Treatment of Penicillium chrysogenum extracts (PDMP) restricts the spread of Tobacco mosaic virus by priming callose deposition in Nicotiana benthamiana

Plants are often primed to enhanced resistance upon recognizing certain microbes and microbial metabolites/ molecules. We investigated the effect of PDMP, the peptides extract of dry mycelia of Penicillium chrysogenum, on defense of Nicotiana benthamiana to Tobacco mosaic virus (TMV). The 30B vector harboring the green fluorescent protein gene (30B:GFP) was used to monitor virus movement. Movement of the virus vector was limitied in PDMP-pretreated tobacco, in which significant callose accumulation was observed after challenge inoculation with the TMV vector. Callose accumulation was absent in plants pretreated with both the PDMP and callose synthesis inhibitor, resulting in elimination of PDMP-induced inhibition of TMV spread. Transcripts of the defense-related genes were significantly accumulated after challenge inoculation with TMV in PDMP-pretreated tobacco. Interestingly, PDMP treatment or TMV inoculation alone did neither induce callose deposition, nor enhance the transcript abundance of the defense-related genes, indicating that PDMP was more likely to promote tobacco to a primed state than induce defense responses directly. The primed callose accumulation plays a crucial role in restricting TMV spread in PDMP-pretreated tobacco. The present results provide evidence of PDMP can promote N. benthamiana to a primed state of enhance defense against TMV.

Automated summary

The peptide extract of Penicillium chrysogenum induced callose accumulation in Nicotiana benthamiana, restricting Tobacco mosaic virus movement. The primed state enhanced defense against TMV, indicating a potential role of PDMP in promoting plant immunity.