Abstract
Mycoparasite Coniothyrium minitans parasitizes specifically the mycelia or sclerotia of Sclerotinia sclerotiorum, a worldwidely spread plant fungal pathogen causing serious diseases on crops. The interaction of C. minitans with S. sclerotiorum remains reciprocal and complex and little is known, especially on the side of the host (S. sclerotiorum). In this study, the early transcriptional response of S. sclerotiorum to the mycoparasitism by C. minitans was explored and the differentially expressed genes (DEGs) were analyzed. Based on GO ontology, KEGG pathway and fungal categories database, 887 up-regulated DEGs were enriched in the growth related function (i.e., rRNA processing, ribosome biogenesis, binding and transport), while the 546 down-regulated DEGs were enriched in the stress-related functions (i.e., oxidoreductase, response to stress and heat and the chorismate biosynthetic process). The expression of shikimate pathway and the biosynthesis of phenylalanine involving genes was significantly suppressed. Furthermore, 581 unenriched DEGs were explored in the parasitizing process and were mapped on the Pfam domains of redox enzymes, Alpha/Beta hydrolase, haloacid dehalogenase, and other universal conserved domain containing proteins. Thirty-two DEGs encoding candidate effectors, with 16 up-regulated and 16 down-regulated, were observed with diverse function. SS1G_11912 (encoding SsNEP2) was significantly up-regulated and may function in the parasitism. The involving of the shikimate pathway of phenylalanine biosynthesis and effector candidates were discussed. The results provide a basal understand on the interaction of S. sclerotiorum and C. minitans.
Highlights
Sclerotinia sclerotiorum is a worldwide distributed destructive plant fungal pathogen, attacks more than 400 plant species (Boland and Hall, 1994) and causes huge economic losses (Schwartz and Singh, 2013)
The gene expression of S. sclerotiorum was compared to each parasitizing stage and a total of 1368 Differentially Expressed Genes (DEGs) were detected during all the early stages of mycoparasitism process
During 0–4 hpi, 171 stage-specific DEGs were upregulated and 237 were down-regulated; 237 up-regulated DEGs and 98 down-regulated DEGs were identified during 0–12 hpi; 154 up-regulated DEGs and 34 down-regulated DEGs were identified during 4–12 hpi; 227 up-regulated DEGs and 151 down-regulated DEGs were shared at the two stages of 4 or 12 hpi comparing to 0 hpi (Figure 1)
Summary
Sclerotinia sclerotiorum is a worldwide distributed destructive plant fungal pathogen, attacks more than 400 plant species (Boland and Hall, 1994) and causes huge economic losses (Schwartz and Singh, 2013). Coniothyrium minitans, a mycoparasitic fungus specific to some species in Sclerotinia (Campbell, 1947; Boland and Hall, 1994), parasitizes hypha and sclerotia of S. sclerotiorum efficiently and reduces the sclerotia inoculated in the soil In China, a production certificate was given in 2018 to C. minitans strain ZS-1SB, aiming to control stem rot of rapeseed caused by S. sclerotiorum. Coniothyrium minitans synthesizes antifungal substances (AFSs) to inhibit the growth of S. sclerotiorum (McQuilken et al, 2002; Yang et al, 2007), which could be an important mechanism to control the diseases caused by S. sclerotiorum. The interaction of C. minitans with S. sclerotiorum is reciprocal and complex, though some researches have been reported, the mechanism underling is far more undiscovered, especially on the host side S. sclerotiorum
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