Phenylalanine Ammonia-lyase Activity Research Articles

Melatonin mediates phenolic acids accumulation in barley sprouts under MeJA stress.

Phenolic acids are secondary metabolites in higher plants, with antioxidant, anticancer, and anti-aging effects on the human body. Therefore, foods rich in phenolic acids are popular. Methyl jasmonate (MeJA) promoted phenolic acids accumulation but also inhibited sprout growth. Melatonin (MT) was a new type of plant hormone that not only alleviated plants' abiotic stress, but also promoted the synthesis of plant-stimulating metabolism. This study aimed to elucidate the mechanism of exogenous MT on the growth and development, and phenolic acids metabolism of barley sprouts under MeJA treatment. The results showed that MT increased the phenolic acids content in sprouts by increasing the activities of phenylalanine ammonia-lyase and cinnamic acid 4-hydroxylase, and up-regulating the gene expression of phenylalanine ammonia-lyase, cinnamic acid 4-hydroxylase, 4-coumarate: coenzyme a ligase, and ferulic acid-5-hydroxylase. MT attenuated the growth inhibition of barley sprouts under MeJA stress by increasing the activities of regulated antioxidant enzymes and the expression of their corresponding genes. Furthermore, MT increased the NO content and induced Ca2+ burst in barley sprouts under MeJA stress. These events were inhibited by DL-4-Chlorophenylalanine. These results suggested that MT ameliorated growth inhibition and promoted the biosynthesis of phenolic acids in barley sprouts under MeJA stress.

Effect of Chitosan/Gum Arabic Blends Enriched by Sodium Nitroprusside or Methyl Salicylate on the Storability and Antioxidant Activity of Tomato Fruit.

The impact of methyl salicylate (MeSA) or sodium nitroprusside (SNP) in chitosan (CS)/Gum Arabic (GA) mixture on physio-chemical characteristics and antioxidant status during the postharvest ripening of green tomato fruits was studied. CS/GA-MeSA at a 1 mM formulation was the best treatment to retard firmness and titratable acidity (TA) losses. Moreover, this formulation retarded pigmentation progress where it had the lowest significant values of total carotenes (TCs) and lycopene (LYP) contents until the 15th day of the storage period, as well as efficiently faced the rise in malondialdehyde (MDA) levels. Moreover, peroxidase (POD), polyphenol oxidase (PPO), catalase (CAT), and phenylalanine ammonia-lyase (PAL) activities of tomatoes treated with CS/GA-SNP at 2 mM were significantly better than that of control in the primary stages of storage. CS/GA-SNP at a 2 mM formulation showed an extremely high significant content of total polyphenol (TP) in the early stage of storage, while CS/GA and CS/GA-MeSA at 1 and 2 mM accumulated higher significant TP contents than uncoated fruits at the late stage of storage. All formulations were characterized by FTIR spectroscopy. Furthermore, the polymer formulations exhibited strong antifungal activity against Alternaria alternata and Botrytis cinerea as major pathogens of postharvest tomatoes. Transmission electron microscope (TEM) observations for the mycelia of both fungi treated by CS/GA-MeSA at 2 mM revealed serious ultrastructural damage, including distortion of the cell wall and cell membrane and degradation of cytoplasmic organelles.

Physiological and molecular mechanism of Populus pseudo-cathayana × Populus deltoides response to Hyphantria cunea

Populus pseudo-cathayana × Populus deltoides is a crucial artificial forest tree species in Northeast China. The presence of the fall webworm (Hyphantria cunea) poses a significant threat to these poplar trees, causing substantial economic and ecological damage. This study conducted an insect-feeding experiment with fall webworm on P. pseudo-cathayana × P. deltoides, examining poplar's physiological indicators, transcriptome, and metabolome under different lengths of feeding times. Results revealed significant differences in phenylalanine ammonia-lyase activity, total phenolic content, and flavonoids at different feeding durations. Transcriptomic analysis identified numerous differentially expressed genes, including AP2/ERF, MYB, and WRKY transcription factor families exhibiting the highest expression variations. Differential metabolite analysis highlighted flavonoids and phenolic acid compounds of poplar's leaves as the most abundant in our insect-feeding experiment. Enrichment analysis revealed significant enrichment in the plant hormone signal transduction and flavonoid biosynthetic pathways. The contents of jasmonic acid and jasmonoyl-L-isoleucine increased with prolonged fall webworm feeding. Furthermore, the accumulation of dihydrokaempferol, catechin, kaempferol, and naringenin in the flavonoid biosynthesis pathway varied significantly among different samples, suggesting their crucial role in response to pest infestation. These findings provide novel insights into how poplar responds to fall webworm infestation.

Effects of UVA on Flavonol Accumulation in Ginkgo biloba

Ginkgo is an economic tree species with high medicinal value, and flavonols are its main medicinal components. This research was conducted to investigate the molecular mechanism underlying the influence of Ultraviolet A (UVA) treatment on the synthesis of ginkgo flavonols with the aim of increasing their content. Ginkgo full-sib hybrid offspring were used as test materials. The phenylalanine ammonialyase (PAL), cinnamate 4-hydroxylase (C4H), and 4-coumarate: CoA ligase (4CL) enzyme activities, as well as flavonol contents, were measured under the same intensity of white light (300 μmol·m−2·s−1) with the addition of 20, 40, and 60 μmol·m−2·s−1 UVA separately after 20 days of treatment. The control check (CK) and treatment with the highest flavonol content were chosen for transcriptome sequencing analysis. The results showed that the PAL, C4H, and 4CL enzyme activities, as well as the flavonol and totalflavonol glycoside contents, of ginkgo hybrid progeny differed significantly under different UVA treatments. They showed a tendency to increase and then decrease, reaching a maximum value under UVA-4 (40 μmol·m−2·s−1 ultraviolet UVA light intensity) treatment. Ribonucleic acid (RNA) sequencing revealed the presence of 4165 genes with differential expression, and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis revealed that the metabolic pathways commonly enriched across all four comparison groups included ‘phenylpropanoid biosynthesis’, while the pathways commonly enriched in green-leaf ginkgo UVA-4 treatment (TL), yellow-leaf ginkgo mutant CK treatment (CKY), and green-leaf ginkgo CK treatment (CKL) were related to ‘flavonoid biosynthesis’. Treatment with UVA light led to the increased expression of PAL and 4CL enzymes in the phenylpropanoid biosynthesis pathway, as well as increased expression of chalcone synthase (CHS), Flavanone 3-hydroxylase (F3H), and flavonol synthase (FLS) enzymes in the flavonoid biosynthesis pathway, thereby promoting the synthesis of ginkgo flavonols. In summary, the use of 40 μmol·m−2·s−1 UVA treatment for 20 days significantly increased the flavonol content and the expression of related enzyme genes in ginkgo hybrid offspring, enhancing ginkgo flavonoids and increasing the medicinal value of ginkgo.

Nitrogen and Silicon Contribute to Wheat Defense's to Pyrenophora tritici-repentis, but in an Independent Manner.

Nitrogen (N) and silicon (Si) are mineral elements that have shown a reduction in the damage caused by tan spot (Pyrenophora tritici-repentis (Ptr)) in wheat. However, the effects of these elements were studied separately, and the N and Si interaction effect on wheat resistance to tan spot remains elusive. Histocytological and biochemical defense responses against Ptr in wheat leaves treated with Si (+Si) at low (LN) and high N (HN) inputs were investigated. Soil amendment with Si reduced the tan spot severity in 18% due to the increase in the leaf Si concentration (around 30%), but it was affected by the N level used. The superoxide dismutase (SOD) activity was higher in +Si plants and inoculated with Ptr, leading to early and higher H2O2 and callose accumulation in wheat leaf. Interestedly, phenylalanine ammonia-lyase (PAL) activity was induced by the Si supplying, being negatively affected by the HN rate. Meanwhile, catalase (CAT), and peroxidase (POX) activities showed differential response patterns according to the Si and N rates used. Tan spot severity was reduced by both elements, but their interaction does not evidence synergic effects in this disease's control. Wheat plants from -Si and HN and +Si and LN treatments recorded lower tan spot severity.

Exogenous melatonin prolongs raspberry postharvest life quality by increasing some antioxidant and enzyme activity and phytochemical contents

There is a growing trend towards enhancing the post-harvest shelf life and maintaining the nutritional quality of horticultural products using eco-friendly methods. Raspberries are valued for their diverse array of phenolic compounds, which are key contributors to their health-promoting properties. However, raspberries are prone to a relatively short post-harvest lifespan. The present study aimed to investigate the effect of exogenous melatonin (MEL; 0, 0.001, 0.01, and 0.1 mM) on decay control and shelf-life extension. The results demonstrated that MEL treatment significantly reduced the fruit decay rate (P ≤ 0.01). Based on the findings, MEL treatment significantly increased titratable acidity (TA), total phenolics content (TPC), total flavonoid content (TFC), and total anthocyanin content (TAC). Furthermore, the MEL-treated samples showed increased levels of rutin and quercetin content, as well as antioxidant activity as measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH) and ferric reduction activity potential (FRAP). Additionally, the samples exhibited higher levels of phenylalanine ammonia-lyase (PAL) and catalase (CAT) enzymes compared to the control samples. Moreover, the levels of pH, total soluble solids (TSS), and IC50 were decreased in the MEL-treated samples (P ≤ 0.01). The highest amount of TA (0.619 g/100 ml juice), rutin (16.722 µg/ml juice) and quercetin (1.467 µg/ml juice), and PAL activity (225.696 nm/g FW/min) was observed at 0.001 mM treatment, while, the highest amount of TAC (227.235 mg Cy-g/100 ml juice) at a concentration of 0.01 mM and CAT (0.696 u/g FW) and TAL activities (9.553 nm/100 g FW) at a concentration of 0.1 mM were obtained. Considering the lack of significant differences in the effects of melatonin concentrations and the low dose of 0.001 mM, this concentration is recommended for further research. The hierarchical cluster analysis (HCA) and principal component analysis (PCA) divided the treatments into three groups based on their characteristics. Based on the Pearson correlation between TPC, TFC, TAC, and TAA, a positive correlation was observed with antioxidant (DPPH and FRAP) and enzyme (PAL and CAT) activities. The results of this study have identified melatonin as an eco-friendly compound that enhances the shelf life of raspberry fruits by improving phenolic compounds, as well as antioxidant and enzyme activities.

Combined Effect of Biological and Organic Fertilizers on Agrobiochemical Traits of Corn (Zea mays L.) under Wastewater Irrigation.

Corn (Zea mays L.) is an important annual grain that is cultivated as a food staple around the world. The current study examined the effect of wastewater and a combination of biological and organic fertilizers on the morphological and phytochemical traits of corn, using a factorial experiment based on a randomized complete block design with three replications. The first factor was biological and organic fertilizers at seven levels, including the control (no fertilization), bacterial biological fertilizers (NPK) along with iron and zinc Barvar biofertilizers, fungal biofertilizers made from Mycorrhiza and Trichoderma, biochar, a combination of bacterial and fungal biofertilizers, and a combination of bacterial and fungal biofertilizers with biochar. The second factor was irrigation at two levels (conventional irrigation and irrigation with wastewater). The traits studied included the morphological yield, phenols, flavonoids, polyphenols, glomalin, cadmium content in plant parts, and translocation factor (TF). The results disclosed that the best treatment in regard to the morphological traits was related to conventional water + biochar + mycorrhiza + Trichoderma + NPK. The highest phenol and flavonoid content were observed when biochar + mycorrhiza + Trichoderma + NPK treatments were used in both water treatments. Also, the wastewater + biochar + mycorrhiza + Trichoderma + NPK treatment demonstrated the highest total glomalin and phenylalanine ammonia-lyase (PAL) activity. The obtained results demonstrate that combined biological and organic fertilizer use on corn plants can effectively alleviate the deleterious effects of cadmium present in wastewater.

Improving plant adaptation to soil antimony contamination: the synergistic contribution of arbuscular mycorrhizal fungus and olive mill waste

BackgroundThis study aimed to investigate the alterations in biochemical and physiological responses of oat plants exposed to antimony (Sb) contamination in soil. Specifically, we evaluated the effectiveness of an arbuscular mycorrhizal fungus (AMF) and olive mill waste (OMW) in mitigating the effects of Sb contamination. The soil was treated with a commercial strain of AMF (Rhizophagus irregularis) and OMW (4% w/w) under two different levels of Sb (0 and 1500 mg kg−1 soil).ResultsThe combined treatment (OMW + AMF) enhanced the photosynthetic rate (+ 40%) and chlorophyll a (+ 91%) and chlorophyll b (+ 50%) content under Sb condition, which in turn induced more biomass production (+ 67–78%) compared to the contaminated control plants. More photosynthesis in OMW + AMF-treated plants gives a route for phenylalanine amino acid synthesis (+ 69%), which is used as a precursor for the biosynthesis of secondary metabolites, including flavonoids (+ 110%), polyphenols (+ 26%), and anthocyanins (+ 63%) compared to control plants. More activation of phenylalanine ammonia-lyase (+ 38%) and chalcone synthase (+ 26%) enzymes in OMW + AMF-treated plants under Sb stress indicated the activation of phenylpropanoid pathways in antioxidant metabolites biosynthesis. There was also improved shifting of antioxidant enzyme activities in the ASC/GSH and catalytic pathways in plants in response to OMW + AMF and Sb contamination, remarkably reducing oxidative damage markers.ConclusionsWhile individual applications of OMW and AMF also demonstrated some degree of plant tolerance induction, the combined presence of AMF with OMW supplementation significantly enhanced plant biomass production and adaptability to oxidative stress induced by soil Sb contamination.

Biochemical mechanisms preventing wilting under grafting: a case study on pumpkin rootstock grafting to wax gourd.

Wax gourd wilt is a devastating fungal disease caused by a specialized form of Fusarium oxysporum Schl. f. sp. benincasae (FOB), which severely restricts the development of the wax gourd industry. Resistant rootstock pumpkin grafting is often used to prevent and control wax gourd wilt. The "Haizhan 1" pumpkin has the characteristic of high resistance to wilt, but the mechanism through which grafted pumpkin rootstock plants acquire resistance to wax gourd wilt is still poorly understood. In this study, grafted wax gourd (GW) and self-grafted wax gourd (SW) were cultured at three concentrations [2.8 × 106 Colony Forming Units (CFU)·g-1, 8.0 × 105 CFU·g-1, and 4.0 × 105 CFU·g-1, expressed by H, M, and L]. Three culture times (6 dpi, 10 dpi, and 13 dpi) were used to observe the incidence of wilt disease in the wax gourd and the number of F. oxysporum spores in different parts of the soil and plants. Moreover, the physiological indices of the roots of plants at 5 dpi, 9 dpi, and 12 dpi in soil supplemented with M (8.0 × 105 CFU·g-1) were determined. No wilt symptoms in GW. Wilt symptoms in SW were exacerbated by the amount of FOB in the inoculated soil and culture time. At any culture time, the amount of FOB in the GW soil under the three treatments was greater than that in the roots. However, for the SW treatments, at 10 dpi and 13 dpi, the amount of FOB in the soil was lower than that in the roots. The total phenol (TP) and lignin (LIG) contents and polyphenol oxidase (PPO) and chitinase (CHI) activities were significantly increased in the GWM roots. The activities of phenylalanine ammonia lyase (PAL) and peroxidase (POD) initially decreased but then increased in the GWM roots. When the TP content decreased significantly, the LIG content and PAL and CHI activities increased initially but then decreased, whereas the PPO and POD activities did not change significantly in the SWM roots. The results indicated that the roots of the "Haizhan 1" pumpkin stock plants initiated a self-defense response after being infected with FOB, and the activities of PPO, POD, PAL, and CHI increased, and additional LIG and TP accumulated, which could effectively prevent FOB infection.

Changes in physio-biochemical metabolism, phenolics and antioxidant capacity during germination of different wheat varieties

Changes in physio-biochemical metabolism, phenolics and antioxidant capacity during germination were studied in eight different wheat varieties. Results showed that germination enhanced sprout growth, and caused oxidative damage, but enhanced phenolics accumulation. Ferulic acid and p-coumaric acid were the main phenolic acids in wheat sprouts, and dihydroquercetin, quercetin and vitexin were the main flavonoids. The phenolic acid content of Jimai 44 was the highest on the 2th and 4th day of germination, and that of Bainong 307 was the highest on the 6th day. The flavonoid content of Hei jingang was the highest during whole germination. The enzymes activities of phenylalanine ammonia lyase (PAL), cinnamic acid 4-hydroxylase (C4H) and 4-coumarate coenzyme A ligase (4CL) were up-regulated. The activities of catalase, polyphenol oxidase and peroxidase were also activated. Antioxidant capacity of wheat sprouts was enhanced. The results provided new ideas for the production of naturally sourced phenolic rich foods.

Potential biocontrol agents involved in induction of defense related enzymes in brinjal (solanum melongena l.) Against phomopsis blight caused by phomopsis vexans

Phomopsis blight, caused by Phomopsis vexans (P. vexans) in brinjal plants is one of the main diseases in India. In order to manage this malady, we initially screened seed samples of 14 cultivars obtained from seed suppliers for the disease incidence. Based on the disease incidence and severity, the samples were categorized as resistant and susceptible cultivars of brinjal. It was established that MEBH-9' was a sensitive cultivar, while the Kolar local was resistant to the disease. Two ideal strains of Rhizosphere colonizing bacteria (RCB), Pseudomonas putida strain Has-1/c (HM229805), and Phylloplane Colonizing Bacteria (PCB), Bacillus subtilis strain Br/ph-33 (KJ867501), previously characterized as potential plant growth-promoting rhizobacteria, were tested for their potential biocontrol of this disease. Both susceptible and resistant cultivars' seedlings were treated with different combinations of PCB and RCB, PCB alone, RCB alone, and challenge inoculated with P. vexans. In order to ascertain whether there was signalling between defense enzyme activation and plant protection after PCB and RCB treatment, defense enzymes were quantified. Brinjal plants treated with PCB+RCB combination and challenge inoculated with P. vexans showed a significant increase in the activity of Phenylalanine ammonia-lyase (PAL), Peroxidase (POX), Lipoxygenase (LOX), Polyphenol oxidase (PPO), Catalase, Chitinase, β -1,3-glucanase, and Hydrogen peroxide (H2O2) content. The current study reveals that the defense enzymes and PR-proteins are gradually induced and accumulated, which enhance the resistance in brinjal plants against P. vexans-causing fruit rot disease.

Elicitation of salicylic acid and methyl jasmonate provides molecular and physiological evidence for potato susceptibility to infection by Erwinia carotovora subsp. carotovora

Among the range of severe plant diseases, bacterial soft rot caused by Erwinia carotovora is a significant threat to crops. This study aimed to examine the varying response patterns of distinct potato cultivars to the influence of E. carotovora. Furthermore, it seeks to highlight the potential role of salicylic acid (SA) and methyl jasmonate (MeJA) in stimulating the antioxidant defence system. We collected eight bacterial isolates from diseased and rotted tubers which were morphologically and physiologically identified as E. carotovora subsp. carotovora. We conducted a greenhouse experiment to analyse the antioxidant responses of three different potato cultivars (Diamont, Kara, and Karros) at various time intervals (2, 4, 6, 8, 12, and 24 h) after bacterial infection (hpi). We assessed the extent of disease damage by applying a foliar spray of 0.9 mM salicylic acid (SA) and 70 μM methyl jasmonate (MeJA). Inoculating with Ecc led to an increase in total phenolic levels, as well as the activities and gene expression of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POX) as time progressed. Additionally, the application of SA and MeJA resulted in a further increase relative to the diseased treatments. The Karros cultivar, unlike the Diamont and Kara cultivars, demonstrated the highest expression levels of PAL, PPO and POX through inoculation, reflecting its higher levels of activity and resistance. Furthermore, the genetic response of potato cultivars to infection at 0 hpi varied depending on their susceptibility. The examination of the rate of PAL activity upregulation following SA or MeJA stimulation clarifies the cultivars' susceptibility over time. In conclusion, the study identified E. carotovora subsp. carotovora as the most virulent isolate causing soft rot disease in potato tubers. It further revealed that the Karros cultivar displayed superior resistance with high activities and gene expression of PAL, PPO and POX, while the cv. Diamont exhibited sensitivity. Additionally, foliar exposure to SA and MeJA induced antioxidant responses, enhancing the potato plants' resistance against Ecc pathogenesis and overall plant defence.

The Transcription Factor MiMYB8 Suppresses Peel Coloration in Postharvest 'Guifei' Mango in Response to High Concentration of Exogenous Ethylene by Negatively Modulating MiPAL1.

Anthocyanin accumulation is regulated by specific genes during fruit ripening. Currently, peel coloration of mango fruit in response to exogenous ethylene and the underlying molecular mechanism remain largely unknown. The role of MiMYB8 on suppressing peel coloration in postharvest 'Guifei' mango was investigated by physiology detection, RNA-seq, qRT-PCR, bioinformatics analysis, yeast one-hybrid, dual-luciferase reporter assay, and transient overexpression. Results showed that compared with the control, low concentration of exogenous ethylene (ETH, 500 mg·L-1) significantly promoted peel coloration of mango fruit (cv. Guifei). However, a higher concentration of ETH (1000 mg·L-1) suppressed color transformation, which is associated with higher chlorophyll content, lower a* value, anthocyanin content, and phenylalanine ammonia-lyase (PAL) activity of mango fruit. M. indica myeloblastosis8 MiMYB8 and MiPAL1 were differentially expressed during storage. MiMYB8 was highly similar to those found in other plant species related to anthocyanin biosynthesis and was located in the nucleus. MiMYB8 suppressed the transcription of MiPAL1 by binding directly to its promoter. Transient overexpression of MiMYB8 in tobacco leaves and mango fruit inhibited anthocyanin accumulation by decreasing PAL activity and down-regulating the gene expression. Our observations suggest that MiMYB8 may act as repressor of anthocyanin synthesis by negatively modulating the MiPAL gene during ripening of mango fruit, which provides us with a theoretical basis for the scientific use of exogenous ethylene in practice.

Pre-storage melatonin treatment maintains cell membrane integrity, reduces fruit browning and decay incidence in guava (Psidium guajava)

An experiments were conducted during 2021–22 at ICAR-Indian Agricultural Research Institute, New Delhi to study the impact of melatonin (MT) on key characteristics of guava (Psidium guajava L. cv. Barafkhana). Guava fruits were treated with different MT concentrations (200, 400, 600 and 800 μM) and stored at 10±1°C with 85–90% RH. The research revealed that treating with 600 μM MT notably decreased polyphenoloxidase activity by 57%, leading to delayed peel browning and also suppressed polygalacturonase (PG) activity by approximately 45% and pectine methylesterase activity by about 73%, resulting in higher firmness (5.33 N). Following a 20-days period of cold storage, significant reductions in electrolyte leakage, hydrogen peroxide accumulation and lipoxygenase activity were observed, thereby preserving cell membrane integrity. Additionally, MT stimulated the antioxidant defense system, boosted proline content accumulation, and enhanced phenylalanine ammonia-lyase activity. Together, these effects contributed to enhanced resistance against postharvest fungal decay (8.75%). In conclusion, MT at a concentration of 600 μM proves to be an effective postharvest treatment for maintaining texture, reducing fruit decay and extending the shelf-life of guava during cold storage.

Reduction of flavonoid content in honeysuckle via Erysiphe lonicerae-mediated inhibition of three essential genes in flavonoid biosynthesis pathways.

Honeysuckle, valued for its wide-ranging uses in medicine, cuisine, and aesthetics, faces a significant challenge in cultivation due to powdery mildew, primarily caused by the Erysiphe lonicerae pathogen. The interaction between honeysuckle and E. lonicerae, especially concerning disease progression, remains insufficiently understood. Our study, conducted in three different locations, found that honeysuckle naturally infected with E. lonicerae showed notable decreases in total flavonoid content, with reductions of 34.7%, 53.5%, and 53.8% observed in each respective site. Controlled experiments supported these findings, indicating that artificial inoculation with E. lonicerae led to a 20.9% reduction in flavonoid levels over 21 days, worsening to a 54.8% decrease by day 42. Additionally, there was a significant drop in the plant's total antioxidant capacity, reaching an 81.7% reduction 56 days after inoculation. Metabolomic analysis also revealed substantial reductions in essential medicinal components such as chlorogenic acid, luteolin, quercetin, isoquercetin, and rutin. Investigating gene expression revealed a marked decrease in the relative expression of the LjPAL1 gene, starting as early as day 7 post-inoculation and falling to a minimal level (fold change = 0.29) by day 35. This trend was mirrored by a consistent reduction in phenylalanine ammonia-lyase activity in honeysuckle through the entire process, which decreased by 72.3% by day 56. Further analysis showed significant and sustained repression of downstream genes LjFNHO1 and LjFNGT1, closely linked to LjPAL1. We identified the mechanism by which E. lonicerae inhibits this pathway and suggest that E. lonicerae may strategically weaken the honeysuckle's disease resistance by targeting key biosynthetic pathways, thereby facilitating further pathogen invasion. Based on our findings, we recommend two primary strategies: first, monitoring medicinal constituent levels in honeysuckle from E. lonicerae-affected areas to ensure its therapeutic effectiveness; and second, emphasizing early prevention and control measures against honeysuckle powdery mildew due to the persistent decline in crucial active compounds.

Cinnamaldehyde affects the storage quality of freshly cut water chestnuts through the regulation of reactive oxygen species and the AsA-GSH cycle

The quality of fresh-cut Chinese water chestnuts (CWCs) rapidly deteriorates with prolonged storage time, thus affecting its commercial value. This study aimed to investigate the effect of cinnamaldehyde (CA) treatment on the quality of fresh-cut CWCs and its mechanism of action. CA treatment maintained good appearance and higher total soluble solids content (TSS) of fresh-cut CWCs and also significantly inhibited microbial proliferation, respiration, phenylalanine ammonia-lyase activity (PAL) and enzymatic browning substance content. Moreover, CA treatment increased the antioxidant capacity and defense function-related enzyme activities (PPO and POD) of fresh-cut CWCs, and suppressed ·OH production rate and MDA content. Meanwhile, CA treatment significantly increased the content of antioxidant compounds and enzyme activities of the AsA-GSH cycle system. In conclusion, CA can inhibit surface discoloration of fresh-cut CWCs and extend their shelf life, thus increasing their commercial value.

Investigating the simultaneous effect of chitosan and arbuscular mycorrhizal fungi on growth, phenolic compounds, PAL enzyme activity and lipid peroxidation in Salvia nemorosa L.

Considering the importance of Salvia nemorosa L. in the pharmaceutical and food industries, and also beneficial approaches of arbuscular mycorrhizal fungi (AMF) symbiosis and the use of bioelicitors such as chitosan to improve secondary metabolites, the aim of this study was to evaluate the performance of chitosan on the symbiosis of AMF and the effect of both on the biochemical and phytochemical performance of this plant and finally introduced the best treatment. Two factors were considered for the factorial experiment: AMF with four levels (non-inoculated plants, Funneliformis mosseae, Rhizophagus intraradices and the combination of both), and chitosan with six levels (0, 50, 100, 200, 400 mg L−1 and 1% acetic acid). Four months after treatments, the aerial part and root length, the levels of lipid peroxidation, H2O2, phenylalanine ammonia lyase (PAL) activity, total phenol and flavonoid contents and the main secondary metabolites (rosmarinic acid and quercetin) in the leaves and roots were determined. The flowering stage was observed in R. intraradices treatments and the highest percentage of colonization (78.87%) was observed in the treatment of F. mosseae × 400 mg L−1 chitosan. Furthermore, simultaneous application of chitosan and AMF were more effective than their separate application to induce phenolic compounds accumulation, PAL activity and reduce oxidative compounds. The cluster and principal component analysis based on the measured variables indicated that the treatments could be classified into three clusters. It seems that different treatments in different tissues have different effects. However, in an overview, it can be concluded that 400 mg L−1 chitosan and F. mosseae × R. intraradices showed better results in single and simultaneous applications. The results of this research can be considered in the optimization of this medicinal plant under normal conditions and experiments related to abiotic stresses in the future.

Immunocompromisation of wheat host by L-BSO and 2,4-DPA induces susceptibility to the fungal pathogen Fusarium oxysporum

Susceptibility is defined as the disruption of host defence systems that promotes infection or limits pathogenicity. Glutathione (GSH) is a major component of defence signalling pathways that maintain redox status and is synthesised by γ-glutamyl cysteine synthetase (γ-ECS). On the other hand, lignin acts as a barrier in the primary cell wall of vascular bundles (VBs) synthesised by phenylalanine ammonia-lyase (PAL) in the intracellular system of plants. In this study, we used two inhibitors, such as L-Buthionine-sulfoximine (BSO), which irreversibly inhibits γ-ECS, and 2,4-dichlorophenoxyacetic acid (DPA), which reduces PAL activity and leads to the induction of oxidative stress in wheat (Triticum aestivum) seedlings after exposure to Fusarium oxysporum. Seedlings treated with 1 mM L-BSO and 2,4-DPA showed high levels of hydrogen peroxide (H2O2), malondialdehyde (MDA), carbonyl (CO) content, and low activity of antioxidative enzymes [superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX), and glutathione reductase (GR)] as compared to wild-type (WT) seedlings under F. oxysporum infection. Further, the content of reduced glutathione (RGSH), ascorbate (ASC), and lignin was decreased in BSO and DPA treated seedlings as compared to WT seedlings during Fusarium infection. Moreover, treatment with BSO and DPA significantly inhibited the relative activity of γ-ECS and PAL (P ≤ 0.001) in WT seedlings during Fusarium infection, which led to disintegrated VBs and, finally, cell death. Our results demonstrate that inhibition of γ-ECS and PAL by BSO and DPA, respectively, disrupts the defence mechanisms of wheat seedlings and induces susceptibility to F. oxysporum.

Redox priming could be an appropriate technique to minimize drought-induced adversities in quinoa.

The exogenous use of the redox compound (H2O2) plays a significant role in abiotic stress tolerance. The present study investigated various H2O2 application methods (seed priming, foliar spray, and surface irrigation) with varying concentration levels (0 mM, 5 mM, 10 mM, 15 mM, 40 mM, 80 mM, and 160 mM) to evaluate the efficiency of supplying exogenous H2O2 to quinoa under water-deficit conditions. Drought stress reduced quinoa growth and yield by perturbing morphological traits, leading to the overproduction of reactive oxygen species and increased electrolyte leakage. Although all studied modes of H2O2 application improved quinoa performance, surface irrigation was found to be sensitive, causing oxidative damage in the present study. Seed priming showed a prominent increase in plant height due to profound emergence indexes compared to other modes under drought conditions. Strikingly, seed priming followed by foliar spray improved drought tolerance in quinoa and showed higher grain yield compared to surface irrigations. This increase in the yield performance of quinoa was attributed to improvements in total chlorophyll (37%), leaf relative water content (RWC; 20%), superoxide dismutase (SOD; 35%), peroxidase (97%), polyphenol oxidase (60%), and phenylalanine ammonia-lyase (58%) activities, and the accumulation of glycine betaine (96%), total soluble protein (TSP; 17%), proline contents (35%), and the highest reduction in leaf malondialdehyde contents (MDA; 36%) under drought stress. PCA analysis indicated that physio-biochemical traits (proline, SOD, TSP, total chlorophyll, MSI, and RWC) were strongly positively correlated with grain yield, and their contribution was much higher in redox priming than other application methods. In conclusion, exogenous H2O2 application, preferably redox priming, could be chosen to decrease drought-induced performance and yield losses in quinoa.

NaCl elicitation enhances metabolite accumulation and stress resilience in Inula crithmoides L. shoot cultures: implications for its nutritional and medicinal value

This study explored the impact of sodium chloride (NaCl) elicitation on the accumulation of primary and secondary metabolites and the oxidative stress responses of Inula crithmoides L. (golden samphire) in vitro shoot cultures. Elicitation involved applying different concentrations of NaCl (0, 50, 100, and 200 mM) for 4 weeks. This was followed by assessing its impact on plant growth, physiological parameters (pigments, hydrogen peroxide content, total soluble sugars and proteins, and proline), and secondary metabolism (phenylalanine ammonia-lyase activity, shikimic acid, phenolics, flavonoids, and hydroxycinnamic acids) in the shoots. The extracts were also analysed using high-performance liquid chromatography (HPLC). The NaCl elicitation did not affect shoot growth but increased physiological functions such as photosynthesis and oxidative stress management under moderate salinity levels. In addition, NaCl treatments increased the synthesis of soluble sugars and proteins, particularly proline, as well as bioactive phenolics such as gentisic acid, chlorogenic acid, 4-hydroxybenzoic acid, luteolin-7-O-glucoside, and naringenin-7-O-glucoside. The NaCl elicitation in golden samphire shoot cultures offers a significant method for enhancing the production of important nutritional and bioactive compounds. This underscores the species’ potential for cultivation in saline environments and provides valuable prospects for its utilization in the health and nutrition sectors.