Pea Tissue Research Articles

Role of organic and inorganic amendments on physiological attributes of germinating pea seedlings under arsenic stress

There are scarce data regarding the effects of soil amendments on biophysicochemical responses of plants at the early stages of growth/germination. This study critically compares the effects of ethylene-diamine-tetra-acetic-acid (EDTA) and calcium (Ca) on biophysicochemical responses of germinating pea seedlings under varied arsenic levels (As, 25, 125, 250 µM). Arsenic alone enhanced hydrogen peroxide (H2O2) level in pea roots (176%) and shoot (89%), which significantly reduced seed germination percentage, pigment contents, and growth parameters. Presence of EDTA and Ca in growth culture minimized the toxic effects of As on pea seedlings, EDTA being more pertinent than Ca. Both the amendments decreased H2O2 levels in pea tissues (16% in shoot and 13% in roots by EDTA, and 7% by Ca in shoot), and maintained seed germination, pigment contents, and growth parameters of peas close to those of the control treatment. The effects of all As-treatments were more pronounced in the pea roots than in the shoot. The presence of organic and inorganic amendments can play a useful role in alleviating As toxicity at the early stages of pea growth. The scarcity of data demands comparing plant biophysicochemical responses at different stages of plant growth (germinating vs mature) in future studies.

Negotiating authenticity and biodiversity in heritage gardens

With this paper we explore and discuss the priorities of and possible goal conflicts between authenticity and climate change in heritage gardens. How can climate change mitigation, adaptation, resilience, and cultural heritage conservation be combined in heritage gardens? Our study was guided by the following research question: How do gardeners negotiate climate change and authenticity in heritage gardens? From Rachel Carson's Silent Spring in the 1960s through to the 2002 report Gardening in the Global Greenhouse and the recent Gardening in a Changing World in 2022 mankind's impact on the environ­ment and the emerging climate change has been the focus of increasing attention. By invest­i­gat­ing and interviewing multiple gardeners our objective was to pinpoint common challenges, as well as what can be learned from one another within the field of gardening and heritage conservation. The case study method was adopted for this study, involving three head gardeners in the United Kingdom. Interviews were conducted with Joseph Atkin at Aberglasney Gardens, Claire Greenslade at Hestercombe Gardens, and Steve Lannin at Iford Manor about their expertise and knowledge. The gardeners expressed concern re­garding climate change and the challenges it poses. The interviewees shared their experience with drought, reduced use of pesticides and herbicides, and the peat legislation in relation to their role as head gardeners. We argue that authenticity and the traditional gardening practised before the advent of power tools, plastic, peat issues, and uninformed transportation can be part of the solution to loss of bio­diversity and climate change. This paper identifies some of the obstacles encountered in relation to negotiating questions of authenticity and climate change in heritage gardens.

Under cadmium stress, silicon has a defensive effect on the morphology, physiology, and anatomy of pea (Pisum sativum L.) plants.

Soil pollution with cadmium (Cd) is a serious threat to plant growth and development. On the other hand, silicon (Si) can support plants to cope with Cd stress. However, the Cd stress mitigating impact of Si reduction in pea (Pisum sativum L.) is not known. The objective of this study is to see if and how Si can reduce Cd toxicity. To the end, a greenhouse pot experiment was performed twice during the 2018/2019 and 2019/2020 seasons to investigate the effect of Si on the growth, anatomy, and biochemistry of Cd stressed peas plants. Cd exposure increased the contents of Cd ions in the root and shoot of pea plants. Consequentially, Cd accumulation in pea tissue significantly reduced plant growth i.e., plant height, leaf area, and shoot and root dry weights. The effect of Cd was concentration-dependent, where at low concentration (50 mg/kg soil), the plant height was 94.33 and 97.33cm and at high concentration (100 mg/kg soil), it was 89.0 and 91.0cm in the two seasons, respectively. This growth reduction can be explained by the decrease in plants' photosynthesis, whereas plants exposed to Cd toxicity had lower chlorophyll levels. At the anatomy level, high Cd concentrations resulted in anatomical abnormalities such as an unusual vascular system, abnormal lignification in the pith parenchyma, and enlarged cortical cells. Moreover, all Cd concentrations resulted in a highly significant decrease in stomatal area and stomatal density (the number of stomata per mm2). In addition to growth inhibition, Cd-induced oxidative damage to pea plants as indicated by increased hydrogen peroxide (H2O2) and Malondialdehyde (MDA) levels. To reduce stress toxicity, plants treated with Cd at 50 and 100 (mg/kg) showed a significant increase in antioxidant capacity. Peroxidase (POD) enzyme activity was significantly increased by 41.26%, 28.64%, 77.05%, and 60.77% in both seasons, respectively. Si at 300 ppm under Cd (100 mg/kg) stress conductions considerably reduced (MDA) contents by 29.02% and 29.12%, in the two seasons, respectively. The findings pointed out that Si's ability to protect pea against the oxidative stress caused by Cd toxicity.

Bioavailability, Speciation, and Crop Responses to Copper, Zinc, and Boron Fertilization in South-Central Saskatchewan Soil

An appropriate fertilization strategy is essential for improving micronutrient supply, crop nutrition, yield and quality. Comparative effects of different application strategies of micronutrient fertilizer were evaluated in two contrasting sites/soils (upper slope Chernozem and lower slope Solonetz) within a farm field located in the Brown soil zone of Saskatchewan, Canada. The study objective was to examine the impact of Cu, Zn, and B fertilizer application strategies on their mobility, bioavailability and fate in the soil as well as crop yield responses. The application strategies were broadcast, broadcast and incorporation, seed row banding, and foliar application of Cu, Zn, and B on wheat, pea, and canola, respectively. The study was laid out in a randomized complete block design (RCBD) with four treatment replicates for a specific crop and site. Crop biomass yields were not significantly influenced by micronutrient placement strategies at both sites. Pea tissue Zn concentration (35.2 mg Zn kg−1 grain and 5.15 mg Zn kg−1 straw) was increased by broadcast and incorporation of Zn sulfate on the Solonetz soil. Residual levels of soil extractable available Cu were increased significantly to 3.18 mg Cu kg−1 soil at Chernozem and 2.53 mg Cu kg−1 soil Solonetz site with the seed row banding of Cu sulfate. The PRS™-probe supply of Cu (1.84 µm Cu/cm2) and Zn (1.18 µm Zn/cm2) were significantly higher with broadcast application of corresponding micronutrient fertilizer in the Chernozem soil. Both the chemical and spectroscopic speciation revealed that carbonate associated Cu and Zn were dominant species that are likely to control the bioavailability of these micronutrients under field conditions.

Inorganic Nitrogen Transport and Assimilation in Pea (Pisum sativum).

The genome sequences of several legume species are now available allowing the comparison of the nitrogen (N) transporter inventories with non-legume species. A survey of the genes encoding inorganic N transporters and the sensing and assimilatory families in pea, revealed similar numbers of genes encoding the primary N assimilatory enzymes to those in other types of plants. Interestingly, we find that pea and Medicago truncatula have fewer members of the NRT2 nitrate transporter family. We suggest that this difference may result from a decreased dependency on soil nitrate acquisition, as legumes have the capacity to derive N from a symbiotic relationship with diazotrophs. Comparison with M. truncatula, indicates that only one of three NRT2s in pea is likely to be functional, possibly indicating less N uptake before nodule formation and N-fixation starts. Pea seeds are large, containing generous amounts of N-rich storage proteins providing a reserve that helps seedling establishment and this may also explain why fewer high affinity nitrate transporters are required. The capacity for nitrate accumulation in the vacuole is another component of assimilation, as it can provide a storage reservoir that supplies the plant when soil N is depleted. Comparing published pea tissue nitrate concentrations with other plants, we find that there is less accumulation of nitrate, even in non-nodulated plants, and that suggests a lower capacity for vacuolar storage. The long-distance transported form of organic N in the phloem is known to be specialized in legumes, with increased amounts of organic N molecules transported, like ureides, allantoin, asparagine and amides in pea. We suggest that, in general, the lower tissue and phloem nitrate levels compared with non-legumes may also result in less requirement for high affinity nitrate transporters. The pattern of N transporter and assimilatory enzyme distribution in pea is discussed and compared with non-legumes with the aim of identifying future breeding targets.

Optimization of Processing Technology of Plant-Based Sausage by Response Surface Methodology

This study utilized pea protein isolate, pea tissue protein and gluten as the main protein materials in the production of plant-based sausage. Textural properties, cooking loss, and sensory evaluation were analyzed to determine the protein formula of the sausage. On the basis of single factor experiment, Box-Behnken response surface test was used to optimize the formula of plant-based sausage. Results showed that the sausage composed of 19.19% pea protein isolate, 9.83% tissue protein and 7.13% gluten powder was the best. Under these conditions, the sensory score of sausage was 81.20, which was close to the predicted value of 80.11. The chewiness was 4791.2 g·s, which was close to the predicted value of 4767.09 g·s.The optimized plant-based sausage has hardness of 6245.11 g, cohesion of 0.83, recovery of 0.51% and cooking loss rate of 2.72%, compared with the commercially available plant-based sausage, the cooking loss rate was lower, the cohesiveness and resilience were better, and the hardness was within the hardness range of commercially available sausage. This study would provide guidance for the development of plant-based products and related industrial production.

Isolation and Characterization of Rhodococcus spp. from Pistachio and Almond Rootstocks and Trees in Tunisia

The purpose of this study was to isolate and identify Rhodococcus spp. strains from almond and pistachio rootstocks and trees in Tunisia. Twenty-eight strains were identified through 16S rDNA and vicA genes amplification and sequencing. Pea bioassay was performed to determine the pathogenicity of the strains. Representative 16S rDNA and vicA sequences of eight strains from pistachio and seven strains from almond were closely related (>98% similarity) to Rhodococcus spp. accessions in GenBank. Phylogenetic analysis based on 16S rDNA sequences revealed that the yellow-colored strains clustered with phytopathogenic Rhodococcusfascians. The red and orange-colored strains were separated into a different group with R. kroppenstedtii and R. corynebacteiroides isolates. Eleven strains affected the pea seedlings’ growth and exhibited different levels of virulence. The number of shoots was significantly higher in seedlings inoculated with four Rhodococcus strains, whereas the other three strains caused up to 80% of plant height reduction and reduced root secondary growth compared to non-inoculated pea seedlings. These strains, most of which are epiphytes from asymptomatic hosts, showed strong pathogenicity during pea bioassay and were established endophytically in pea tissues. Ten att and five fas genes were detected in four strains and may represent a novel model of plant pathogenic Rhodococcus virulence. The results of our survey showed that Rhodococcus is present but not prevalent in all visited orchards of almond and pistachio rootstocks and trees. Our surveys complemented the investments being made on ornamental species in Tunisia and unveiled the presence of undocumented plant-associated Rhodococcus spp. on economically important crops.

Nonhost Disease Resistance in Pea: Chitosan's Suggested Role in DNA Minor Groove Actions Relative to Phytoalexin-Eliciting Anti-Cancer Compounds.

A stable intense resistance called “nonhost resistance” generates a complete multiple-gene resistance against plant pathogenic species that are not pathogens of pea such as the bean pathogen, Fusarium solani f. sp. phaseoli (Fsph). Chitosan is a natural nonhost resistance response gene activator of defense responses in peas. Chitosan may share with cancer-treatment compounds, netropsin and some anti-cancer drugs, a DNA minor groove target in plant host tissue. The chitosan heptamer and netropsin have the appropriate size and charge to reside in the DNA minor groove. The localization of a percentage of administered radio-labeled chitosan in the nucleus of plant tissue in vivo indicates its potential to transport to site(s) within the nuclear chromatin (1,2). Other minor groove-localizing compounds administered to pea tissue activate the same secondary plant pathway that terminates in the production of the anti-fungal isoflavonoid, pisatin an indicator of the generated resistance response. Some DNA minor groove compounds also induce defense genes designated as “pathogenesis-related” (PR) genes. Hypothetically, DNA targeting components alter host DNA in a manner enabling the transcription of defense genes previously silenced or minimally expressed. Defense-response-elicitors can directly (a) target host DNA at the site of transcription or (b) act by a series of cascading events beginning at the cell membrane and indirectly influence transcription. A single defense response, pisatin induction, induced by chitosan and compounds with known DNA minor groove attachment potential was followed herein. A hypothesis is formulated suggesting that this DNA target may be accountable for a portion of the defense response generated in nonhost resistance.

Insecticidal diversity of butterfly pea (Clitoria ternatea) accessions

Butterfly pea (Clitoria ternatea) is currently the only leguminous plant species known to produce a suite of ultrastable cyclic plant defense peptides called cyclotides. For agricultural applications, cyclotides have attracted significant interest, leading to the recent registration of a butterfly pea extract as an ecofriendly pesticide (Sero-X®). In this study, we set out to distinguish the variation in cyclotide expression and toxicity towards insect cells for butterfly pea accessions sourced worldwide. In characterizing the peptide extracts from 23 butterfly pea accessions sourced from 11 countries, we show that significant variation in cyclotide expression exists between them. For some accessions, the cyclotide Cter M, typically the most abundantly expressed cyclotide in vegetative butterfly pea tissues, is absent. Genomic and transcriptomic sequencing revealed the presence of CterM-like precursor genes in these accessions that contained missense mutations that were likely contributing to the lack of Cter M expression. Peptide profiling also showed that one accession does not produce detectable levels of other cyclotides: cliotide T1, cliotide T4, Cter A and Cter Q. A comparison of cytotoxicity against Sf9 (Spodoptera frugiperda) cells revealed that cytotoxicity is not dependent on Cter M, with accessions lacking this peptide also displaying cytotoxicity. Overall, insights from this study provides foundational knowledge about characters to be considered for selective breeding of butterfly pea with enhanced insecticidal properties.

Linking a rapid throughput plate-assay with high-sensitivity stable-isotope label LCMS quantification permits the identification and characterisation of low \u03b2-L-ODAP grass pea lines

BackgroundGrass pea (Lathyrus sativus) is an underutilised crop with high tolerance to drought and flooding stress and potential for maintaining food and nutritional security in the face of climate change. The presence of the neurotoxin β-L-oxalyl-2,3-diaminopropionic acid (β-L-ODAP) in tissues of the plant has limited its adoption as a staple crop. To assist in the detection of material with very low neurotoxin toxin levels, we have developed two novel methods to assay ODAP. The first, a version of a widely used spectrophotometric assay, modified for increased throughput, permits rapid screening of large populations of germplasm for low toxin lines and the second is a novel, mass spectrometric procedure to detect very small quantities of ODAP for research purposes and characterisation of new varieties.ResultsA plate assay, based on an established spectrophotometric method enabling high-throughput ODAP measurements, is described. In addition, we describe a novel liquid chromatography mass spectrometry (LCMS)-based method for β-L-ODAP-quantification. This method utilises an internal standard (di-13C-labelled β-L-ODAP) allowing accurate quantification of β-L-ODAP in grass pea tissue samples. The synthesis of this standard is also described. The two methods are compared; the spectrophotometric assay lacked sensitivity and detected ODAP-like absorbance in chickpea and pea whereas the LCMS method did not detect any β-L-ODAP in these species. The LCMS method was also used to quantify β-L-ODAP accurately in different tissues of grass pea.ConclusionsThe plate-based spectrophotometric assay allows quantification of total ODAP in large numbers of samples, but its low sensitivity and inability to differentiate α- and β-L-ODAP limit its usefulness for accurate quantification in low-ODAP samples. Coupled to the use of a stable isotope internal standard with LCMS that allows accurate quantification of β-L-ODAP in grass pea samples with high sensitivity, these methods permit the identification and characterisation of grass pea lines with a very low ODAP content. The LCMS method is offered as a new ‘gold standard’ for β-L-ODAP quantification, especially for the validation of existing and novel low- and/or zero-β-L-ODAP genotypes.

Metabolomics Approach To Understand Mechanisms of β-N-Oxalyl-l-α,β-diaminopropionic Acid (β-ODAP) Biosynthesis in Grass Pea (Lathyrus sativus L.).

A study was performed to identify metabolic processes associated with β-ODAP synthesis in grass pea using a metabolomics approach. GC-MS metabolomics was performed on seedlings at 2, 6, and 25 days after sowing. A total of 141 metabolites were detected among the three time points representing much of grass pea primary metabolism, including amino acids, carbohydrates, purines, and others. Principal component analysis revealed unique metabolite profiles of grass pea tissues among the three time points. Fold change, hierarchical clustering, and orthogonal projections to latent structures-discriminant analyses, and biochemical pathway ontologies were used to characterize covariance of metabolites with β-ODAP content. The data indicates that alanine and nitrogen metabolism, cysteine and sulfur metabolism, and purine, pyrimidine, and pyridine metabolism were associated with β-ODAP metabolism. Our results reveal the metabolite profiles in grass pea development and provide insights into mechanisms of β-ODAP accumulation and degradation.

Heat stress differentially modifies ethylene biosynthesis and signaling in pea floral and fruit tissues.

Ethylene biosynthesis is regulated in reproductive tissues in response to heat stress in a manner to optimize resource allocation to pollinated fruits with developing seeds. High temperatures during reproductive development are particularly detrimental to crop fruit/seed production. Ethylene plays vital roles in plant development and abiotic stress responses; however, little is known about ethylene's role in reproductive tissues during development under heat stress. We assessed ethylene biosynthesis and signaling regulation within the reproductive and associated tissues of pea during the developmental phase that sets the stage for fruit-set and seed development under normal and heat-stress conditions. The transcript abundance profiles of PsACS [encode enzymes that convert S-adenosyl-L-methionine to 1-aminocyclopropane-1-carboxylic acid (ACC)] and PsACO (encode enzymes that convert ACC to ethylene), and ethylene evolution were developmentally, environmentally, and tissue-specifically regulated in the floral/fruit/pedicel tissues of pea. Higher transcript abundance of PsACS and PsACO in the ovaries, and PsACO in the pedicels was correlated with higher ethylene evolution and ovary senescence and pedicel abscission in fruits that were not pollinated under control temperature conditions. Under heat-stress conditions, up-regulation of ethylene biosynthesis gene expression in pre-pollinated ovaries was also associated with higher ethylene evolution and lower retention of these fruits. Following successful pollination and ovule fertilization, heat-stress modified PsACS and PsACO transcript profiles in a manner that suppressed ovary ethylene evolution. The normal ethylene burst in the stigma/style and petals following pollination was also suppressed by heat-stress. Transcript abundance profiles of ethylene receptor and signaling-related genes acted as qualitative markers of tissue ethylene signaling events. These data support the hypothesis that ethylene biosynthesis is regulated in reproductive tissues in response to heat stress to modulate resource allocation dynamics.

Non-host Resistance: DNA Damage Is Associated with SA Signaling for Induction of PR Genes and Contributes to the Growth Suppression of a Pea Pathogen on Pea Endocarp Tissue.

Salicylic acid (SA) has been reported to induce plant defense responses. The transcriptions of defense genes that are responsible for a given plant’s resistance to an array of plant pathogens are activated in a process called non-host resistance. Biotic signals capable of carrying out the activation of pathogenesis-related (PR) genes in pea tissue include fungal DNase and chitosan, two components released from Fusarium solani spores that are known to target host DNA. Recent reports indicate that SA also has a physical affinity for DNA. Here, we report that SA-induced reactive oxygen species release results in fragment alterations in pea nuclear DNA and cytologically detectable diameter and structural changes in the pea host nuclei. Additionally, we examine the subsequent SA-related increase of resistance to the true pea pathogen F. solani f.sp. pisi and the accumulation of the phytoalexin pisatin. This is the first report showing that SA-induced PR gene activation may be attributed to the host pea genomic DNA damage and that at certain concentrations, SA can be temporally associated with subsequent increases in the defense response of this legume.

Nonhost resistance: Reactive oxygen species (ROS) signal causes DNA damage prior to the induction of PR genes and disease resistance in pea tissue

The defense gene activations that provide non-host disease resistance in plants are signaled by various elicitors. A number of the fungal-derived signal such as chitosan and DNase are uniquely able to promote transcription through direct effects on the DNA of pea chromatin at sites of defense gene transcription. Other biological signals are contained within the reactive oxygen species (ROS) and make substantial changes in DNA in other tissues. The current research probes the ROS elicitor concentrations and the conditions within pea endocarp nuclear material temporally associated with the activation of pathogenesis-related (PR) genes. Within 10 min, ROS accumulate in response to a bean pathogen Fusarium solani f.sp. phaseoli (Fsph) to levels 4-fold those elicited by the pea pathogen Fusarium solani f.sp. pisi (Fspi). Application of Hydrogen peroxide (H2O2) (HP) increases DNA fragmentation and activates the PR genes (DRR206, defensin, PR10, and PR1b) within 50 min and changes the nuclear diameters of the pea host cells in 3 h. Increased levels of the phytoalexin, pisatin and the growth suppression of the pea pathogen, Fspi, were observed within 24 h after H2O2 treatment to the endocarp. Our results suggest that H2O2 contributes to the induction of the defense response in pea endocarp tissue, which is likely mediated by activation of DNA damage responses.

Cloning and biochemical characterization of indole-3-acetic acid-amino acid synthetase PsGH3 from pea

Phytohormone conjugation is one of the mechanisms that maintains a proper hormonal homeostasis and that is necessary for the realization of physiological responses. Gretchen Hagen 3 (GH3) acyl acid amido synthetases convert indole-3-acetic acid (IAA) to IAA-amino acid conjugates by ATP-dependent reactions. IAA-aspartate (IAA-Asp) exists as a predominant amide conjugate of auxin in pea tissues and acts as an intermediate during IAA catabolism. Here we report a novel recombinant indole-3-acetic acid-amido synthetase in Pisum sativum. In silico analysis shows that amino acid sequence of PsGH3 has the highest homology to Medicago truncatula GH3.3. The recombinant His-tag-PsGH3 fusion protein has been obtained in E. coli cells and is a soluble monomeric polypeptide with molecular mass of 69.18 kDa. The PsGH3 was purified using Ni2+-affinity chromatography and native PAGE. Kinetic analysis indicates that the enzyme strongly prefers IAA and L-aspartate as substrates for conjugation revealing KmATP = 0.49 mM, KmL−Asp = 2.2 mM, and KmIAA = 0.28 mM. Diadenosine pentaphosphate (Ap5A) competes with ATP for catalytic site and diminishes the PsGH3 affinity toward ATP approximately 1.11-fold indicating Ki = 8.5 μM. L-Tryptophan acts as an inhibitor of IAA-amido synthesizing activity by competition with L-aspartate. Inorganic pyrophosphatase (PPase) hydrolyzing pyrophosphate to two phosphate ions, potentiates IAA-Asp synthetase activity of PsGH3. Our results demonstrate that PsGH3 is a novel enzyme that is involved in auxin metabolism in pea seeds.

A Simple and efficient protocol for isolation of RNA from different tissues of chickpea and pea

A simple and efficient protocol is developed for isolation of high quality RNA from roots and leaves of chickpea and pea. The procedure is based on use of SDS, sodium acetate and EDTA in an extraction buffer in order to eliminate polysaccharides and prevent oxidation of phenolic compounds. The current method is modification of a method described for RNA isolation from pea leaves only, and yields excess amount of high-quality RNA suitable for cDNA based gene expression analysis. The protocol requires only three disposable micro centrifuge tubes during extraction, single phenol extraction step and a single precipitation step to yield high-quality RNA. RNA extracted with this method was free from protein and phenolic contaminants as evident from gel electrophoresis analysis. This method is applicable not only for leaves but also for roots and shoots and equally applicable to both chickpea and pea. cDNA is prepared and PCR amplification have been done with universal ubiqutin primer to check the integrity of RNA and absence of inhibitory compounds in RNA samples, which proves the suitability of samples towards qRTPCR.

The auxin conjugate indole-3-acetyl-aspartate affects responses to cadmium and salt stress in Pisum sativum L.

The synthesis of IAA-amino acid conjugates is one of the crucial regulatory mechanisms for the control of auxin activity during physiological and pathophysiological responses. Indole-3-acetyl-aspartate (IAA-Asp) is a low molecular weight amide conjugate that predominates in pea (Pisum sativum L.) tissues. IAA-Asp acts as an intermediate during the auxin degradation pathway. However, some recent investigations suggest a direct signaling function of this conjugate in various processes. In this study, we examine the effect of 100μM IAA-Asp alone and in combination with salt stress (160mM NaCl) or heavy metal stress (250μM CdCl2) on H2O2 concentration, protein carbonylation as well as catalase and ascorbate (APX) and guaiacol peroxidase (GPX) activities in 7-day-old pea seedlings. As revealed by spectrophotometric analyses, IAA-Asp increased the carbonylated protein level and reduced the H2O2 concentration. Moreover, IAA-aspartate potentiated the effect of both Cd2+ ions and NaCl on the H2O2 level. The enzymatic activities (catalase and peroxidases) were examined using spectrophotometric and native-PAGE assays. IAA-Asp alone did not affect catalase activity, whereas the two peroxidases were regulated differently. IAA-Asp reduced the APX activity during 48h cultivation. APX activity was potentiated by IAA-Asp+NaCl after 48h. Guaiacol peroxidase activity was diminished by all tested compounds. Based on these results, we suggest that IAA-Asp can directly and specifically affect the pea responses to abiotic stress.

Nonhost resistance: Self-inflicted DNA damage by fungal DNase accumulation is a major factor in terminating fungal growth in the pea-Fusarium solani f.sp. phaseoli interaction

Pea endocarp tissue generates a total nonhost resistance response against inappropriate pathogens such as the bean pathogen, Fusarium solani f. sp. phaseoli (Fsph) within 6 h. An array of plant components induced include: Pisatin (a phytoalexin), defensins, PR genes and hydrolytic enzymes in the non-host resistance response. This nonhost resistance response is similar but swifter than the responses induced by the compatible true pathogen, F. solani f. sp. pisi (Fspi). It was previously noted that a DNase released by both fungi is involved in induction of these resistance responses within pea endocarp tissue. This report demonstrates the cytological damage that occurs within nuclear DNA of both compatible and incompatible fungi when in contact with pea endocarp tissue and in the presence of DNase activity. The severity of damage to the bean pathogen exceeds that of the pea pathogen and requires only 2 h of contact with the pea tissue to develop. This accumulation of DNA damage is proposed to be the ultimate termination factor in this and other non-host resistance reactions. An updated DNase signaling scheme of the nonhost resistance of pea is presented.

Impact of cold atmospheric pressure plasma on physiology and flavonol glycoside profile of peas (Pisum sativum ‘Salamanca’)

Application of plasma is well-established in various industrial processes; its use has also been suggested as an innovative technology in the food sector. Besides the ability to inactivate undesirable microorganisms on heat-sensitive foods, cold atmospheric pressure plasma (CAPP) may also modify and intensify the secondary metabolism in agricultural plant produces along the whole value-added chain. This is because CAPP provides a source of reactive oxygen and nitrogen species and specific UV radiation.The objective of this study was to determine the effects of CAPP treatment on the flavonol glycoside profile of pea seedlings (Pisum sativum ‘Salamanca’), while considering the potential impact on their metabolic activity in different growth stages. Pea seeds, sprouts, and seedlings were exposed to semi-direct CAPP using a dielectric barrier discharge device with air as the process gas. Applying voltages between 6 and 12kVpp at a frequency of 3.0kHz resulted in optical emission spectra dominated by UV-B and UV-C radiation. The specific energy densities were monitored upon varying voltages and treatment times.Exposing swollen pea seeds to plasma (9kVpp) between 1 and 10min increased germination rate and dry matter content but decreased growth rate. Non-acylated and monoacylated triglycosides of quercetin and kaempferol dominated the flavonol glycoside profile, quercetin-3-O-p-coumaroyl-triglucoside being the main flavonoid glycoside. In 15d-old pea seedlings, the concentration of flavonoid glycosides was dose-dependently decreased after two CAPP treatments compared to none or three treatments. Furthermore, photosynthetic efficiency of treated pea sprouts and seedlings declined potentially indicating a negative effect of CAPP treatment on plant metabolism. The responses of pea tissues greatly depended on time point and duration of CAPP treatments. This study represents a first step towards the implementation of the CAPP technology for a targeted modification of valuable secondary plant metabolites during post-harvest chain of agricultural produces.

Potential of high isostatic pressure and pulsed electric fields to improve mass transport in pea tissue

The aim of this study was to investigate and evaluate the potential of high isostatic pressure (HP) and pulsed electric fields (PEF) for implementation in innovative legume processing concepts. Whole peas were subjected to HP (400MPa, 40°C, 10min) and PEF (5kVcm−1, 125kJkg−1) treatments. The impact on the pea tissue was assessed by means of microscopic changes, release of protein and oligosaccharides during treatment and rate of subsequent drying and rehydration steps. HP and PEF resulted in altered cell wall structures and improved mass transport in comparison to the control samples (20°C, 10min). Effects on the extent of diffusion depended on the molecular size of the cell compounds. More than 10% of raffinose equivalent sugars were removed during treatments while preserving more than 99.9% of nutritionally valuable protein. Hence, both emerging technologies may be implemented in pea processing for a targeted reduction of flatulence causing oligosaccharides. The drying and rehydration rates of whole peas were increased to a higher extent by HP and PEF than by conventional thermal treatments (80°C, 10min). These innovative pre-treatments may therefore be applied to enhance the efficiency of industrial mass transfer processes or to decrease the preparation time of meals with whole dried peas and thus increase the flexibility for the consumer.