Effects of Excess Manganese on the Xylem Sap Protein Profile of Tomato (Solanum lycopersicum) as Revealed by Shotgun Proteomic Analysis

Genome-wide identification and characterization of the FLA gene family in sorghum under salt-alkali stress

Fasciclin-like arabinogalactan proteins (FLAs) are crucial for plant growth and development. Utilizing whole genome data, this study delineated the number of genes, gene structure, chromosomal localization, protein structure, evolutionary relationships, and Gene Ontology (GO) annotations of the FLA family in sorghum (Sorghum bicolor L.). In addition, FLA genes' expression in wild-type sorghum (P898012) under salt-alkali stress (SAS) was examined. We identified 26 FLA genes in sorghum. Phylogenetic analysis divided these genes into five subgroups, where members within the same subgroup exhibited extremely similar, though not identical, gene structures. A collinearity analysis of the sorghum FLA genes revealed that SbFLA19 does not share a homologous relationship with those in Zea and Arabidopsis, suggesting its uniqueness to sorghum. Promoter element analysis indicated that the FLA genes contain various response elements associated with abiotic stress. GO annotations demonstrated that most FLA proteins are primarily located on the plasma membrane and are involved in diverse biological processes. Transcriptomic data and qRT-PCR analysis under SAS revealed that members of the SbFLA family responded to stress at different times. These findings provide valuable references for breeding sorghum varieties tolerant to salt-alkali conditions.

Identification of critical transition signal (CTS) to characterize regulated stochasticity during ABA-induced growth-to-defense transition

BACKGROUND

Abscisic acid (ABA) plays a central role in regulating plant responses to abiotic stress. It orchestrates a complex regulatory network that facilitates the transition from growth to defense. Understanding the molecular mechanisms underlying this ABA-induced transition from growth to defense is essential for elucidating plant adaptive strategies under environmental stress conditions.

RESULTS

In this study, we used a refined dynamic network biomarker (DNB) approach to quantitatively identify the critical transition signal (CTS) and characterize the regulated stochasticity during the ABA-induced transition from growth to defense in Arabidopsis thaliana. By integrating high-resolution time-series RNA-seq data with dynamic network analysis, we identified a set of DNB genes that serve as key molecular regulators of this transition. The critical transition phase was identified precisely at the ninth time point (6 h after treatment), which marks the crucial switch from a growth-dominated to a defense -oriented state. Gene Ontology (GO) enrichment analysis revealed a significant overrepresentation of defense-related biological processes, while STRING network analysis revealed strong functional interactions between DNB genes and differentially expressed genes (DEGs) and highlighted key regulatory hubs. In particular, key hub genes such as PIF4, TPS8, NIA1, and HSP90-5 were identified as potential master regulators of ABA-mediated defense activation, highlighting their importance for plant stress adaptation.

CONCLUSIONS

By integrating a network-driven transcriptomic analysis, this study provides new insights into the molecular basis of ABA-induced transitions from growth to defense. The identification of CTS provides a new perspective on regulated stochasticity in plant stress responses and provides a conceptual framework for improving crop stress resistance. In addition, the establishment of a comprehensive database of ABA-responsive defense genes represents a valuable resource for future research on plant adaptation and resilience.

Multi-omics analysis of non-pungent (Capsicum annuum) and fiery hot ghost chili (C. chinense) provides insights into proteins involved in fruit development and metabolites biosynthesis

Global omics offer extensive insights into the diversity of essential biomolecules across various plant developmental stages. Despite advancements in high-throughput technologies, the integrated analysis of global omics such as proteomics, transcriptomics, and metabolomics, is yet to be fully explored in fruits of Capsicum species. In this study, we used an integrated omics approach to identify proteins involved in fruit development, and metabolite biosynthesis in the placenta and pericarp tissues of two contrasting genotypes belonging to ghost chili (Capsicum chinense) and C. annuum. The mass spectrometry analysis identified a total of 4,473 and 2,012 proteins from the pericarp and placenta tissues of Capsicum fruits. We observed expression of developmental stage-specific proteins, such as kinases, transferases, ion transporters, F-box proteins, and transcription factors that were enriched in the biosynthesis of primary and secondary metabolites. The abundance of these proteins corresponded with RNAseq data. Key proteins related to capsaicinoids biosynthesis, such as Acyltransferase 3, 3-oxoacyl-[acyl-carrier protein], 4-coumaroyl co-A ligase, and 3-ketoacyl-coA synthase 3, were identified in placenta of highly pungent ghost chili, along with J-domain proteins and transcription factors such as MYB101, MYB 14-like, bHLH112, NAC, and Cyt p450 CYP82D47, suggesting their role in capsaicinoids and secondary metabolites biosynthesis. Further, we observed a correlation of the expression of genes and proteins with the abundance of primary and secondary metabolites, such as carbohydrates, alcohols, fatty acids, phenolics, glycerides, polyamines, and amino acids. Our findings provide a novel multiomics resources for future functional studies, with potential applications in breeding programs.

Graphical Abstract

Supplementary Information

The online version contains supplementary material available at 10.1007/s12298-025-01581-7.

Phosphorus-induced restructuring of the ascorbate-glutathione cycle and lignin biosynthesis alleviates manganese toxicity in peach roots

Manganese (Mn) is indispensable for plant growth, but its excessive uptake in acidic soils leads to toxicity, hampering food safety. Phosphorus (P) application is known to mitigate Mn toxicity, yet the underlying molecular mechanism remains elusive. Here, we conducted physiological and transcriptomic analyses of peach roots response to P supply under Mn toxicity. Manganese treatment disrupted root architecture and caused ultrastructural damage due to oxidative injury. Notably, P application ameliorated the detrimental effects and improved the damaged roots by preventing the shrinkage of cortical cells, epidermis and endodermis, as well as reducing the accumulation of reactive oxygen species (ROS). Transcriptomic analysis revealed the differentially expressed genes enriched in phenylpropanoid biosynthesis, cysteine, methionine and glutathione metabolism under Mn and P treatments. Phosphorus application upregulated the transcripts and activities of core enzymes crucial for lignin biosynthesis, enhancing cell wall integrity. Furthermore, P treatment activated ascorbate-glutathione cycle, augmenting ROS detoxification. Additionally, under Mn toxicity, P application downregulated Mn uptake transporter while enhancing vacuolar sequestration transporter transcripts, reducing Mn uptake and facilitating vacuolar storage. Collectively, P application prevents Mn accumulation in roots by modulating Mn transporters, bolstering lignin biosynthesis and attenuating oxidative stress, thereby improving root growth under Mn toxicity. Our findings provide novel insights into the mechanism of P-mediated alleviation of Mn stress and strategies for managing metal toxicity in peach orchards.

How plants respond to heavy metal contamination: a narrative review of proteomic studies and phytoremediation applications

MAIN CONCLUSION

Heavy metal pollution caused by human activities is a serious threat to the environment and human health. Plants have evolved sophisticated defence systems to deal with heavy metal stress, with proteins and enzymes serving as critical intercepting agents for heavy metal toxicity reduction. Proteomics continues to be effective in identifying markers associated with stress response and metabolic processes. This review explores the complex interactions between heavy metal pollution and plant physiology, with an emphasis on proteomic and biotechnological perspectives. Over the last century, accelerated industrialization, agriculture activities, energy production, and urbanization have established a constant need for natural resources, resulting in environmental degradation. The widespread buildup of heavy metals in ecosystems as a result of human activity is especially concerning. Although some heavy metals are required by organisms in trace amounts, high concentrations pose serious risks to the ecosystem and human health. As immobile organisms, plants are directly exposed to heavy metal contamination, prompting the development of robust defence mechanisms. Proteomics has been used to understand how plants react to heavy metal stress. The development of proteomic techniques offers promising opportunities to improve plant tolerance to toxicity from heavy metals. Additionally, there is substantial scope for phytoremediation, a sustainable method that uses plants to extract, sequester, or eliminate contaminants in the context of changes in protein expression and total protein behaviour. Changes in proteins and enzymatic activities have been highlighted to illuminate the complex effects of heavy metal pollution on plant metabolism, and how proteomic research has revealed the plant's ability to mitigate heavy metal toxicity by intercepting vital nutrients, organic substances, and/or microorganisms.

Tissue-level distribution and speciation of foliar manganese in Eucalyptus tereticornis by µ-SXRF and µ-XANES shed light on its detoxification mechanisms

This study is the first to investigate the speciation and spatial distribution patterns of manganese (Mn) accumulated at elevated concentrations in Eucalyptus leaves by X-ray fluorescence (µ-XRF) and absorption near-edge spectroscopy (µ-XANES). Eucalyptus tereticornis is a tree species with great economic value and potential to accumulate and tolerate high Mn despite not being considered a hyperaccumulator. Seedlings grown under glasshouse conditions were irrigated with two Mn treatments: control Mn (9 µM) and high Mn solution (1000 µM). Biomass and total nutrient concentrations were assessed in roots, stems and leaves. Manganese, calcium (Ca) and potassium (K) spatial patterns were imaged by µ-SXRF in different foliar structures, and Mn speciation was conducted in these compartments by µ-XANES. Under high supply, Mn was distributed across the leaf mesophyll suggesting vacuolar sequestration in these cells. High Mn decreased cytosolic Ca by almost 50% in mesophyll cells, but K remained unaltered. Speciation suggests that a majority of the Mn fraction was complexed by organic ligands modeled as Mn-bound malate and citrate, instead of as free aqueous Mn2+ or oxidised forms. These two detoxification mechanisms: effective vacuolar sequestration and organic acid complexation, may be responsible for the impressively high Mn tolerance found in eucalypts.

A new versatile peroxidase with extremophilic traits over-produced in MicroTom cell cultures

Peroxidases are widespread key antioxidant enzymes that catalyse the oxidation of electron donor substrates in parallel with the decomposition of H2O2. In this work, a novel tomato peroxidase, named SAAP2, was isolated from MicroTom cell cultures, purified, and characterised. The enzyme was identified with 64% sequence coverage as the leprx21 gene product (suberization-associated anionic peroxidase 2-like) from Solanum lycopersicum, 334 amino acids long. Compared to other plant peroxidases, SAAP2 was more active at elevated temperatures, with the optimal temperature and pH at 90 °C and 5.0, respectively. Furthermore, the enzyme retained more than 80% of its maximal activity over the range of 70-80 °C and the presence of NaCl (1.0-4.5 M). It also exhibited broad pH versatility (65% relative activity over the pH range 2.0-7.0), acid-tolerance (80% residual activity after 22 h at pH 2.0-7.0), high thermostability (50% residual activity after 2 h at 80 °C) and proteolytic resistance. SAAP2 exhibited exceptional resistance under thermo-acidic conditions compared to the horseradish peroxidase benchmark, suggesting that it may find potential applications as a supplement or anti-pollution agent in the food industry.

Cucurbita pepo contains characteristic proteins without a signal peptide in the xylem sap

Xylem sap is a fluid that transfers water and nutrients from the rhizosphere. This sap contains relatively low concentrations of proteins that originate from the extracellular space among the root cells. One of the characteristic proteins in the xylem sap of the Cucurbitaceae family, which includes cucumber and zucchini, is a major latex-like protein (MLP). MLPs are responsible for crop contamination through the transport of hydrophobic pollutants from the roots. However, detailed information on the content of MLPs in the xylem sap is not available. Proteomic analysis of root and xylem sap proteins from the Cucurbita pepo cultivars Patty Green (PG) and Raven (RA) showed that the xylem sap of cv. RA, a high accumulator of hydrophobic pollutants, contained four MLPs that accounted for over 85% of the total xylem sap proteins in this cultivar. The xylem sap of PG, a low accumulator, mainly contained an uncharacterized protein. The amount of each root protein between the PG and RA cultivars was significantly and positively correlated in spite of being with and without a signal peptide (SP). However, the amount of xylem sap proteins without an SP was not correlated. These results suggest that cv. RA is characterized by MLPs in the xylem sap.

LSPpred Suite: Tools for Leaderless Secretory Protein Prediction in Plants

Plant proteins that are secreted without a classical signal peptide leader sequence are termed leaderless secretory proteins (LSPs) and are implicated in both plant development and (a)biotic stress responses. In plant proteomics experimental workflows, identification of LSPs is hindered by the possibility of contamination from other subcellar compartments upon purification of the secretome. Applying machine learning algorithms to predict LSPs in plants is also challenging due to the rarity of experimentally validated examples for training purposes. This work attempts to address this issue by establishing criteria for identifying potential plant LSPs based on experimental observations and training random forest classifiers on the putative datasets. The resultant plant protein database LSPDB and bioinformatic prediction tools LSPpred and SPLpred are available at lsppred.lspdb.org. The LSPpred and SPLpred modules are internally validated on the training dataset, with false positives controlled at 5%, and are also able to classify the limited number of established plant LSPs (SPLpred (3/4, LSPpred 4/4). Until such time as a larger set of bona fide (independently experimentally validated) LSPs is established using imaging technologies (light/fluorescence/electron microscopy) to confirm sub-cellular location, these tools represent a bridging method for predicting and identifying plant putative LSPs for subsequent experimental validation.

Proteomics of Reproductive Development, Fruit Ripening, and Stress Responses in Tomato

The fruits of the tomato crop (Solanum lycopersicum L.) are increasingly consumed by humans worldwide. Due to their rich nutritional quality, pharmaceutical properties, and flavor, tomato crops have gained a salient role as standout crops among other plants. Traditional breeding and applied functional research have made progress in varying tomato germplasms to subdue biotic and abiotic stresses. Proteomic investigations within a span of few decades have assisted in consolidating the functional genomics and transcriptomic research. However, due to the volatility and dynamicity of proteins in the regulation of various biosynthetic pathways, there is a need for continuing research in the field of proteomics to establish a network that could enable a more comprehensive understanding of tomato growth and development. With this view, we provide a comprehensive review of proteomic studies conducted on the tomato plant in past years, which will be useful for future breeders and researchers working to improve the tomato crop.

Comparative proteome analysis reveals the role of negative floral regulators and defense-related genes in phytoplasma infected sesame

"Candidatus Phytoplasma australiense" is associated with floral malformations in sesame but the interaction remains largely unexplored. A label-free quantitative shotgun proteomics approach through liquid chromatography-mass spectrometry quadruple time-of-flight was used to analyze changes in the proteome of asymptomatic (control) and symptomatic (phytoplasma-infected) sesame plants to identify proteins differentially expressed during phytoplasma infection at early stages of flower development. A total of 3457 and 1704 proteins were identified from asymptomatic and symptomatic samples respectively through proteome profiling with three runs per sample. Several differentially abundant proteins (DAPs) were identified which might be involved in sesame-phytoplasma interaction. The DAPs identified were related to transcription, cell division, chromosome partitioning, defense mechanisms, negative regulation of flower development, amino acid transport and metabolism, signal transduction and RNA processing, and its modifications. Of these proteins, 21 were downregulated while 212 were significantly upregulated in symptomatic sesame plants compared to the control plants. The floral development-related proteins like UBP16 and DCAF1 were found to be downregulated while negative regulators/repressors of floral development genes, HUA2, PIE1, and ICU2, were upregulated in symptomatic samples indicating phytoplasma's role in altering the expression of these genes. Validation of these genes through quantitative retro-transcripted PCR suggested that the DAPs observed in symptomatic sesame might be induced by phytoplasma presence to suppress flowering via negative regulation of flower development.

Recent advances in proteomics and metabolomics in plants

Over the past decade, systems biology and plant-omics have increasingly become the main stream in plant biology research. New developments in mass spectrometry and bioinformatics tools, and methodological schema to integrate multi-omics data have leveraged recent advances in proteomics and metabolomics. These progresses are driving a rapid evolution in the field of plant research, greatly facilitating our understanding of the mechanistic aspects of plant metabolisms and the interactions of plants with their external environment. Here, we review the recent progresses in MS-based proteomics and metabolomics tools and workflows with a special focus on their applications to plant biology research using several case studies related to mechanistic understanding of stress response, gene/protein function characterization, metabolic and signaling pathways exploration, and natural product discovery. We also present a projection concerning future perspectives in MS-based proteomics and metabolomics development including their applications to and challenges for system biology. This review is intended to provide readers with an overview of how advanced MS technology, and integrated application of proteomics and metabolomics can be used to advance plant system biology research.