PAL Activity Research Articles

Effect of Bio-Agents on Enzymatic Activity and Nematode Management in Tomato Plants Infected with Meloidogyne javanica

The tomato (Solanum esculentum Mill.) is one of the most widely cultivated vegetable crops worldwide. It serves as a favorable host for plant-parasitic nematodes, particularly the root-knot nematode (Meloidogyne javanica). Investigations were carried out to determine the effectiveness of bio-agents against root-knot nematodes in pot conditions. The bio-agents included Metarhizium anisopliae, Bacillus subtilis, Verticillium lecanii, Trichoderma harzianum and, Trichoderma asperellum) against root-knot nematode in pot condition. Effect of bio-agents was also estimated for accumulation of PPO and PAL and Root-knot nematode-infected tomato roots containing phenol. The results of the experiment showed that all the bio-agents significantly increased the levels of PPO, PAL, and phenol in tomato roots, improved plant growth parameters, and reduced nematode reproduction compared to the untreated control. The best treatment with the highest PPO, PAL, and phenol activity among the investigated bio-agents was determined to be Trichoderma harzianum at 3 gm/kg soil, followed by Bacillus subtilis and Metarhizium anisopliae. It improves the plant growth parameter and lowers the number of nematodes in the pot.

Chitosan, Methyl Jasmonate, and Silicon Induce Resistance to Angular Leaf Spot in Common Bean, Caused by Pseudocercospora griseola, with Expression of Defense-Related Genes and Enzyme Activities

This study assessed the efficacy of chitosan, methyl jasmonate, and silicon in the reduction of disease severity and the induction of defense responses in common bean plants against angular leaf spot caused by Pseudocercospora griseola. The expression level of several pathogenesis-related (PR) proteins, PR1, PR2 (β-1,3-glucanase), and PR3 (chitinase), and defense-related enzymes, phenylalanine ammonia-lyase, peroxidase, and lipoxygenase, was analyzed at different time points in common bean plants after different treatments. Elicitor treatments significantly reduced disease severity 21 days after inoculation, with silicon at a 2 mM concentration proving most effective with 38.93% disease control, followed by 1 mM MeJA and 2% chitosan, respectively. Treatments with chitosan, methyl jasmonate, and silicon, regardless of pathogen infection, significantly elevated PR1, PR2, and PR3 gene expressions at 48 h after inoculation (hpi). PAL and POD activities were similarly increased following elicitor treatments and pathogen infection, especially at 48 hpi. Chemical elicitors applied post-inoculation induced PR proteins, PAL, and POD enzyme activities at 48 hpi, while LOX activity exhibited a variable fluctuation with treatments. These findings suggested that chemical elicitors, especially silicon, were effective in reducing ALS disease severity in common beans, with improved resistance associated with the expression of pathogen-responsive genes. This study is the first to analyze the expression profiles of defense-related genes in common beans treated with chemical elicitors prior to P. griseola infection.

NaCl Stress Stimulates Phenolics Biosynthesis and Antioxidant System Enhancement of Quinoa Germinated after Magnetic Field Pretreatment.

Our previous study showed that magnetic field pretreatment promoted germination and phenolic enrichment in quinoa. In this study, we further investigated the effects of NaCl stress on the growth and phenolic synthesis of germinated quinoa after magnetic field pretreatment (MGQ). The results showed that NaCl stress inhibited the growth of MGQ, reduced the moisture content and weight of a single plant, but increased the fresh/dry weight. The higher the NaCl concentration, the more obvious the inhibition effect. In addition, NaCl stress inhibited the hydrolysis of MGQ starch, protein, and fat but increased the ash content. Moreover, lower concentrations (50 and 100 mM) of NaCl stress increased the content of MGQ flavonoids and other phenolic compounds. This was due to the fact that NaCl stress further increased the enzyme activities of PAL, C4H, 4CL, CHS, CHI, and CHR and up-regulated the gene expression of the above enzymes. NaCl stress at 50 and 100 mM increased the DPPH and ABTS scavenging capacity of MGQ and increased the activities of antioxidant enzymes, including SOD, POD, CAT, APX, and GSH-Px, further enhancing the antioxidant system. Furthermore, principal component analysis showed that NaCl stress at 100 mM had the greatest combined effect on MGQ. Taken together, NaCl stress inhibited the growth of MGQ, but appropriate concentrations of NaCl stress, especially 100 mM, helped to further increase the phenolic content of MGQ and enhance its antioxidant system.

Key factors uncovered by transcriptomic analysis in the regulation of glutamic acid repressing the browning of fresh-cut potatoes

Enzymatic browning is a major problem that seriously impacts the quality of fresh-cut potatoes. Our previous study found that glutamic acid (Glu) treatment could repress the discoloration of fresh-cut potatoes, but the molecular mechanism was still unknown. Herein, it was found that the content of total phenolic, H2O2, O2.- and the activities of PPO, POD and PAL were repressed, but the activities of CAT, APX, SOD and GPX were improved by Glu treatment. Moreover, transcriptomic analysis showed that an abundant number of differentially expressed genes (DEGs) were selected from fresh-cut potatoes browning between Glu and control groups. A comprehensive functional enrichment analysis showed that the metabolic pathways of glutathione metabolism, flavonoid biosynthesis, phenylalanine metabolism, phenylpropanoid biosynthesis, starch and sucrose metabolism, and plant hormone signal transduction were markedly enriched, which transcriptional levels were markedly altered by Glu treatment. RT-qPCR confirmed the results of RNA-Seq that Glu repressed the transcription of StPPO2, StPPO3, StPPO7, and StERF-BR1-like. More importantly, as a nuclear protein, StERF-BR1-like activated the transcription of StPPO2 by directly binding with its promoter. Overall, these data indicate that Glu could repress the browning of fresh-cut potatoes by regulating the pathways mentioned above, and StERF-BR1-like may involve this process by stimulating the expression of StPPO2.

NaCl inhibits Geotrichum citri-aurantii growth by inducing lipid droplets accumulation and enhances the biocontrol efficacy of Kloeckera apiculata 34-9

Decays resulting from infections by Geotrichum citri-aurantii cause a significant reduction in citrus postharvest quality and marketable yield. In the present work, 0.8 mol · L-1 NaCl of Generally Recognized as Safe (GRAS) salts were identified to have complete inhibition activity to G. citri-aurantii in vitro and in vivo. An inhibitory mechanism study showed that 0.1 mol · L-1 NaCl changed the expression of six genes (Gci002087, Gci003354, Gci000013, Gci000394, Gci003505 and Gci004433) in target of rapamycin (TOR) pathway, thus inducing a large number of lipid droplets (LDs) accumulation with TEM observations and staining. In vivo, 0.1 mol · L-1 NaCl could raise up the activities of CAT, PAL, PPO and cellulase which hence to strengthen the ability of resistance tolerance of citrus. In addition, NaCl not only accelerated the growth of the biocontrol yeast Kloeckera apiculata strain 34-9, but also increased the expression level of adhesin-encoding genes and biofilm-formation encoding gene (34-9 - 3691). Finally, the storage experiments in 3 months demonstrated that the combination of NaCl and the yeast 34-9 could keep fresh, reduce decay and prolong its shelf-life, thus implying that the combination of biocontrol strain and GRAS salts has been explored as a promising alternative to synthetic fungicides.

Mitigating the impact of Erysiphe Lonicerae on honeysuckle through preventive use of potassium dihydrogen phosphate and a comparative analysis of floral composition across three developmental stages

Honeysuckle, a key traditional Chinese medicinal herb, holds significant economic and therapeutic value. However, its three flowering stages lack clarity in component differentiation, leading to resource waste. Furthermore, the plant is consistently challenged by powdery mildew caused by Erysiphe lonicerae during cultivation. This study demonstrates that E. lonicerae reduces the flowering period from 12.4 to 8.6 days and alters the expression of two key flowering genes. However, foliar application of 0.1 % KH₂PO₄ three times weekly effectively mitigates the reduction in flowering duration. Initiating treatment at least one month prior to E. lonicerae inoculation significantly reduces the disease's impact, with earlier treatments proving more effective. Further, A comprehensive analysis of the three floral stages revealed significant metabolite and enzyme activity differences. We identified 175 differentially expressed metabolites (DEMs) between gold flowers and buds, 60 between gold and silver flowers, and 162 between buds and silver flowers, particularly in lipids, phenylpropanoids, and polyketides. Enzyme activities of PPD, SOD, PPO, and PAL, along with flavonoid content and antioxidant capacity, varied significantly across these stages. Notably, a total of 13 medicinal compounds were uniquely distributed across the floral stages, indicating that these compounds are not concentrated solely in the buds.In summary, The prophylactic use of KH₂PO₄ can effectively reduce the damage caused by E. lonicerae.The distinct metabolic profiles of the buds, silver flowers, and gold flowers highlight the need for further research into their optimal medicinal applications.

Enzymatic Characterization of SpPAL Genes in S. polyrhiza and Overexpression of the SpPAL3.

Phenylalanine ammonia-lyase (PAL, EC 4.3.1.5) catalyzes the deamination of phenylalanine, which is the initial step in the biosynthesis of phenylpropanoids. It serves as a crucial enzyme that facilitates the transfer of carbon from primary to secondary metabolism in plants. Duckweed is regarded as a promising chassis plant in synthetic biology research and application, due to its being rich in secondary metabolites and other advantages. The genes encoding PAL in Spirodela polyrhiza (L.) Schleid, the giant duckweed, were investigated in this study. Three SpPAL genes (SpPAL1-SpPAL3) were identified and cloned. All of them were successfully expressed in E. coli, and their recombinant proteins all showed PAL activity. In addition, SpPAL1 and SpPAL2 proteins could also utilize tyrosine as substrate, although the activity was low. A qRT-PCR analysis demonstrated that the expression of SpPAL3 was most pronounced in young fronds. It was found that the expression of SpPAL1 and SpPAL3 was significantly induced by MeJA treatment. Overexpression of SpPAL3 in Lemna turionifera inhibited the growth of fronds and adventitious roots in the transgenic plants, indicating the importance of SpPAL3 in duckweed besides its involvement in the secondary metabolism.

Synergistic suppression of grey mold on cut rose flower by combined application of methyl jasmonate and lipopeptides from Bacillus altitudinis

Roses are the most popular cut flowers that are widely used in various occasions and celebrations, yet can also be easily infected by grey mold caused by Botrytis cinerea; a notorious pathogen in the cut flower industry. A wide range of methods, including fungicides, have been used to control B. cinerea. Environmentally benign methods are increasingly sought after to minimize disease incidence. In this study, we evaluated 10 strains of Bacillus across eight species for their action against B. cinerea. Strains TM22A (Bacillus altitudinis) and S2 (Bacillus subtilis) were identified to be effective in disease suppression. Lipopeptides (LPs) were isolated from two strains, and their activity for inhibiting the growth of B. cinerea was tested. Additionally, methyl jasmonate (MeJA), a natural growth regulator, was evaluated for disease suppression using a in planta assay. Subsequently, LPs from TM22A and MeJA, alone or in combination, were evaluated for disease occurrence in cut rose flowers. Results showed that either LPs or MeJA at concentrations of 250 μmol/L significantly reduced lesion size and disease incidence. The combined application of LPs from TM22A with MeJA further reduced the disease occurrence in cut rose flowers. Furthermore, the activities of POD, PPO, PAL, CAT, and SOD enzymes were much higher in flowers treated with combined application of LPs from TM22A with MeJA. The enhanced suppression of B. cinerea is attributed to the antifungal effects of LPs and MeJA and activation of antioxidant enzymes. This study suggests that the combined application of LPs from TM22A with MeJA could be an environmentally friendly approach for control of grey mold disease in cut roses.

The ERF transcription factor SlERF7 promotes UV-C-induced biosynthesis of phenolic compounds in tomato

In this study, the molecular pathways of SlERF7 in regulating the synthesis and accumulation of phenolic compounds induced by postharvest UV-C in tomato fruit was deeply investigated by constructing transgenic plants. The findings revealed a pronounced induction of phenolic compounds accumulation following UV-C irradiation, coupled with heightened activities of PAL, 4CL, C4H, CHS, and CHI enzymes, alongside upregulated expression levels of SlPAL5, SlC4H, Sl4CL, SlCHS2, and SlCHI within SlERF7 overexpressed fruit. Conversely, SlERF7 knockout fruit exhibited diminished levels of phenolic compounds, enzyme activities, and gene expression after UV-C irradiation. Furthermore, subcellular localization analysis showed that SlERF7 was localized in the nucleus. Dual luciferase assay and electrophoretic mobility shift assay (EMSA) indicated that SlERF7 directly bound to the GCC-box in the SlPAL5 promoter and activated its transcriptional activity. Therefore, it was confirmed that SlERF7 might positively promote UV-C-induced phenolic biosynthesis in postharvest tomato fruit by targeting the promoter of SlPAL5.

Exploring the potential of cold plasma in Optimising quality and boosting antioxidant defence in fresh‐cut bamboo shoots

SummaryCold plasma (CP) is a promising technology for fresh‐cut fruits and vegetables. In this study, the effects of CP on postharvest senescence, especially from the perspective of oxidative response of fresh‐cut bamboo shoots were examined, including the colour, firmness, lignin content, reactive oxygen species (ROS) accumulation and antioxidant enzymatic activities. CP treatments delayed the browning of bamboo shoots indicating by the increase of L* and b* values and decrease of a* value. The browning inhibition coincided with the reduction of PPO activities up to 62% by CP at 20 kV. Cellulose and lignin accumulated during storage. CP at 30 kV accelerated lignification, whereas CP at 10 and 20 kV inhibited the increase. These results were also reflected by PAL, CAD and POD activities that were enhanced by CP at 30 kV and inhibited by CP at 10 and 20 kV. The content of O2− and H2O2 was significantly increased at the first 3 days and decreased afterwards, with a similar trend of antioxidant enzymes SOD and CAT. As smaller increases in H2O2 and O2− production in CP treated samples than in control were probably attributed to elevated CP‐induced SOD activity. In addition, there was a delay effect observed in the internal parts of bamboo shoots compared with the surface (<5 mm thick). CP extended the shelf‐life of bamboo shoots by triggering the antioxidant defence. CP at 20 kV exhibited the best preservative effect on fresh‐cut bamboo shoots.

The Eliciting Effect of Aqueous Extracts from Ascophyllum nodosum Algae on the Cultivation of Arugula (Eruca sativa Mill.) Microgreens

This study showed the eliciting effect of aqueous extracts from Ascophyllum nodosum on the development of Eruca sativa microgreens in a quartz-based substrate. There is no information in the literature on the impact of its use on the quality, bioactive compound content, and nutritional value of arugula microgreens. Assays that have been made include the following: total phenolic content (TPC), total flavonoid content (TFV), enzymes such as phenylalanine ammonia (PAL) and polyphenol oxidase (PPO), and enzymes involved in the scavenging of reactive oxygen species such as catalase (CAT) and superoxide dismutase (SOD). The antioxidant activity against DPPH (2,2-diphenyl-1-picrylhydrazyl) was also evaluated. The total phenolic content of arugula microgreens increased significantly after an application of aqueous extracts of A. nodosum to the substrate. The greatest increase in flavonoid content (89%) and antioxidant activity against DPPH (82%) was observed at a concentration of 2.5%. The highest increase in activity of CAT (68.2%), SOD (25%), PAL (13-fold), and PPO (84.2%) was observed with the application of 5% extract. In conclusion, the use of Ascophyllum nodosum algae affects TPC and TFV, antioxidant activity, PAL, PPO, SOD, and CAT in the microgreens studied. By prioritising organic and environmentally friendly extracts, growers can contribute to a more sustainable and healthier food system, especially in the case of the production of Eruca sativa microgreens.

Protecting celtuce (Lactuca sativa L. var. augustana) slices against storage-induced oxidative stress and discoloration by using diode laser exposure

Diode laser irradiation is a novel approach applied to preserve the quality of fresh commodities and minimise oxidative processes, including browning in fresh-cut products. The objective of this study was to investigate the efficacy of diode laser treatment in enhancing the quality of celtuce slices during refrigerated storage at 4 °C. The celtuce slices were subjected to a 660 or 450 nm diode laser for 5 min and then stored for 10 d. Both laser treatments hindered the progression of weight loss and firmness increase in the celtuce slices. The use of a 450 nm diode laser effectively prevented the development of browning and preserved the surface colour by inhibiting the increase in a* and overall colour difference values, as compared to other treatments, during storage for 10 d. The diode laser treatment suppressed the increase in oxidative stress by lowering the levels of MDA, H2O2, and O-2 while retaining a high level of DPPH scavenging activity, AsA, and antioxdant enzyme activities, including SOD, CAT, APX, and GR, in comparison to the untreated slices. The treatment enhanced chlorophylls content due to the up-regulation of LsHEMA1 gene and down-regulation of LsNYC1 gene. The treatment also inhibited factors involving enzymatic browning reaction by suppressing PAL activity, total phenols content, PPO activity and LsPPO gene expression. These suggest that the blue diode laser exposure at 450 nm for 5 min is an effective approach hindering oxidative stress and discoloration of celtuce slices during storage.

Effects of ultrasound with slightly acid electrolytic water on storage of sweet potato: Physiological, nutritional, sensory and microstructural characteristics

Effects of ultrasound (US, 300, 400 and 500 W) combined with slightly acid electrolytic water (SAEW) at 25, 40 and 55 °C on physiological, nutritional, sensory and microstructural characteristics of sweet potato tuberous roots (TRs, Pushu 32) during 10, 30 and 60 d of storage were investigated, to explore a potential postharvest preservation technique for TRs. Sweet potato TRs by US500+SAEW50 exhibited the strongest PAL activity (10.63 U g−1) at 30 d of storage and SOD activity (83,707.42 U g−1) at 60 d of storage, suggesting the activation of strong defense system. Sweet potato TRs by US500+SAEW50 also showed integral cell walls, and presented the highest sensory acceptability (73.45). In addition, rotting rate of the TRs treated by US500+SAEW50 was reduced by 55% after 6 months of storage as compared to the untreated TRs in industrial application. Therefore, US500+SAEW50 could be a promising postharvest preservation technique for sweet potato TRs.

Monitoring of parasite Orobanche cumana using Vis-NIR hyperspectral imaging combining with physio-biochemical parameterson host crop Helianthus annuus.

This study provided a non-destructive detection method with Vis-NIR hyperspectral imaging combining with physio-biochemical parameters in Helianthus annuus in response to Orobanche cumana infection that took insights into the monitoring of sunflower weed. Sunflower broomrape (Orobanche cumana Wallr.) is an obligate weed that attaches to the host roots of sunflower (Helianthus annuus L.) leading to a significant reduction in yield worldwide. The emergence of O. cumana shoots after its underground life-cycle causes irreversible damage to the crop. In this study, a fast visual, non-invasive and precise method for monitoring changes in spectral characteristics using visible and near-infrared (Vis-NIR) hyperspectral imaging (HSI) was developed. By combining the bands sensitive to antioxidant enzymes (SOD, GR), non-antioxidant enzymes (GSH, GSH + GSSG), MDA, ROS (O2-, OH-), PAL, and PPO activities obtained from the host leaves, we sought to establish an accurate means of assessing these changes and conducted imaging acquisition using hyperspectral cameras from both infested and non-infested sunflower cultivars, followed by physio-biochemical parameters measurement as well as analyzed the expression of defense related genes. Extreme learning machine (ELM) and convolutional neural network (CNN) models using 3-band images were built to classify infected or non-infected plants in three sunflower cultivars, achieving accuracies of 95.83% and 95.83% for the discrimination of infestation as well as 97.92% and 95.83% of varieties, respectively, indicating the potential of multi-spectral imaging systems for early detection of O. cumana in weed management.

Physiological-Biochemical Characteristics and a Transcriptomic Profiling Analysis Reveal the Postharvest Wound Healing Mechanisms of Sweet Potatoes under Ascorbic Acid Treatment.

Sweet potatoes are extremely vulnerable to mechanical wounds during harvesting and postharvest handling. It is highly necessary to take measures to accelerate wound healing. The effect of 20 g L-1 of ascorbic acid (AA) treatment on the wound healing of sweet potatoes and its mechanisms were studied. The results validated that AA treatment significantly reduced the weight loss rate and disease index. AA treatment effectively enhanced the formation speed of lignin and SPP at the wound sites, decreased the MDA content, and maintained the cell membrane integrity. AA enhanced the activities of PAL, C4H, 4CL, CAD, and POD and increased the contents of chlorogenic acid, caffeic acid, sinapic acid, ferulic acid, cinnamic acid, p-coumaryl alcohol, sinapyl alcohol, coniferyl alcohol, and lignin. Based on a transcriptomic analysis, a total of 1200 genes were differentially expressed at the sweet potato wound sites by the AA treatment, among which 700 genes were upregulated and 500 genes were downregulated. The KEGG pathway analysis showed that the differentially expressed genes were mainly involved in phenylalanine, tyrosine, and tryptophan biosynthesis; phenylpropanoid biosynthesis; and other wound healing-related pathways. As verified by a qRT-PCR, the AA treatment significantly upregulated the gene expression levels of IbSKDH, IbADT/PDT, IbPAL, and Ib4CL at the wound sties.

Streptomyces pratensis S10 Promotes Wheat Plant Growth and Induces Resistance in Wheat Seedlings against Fusarium graminearum.

Fusarium graminearum, a devastating fungal pathogen, causes great economic losses to crop yields worldwide. The present study investigated the potential of Streptomyces pratensis S10 to alleviate F. graminearum stress in wheat seedlings based on plant growth-promoting and resistance-inducing assays. The bioassays revealed that S10 exhibited multiple plant growth-promoting properties, including the production of siderophores, 1-aminocyclopropane-1-carboxylic acid deaminase (ACC), and indole-3-acetic acid (IAA), phosphate solubilization, and nitrogen fixation. Meanwhile, the pot experiment demonstrated that S10 improved wheat plant development, substantially enhancing wheat height, weight, root activity, and chlorophyll content. Consistently, genome mining identified abundant genes associated with plant growth promotion. S10 induced resistance against F. graminearum in wheat seedlings. The disease incidence and disease index reduced by nearly 52% and 65% in S10 pretreated wheat seedlings, respectively, compared with those infected with F. graminearum only in the non-contact inoculation assay. Moreover, S10 enhanced callose deposition and reactive oxygen species (ROS) accumulation and induced the activities of CAT, SOD, POD, PAL, and PPO. Furthermore, the quantitative real-time PCR (qRT-PCR) results indicated that S10 pretreatment increased the expression of SA- (PR1.1, PR2, PR5, and PAL1) and JA/ET-related genes (PR3, PR4a, PR9, and PDF1.2) in wheat seedlings upon F. graminearum infection. In summary, S. pratensis S10 could be an integrated biological agent and biofertilizer in wheat seedling blight management and plant productivity enhancement.

The Expression of Genes Involved in Synthesis of Bitter Acids and Xanthohumol and the Content of These Compounds in Aroma and Bitter Hop under Reduced Nitrogen Fertilisation

Hop (Humulus lupulus) is cultivated for industrial purposes, primarily for brewing, but also for pharmaceutical and cosmetic applications. The hop cones are valued for their secondary metabolites, including bitter acids and prenylflavonoids. The objective of the presented study was to investigate the impact of reducing nitrogen fertilisation on the activity of genes involved in the production of bitter acids and xanthohumol in cultivars Lubelski (aroma) and Magnat (bitter) grown in the field. Furthermore, the content of these compounds was determined. The results demonstrated that the majority of studied genes were expressed at a similar level despite the reduction in the nitrogen dose by 25–30%. Nitrogen dose influenced the activity of genes BCAT2, HS1, and PAL. Moreover, the differences in gene expression were observed between cultivars and developmental stages. The reduction in nitrogen dose did not result in a reduction in secondary metabolite content. The content of alpha and beta acids in Magnat was approximately 14.8% and 3.2%, respectively, while in Lubelski it was approximately 7.7% and 5.8%, respectively. The content of xanthohumol in both cultivars was approximately 0.7%.

Chitosan boosts ginger disease resistance: Insights from transcriptomic and metabolomic analyses

Chitosan exhibits efficacy in controlling ginger diseases, yet its systemic regulatory mechanisms remain unknown. This study explored the potential mechanisms underlying chitosan-regulated resistance by conducting physiological, comparative transcriptome, and metabolome analyses in Fusarium solani-inoculated ginger rhizomes with and without chitosan treatment. Chitosan treatment decreased decay severity and water loss, and reduced reactive oxygen species accumulation by enhancing antioxidant enzyme activities. Chitosan increased PAL, C4H, and CHI activities, along with elevated levels of lignin, total phenolic, total flavonoid, and the accumulation of suberin polyphenolic. RNA-seq analysis identified 1158 differentially expressed genes, predominantly involved in active oxygen and phenylpropanoid metabolism. Metabolomics identified 226 differential metabolites, including numerous phenylpropanoids and flavonoids. Integrated RNA-seq and metabolome analyses revealed chitosan's regulatory impact on gene expression and metabolite accumulation in the phenylpropanoid metabolism. These findings provide novel insights into chitosan's mechanisms against Fusarium solani.

Triacontanol ‘TRIA’ application to mitigate the adverse effects of drought and salinity stress under in vitro culture of date palm plants

Abstract This study was conducted to attempt adaptation to combined drought and salt stresses (DS) (PEG- 6000 + NaCl) in date palm cv. Barhee implanted in vitro, keeping in mind the detrimental influence of DS. In vitro experimentation was executed on P. dactylifera L. to examine the efficacy of the application of triacontanol (TRIA), on growth attributes, and some biochemical constituents under DS. The optimal treatment was 10 µg l–1 TRIA. Such treatment under DS improved the callus growth and increased its weight to 215.0 mg. This treatment also showed the highest response rate and the number of shoots per jar (72.23% and 10.30 shoots, respectively) under DS stress. TRIA enhanced DS tolerance by increasing the contents of osmoregulatory substances such as proline, total soluble carbohydrates, and total soluble proteins, were obtained by adding 20 and 10 mg l–1 TRIA. This treatment was also more effective under DS in increasing Ca2+, Mg2+, and K+, as well as Fe2+, and chlorophyll pigment. These results also indicate that using 10 µg l–1 TRIA as a supplement under DS can increase SOD, APX, and PAL activity, to 31.68, 3.377 unit g–1 min–1, and 33.78%, respectively. Data analysis also indicated that the application of 10 µg l–1 TRIA countered the DS-induced harmful effects by reducing the content of malondialdehyd (MDA) and H2O2 in stressed tissues to 1.06, and 1.278 μMg of fresh weight (FW). Our work could reveal detailed changes in the quantity and number of protein bands by SDS-PAGE. New protein bands appeared in both stressed with TRIA-treated plants. The result of the present study will be useful for rapid clonal propagation of date palm which can be used to enhance the tolerance of plants to drought and salt stress.

α-Lipoic acid treatment regulates enzymatic browning and nutritional quality of fresh-cut pear fruit by affecting phenolic and carbohydrate metabolism

Fresh-cut pear fruit is greatly impacted by enzymatic browning, and maintaining quality remains a challenge. This study examined the impact of exogenous α-lipoic acid (α-LA) treatment on enzymatic browning and nutritional quality of fresh-cut pears. Results revealed that 0.5 g/L α-LA treatment effectively maintained color and firmness, and inhibited the increase in microbial number. The α-LA treatment also reduced MDA and H2O2 contents, decreased PPO activity, and enhanced SOD, CAT, and PAL activities. The α-LA treatment notably upregulated phenolic metabolism-related gene expression, including PbPAL, Pb4CL, PbC4H, PbCHI and PbCHS, and then increasing total phenols and flavonoids contents. Furthermore, it also influenced carbohydrate metabolism-related gene expression, including PbSS, PbSPS, PbAI and PbNI, maintaining a high level of sucrose content. These findings indicated that α-LA treatment showed promise in reducing browning and enhancing fresh-cut pears quality, offering a potential postharvest method to prolong the lifespan and maintain nutritional quality.