Proteome readjustments in the apoplastic space of Arabidopsis thaliana ggt1 mutant leaves exposed to UV-B radiation

Ultraviolet-B radiation acts as an environmental stimulus, but in high doses it has detrimental effects on plant metabolism. Plasma membranes represent a major target for ROS generated by this harmful radiation. Oxidative reactions occurring in the apoplastic space are counteracted by antioxidative systems mainly involving ascorbate and, to some extent, glutathione. The occurrence of the latter and its exact role in the extracellular space are not well documented, however. In Arabidopsis thaliana, the gamma-glutamyl transferase isoform GGT1 bound to the cell wall takes part in the so-called gamma-glutamyl cycle for extracellular glutathione degradation and recovery, and may be implicated in redox sensing and balance. In this work, oxidative conditions were imposed with UV-B and studied in redox altered ggt1 mutants. The response of ggt1 knockout Arabidopsis leaves to UV-B radiation was assessed by investigating changes in extracellular glutathione and ascorbate content and their redox state, and in apoplastic protein composition. Our results show that, on UV-B exposure, soluble antioxidants respond to the oxidative conditions in both genotypes. Rearrangements occur in their apoplastic protein composition, suggesting an involvement of H2O2, which may ultimately act as a signal. Other important changes relating to hormonal effects, cell wall remodeling, and redox activities are discussed. We argue that oxidative stress conditions imposed by UV-B and disruption of the gamma-glutamyl cycle result in similar stress-induced responses, to some degree at least. Data are available via ProteomeXchange with identifier PXD001807

DNA barcoding: a way forward to obtain deep insights about the realistic diversity of living organisms

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Protein profile of commercial soybean milks analyzed by label-free quantitative proteomics

The consumption of soy milk is increasing worldwide for its nutritional value and health benefits, however, its protein composition after commercialization is not well known. Technological and thermal treatments to which soy milk is subjected could affect the protein composition of the commercial products. This study compared the protein profile of 15 different commercial soy milks using a label-free quantitative proteomics approach. Proteins related to nutrient reservoir activity, endopeptidase inhibitor activity, lipid binding, and seed maturation contribute the most in terms of percentage mass. Their associated Gene Ontology terms are also enriched. Samples clustered into three groups based on their protein composition, with glycinins and beta-conglycinins being the most influential for determining the clustering. Amino acid composition estimated from the proteomics data also reflects the clustering of samples. Twenty allergenic proteins varying in abundance were identified, with Gly m 5 and Gly m 6 being the predominantly abundant allergens

Perfluoroalkyl compounds (PFAS) exposure alters xylem hydraulics and gas exchange in willow plants

Poly- and Per-Fluorinated Alkyl Substances (PFAS) are among the most common pollutants derived from industry causing worldwide environmental contamination. PFAS are a class of more than 4700 artificial aliphatic compounds partially or fully fluorinated, which may contain functional groups. This particular chemical structure makes PFAS extremely persistent and resistant to degradation, and provides both hydrophobic and lipophobic properties, as well as high chemical and thermal stability. PFAS can move across water and are known to translocate and accumulate in living organisms, according to their chain length and functional group. Toxic effects on human health have been widely reported. PFAS occurrence in the xylem of the stem was demonstrated by DESI-MS and TEMEDS technologies by Wang et al., (2020), but there is still limited knowledge about PFAS effects on the plant vascular system and physiology. The aim of this research was to investigate if accumulation of PFAS may occur in conductive elements of willow plants, thus altering their hydrophilicity and hydraulic properties. Willow cuttings (Salix triandra) were grown hydroponically in water under greenhouse conditions to induce rooting and shooting. 50 plants were selected for uniformity and transferred to single pots filled with Hoagland nutrient solution. After a few days of adaptation in agronomically suitable condition, they were equally divided in two groups and the nutrient solution was changed. In one of the groups the new nutrient solution was spiked with a PFAS mixture containing PFBA, PFBS, PFPeA, PFHxA, PFHpA, PFOA, PFOS, PFNA, PFDA, PFDoA, each one at 100 µg L-1, while nutrient solution without PFAS was added to the control group. The experiment lasted 8 days to avoid refilling with the nutrient solution. Chlorophyll fluorescence and gas exchange measurements were carried out on two fully expanded leaves of uniform size for all 50 plants before and after the PFAS exposure. The uptake of PFAS was determined in terms of depletion from the nutrient solution and accumulation in the plant tissues at the end of the experiment. PFAS were extracted from root and leaf samples with methanol using an accelerated solvent extraction system. The amount of PFAS in nutrient solution, roots and leaves samples was measured by LC-MS/MS. Hydraulic vulnerability curves were obtained from samples with a minimal length of 200 mm using the air injection method. The pressure in the chamber was gradually increased with steps of 0.5 MPa to reach a maximum of 4 MPa. PFAS were detected in all the nutrient solution samples at a lower concentration compared to the beginning of the experiment, indicating that they were partially absorbed by the plants but remained available throughout the experiment. All the PFAS were detected in both leaves and roots: short chain molecules were accumulated at higher concentration in the leaves, whereas long chain PFAS were more abundant in the roots, consistent with the previous literature. Phenotypical differences between control and treated plants were not observed. In PFAS-exposed plants, parameters related to both gas exchange and chlorophyll fluorescence were significantly altered with respect to the control plants. In particular, transpiration rate (E), net CO2 assimilation rate (A), stomatal conductance to water vapor (gsw), electron transport rate (ETR) and photosynthesis efficiency net of NPQ losses (Fv’/Fm’) were increased in treated plants, whereas vapor pressure deficit at leaf temperature (VPD) and non-photochemical quenching (NPQ) were decreased. An increased A and gsw could be interpreted as an increase in CO2 influx and a decreased water loss. However, there is no demonstrated evidence to consider the PFAS exposure as a stimulating effect on photosynthesis, since our experiments were carried out in hydroponics and water availability was not limiting. To evaluate possible effects on the xylem vulnerability to drought-induced embolism formation due to PFAS presence, we compared the values of the water potential at which 50% of hydraulic conductance is lost (P50) between control and treated plants. PFAS-exposed plants are characterized by a higher P50 value with respect to untreated plants and this reflects an increased susceptibility to xylem embolism under drought conditions. These results support the hypothesis that PFAS can adhere to inner walls of xylem conduits and to plant tissues, making them more hydrophobic. Although the driving force for water movement in plants is the low water potential established by stomatal opening, adhesion forces play a major role in preventing cavitation events. The reduction of adhesion forces provoked by PFAS increases the vulnerability to embolism and the stomatal conductanc

Perfluoroalkyl substances exposure alters stomatal opening and xylem hydraulics in willow plants

Climate change and pollution are increasingly important stress factors for life on Earth. Dispersal of poly- and perfluoroalkyl substances (PFAS) are causing worldwide contamination of soils and water tables. PFAS are partially hydrophobic and can easily bioaccumulate in living organisms, causing metabolic alterations. Different plant species can uptake large amounts of PFAS, but little is known about its consequences for the plant water relation and other physiological processes, especially in woody plants. In this study, we investigated the fractionation of PFAS bioaccumulation from roots to leaves and its effects on the conductive elements of willow plants. Additionally, we focused on the stomal opening and the phytohormonal content. For this purpose, willow cuttings were exposed to a mixture of 11 PFAS compounds and the uptake was evaluated by LC-MS/MS. Stomatal conductance was measured and the xylem vulnerability to air embolism was tested and further, the abscisic acid and salicylic acid content was quantified using LC-MS/MS. PFAS accumulated from roots to leaves based on their chemical structure. PFAS-exposed plants showed reduced stomatal conductance, while no differences were observed in abscisic acid and salicylic acid contents. Interestingly, PFAS exposure caused a higher vulnerability to drought-induced xylem embolism in treated plants. Our study provides novel information about the PFAS effects on the xylem hydraulics, suggesting that the plant water balance may be affected by PFAS exposure. In this perspective, drought events may be more stressful for PFAS-exposed plants, thus reducing their potential for phytoremediation

Effects of Soil Amendment With Wood Ash on Transpiration, Growth, and Metal Uptake in Two Contrasting Maize (Zea mays L.) Hybrids to Drought Tolerance

Wood ash as a soil amendment has gained wide spread acceptance in the recent years as a sustainable alternative to chemical fertilizers, although information regarding the effects of its application on maize growth and yield in the context of climate change and increasing drought severity is lacking till date. In the present study, field and pot trials were carried out at the experimental farm of the University of Padova at Legnaro (NE Italy) in a silty-loam soil in order to investigate the effects of soil amendment with wood ash (0.1% w/w, incorporated into the 0.2-m top soil) on the bioavailability of mineral elements and their uptake by maize. Characteristics analyzed included plant growth, leaf transpiration dynamics, and productivity in two contrasting hybrids, P1921 (drought sensitive) and D24 (drought tolerant). Wood ash contained relevant amounts of Ca, K, Mg, P, and S, and hazardous levels of Zn (732 mg kg 121), Pb (527 mg kg 121), and Cu (129 mg kg 121), although no significant changes in total soil element concentration, pH, and electrical conductivity were detected in open field. Ash application led to a general increasing trend of diethylene triamine penta-acetic acid (DTPA)-extractable of various elements, bringing to higher grain P in D24 hybrid, and Zn and Ni reductions in P1921 hybrid. Here, the results demonstrated that ash amendment enhanced shoot growth and the number of leaves, causing a reduction of harvest index, without affecting grain yield in both hybrids. The most relevant result was a retarded inhibition of leaf transpiration under artificial progressive water stress, particularly in the drought-tolerant D24 hybrid that could be sustained by root growth improvements in the field across the whole 0\u20131.5 m soil profile in D24, and in the amended top soil in P1921. It is concluded that woody ash can be profitably exploited in maize fertilization for enhancing shoot and root growth and drought tolerance, thanks to morphological and physiological improvements, although major benefits are expected to be achieved in drought tolerant hybrids. Attention should be payed when using ash derived by metal contaminated wood stocks to avoid any health risk in food uses

CfPDIP1, a novel secreted protein of Colletotrichum falcatum, elicits defense responses in sugarcane and triggers hypersensitive response in tobacco

Colletotrichum falcatum, a hemibiotrophic fungal pathogen, causes one of the major devastating diseases of sugarcane-red rot. C. falcatum secretes a plethora of molecular signatures that might play a crucial role during its interaction with sugarcane. Here, we report the purification and characterization of a novel secreted protein of C. falcatum that elicits defense responses in sugarcane and triggers hypersensitive response (HR) in tobacco. The novel protein purified from the culture filtrate of C. falcatum was identified by MALDI TOF/TOF MS and designated as C. falcatum plant defense-inducing protein 1 (CfPDIP1). Temporal transcriptional profiling showed that the level of CfPDIP1 expression was greater in incompatible interaction than the compatible interaction until 120 h post-inoculation (hpi). EffectorP, an in silico tool, has predicted CfPDIP1 as a potential effector. Functional characterization of full length and two other domain deletional variants (CfPDIP1ΔN1-21 and CfPDIP1ΔN1-45) of recombinant CfPDIP1 proteins has indicated that CfPDIP1ΔN1-21 variant elicited rapid alkalinization and induced a relatively higher production of hydrogen peroxide (H2O2) in sugarcane suspension culture. However, in Nicotiana tabacum, all the three forms of recombinant CfPDIP1 proteins triggered HR along with the induction of H2O2 production and callose deposition. Further characterization using detached leaf bioassay in sugarcane revealed that foliar priming with CfPDIP1∆1-21 has suppressed the extent of lesion development, even though the co-infiltration of CfPDIP1∆1-21 with C. falcatum on unprimed leaves increased the extent of lesion development than control. Besides, the foliar priming has induced systemic expression of major defense-related genes with the concomitant reduction of pathogen biomass and thereby suppression of red rot severity in sugarcane. Comprehensively, the results have suggested that the novel protein, CfPDIP1, has the potential to trigger a multitude of defense responses in sugarcane and tobacco upon priming and might play a potential role during plant-pathogen interactions

A proteomic and biochemical investigation on the effects of sulfadiazine in Arabidopsis thaliana

Animal manure or bio-solids used as fertilizers are the main routes of antibiotic exposure in the agricultural land, which can have immense detrimental e\ufb00ects on plants. Sulfadiazine (SDZ), belonging to the class of sulfonamides, is one of the most detected antibiotics in the agricultural soil. In this study, the e\ufb00ect of SDZ on the growth, changes in antioxidant metabolite content and enzyme activities related to oxidative stress were analysed. Moreover, the proteome alterations in Arabidopsis thaliana roots in response to SDZ was examined by means of a combined iTRAQ-LC-MS/MS quantitative proteomics approach. A dose-dependent decrease in leaf biomass and root length was evidenced in response to SDZ. Increased malondialdehyde content at higher concentration (2 \u3bcM) of SDZ indicated increased lipid peroxidation and suggest the induction of oxidative stress. Glutathione levels were signifcantly higher compared to control, whereas there was no increase in ascorbate content or the enzyme activities of glutathione metabolism, even at higher concentrations. In total, 48 di\ufb00erentially abundant proteins related to stress/stimuli response followed by transcription and translation, metabolism, transport and other functions were identifed. Several proteins related to oxidative, dehydration, salinity and heavy metal stresses were represented. Upregulation of peroxidases was validated with total peroxidase activity. Pathway analysis provided an indication of increased phenylpropanoid biosynthesis. Probable molecular mechanisms altered in response to SDZ are highlighted

Metabolic-GWAS provides insights into genetic architecture of seed metabolome in buckwheat

Abstract Background Buckwheat (Fagopyrum spp.), belonging to the Polygonaceae family, is an ancient pseudo-cereal with high nutritional and nutraceutical properties. Buckwheat proteins are gluten-free and show balanced amino acid and micronutrient profiles, with higher content of health-promoting bioactive flavonoids that make it a golden crop of the future. Plant metabolome is increasingly gaining importance as a crucial component to understand the connection between plant physiology and environment and as a potential link between the genome and phenome. However, the genetic architecture governing the metabolome and thus, the phenome is not well understood. Here, we aim to obtain a deeper insight into the genetic architecture of seed metabolome in buckwheat by integrating high throughput metabolomics and genotyping-by-sequencing applying an array of bioinformatics tools for data analysis. Results High throughput metabolomic analysis identified 24 metabolites in seed endosperm of 130 diverse buckwheat genotypes. The genotyping-by-sequencing (GBS) of these genotypes revealed 3,728,028 SNPs. The Genome Association and Prediction Integrated Tool (GAPIT) assisted in the identification of 27 SNPs/QTLs linked to 18 metabolites. Candidate genes were identified near 100 Kb of QTLs, providing insights into several metabolic and biosynthetic pathways. Conclusions We established the metabolome inventory of 130 germplasm lines of buckwheat, identified QTLs through marker trait association and positions of potential candidate genes. This will pave the way for future dissection of complex economic traits in buckwheat