Transcriptome Profiling of Resistance Gene Analogs in Soybean's Cross-Tolerance to Water Limitation and Rust Stress Gustavo Husein, Thiago Maia, Fernanda R. Castro‐Moretti, Jessica D. K. Nunes, Lilian Amorim, et al. Food and Energy Security, 2025 Asian soybean rust (ASR), caused by Phakopsora pachyrhizi , is the most destructive foliar disease of soybean, with yield losses up to 90%. With climate change intensifying drought and expanding disease incidence, it is critical to understand how combined abiotic and biotic stresses influence plant defense. We investigated the transcriptomic response of a susceptible soybean cultivar to ASR infection under normal and water‐limited conditions at four infection stages (12, 24, 72, and 192 h after inoculation). We observed a biphasic expression of defense‐related genes, particularly resistance gene analogs (RGAs), with an early peak at 12 h and a late resurgence at 192 h. Combined stress induced a greater number of differentially expressed genes (DEGs) than rust alone, especially at early infection. Among the differentially expressed RGAs (RGADEs), over 64% belonged to the TM‐LRR class, and NBS‐LRR genes were the most enriched at known ASR resistance loci, particularly Rpp2. Water limitation strongly modulated gene expression at late stages, revealing stress‐specific transcriptional reprogramming. These findings were consistent with the activation of potential cross‐tolerance mechanisms in soybean, highlighted the temporal dynamics of RGADEs under dual stress, and provided potential targets for developing cultivars with improved resilience to both rust and water scarcity.
A metabolomic platform to identify and quantify polyphenols in coffee and related species using liquid chromatography mass spectrometry Fernanda R. Castro-Moretti, Jean-Christophe Cocuron, Humberto Castillo-Gonzalez, Efrain Escudero-Leyva, Priscila Chaverri, et al. Frontiers in Plant Science, 2023 IntroductionProducts of plant secondary metabolism, such as phenolic compounds, flavonoids, alkaloids, and hormones, play an important role in plant growth, development, stress resistance. The plant family Rubiaceae is extremely diverse and abundant in Central America and contains several economically important genera, e.g. Coffea and other medicinal plants. These are known for the production of bioactive polyphenols (e.g. caffeine and quinine), which have had major impacts on human society. The overall goal of this study was to develop a high-throughput workflow to identify and quantify plant polyphenols.MethodsFirst, a method was optimized to extract over 40 families of phytochemicals. Then, a high-throughput metabolomic platform has been developed to identify and quantify 184 polyphenols in 15 min.ResultsThe current metabolomics study of secondary metabolites was conducted on leaves from one commercial coffee variety and two wild species that also belong to the Rubiaceae family. Global profiling was performed using liquid chromatography high-resolution time-of-flight mass spectrometry. Features whose abundance was significantly different between coffee species were discriminated using statistical analysis and annotated using spectral databases. The identified features were validated by commercially available standards using our newly developed liquid chromatography tandem mass spectrometry method.DiscussionCaffeine, trigonelline and theobromine were highly abundant in coffee leaves, as expected. Interestingly, wild Rubiaceae leaves had a higher diversity of phytochemicals in comparison to commercial coffee: defense-related molecules, such as phenylpropanoids (e.g., cinnamic acid), the terpenoid gibberellic acid, and the monolignol sinapaldehyde were found more abundantly in wild Rubiaceae leaves.
Targeted metabolic profiles of the leaves and xylem sap of two sugarcane genotypes infected with the vascular bacterial pathogen leifsonia xyli subsp. Xyli Fernanda R. Castro-Moretti, Jean-Christophe Cocuron, Mariana C. Cia, Thais R. Cataldi, Carlos A. Labate, et al. Metabolites, 2021 Ratoon stunt (RS) is a worldwide disease that reduces biomass up to 80% and is caused by the xylem-dwelling bacterium Leifsonia xyli subsp. xyli. This study identified discriminant metabolites between a resistant (R) and a susceptible (S) sugarcane variety at the early stages of pathogen colonization (30 and 120 days after inoculation—DAI) by untargeted and targeted metabolomics of leaves and xylem sap using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-tandem mass spectrometry (LC-MS/MS), respectively. Bacterial titers were quantified in sugarcane extracts at 180 DAI through real-time polymerase chain reaction. Bacterial titers were at least four times higher on the S variety than in the R one. Global profiling detected 514 features in the leaves and 68 in the sap, while 119 metabolites were quantified in the leaves and 28 in the sap by targeted metabolomics. Comparisons between mock-inoculated treatments indicated a greater abundance of amino acids in the leaves of the S variety and of phenolics, flavonoids, and salicylic acid in the R one. In the xylem sap, fewer differences were detected among phenolics and flavonoids, but also included higher abundances of the signaling molecule sorbitol and glycerol in R. Metabolic changes in the leaves following pathogen inoculation were detected earlier in R than in S and were mostly related to amino acids in R and to phosphorylated compounds in S. Differentially represented metabolites in the xylem sap included abscisic acid. The data represent a valuable resource of potential biomarkers for metabolite-assisted selection of resistant varieties to RS.
Metabolomics as an emerging tool for the study of plant–pathogen interactions Fernanda R. Castro-Moretti, Irene N. Gentzel, David Mackey, Ana P. Alonso Metabolites, 2020 Plants defend themselves from most microbial attacks via mechanisms including cell wall fortification, production of antimicrobial compounds, and generation of reactive oxygen species. Successful pathogens overcome these host defenses, as well as obtain nutrients from the host. Perturbations of plant metabolism play a central role in determining the outcome of attempted infections. Metabolomic analyses, for example between healthy, newly infected and diseased or resistant plants, have the potential to reveal perturbations to signaling or output pathways with key roles in determining the outcome of a plant–microbe interaction. However, application of this -omic and its tools in plant pathology studies is lagging relative to genomic and transcriptomic methods. Thus, it is imperative to bring the power of metabolomics to bear on the study of plant resistance/susceptibility. This review discusses metabolomics studies that link changes in primary or specialized metabolism to the defense responses of plants against bacterial, fungal, nematode, and viral pathogens. Also examined are cases where metabolomics unveils virulence mechanisms used by pathogens. Finally, how integrating metabolomics with other -omics can advance plant pathology research is discussed.
First report of powdery mildew caused by erysiphe platani on Platanus × acerifolia in Rio Grande do Sul, Brazil T. S. de Oliveira, L. J. Dallagnol, J. V. de Araujo Filho, F. R. de Castro Moretti, L. E. A. Camargo Plant Disease, 2015 Platanus × acerifolia (Aiton) Willd. (London planetree) is a tree commonly used as an ornamental and in the furniture industry. In the summer of 2013, powdery mildew was observed on shoots of P. × acerifolia plants in the cities of Pelotas and Canela (State of Rio Grande do Sul, Brazil). Voucher specimens (n = 2) were deposited in the Phytopathological Museum Manoel Alves Oliveira at Federal University of Pelotas. Dense white powdery masses of conidia and mycelium were observed on leaves (abaxial and adaxial surfaces), petioles, and young stems. Leaves with high disease severities (≥70%) were deformed with curved edges to the adaxial side, and they often died. Mycelia were superficial with lobed appressoria. Conidiophores were straight, sometimes curved at the base, unbranched, cylindrical, 98 to 236 μm long (137.3 ± 41.2 μm) and composed of a cylindrical foot cell 49 to 102 μm long (66.9 ± 19.5 μm) and 4.4 to 6.4 μm wide (5.3 ± 0.8 μm) followed by two to four cells. Conidia were produced singly or in short chains (two to three), without distinct fibrosin bodies, ellipsoid to ovoid and measuring 24 to 37 μm long (29.5 ± 3.2 μm) and 12 to 19 μm wide (15.2 ± 1.4 μm), often with a wrinkled appearance. Primary conidia had truncate bases and rounded apex while both base and apex were truncated in secondary conidia. Germ tubes were produced apically (pseudoidium type). Chasmothecia were not observed. Genomic DNA was used to amplify the internal transcribed spacer (ITS) region using the ITS1 and ITS4 primers. The resulting sequence (602 bp) was deposited (Accession No. KF499270) in GenBank. BLASTn searches revealed similarity of 100 and 99% with Erysiphe platani from P. orientalis L. (Accession No. JQ365943.1) and P. occidentalis L. (Accession No. JX997805.1), respectively. Phylogenetic analysis placed our sequence in a clade (99% bootstrap support) which included only other E. plantani sequences. In short, morphological and molecular approaches allowed us to identify the infecting fungus as E. platani. For Koch's postulates, 10 detached leaves were inoculated (10 to 15 conidia cm2) on their adaxial surface using an eyelash brush. Non-inoculated leaves served as control. All leaves were kept inside trays with petiole immersed in humidified cotton and maintained at 25 ± 1°C. Symptoms identical to those of the original leaves were observed 6 to 8 days after inoculation, whereas the control leaves remained symptomless. Although E. platani has been previously reported on P. × acerifolia in the city of Poços de Calda, state of Minas Gerais, Brazil (1) and on P. occidentalis in Korea (2), to our knowledge, this is the first record of E. platani on P. × acerifolia in Rio Grande do Sul, Brazil. References: (1) E. M. Inokuti et al. New Dis. Rep. 15:38, 2007. (2) Y. J. La and H. D. Shin. Plant Dis. 97:843, 2013.
Pratylenchus brachyurus (Nematoda: Pratylenchidae) in Guariroba in the state of Goiás, Brazil J. De Araújo Filho, F. Castro-Moretti, M. Bonfim Junior Helminthologia Poland, 2014 Roots of Syagrus oleracea were collected in two growing areas in the municipality of Rio Verde, state of Goiás (Brazil). Morphological, morphometric and molecular (ITS1 sequences) approaches allowed us to identify the infecting nematode as Pratylenchus brachyurus. To our knowledge, this is the first record of P. brachyurus parasitizing guariroba elsewhere (new host).