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PubMed2025

Proteomic snapshot of pattern triggered immunity in the Arabidopsis leaf apoplast.

The apoplast is a critical interface in plant-pathogen interactions, particularly in the context of pattern-triggered immunity (PTI), which is initiated by recognition of microbe-associated molecular patterns. Our study characterizes the proteomic profile of the Arabidopsis apoplast during PTI induced by flg22, a 22-amino-acid bacterial flagellin epitope, to elucidate the output of PTI. Apoplastic washing fluid was extracted with minimal cytoplasmic contamination for liquid chromatography-tandem mass spectrometry analysis. By comparing our data to publicly available transcriptome profiles of flg22 treatment from 1 to 18 h, we observed that several highly abundant proteins exhibit relatively unchanged gene expression across all time points. We also observed topological bias in peptide recovery of 19 enriched receptor-like kinases with peptides predominantly recovered from their ectodomains. Notably, tetraspanin 8, an exosome marker, was enriched in PTI samples. We additionally confirmed increased concentrations of exosomes during PTI. This study enhances our understanding of the proteomic changes in the apoplast during plant immune responses and lays the groundwork for future investigations into the molecular mechanisms of plant defense under recognition of pathogen molecular patterns.

Arabidopsis↗

PubMed2026

Identification of tomato leaf miner secretory proteins and their roles in influencing plant defenses.

The tomato leaf miner (Tuta absoluta) is a globally destructive pest that cause extensive damage to tomato crops by chewing mouthparts, leading to severe necrosis, fruit abortion, and substantial yield losses. To date, the elicitors/effectors of T. absoluta have not been characterized. In this study, we combined proteomic profiling of T. absoluta-infested tomato leaves with transcriptomic analysis of salivary glands to identify candidate molecules involved in herbivory-driven plant responses. Bioinformatics analyses predicted 40 candidate elicitors and effectors, which were subsequently assessed through transient expression assays in Nicotiana benthamiana. The results demonstrated that the candidate number 33 (T. absoluta 33, Ta33) induced cell death in both the intracellular space and the apoplast, while Ta21 triggered a strong apoplastic reactive oxygen species (ROS) burst. Conversely, Ta38 effectively suppressed INF1-induced cell death. Quantitative real-time PCR analysis further showed that these genes were highly expressed during the feeding stage, supporting their involvement in plant-insect molecular dialogue. This study systematically identified and characterized elicitors and effectors of T. absoluta, providing a foundational framework for elucidating its herbivory mechanisms and developing targeted management strategies.

Moths↗

PubMed2026

Rs_MEP1 Is Required for the Pathogenesis of Rhizoctonia solani AG1-IA in Plants.

Rhizoctonia solani AG1-IA is a polyphagous necrotrophic fungal pathogen that causes sheath blight disease in rice. Efforts are being made to identify pathogenicity-associated genes in R. solani and modulate them to develop a disease control strategy. Here, we investigated the roles of some predicted pathogenicity-associated genes of R. solani that have previously been reported to be upregulated during infection in rice. The tobacco rattle virus-based host-induced gene silencing of the selected pathogenicity-associated genes revealed that silencing of Rs_MEP1, a zinc-containing Peptidase_M43 domain metalloprotease, severely compromises R. solani infection in tomato. Moreover, double-stranded RNA-mediated silencing of Rs_MEP1 prevented R. solani infection in rice. The signal sequence trap assay indicated the secretory nature of Rs_MEP1, and the reporter assay suggested its localization in the plant apoplast. Notably, Agrobacterium-mediated transient overexpression of Rs_MEP1 induces necrotic cell death responses in plants. We provide evidence that Rs_MEP1 interacts with the GH19 family of rice chitinases and potentially modulates their functions. Overall, our study emphasizes that Rs_MEP1 facilitates R. solani in promoting necrotic responses and targets rice GH19 chitinases to impart disease susceptibility in plants. [Formula: see text] Copyright © 2026 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Rhizoctonia↗

PubMed1992

Subcellular localization of ubiquitin and ubiquitinated proteins in Arabidopsis thaliana.

Ubiquitin is a highly conserved, 76-amino acid, eukaryotic protein. Its widely accepted role as a proteolytic cofactor depends on its unique ability to covalently ligate to other cellular proteins. While there is good evidence for the existence of such ubiquitinated proteins in the cytosolic and nuclear compartments, relatively little is known about the presence of free ubiquitin and ubiquitinated proteins in other subcellular compartments. This is especially true of higher plants, which have not previously been the subject of extensive biochemical subcellular localizations of ubiquitinated proteins. We extracted cell wall proteins and purified nuclei, vacuoles, chloroplasts, and microsomes from chlorophyllous tissues of Arabidopsis. Immunoblot analyses were used to compare the profiles of ubiquitinated proteins from purified subcellular fractions to those from unfractionated extracts. Purified nuclei contained, in addition to a complex mixture of high molecular mass ubiquitinated proteins, a strongly immunoreactive 28-kDa protein. In the apoplastic extract, we did not detect any ubiquitinated proteins enriched above the background level of those due to cytosolic contamination. Vacuoles appeared to contribute significantly to the ubiquitinated proteins present in the whole protoplast extract. At least three high molecular mass ubiquitinated proteins were unique to the vacuolar extract. Chloroplast stromal proteins did not react specifically with anti-ubiquitin antibodies. When microsomal ubiquitinated proteins were compared to those found in a whole protoplast extract, a distinct pattern was evident. Microsomal ubiquitinated proteins were not visible in the 10,000 x g supernatant used to prepare the 100,000 x g pellet, indicating that they were probably low abundance proteins in the protoplast extract.

Cell Fractionation↗