splicing, and degradation pathways.

Fungistatic Mechanism of Ammonia against Nematode-Trapping Fungus Arthrobotrys oligospora, and Strategy for This Fungus To Survive Ammonia

“…To analyze the transcriptome, at least 0.3 g of fresh, germinated, and fungistatic conidia, which have two duplicates, were sent to the Beijing Genomics Institute (BGI, China) for transcriptome sequencing using a reported method ( 57 ). The same amounts of three conidium samples with two duplicates were sent to PTM BIO Co., Ltd. (Hangzhou City, China) for quantitative ubiquitylome determination.…”

“…The disruption vectors of genes AOL_s00054g963 and AOL_s00210g337 were constructed following a previously described procedure ( 39 , 57 ). The primer pairs 963-5f/963-5r and 963-3f/963-3r were used for PCR amplification of the upstream and downstream homologous fragments of AOL_s00054g963 , respectively.…”

The Autophagy-Related Gene Aolatg4 Regulates Hyphal Growth, Sporulation, Autophagosome Formation, and Pathogenicity in Arthrobotrys oligospora

“…Finally, three PCR fragments and a linearized pRS426 vector were co-transformed into yeast strain FY834 via electroporation ( Bernhards and Pöggeler, 2011 ; Park et al, 2011 ). The complete fragment for gene disruption was amplified from the recombinant plasmid pRS426-ATG4-hph using primers AolAtg4-5f and AolAtg4-3r ( Supplementary Table S1 ), then it was transformed into A. oligospora using protoplast transformation method ( Tunlid et al, 1999 ; Liu et al, 2020 ). Hygromycin-resistant transformants were selected on PDAS medium containing 200 mg/ml hygromycin B (Amresco, Solon, United States; Zhen et al, 2019 ; Liu et al, 2020 ).…”

“…The complete fragment for gene disruption was amplified from the recombinant plasmid pRS426-ATG4-hph using primers AolAtg4-5f and AolAtg4-3r ( Supplementary Table S1 ), then it was transformed into A. oligospora using protoplast transformation method ( Tunlid et al, 1999 ; Liu et al, 2020 ). Hygromycin-resistant transformants were selected on PDAS medium containing 200 mg/ml hygromycin B (Amresco, Solon, United States; Zhen et al, 2019 ; Liu et al, 2020 ). Two deletion mutants of Aolatg4 gene were verified using PCR amplification and Southern blotting analyses as described previously ( Xie et al, 2019 , 2020 ).…”

Methylglyoxal Has Different Impacts on the Fungistatic Roles of Ammonia and Benzaldehyde, and Lactoylglutathione Lyase Is Necessary for the Resistance of Arthrobotrys oligospora to Soil Fungistasis

“…According to the reported method (Liu et al, 2020), soil and deionized water were added to a beaker at a mass ratio of 2.5:1, 1:1, and 1:2.5, and were mixed well to produce a high fungistatic soil suspension, a medium fungistatic soil suspension, and a low fungistatic soil suspension, respectively. The fresh conidia of wild-type and mutant strains were transferred into a dialysis bag (300 kDa; Spectrum, USA), and the dialysis bag was then placed into three kinds of soil suspension at 28°C, with the agitation of the soil suspension using a magnetic stirrer, as described previously (Liu et al, 2020). After 24 h, the dialysis bags were removed from the soil suspension, and the conidia germination rate was tested microscopically.…”