Tripartite Interaction Between Penicillium pinophilum-Host Plants and CMV-Y: A Model for Endophyte-Mediated Viral Biocontrol.

Mycorrhiza‐induced resistance against Botrytis cinerea in tomato operates through the systemin signalling cascade

Arbuscular mycorrhizal fungi enhance plant resistance against necrotrophic fungi by priming jasmonic acid‐dependent defences. Systemin is a solanaceous peptide hormone that mediates resistance against Botrytis cinerea, and JA signalling is critical for this systemin‐mediated defence. Mycorrhizal symbiosis primes prosystemin expression in the tomato (Solanum lycopersicum)–B. cinerea pathosystem. Whether prosystemin or systemin mediates mycorrhiza‐induced resistance (MIR) against B. cinerea remains unclear. We hypothesise that systemin mediates JA priming during MIR. We integrated transcriptional and phosphoproteomic and physiological analysis with functional validation via prosystemin overexpression and virus‐induced gene silencing of key signalling components. Plants treated with systemin, colonised by mycorrhizas, or overexpressing prosystemin exhibited similar levels of resistance. Systemin and MIR primed callose accumulation and JA‐related gene expression. Phosphoproteome analysis revealed a strong overlap between phosphorylated proteins induced during MIR and systemin‐mediated resistance, indicating that systemin modulates MIR via phosphorylation. Components of systemin signalling, including Systemin Receptor‐1 (SYR1), PEPR‐like Kinase‐1 (PORK1), and kinases MPK1/3, were primed during MIR. Silencing of these genes impaired MIR, indicating that intact systemin perception and signalling are required to express functional MIR. MIR is mediated by systemin hypersensitisation, which primes a kinase cascade regulating downstream JA‐dependent responses following fungal infection.

Comparative transcriptomics reveals conserved infection-associated gene expression in Phytophthora agathidicida across its natural gymnosperm host kauri and the model angiosperm host Nicotiana benthamiana.

Phytophthora species cause many devastating diseases of plants, including those of forest trees. Agathis australis (New Zealand kauri) is an ancient and culturally significant tree species that is susceptible to a lethal root and collar rot caused by Phytophthora agathidicida. Functional characterisation of P. agathidicida virulence factors is limited by difficulties in working with its natural host. The angiosperm Nicotiana benthamiana is widely used as a model plant host for studying plant-pathogen interactions, including P. agathidicida. To help determine whether N. benthamiana is a reliable model for the gymnosperm A. australis, we analysed P. agathidicida gene expression in leaves and roots of N. benthamiana and compared this to an earlier transcriptomic analysis in A. australis. A core set of 1129 genes upregulated in both hosts and organs was enriched for secreted RXLR effector, CAZyme and elicitin proteins, indicating a conserved infection-associated transcriptional programme. Similarities between the suites of genes expressed in leaves and roots support the approach of performing assays of gene function on leaves which are technically easier to use than roots. While many genes were similarly expressed across hosts, there were also some differences. A CAP protein, highly expressed only in N. benthamiana, increased P. agathidicida growth in N. benthamiana but not in A. australis under the conditions tested. These findings suggest that P. agathidicida deploys a largely conserved molecular strategy to colonise gymnosperm and angiosperm hosts, supporting the use of N. benthamiana as a model system for functional studies, while also highlighting pathogen genes that are highly expressed and upregulated in each of the hosts.

The bZIP transcription factor PnAda1 functions as a regulator of virulence, fungicide tolerance and necrotrophy in the wheat pathogen Parastagonospora nodorum

It is shown that the understudied bZIP transcription factor PnAda1 is an important downstream component of this PnPf2-regulatory network, and current understanding of the transcriptional network underlying virulence, metabolism and stress adaptation in an important fungal wheat pathogen is expanded.

Botrytis virus X ORF2 suppresses RNA silencing in a trigger-restricted manner and is associated with altered Dicer-like gene expression in Botrytis cinerea

Agroecological functions of Trichoderma harzianum, an endophytic fungus of the avocado root: its role in plant growth, defense and multitrophic interactions.

The results support the use of T. harzianum as an effective bioinoculant to enhance plant growth and suppress pests, offering a sustainable alternative to synthetic agrochemicals.

The transcription factor CfMBZ1 of Colletotrichum fructicola governs host penetration to mediate Glomerella leaf spot pathogenesis in apple

Colletotrichum fructicola, the primary causal agent of Glomerella leaf spot (GLS), is a destructive fungal pathogen of apple, whose underlying pathogenic mechanisms remain largely unknown. A previous transcriptomic analysis of infected leaves indicated induction of the transcription factor CfMBZ1. This study confirmed that CfMBZ1 is highly expressed in conidia and during early infection. To elucidate its function, we generated a ΔCfMBZ1 deletion mutant via homologous recombination. Phenotypic analysis revealed that ΔCfMBZ1 lost pathogenicity on apple leaves due to a blockage in appressorium-mediated host penetration, despite retaining the ability to form penetration pegs on cellophane. However, extension of invasive hyphae and necrotrophic growth in wounded apple fruit were unaffected. The mutant also exhibited defects in maintaining the integrity of the cell wall and cell membrane, as well as in tolerating oxidative and acid–base stress. Comparative transcriptome analysis suggested that CfMBZ1 regulates appressorium-mediated penetration by modulating genes involved in peroxisome biogenesis, lipid droplet metabolism, and other penetration-related pathways. Our findings reveal that CfMBZ1 plays a critical role in the pathogenesis of Glomerella leaf spot caused by C. fructicola.