Phenylalanine Ammonia-lyase Enzyme Research Articles

Effect of Nitrogen Fertilizer on Capsaicinoids and Related Metabolic Substances of Dried Chili Pepper Fruit

Reducing fertilizer pollution is an important direction for modern ecological agriculture. Commonly, excessive nitrogen is applied to pepper. Capsaicin is one of the most important economic qualities of spicy peppers, but the effect of nitrogen on capsaicin is still inconsistent. This study aims to elucidate the impact of nitrogen fertilizer on capsaicin accumulation and to provide guidance on fertilizer application on highly spicy chili peppers. The experiment was conducted with five nitrogen fertilizer concentrations: N1 (urea 750 kg ha−1), N2 (urea 562.5 kg ha−1), N3 (urea 375 kg ha−1), N4 (urea 187.5 kg ha−1), and N0 (no nitrogen fertilizer). Nitrogen treatment was applied to two varieties with different spiciness levels from the seedling stage. The fruits in different layers of pepper plants were sampled on the 20th, 35th, and 50th day after anthesis, and the fruits’ size, content of capsaicin, capsaicin precursors, capsaicin competitors, as well as capsaicin-related enzyme activities and gene expression level were analyzed. The results indicate that, when applying N2 and N3, both chili pepper varieties exhibited higher fruit length, diameter, weight, and yield values. There were increased contents of total phenol, flavonoids, and tannins in both fruit varieties with N2 application. Moreover, the placenta weights of the bottom, middle, and top layers of the fruits on the 35th day were improved by 40.14%, 26.80%, and 55.91% for ‘Honglong 23’ and 55.10%, 37.04%, and 75.56% for ‘Hongxi’ compared with N0. At the same time, under N2 treatment, the phenylalanine ammonia-lyase (PAL) enzyme activity of capsaicin synthase significantly increased. In contrast, the capsaicin-degrading enzyme activities of peroxidase (POD) and polyphenol oxidase (PPO) decreased notably. The expression levels of capsaicin-synthetic genes such as phenylalanine cleavage enzyme gene (PAL), acyltransferase gene (AT3), 4-Coumaroyl coenzyme A ligase gene (4CL), cinnamate 4-hydroxylase gene (C4H), caffeoyl coenzyme A-3-oxo-methyltransferase gene (COMT), paminotransferase gene (PAMT), and hydroxycinnamyltransferase gene (HCT) were up-regulated in N2 fruits, which led to a significant increase in capsaicin content compared with the other four nitrogen amounts. A further reduction in nitrogen application to N3 and N4 resulted in a decrease in the precursor substance’s total phenol content and PAL activity and an increase in the competitive substance’s flavonoid, lignin, POD, and PPO enzyme activities. At the same time, the expression levels of capsaicinoid synthetic genes were downregulated in the N3 and N4 treatments, leading to a low content of total capsaicinoids. The capsaicinoid content showed a trend of 35th day > 50th day > 20th day for both varieties. Additionally, the contents of total capsaicinoids, total phenols, flavonoids, and lignins, as well as PAL enzyme activity, and the expression levels of PAL, AT3, 4CL, C4H, COMT, PAMT, and HCT exhibited characteristics of bottom layers > middle layers > top layers. The activities of POD and PPO gradually increased from the bottom to the top layers. The N2 (562.5 kg ha−1) treatment resulted in increases in placenta mass, maximum capsaicinoid precursor substance of total phenol content, and synthase enzyme activity, as well as decreases in capsaicinoid competing substances and degradative enzyme activity, so there were more substances available for capsaicin synthesis. Combined with the higher fruit weight and capsaicinoid content in the N2 treatment, N2 was considered a suitable nitrogen fertilizer dosage for highly spicy chili pepper cultivation.

Host Plants and Fertilization Mediated Life History of American Serpentine Leaf Miner, Liriomyza trifolii (Burgess) (Diptera: Agromyzidae).

Herbivorous insects depend on the host plant to optimize their overall reproductive success, and balanced fertilization may alter the plant's quality against herbivory. Life history traits of the Liriomyza trifolii (Burgess) were determined under laboratory conditions using either unfertilized and fertilized plants of bean [Phaseolus vulgaris L. (Fabaceae)], chrysanthemum [Chrysanthemum × morifolium (Asteraceae)], potato [Solanum tuberosum (Solanaceae)], bell pepper [Capsicum annuum (Solanaceae)], and tomato [Solanum lycopersicum (Solanaceae)]. Results indicated that L. trifolii completed development on all studied unfertilized and fertilized plants. Nevertheless, a higher performance of the leaf miner was observed on bean and bell pepper plants compared to the other plants. Furthermore, there was an interaction of the host plant and fertilization with Calcium Aria or Sitam negatively affecting the fitness-related traits of the leaf miner. Application of these fertilizers resulted in delayed immature development of L. trifolii, decreased survival rate, and reduced adult longevity and fecundity. The activity of cinnamyl alcohol dehydrogenase (CAD), peroxidase (POD), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) enzymes, as well as phenolic, flavonoid, and lignin content were higher in Calcium Aria + Sitam fertilized plants, intermediate in Calcium Aria and Sitam treated plants, and the lower in unfertilized plants. The development and survival of L. trifolii on different host plants, considering fertilization options, become important for deploying cultural control practices against this important pest species.

Volatiles emitted by Pseudomonas aurantiaca ST-TJ4 trigger systemic plant resistance to Verticillium dahliae

Verticillium dahliae is among the most devastating fungal pathogens, causing significant economic harm to agriculture and forestry. To address this problem, researchers have focused on eliciting systemic resistance in host plants through utilizing volatile organic compounds (VOCs) produced by biological control agents. Herein, we meticulously measured the quantity of V. dahliae pathogens in plants via RTqPCR, as well as the levels of defensive enzymes and pathogenesis-related (PR) proteins within plants. Finally, the efficacy of VOCs in controlling Verticillium wilt in cotton was evaluated. Following treatment with Pseudomonas aurantiaca ST-TJ4, the expression of specific VdEF1-α genes in cotton decreased significantly. The incidence and disease indices also decreased following VOC treatment. In cotton, the salicylic acid (SA) signal was strongly activated 24 h posttreatment; then, hydrogen peroxide (H2O2) levels increased at 48 h, and peroxidase (POD) and catalase (CAT) activities increased to varying degrees at different time points. The malondialdehyde (MDA) content and electrolyte leakage in cotton treated with VOCs were lower than those in the control group, and the expression levels of chitinase (CHI) and PR genes (PR10 and PR17), increased at various time points under the ST-TJ4 treatment. The activity of phenylalanine ammonia lyase (PAL) enzymes in cotton treated with VOCs was approximately 1.26 times greater than that in control plants at 24 h，while the contents of phenols and flavonoids increased significantly in the later stage. Additionally, 2-undecanone and 1-nonanol can induce a response in plants that enhances disease resistance. Collectively, these findings strongly suggest that VOCs from ST-TJ4 act as elicitors of plant defence and are valuable natural products for controlling Verticillium wilt.

Improving blueberry cold storage quality: the effect of preharvest hexanal application on chilling injuries and antioxidant defense mechanisms.

Blueberries are vulnerable to chilling injury (CI). This can lead to limited longevity when they are subjected to cold storage conditions. This study investigated the effectiveness of a preharvest spray containing 0.02% hexanal in reducing CI and improving the postharvest storage quality of 'Star' and 'Biloxi' blueberries. The blueberries were stored for a period of 5 weeks at 2 °C and in 90% relative humidity (RH). The findings revealed that the preharvest hexanal spraying of both cultivars delayed senescence by mitigating CI, as evidenced by the bolstering of the antioxidant defense system through increased superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), catalase (CAT), and phenylalanine ammonia lyase (PAL) enzyme activity. The treated fruit also maintained elevated levels of total phenol content (TPC), total flavonoids (TFC), and vitamin C, demonstrating enhanced free radical scavenging capacity (FRSC), while exhibiting reduced polyphenoloxidase (PPO) activity, and reduced malondialdehyde (MDA), and H2O2 content in comparison with the control group. The preharvest hexanal treatment also suppressed fruit softening by maintaining greater firmness and higher membrane stability index (MSI) scores, inhibiting the activity of polygalacturonase (PG), pectinmethylesterase (PME), xylanase, and α-amylase, and reducing microbial counts (MC) and incidence of decay (DI) in comparison with the control. Preharvest hexanal treatment also improved the overall storage quality by reducing weight loss, total soluble solids (TSS), pH, and the TSS/acid ratio, while increasing titratable acidity (TA) in comparison with the control during cold storage. The findings suggest that hexanal, as a preharvest application, delays senescence effectively and preserves overall quality by enhancing cold tolerance through antioxidant defense mechanisms in blueberry storage under cold conditions. © 2024 The Author(s). Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.

Humic acid and grafting as sustainable agronomic practices for increased growth and secondary metabolism in cucumber subjected to salt stress

Salinity stress poses a significant treat to crop yields and product quality worldwide. Application of a humic acid bio stimulant and grafting onto tolerant rootstocks can both be considered sustainable agronomic practices that can effectively ameliorate the negative effects of salinity stress. This study aimed to assess the above mentioned ameliorative effects of both practices on cucumber plants subjected to saline environments. To attain this goal a factorial experiment was carried out in the form of a completely randomized design with three replications. The three factors considered were (a) three different salinity levels (0, 5, and 10 dS m−1 of NaCl), (b) foliar application of humic acid at three levels (0, 100, and 200 mg L−1), and (c) both grafted and ungrafted plants. Vegetative traits including plant height, fresh and dry weight and number of leaf exhibited a significant decrease under increasing salinity stress. However, the application of humic acid at both levels mitigated these effects compared to control plants. The reduction in relative water content (RWC) of the leaf caused by salinity, was compensated by the application of humic acid and grafting. Thus, the highest RWC (86.65%) was observed in grafting plants with 0 dS m−1 of NaCl and 20 mg L−1 of humic acid. Electrolyte leakage (EL) increased under salinity stress, but the application of humic acid and grafting improved this trait and the lowest amount of EL (26.95%) was in grafting plants with 0 dS m−1 of NaCl and 20 mg L−1 of humic acid. The highest amount of catalase (0.53 mmol H2O2 g−1 fw min−1) and peroxidase (12.290 mmol H2O2 g−1 fw min−1) enzymes were observed in the treatment of 10 dS m−1 of NaCl and 200 mg L−1 humic acid. The highest amount of total phenol (1.99 mg g−1 FW), total flavonoid (0.486 mg g−1 FW), total soluble carbohydrate (30.80 mg g−1 FW), soluble protein (34.56 mg g−1 FW), proline (3.86 µg g−1 FW) was in grafting plants with 0 dS m−1 of NaCl and 200 mg L−1 of humic acid. Phenolic acids and phenylalanine ammonia lyase (PAL) and polyphenol oxidase (PPO) enzymes increased with increasing salinity and humic acid levels. Contrary to humic acid, salt stress increased the sodium (Na+) and chlorine (Cl−) and decreased the amount of potassium (K+) and calcium (Ca2+) in the root and leaf of ungrafted cucumber. However, the application 200 mg L−1 humic acid appeared to mitigate these effects, thereby suggesting a potential role in moderating physiological processes and improving growth of cucumber plants subjected to salinity stress. According to the obtained results, spraying of humic acid (200 mg L−1) and the use of salt resistant rootstocks are recommended to increase tolerance to salt stress in cucumber. These results, for the first time, clearly demonstrated that fig leaf gourd a new highly salt-tolerant rootstock, enhances salt tolerance and improves yield and quality of grafted cucumber plants by reducing sodium transport to the shoot and increasing the amount of compatible osmolytes.

Genome-wide analysis of R2R3-MYB transcription factors in poplar and functional validation of PagMYB147 in defense against Melampsora magnusiana

Main conclusionTranscription of PagMYB147 was induced in poplar infected by Melampsora magnusiana, and a decline in its expression levels increases the host's susceptibility, whereas its overexpression promotes resistance to rust disease.Poplars are valuable tree species with diverse industrial and silvicultural applications. The R2R3-MYB subfamily of transcription factors plays a crucial role in response to biotic stresses. However, the functional studies on poplar R2R3-MYB genes in resistance to leaf rust disease are still insufficient. We identified 191 putative R2R3-MYB genes in the Populus trichocarpa genome. A phylogenetic analysis grouped poplar R2R3-MYBs and Arabidopsis R2R3-MYBs into 33 subgroups. We detected 12 tandem duplication events and 148 segmental duplication events, with the latter likely being the main contributor to the expansion of poplar R2R3-MYB genes. The promoter regions of these genes contained numerous cis-acting regulatory elements associated with response to stress and phytohormones. Analyses of RNA-Seq data identified a multiple R2R3-MYB genes response to Melampsora magnusiana (Mmag). Among them, PagMYB147 was significantly up-regulated under Mmag inoculation, salicylic acid (SA) and methyl jasmonate (MeJA) treatment, and its encoded product was primarily localized to the cell nucleus. Silencing of PagMYB147 exacerbated the severity of Mmag infection, likely because of decreased reactive oxygen species (ROS) production and phenylalanine ammonia-lyase (PAL) enzyme activity, and up-regulation of genes related to ROS scavenging and down-regulation of genes related to PAL, SA and JA signaling pathway. In contrast, plants overexpressing PagMYB147 showed the opposite ROS accumulation, PAL enzyme activity, SA and JA-related gene expressions, and improved Mmag resistance. Our findings suggest that PagMYB147 acts as a positive regulatory factor, affecting resistance in poplar to Mmag by its involvement in the regulation of ROS homeostasis, SA and JA signaling pathway.

Combined Ascorbic Acid and Mild Heat Treatment to Improve the Quality of Fresh-Cut Carrots.

Mild heat (MH) treatment and ascorbic acid (AsA) addition can improve the quality of fresh-cut produce when used individually; however, their combined effect remains unclear. Herein, fresh-cut carrots were used as models to explore the effects of MH (50 °C)-AsA (0.5%) on quality properties including reactive oxygen species (ROS) metabolism, antioxidants, lignin metabolism, naturally present microbes, and inoculated pathogens (Escherichia coli O157: H7 and Salmonella Typhimurium) during storage (0-5 d, 4 °C). The results indicate that the antioxidant properties in the MH-AsA group were consistent with those of single treatments, resulting in a consistent ROS-scavenging effect. From day 3-5, lignin synthesis was significantly inhibited by MH-AsA as compared with single treatments, probably because the two enzymes (phenylalanine ammonia-lyase and peroxidase) responsible for lignin synthesis exhibited lower expressions. Microbial analysis revealed that MH-AsA treatment led to the lowest counts of both pathogens and aerobic mesophilic bacteria at 0-5 d. Conversely, the inhibitory effect of MH-AsA treatment on mold and yeast was consistent with the single treatments. These results suggest that MH-AsA is a low-cost and safe approach to improve the physiological characteristics of fresh-cut produce while reducing microbial risk.

Ficus carica Linn leaves extract induces cucumber resistance to Podosphaera xanthii by inhibiting conidia and regulating enzyme activity

Cucumbers(Cucumis sativus L.) are highly susceptible to infection by powdery mildew (PM), resulting in a deterioration of cucumber quality. The utilization of chemical control measures can effectively control cucumber PM; however, it may potentially give rise to issues such as environmental pollution, compromised safety, and drug resistance. The urgent need for a green, secure, and efficient strategy to manage cucumber PM necessitates attention. The predominant fungal pathogen causing PM in cucumbers is Podosphaera xanthii (P. xanthii) in this study. The preventive and control efficacy of Ficus carica Linn leaf extract (FLE) against P. xanthii was investigated for the first time. The preventive experiments entail pre-infection spraying of FLE prior to the occurrence of P. xanthii, while the curative experiments involve post-outbreak spraying of FLE. After comprehensive consideration, the optimal approach was determined to be spraying the front of cucumber leaves with a concentration of 0.04 mg/mL FLE in order to effectively control P. xanthii in leaf disc bioassay. The lowest superposition rate from FLE and trisodium phosphate dodecahydrate was 12.86%, indicating that the impact of FLE on the respiratory metabolism of P. xanthii conidia primarily operates through the hexose monophosphate pathway (HMP). The growth of P. xanthii conidia and mycelium can be inhibited or delayed by FLE. The application of FLE can effectively mitigated chlorophyll loss, suppressed the activities of peroxidase (POD) and polyphenol oxidase (PPO), as well as enhanced the activities of phenylalanine ammonia lyase (PAL), chitinase, and β- 1,3-glucanase. Furthermore, three representative enzyme genes, PAL, POD, and chitinase, were chosen for the purpose of validation. The results suggested that FLE has the ability to modulate the expression of relevant enzyme genes, with peak effects observed after 3 to 4 days of treatment. The findings offer theoretical support for the advancement of novel botanical pesticides aimed at controlling crop diseases.

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.

The effect of cold plasma treatment on quality attributes and shelf life of apples

The effectiveness of atmospheric air dielectric barrier discharge (DBD) cold plasma was compared with existing decontamination methods for improving the quality and shelf life of apples. The samples were stored in two different storage conditions (ambient, 27 ± 3 °C; and cold, 10 ± 1 °C) to check the effect of storage temperature on their shelf life. The microbial load on the apples was reduced after all the treatments, and samples stored at 10 ℃ showed a higher reduction in microbial load with increased shelf life. The polyphenol oxidase (PPO) and phenylalanine ammonia-lyase (PAL) enzyme activities showed a significant reduction after cold plasma treatment; however, peroxidase (POD) activity showed a lower reduction than PPO and PAL enzymes. Color changes evaluated using L*, a*, and b* values showed higher retention for the red color in the treated samples compared to control samples, and the firmness of all treated samples was maintained throughout the storage period. The total phenolic content (TPC) increased after cold plasma treatment and carotenoid content was retained in the treated samples. In addition, the present study demonstrated that the novel cold plasma decontamination method was more effective in reducing the pesticides (Malathion, Fenthion, and Chlorpyrifos) from the apple surfaces than the conventional methods. Cold plasma can be a better alternative for decontaminating apples; however, other hurdles may be required to increase their shelf life further.

Silicon induces ROS scavengers, hormone signalling, antifungal metabolites, and silicon deposition against brown stripe disease in sugarcane.

Bipolaris setariae is known to cause brown stripe disease in sugarcane, resulting in significant yield losses. Silicon (Si) has the potential to enhance plant growth and biotic resistance. In this study, the impact of Si on brown stripe disease was investigated across susceptible and resistant sugarcane varieties, utilizing four Si concentrations (0, 15, 30, and 45 g per barrel of Na2SiO3·5H2O). Si significantly reduced the incidence of brown stripe disease (7.41-59.23%) and alleviated damage to sugarcane growth parameters, photosynthetic parameters, and photosynthetic pigments. Submicroscopic observations revealed that Si induced the accumulation of silicified cells in leaves, reduced spore accumulation, decreased stomatal size, and protected organelles from B. setariae damage. In addition, Si increased the activity of antioxidant enzymes (superoxide dismutase, peroxidase, and catalase), reduced reactive oxygen species production (malondialdehyde and hydrogen peroxide) and modulated the expression of genes associated with hormone signalling (PR1, TGA, AOS, AOC, LOX, PYL8, and SnRK2), leading to the accumulation of abscisic acid and jasmonic acid and inhibiting SA synthesis. Si also activated the activity of metabolism-related enzymes (polyphenol oxidase and phenylalanine ammonia lyase) and the gene expression of PAL-dependent genes (PAL, C4H, and 4CL), regulating the accumulation of metabolites, such as chlorogenic acid and lignin. The antifungal test showed that chlorogenic acid (15ug μL-1) had a significant inhibitory effect on the growth of B. setariae. This study is the first to demonstrate the inhibitory effect of Si on B. setariae in sugarcane, highlighting Si as a promising and environmentally friendly strategy for managing brown stripe disease.

Evaluation of Biocontrol-based Formulations against Late Leaf Spot and Rust in Groundnut

This study investigated the efficacy of various biocontrol-based formulations against late leaf spot (LLS) (Phaeoisariopsis personata) and rust (Puccinia arachidis) in groundnut. Pot culture and field experiments were conducted during the Kharif season (June-September) of 2022. Disease incidence of both late leaf spot and rust was significantly lower in groundnut plants treated with a combination of biocontrol-based formulations compared to control. The most effective eco-friendly treatment included a combination of Trichoderma asperellum, Pseudomonas fluorescens, fortified lignite fly ash and Annamalai mixture. This combination significantly reduced lesion frequency and Percent Disease Index (PDI) for both diseases at 50, 70 and 90 DAS, compared to other treatments. The combination of biocontrol-based formulations also significantly increased the pod yield. Furthermore, the same treatment increased the induction of defense enzymes peroxidase (2.22 fold), polyphenol oxidase (1.28 fold) and phenylalanine ammonia-lyase (6.25 fold). While Carbendazim effectively reduced disease incidence, it was surpassed by the biocontrol-based module in terms of both disease control and yield. These findings suggest that biocontrol-based formulations can be a sustainable approach for managing LLS and rust diseases in groundnut cultivation.

Dissecting the role of salicylic acid in mediating stress response in mungbean cultivars concurrently exposed to Macrophomina phaseolina infection and drought stress

The combined stress studies provide fundamental knowledge that could assist in producing multiple stress resilient crops. The fungal phytopathogen, Macrophomina phaseolina is a major limiting factor in the productivity of the crop, Vigna radiata (mungbean). This fungal species tends to flourish under hot and dry conditions. Therefore, in this study the salicylic acid (SA) mediated stress responses in contrasting mungbean cultivars (Shikha and RMG-975) exposed to combined M. phaseolina infection (F) and drought stress (D) have been elucidated. The combined stress was applied to ten days seedlings in three orders i.e. drought followed by fungal infection (DF), drought followed by fungal infection with extended water deficit (DFD) and fungal infection followed by drought stress (FD). The severity of infection was analyzed using ImageJ analysis. Besides, the concentration of SA has been correlated with the phenylpropanoid pathway products, expression of pathogenesis-related proteins (β-1,3-glucanase and chitinase) and the specific activity of certain related enzymes (phenylalanine ammonia lyase, lipoxygenase and glutathione-S-transferase). The data revealed that the cultivar RMG-975 was relatively more tolerant than Shikha under individual stresses. However, the former became more susceptible to the infection under DFD treatment while the latter showed tolerance. Otherwise, the crown rot severity was reduced in both the cultivars under other combined treatments. The stress response analysis suggested that enhanced chitinase expression is vital for tolerance against both, the pathogen and drought stress. Also, it was noted that plants treat each stress combination differently and the role of SA was more prominently visible under individual stress conditions.

Comparative physiological and transcriptomic analysis reveals an improved biological control efficacy of Sporidiobolus pararoseus Y16 enhanced with ascorbic acid against the oxidative stress tolerance caused by Penicillium expansum in pears

Sporidiobolus pararoseus Y16, a species of significant ecological importance, has distinctive physiological and biological regulatory systems that aid in its survival and environmental adaptation. The goal of this investigation was to understand the complex interactions between physiological and molecular mechanisms in pear fruits as induced by S. pararoseus Y16. The study investigated the use of S. pararoseus Y16 and ascorbic acid (VC) in combination in controlling blue mold decay in pears via physiological and transcriptomic approach. The study results showed that treatment of S. pararoseus Y16 with 150 μg/mL VC reduced pears blue mold disease incidence from 43% to 11%. Furthermore, the combination of S. pararoseus Y16 and VC significantly inhibited mycelia growth and spore germination of Penicillium expansum in the pear's wounds. The pre-treatment did not impair post-harvest qualities of pear fruit but increased antioxidant enzyme activity specifically polyphenol oxidase (PPO), peroxidase (POD), catalase (CAT) activities as well as phenylalanine ammonia-lyase (PAL) enzyme activity. The transcriptome analysis further uncovered 395 differentially expressed genes (DEGs) and pathways involved in defense mechanisms and disease resistance. Notable pathways of the DEGs include plant-pathogen interaction, tyrosine metabolism, and hormone signal transduction pathways. The integrative approach with both physiological and transcriptomic tools to investigate postharvest pathology in pear fruits with clarification on how S. pararoseus Y16 enhanced with VC, improved gene expression for disease defense, and create alternative controls strategies for managing postharvest diseases.

Comparative Effect of Seed Coating and Biopriming of Bacillus aryabhattai Z-48 on Seedling Growth, Growth Promotion, and Suppression of Fusarium Wilt Disease of Tomato Plants.

Beneficial plant microbes can enhance the growth and quality of field crops. However, the benefits of microbes using cheap and efficient inoculation methods are still uncommon. Seed coating with biocontrol agents can reduce the amount of inocula along with having the potential for large-scale application. Hence, in this research work, the comparative potential of tomato seed coating and biopriming with Bacillus aryabhattai Z-48, harboring multiple plant-beneficial traits, to suppress Fusarium wilt disease along with its beneficial effect on seedling and plant growth promotion was analyzed. Among two bacterial strains, B. aryabhattai Z-48 was able to antagonize the mycelial growth of Fusarium oxysporum f.sp. lycopersici in vitro and its application as a seed coating superiorly benefited seedling traits like the germination percentage, vigor index, and seedling growth index along with a reduced germination time. The seed coating with B. aryabhattai Z-48 resulted in significant increases in the shoot length, root length, dry biomass, and total chlorophyll contents when compared with the bioprimed seeds with the same bacterial strain and non-inoculated control plants. The seed coating with B. aryabhattai Z-48 significantly reduced the disease index (>60%) compared with the pathogen control during pot trials. Additionally, the seed coating with B. aryabhattai Z-48 resulted in a significantly higher production of total phenolics, peroxidase, polyphenol oxidase, and phenylalanine ammonia lyase enzyme in tomato plants. The GC/MS-based non-targeted metabolic profiling indicated that the seed coating with B. aryabhattai Z-48 could cause large-scale metabolite perturbations in sugars, sugar alcohols, amino acids, and organic acids to increase the fitness of tomato plants against biotic stress. Our study indicates that a tomato seed coating with B. aryabhattai Z-48 can improve tomato growth and suppress Fusarium wilt disease effectively under conventional agricultural systems.

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.

Low UV radiation influenced DNA methylation, gene regulation, cell proliferation, viability, and biochemical differentiation in the cell suspension cultures of Cannabis indica

The effect of low artificial Ultraviolet (UV) on the DNA methylation remains controversial. This study addresses how differential photoperiods of UV radiation affect the biochemical and molecular behaviors of Cannabis indica cell suspension cultures. The cell suspensions were illuminated with the compact fluorescent lamps (CFL), emitting a combination of 10% UVB, 30% UVA, and the rest visible wavelengths for 0, 4, 8, and 16 h. The applied photoperiods influenced cell morphological characteristics. The 4 h photoperiod was the most effective treatment for improving biomass, growth index and cell viability percentage while these indices remained non-significant in the 16 h treatment. The methylation-sensitive amplified polymorphism (MASP) assay revealed that the UV radiation was epigenetically accompanied by DNA hypermethylation. The light-treated cells significantly displayed higher relative expression of the cannabidiolic‌ acid synthase (CBDAS) and delta9-tetrahydrocannabinolic acid synthase (THCAS) genes about 4-fold. The expression of the olivetolic acid cyclase (OAC) and olivetol synthase (OLS) genes exhibited an upward trend in response to the UV radiation. The light treatments also enhanced the proline content and protein concentration. The 4 h illumination was significantly capable of improving the cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC) concentrations, in contrast with 16 h. By increasing the illumination exposure time, the activity of the phenylalanine ammonia-lyase (PAL) enzyme linearly upregulated. The highest amounts of the phenylpropanoid derivatives were observed in the cells cultured under the radiation for 4 h. Taken collective, artificial UV radiation can induce DNA methylation modifications and impact biochemical and molecular differentiation in the cell suspensions in a photoperiod-dependent manner.

Epigallocatechin-3-gallate-induced tolerance to cadmium stress involves increased flavonoid synthesis and nutrient homeostasis in tomato roots

Cadmium (Cd) is a toxic heavy metal, increasingly accumulating in the environment and its presence in various environmental compartments represents a significant risk to human health via the food chain. Epigallocatechin-3-Gallate (EGCG) is a prominent secondary metabolite, which can safeguard plants from biotic and abiotic stress. However, the role of EGCG in flavonoid synthesis, nutrient acquisition and reactive oxygen species (ROS) metabolism under Cd stress remains unclear. Here, we examined the effects of EGCG and Cd treatment on leaf photochemical efficiency, cell ultrastructure, essential element acquisition, antioxidant system, and secondary metabolism in tomato (Solanum lycopersicum L.). The results showed that O2•−, H2O2, and malondialdehyde levels increased after Cd treatment, but Fv/Fm decreased significantly, suggesting that Cd induced oxidative stress and photoinhibition. However, EGCG mitigated the adverse effects of Cd-induced phytotoxicity in both the roots and leaves. A decrease in ROS accumulation under EGCG + Cd treatment was mainly attributed to the significant enhancement in antioxidant enzyme activity, flavonoid content, and PHENYLALANINE AMMONIA-LYASE expression in roots. Moreover, EGCG reduced Cd content but increased some essential nutrient contents in tomato plants. Transmission electron microscopy-based observations revealed that EGCG treatment safeguards leaf and root cell ultrastructure under Cd stress. This implies that tomato plants subjected to Cd stress experienced advantageous effects upon receiving EGCG treatment. The present work elucidated critical mechanisms by which EGCG induces tolerance to Cd, thereby providing a basis for future investigations into environmentally sustainable agricultural practices in areas contaminated with heavy metals, for utilizing naturally occurring substances found in plants.

Shading in fruit changes the polyphenol accumulation of pellicle by regulating activity of key enzymes and expression of their gene related polyphenol anabolism of Juglans sigillata Dode

Polyphenols, abundant in the pellicle of walnuts, confer health benefits to the human body. The intricate relationship between light and phenolic compounds underscores the impact of shading, which can effectively diminish phenolic content and enhance the palatability of food. In this study, we delved into the connection between polyphenol accumulation, related enzyme activities, and gene expression in the pellicle of Juglans sigillata Dode under varying degrees of shading. The results show that different shade intensities can change polyphenols’ content and affect the activity of key polyphenols anabolism enzymes and their gene expression. With the increase of the shading intensity, the total phenolics content (TPC) and total flavonoids content (TFC) were lower than the nomal light. In the mature stage, shading 60 % was lowest. 7 individual phenolics were identified in the pellicle, and the content of each varied significantly with the decrease of light intensity. Except for p-coumaric acid and ferulic acid, which were higher than the control at mature stage, all phenolics were lower than the control, but the overall trend was the same as that of the control. The activity of key enzymes in the anabolism of polyphenols was significantly affected after shading. In complete darkness phenylalanine ammonia lyase (PAL) was highest at the kernel-filling stage, shading 20 % of chalcone synthase (CHS) and shading 60 % of flavonol synthase (FLS) responded most strongly at the hard-core stage, while flavanone 3-hydroxylase (F3H) was most active at shading 60 % of kernel-filling stage, which was 2.03, 1.38, 4.67, and 2.08 times that of the control, respectively. The expression levels of key genes showed that the expression level of JsPAL was significantly increased at hard-core stage and mature stage, and the expression of JsPAL was 3.85 times higher than that of the control at the mature stage with 60 % shading. Correlation analysis showed that PAL enzyme activity was highly correlated with TPC, TFC and various individual phenolics with the increase of shading intensity. The content of p-coumaric acid was positively correlated with the activities of 4-coumarate coenzyme A ligase (4CL), F3H and FLS. The increase of shading intensity enhanced the correlation between total phenolics content, total flavonoids content, individual phenolics substances and JsPAL, JsC4H, JsCHS, JsCHI and JsFLS. Overall, PAL was a key enzyme affecting polyphenol accumulation under different shading levels, while at the genetic level, JsPAL, JsC4H, JsCHS, JsCHI and JsFLS were the key genes affecting them. This study will potentially provide more information for light management and polyphenol regulation in walnut cultivation.

Effect of Curvularia andropogonis infection on secretory tissues and phenylalanine ammonia lyase enzyme of Cymbopogon nardus

Abstract. Solekha R, Puspaningrum NNT, Ramadani AH, Hapsari FD, Ermavitalini D, Purnobasuki H. 2024. Effect of Curvularia andropogonis infection on secretory tissues and phenylalanine ammonia lyase enzyme of Cymbopogon nardus. Biodiversitas 25: 598-604. Cymbopogon nardus L. oil production decreased due to red spot disease caused by Curvularia andropogonis fungal infection. The objective of this study was to investigate the infection effect of C. andropogonis on secretory tissue formation in citronella leaf epidermis and the enzymatic defense expression response in C. nardus. Anatomical responses were observed from leaf secretory structure slide while PAL reactions were measured from enzyme activity in leaf samples of three treatment groups with healthy, wounded, and infected conditions. The morphological results of infected leaves changed from green to brownish triggered by pathogenic infection conditions that activated the PAL enzyme pathway and phenylpropanoid production as a defense. The results showed that the density of cells storing secondary metabolites flavonoids, tannins, and saponins in infected leaves increased compared to wounded and healthy ones. Secondary metabolites flavonoids, tannins, and saponins in wounded leaves increased compared to healthy leaves. It was observed that enzymatic response escalated when infection occurred. PAL enzyme activity test of C. nardus leaves showed that infected leaves had the highest value (0.0051 U/mL), followed by wounded leaves (0.0033 U/mL) and healthy leaves (0.0027 U/mL). Likewise, the specific activity of PAL enzyme in infected leaves was highest (0.121 U/mg), followed by injured leaves (0.040 U/mg) and healthy leaves (0.022 U/mg). The overall results exhibited that C. andropogonis infection affects the quality of secretory tissue and increases PAL enzyme activity as a form of defense. By detecting secretory tissue and defense enzymes after infection, further research can be carried out regarding controlling Curvularia andropogonis infections by engineering enzymes and secondary metabolites.