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Drought is the most prominent limiting factor to crop productivity. Banana, one of the most important food crops globally, is highly susceptible to drought. However, how banana plants respond to drought stress and post-drought recovery remains unclear. Therefore, this study determined the morphological and protein responses of banana plants (Musa acuminata cultivar Berangan) affected by drought stress, followed by recovery. The results showed that drought significantly reduced the leaf area, plant height, fresh weight, stem circumference, leaf relative water content, chlorophyll contents, and root length of the bananas. In contrast, relative electrolyte leakage, proline, malondialdehyde (MDA) and hydrogen peroxide contents, and the activities of antioxidant enzymes, including catalase (CAT), ascorbate peroxidase (APX), glutathione reductase (GR), peroxidase, and superoxide dismutase, were induced in the drought-treated banana leaves. However, after recovering from drought stress, the relative water content, MDA, hydrogen peroxide, and antioxidant enzyme activities, including CAT, APX, and GR, were comparable with well-watered plants. To determine the protein responses of bananas toward drought stress, the well-watered, drought-stressed, and recovered banana leaves were sampled for tandem mass tags-based quantitative proteomics analysis. Of the 1018 differentially abundant proteins, 274 were significantly changed. The identified proteins differing between the treatments were mainly related to carbohydrate, energy and amino acid metabolisms, genetic information processing, and secondary metabolite biosynthesis. Our data may assist in developing a complete proteome dataset which could be valuable for developing drought-tolerant bananas. [ABSTRACT FROM AUTHOR]

Utilisation of calcium lignosulfonate (CaLS) in Vanilla planifolia has been reported to improve shoot multiplication. However, mechanisms responsible for such observation remain unknown. Here, we elucidated the underlying mechanisms of CaLS in promoting shoot multiplication of V. planifolia via comparative proteomics, biochemical assays, and nutrient analysis. The proteome profile of CaLS-treated plants showed enhancement of several important cellular metabolisms such as photosynthesis, protein synthesis, Krebs cycle, glycolysis, gluconeogenesis, and carbohydrate synthesis. Further biochemical analysis recorded that CaLS increased Rubisco activity, hexokinase activity, isocitrate dehydrogenase activity, total carbohydrate content, glutamate synthase activity and total protein content in plant shoot, suggesting the role of CaLS in enhancing shoot growth via upregulation of cellular metabolism. Subsequent nutrient analysis showed that CaLS treatment elevated the contents of several nutrient ions especially calcium and sodium ions. In addition, our study also revealed that CaLS successfully maintained the cellular homeostasis level through the regulation of signalling molecules such as reactive oxygen species and calcium ions. These results demonstrated that the CaLS treatment can enhance shoot multiplication in V. planifolia Andrews by stimulating nutrient uptake, inducing cell metabolism, and regulating cell homeostasis. [ABSTRACT FROM AUTHOR]

Simple Summary: Vacuolar processing enzyme (VPE) is a cysteine protease responsible for vacuolar proteins' maturation and regulation of programmed cell death in plants. Among four isoforms of Arabidopsis thaliana VPEs, only the functions of βVPE, γVPE, and δVPE were determined. Hence, to investigate the possible function of αVPE, promoter analysis, co-expression network, gene expression profiling, and loss of function studies were performed. Repetitive drought-related cis-elements such as ABRE, MBS, MYC, and MYB were successfully identified with the aid of PlantCARE and PLACE databases. Similarly, the co-expression network also revealed that genes interacting with αVPE were involved in drought-regulation-related function. In addition, A. thaliana under drought treatment recorded an upregulation of αVPE expression (2.7-fold). Loss of function study through αvpe knockout mutants showed that αvpe mutants remained viable with 22% higher water retention as compared with wild-type after drought treatment. Biochemical analyses recorded a 47% reduction in proline activity, 70% decrease in sucrose content, and 39% lower MDA content, but 50% increased photosynthetic pigments in αvpe mutants. Altogether, our study provided important proof and a foundation for understanding the involvement of αVPE in modulating drought tolerance in A. thaliana. Vacuolar processing enzyme (VPE) is a cysteine protease responsible for vacuolar proteins' maturation and regulation of programmed cell death (PCD). Four isoforms of Arabidopsis thaliana VPEs were identified previously, but only the functions of βVPE, γVPE, and δVPE were determined. The specific function of a gene is linked to the cis-acting elements in the promoter region. A promoter analysis found repetitive drought-related cis-elements in αVPE, which highlight its potential involvement in drought regulation in A. thaliana. The further co-expression network portraying genes interacting with αVPE substantiated its drought-regulation-related function. Expression of αVPE was upregulated after drought treatment in A. thaliana. To confirm the role of αVPE, a loss of function study revealed that αVPE knockout mutants remained green compared with WT after drought treatment. The mutants had reduced proline activity, decreased sucrose content, and lower MDA content, but increased photosynthetic pigments, indicating that αVPE negatively regulates drought tolerance in A. thaliana. Taken together, our findings serve as important evidence of the involvement of αVPE in modulating drought tolerance in A. thaliana. [ABSTRACT FROM AUTHOR]

Vandachostylis 'Sri-Siam' is a fragrant orchid, suitable as a potted plant for the floriculture and perfumery industries due to its sweet citrus-like fragrance. Fragrance from the flowers was captured using SPME and subjected to GC–MS analysis. A transcriptome library was constructed from the tepals for sequencing using the Illumina MiSeq Desktop Sequencer and for de novo assembly using the CLC Genomic Workbench version 6.0. All de novo assembly sequences were subjected to bioinformatics analyses including BLASTx analysis, functional annotations and mapping of the annotated genes/gene products to the KEGG database using the Blast2go Pro software. GC–MS analysis reveals the fragrance are dominated by 68.73% monoterpenes, 11.26% esters, 4.20% sesquiterpenes and traces of alcohols (1.20%), dissimilar to both its parents. Analysis of the de novo assembly sequences generated 45,585 contigs which identified 14 fragrance-related transcripts. Information on the fragrance constituents and fragrance-related transcripts is deemed important as a reference for current and future work of using this hybrid in the breeding process of commercially valuable fragrant orchids. [ABSTRACT FROM AUTHOR]

Banana (Musa acuminata) is an important fruit crop and source of income for various countries, including Malaysia. To date, current agrochemical practice has become a disputable issue due to its detrimental effect on the environment. λ-carrageenan, a natural polysaccharide extracted from edible red seaweed, has been claimed to be a potential plant growth stimulator. Hence, the present study investigates the effects of λ-carrageenan on plant growth using Musa acuminata cv. Berangan (AAA). Vegetative growth such as plant height, root length, pseudostem diameter, and fresh weight was improved significantly in λ-carrageenan-treated banana plants at an optimum concentration of 750 ppm. Enhancement of root structure was also observed in optimum λ-carrageenan treatment, facilitating nutrients uptake in banana plants. Further biochemical assays and gene expression analysis revealed that the increment in growth performance was consistent with the increase of chlorophyll content, protein content, and phenolic content, suggesting that λ-carrageenan increases photosynthesis rate, protein biosynthesis, and secondary metabolites biosynthesis which eventually stimulate growth. Besides, λ-carrageenan at optimum concentration also increased catalase and peroxidase activities, which led to a significant reduction in hydrogen peroxide and malondialdehyde, maintaining cellular homeostasis in banana plants. Altogether, λ-carrageenan at optimum concentration improves the growth of banana plants via inducing metabolic processes, enhancing nutrient uptake, and regulation of cell homeostasis. Further investigations are needed to evaluate the effectiveness of λ-carrageenan on banana plants under field conditions. [ABSTRACT FROM AUTHOR]

Vanda 'Tan Chay Yan', a beautiful golden-orange orchid with mild fragrance, is valuable in the floral industry. In this study, the volatile compounds from the flowers were profiled and a transcriptome library was created to search for fragrance-related transcripts. Volatiles from the tepals were captured using a SPME device with PDMS-coated fibre for GC-MS analysis. A transcriptome library was constructed and sequenced using the Illumina MiSeq Desktop Sequencer, de novo assembled using CLC Genomic Workbench version 6.0. BLASTx analysis, functional annotations and gene mapping of the annotated genes to the KEGG database were carried out using the Blast2go Pro software. Twelve compounds were identified in the volatiles including monoterpenes (93.19%), sesquiterpenes (4.32%) and traces of other compounds (2.49%) whereby cis-β-ocimene topped the list as the major constituent (88.41%). De novo assembly of the transcriptome generated a total of 34,027 sequences from which 20 fragrance-related transcripts in the terpenoid and benzenoid/phenylpropanoid biosynthetic pathways were identified. Combined information garnered from the volatiles and fragrance-related transcripts highlights the basic information on the fragrance constituents and biosynthetic pathways of this orchid which are useful for orchid breeders in selection of parents for new hybrids with fragrance as their value-added characteristic for the floriculture industry. [ABSTRACT FROM AUTHOR]

Fusarium oxysporum f. sp. cubense tropical race 4 (Foc TR4) is a destructive necrotrophic fungal pathogen afflicting global banana production. Infection process involves the activation of programmed cell death (PCD). In this study, seven Musa acuminata vacuolar processing enzyme (MaVPE1 – MaVPE7) genes associated with PCD were successfully identified. Phylogenetic analysis and tissue-specific expression categorized these MaVPEs into the seed and vegetative types. Foc TR4 infection induced the majority of MaVPE expressions in the susceptible cultivar "Berangan" as compared to the resistant cultivar "Jari Buaya." Consistently, upon Foc TR4 infection, high caspase-1 activity was detected in the susceptible cultivar, while low level of caspase-1 activity was recorded in the resistant cultivar. Furthermore, inhibition of MaVPE activities via caspase-1 inhibitor in the susceptible cultivar reduced tonoplast rupture, decreased lesion formation, and enhanced stress tolerance against Foc TR4 infection. Additionally, the Arabidopsis VPE -null mutant exhibited higher tolerance to Foc TR4 infection, indicated by reduced sporulation rate, low levels of H2O2 content, and high levels of cell viability. Comparative proteomic profiling analysis revealed increase in the abundance of cysteine proteinase in the inoculated susceptible cultivar, as opposed to cysteine proteinase inhibitors in the resistant cultivar. In conclusion, the increase in vacuolar processing enzyme (VPE)-mediated PCD played a crucial role in modulating susceptibility response during compatible interaction, which facilitated Foc TR4 colonization in the host. [ABSTRACT FROM AUTHOR]

Plectranthus amboinicus (Lour.) Spreng, also known locally as "Bangun-bangun", is an aromatic medicinal herb known for its therapeutic and nutritional properties attributed to its terpenoid-rich phytochemicals. Information to assist in initiating appropriate harvesting time to maximize the yield of targeted chemicals in harvested plant tissues remains an issue that is seldom highlighted. This study reports on the essential oil distribution in P. amboinicus leaves, and total phenolic and flavonoid contents, in addition to GC-MS analysis of hexane extracts of the leaf samples collected at various times throughout the day. The influence of environmental factors on γ-terpinene, p-cymene, carvacrol, and thymoquinone are also discussed. Oil Red O staining showed the highest oil deposition at 2 p.m., which was consistent with the phenolic and flavonoid contents of this plant. GC-MS analysis of the leaf extract showed carvacrol (47.00–60.00%), γ-terpinene (8.00–10.00%), caryophyllene (~6.00%), p-cymene (4.90–6.50%), trans-α-bergamotene (4.70–5.00%), and thymoquinone (3.30–5.60%) were the major components of this plant. Interestingly, thymoquinone, a phytochemical associated with Nigella sativa, was also detected in this hexane-extracted sample with maximum accumulation during midday and a decrease at night, which could be due to the lower temperature and dimmer light conditions. The chemical polymorphism in the oil content indicated that environmental factors such as light exposure and temperature should be considered during harvesting to ensure consistent quality of the phytochemicals extracted from the plant materials. This study indicates that oversight in selecting plant materials might compromise the yield of quality phytochemicals extracted from harvested tissues. [ABSTRACT FROM AUTHOR]

Linalool and nerolidol are terpene alcohols that occur naturally in many aromatic plants and are commonly used in food and cosmetic industries as flavors and fragrances. In plants, linalool and nerolidol are biosynthesized as a result of respective linalool synthase and nerolidol synthase, or a single linalool/nerolidol synthase. In our previous work, we have isolated a linalool/nerolidol synthase (designated as PamTps1) from a local herbal plant, Plectranthus amboinicus, and successfully demonstrated the production of linalool and nerolidol in an Escherichia coli system. In this work, the biochemical properties of PamTps1 were analyzed, and its 3D homology model with the docking positions of its substrates, geranyl pyrophosphate (C10) and farnesyl pyrophosphate (C15) in the active site were constructed. PamTps1 exhibited the highest enzymatic activity at an optimal pH and temperature of 6.5 and 30 °C, respectively, and in the presence of 20 mM magnesium as a cofactor. The Michaelis–Menten constant (Km) and catalytic efficiency (kcat/Km) values of 16.72 ± 1.32 µM and 9.57 × 10–3 µM−1 s−1, respectively, showed that PamTps1 had a higher binding affinity and specificity for GPP instead of FPP as expected for a monoterpene synthase. The PamTps1 exhibits feature of a class I terpene synthase fold that made up of α-helices architecture with N-terminal domain and catalytic C-terminal domain. Nine aromatic residues (W268, Y272, Y299, F371, Y378, Y379, F447, Y517 and Y523) outlined the hydrophobic walls of the active site cavity, whilst residues from the RRx8W motif, RxR motif, H-α1 and J-K loops formed the active site lid that shielded the highly reactive carbocationic intermediates from the solvents. The dual substrates use by PamTps1 was hypothesized to be possible due to the architecture and residues lining the catalytic site that can accommodate larger substrate (FPP) as demonstrated by the protein modelling and docking analysis. This model serves as a first glimpse into the structural insights of the PamTps1 catalytic active site as a multi-substrate linalool/nerolidol synthase. [ABSTRACT FROM AUTHOR]

Lignosulfonate (LS) is a by-product obtained during sulfite pulping process and is commonly used as a growth enhancer in plant growth. However, the underlying growth promoting mechanism of LS on shoot growth remains largely unknown. Hence, this study was undertaken to determine the potential application of eco-friendly ion-chelated LS complex [sodium LS (NaLS) and calcium LS (CaLS)] to enhance recalcitrant indica rice MR 219 shoot growth and to elucidate its underlying growth promoting mechanisms. In this study, the shoot apex of MR 219 rice was grown on Murashige and Skoog medium supplemented with different ion chelated LS complex (NaLS and CaLS) at 100, 200, 300 and 400 mg/L The NaLS was shown to be a better shoot growth enhancer as compared to CaLS, with optimum concentration of 300 mg/L. Subsequent comparative proteomic analysis revealed an increase of photosynthesis-related proteins [photosystem II (PSII) CP43 reaction center protein, photosystem I (PSI) iron-sulfur center, PSII CP47 reaction center protein, PSII protein D1], ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco), carbohydrate metabolism-related proteins (glyceraldehyde-3-phosphate dehydrogenase 3, fructose-bisphosphate aldolase) and stress regulator proteins (peptide methionine sulfoxide reductase A4, delta-1-pyrroline-5-carboxylate synthase 1) abundance in NaLS-treated rice as compared to the control (MSO). Consistent with proteins detected, a significant increase in biochemical analyses involved in photosynthetic activities, carbohydrate metabolism and protein biosynthesis such as total chlorophyll, rubisco activity, total sugar and total protein contents were observed in NaLS-treated rice. This implies that NaLS plays a role in empowering photosynthesis activities that led to plant growth enhancement. In addition, the increased in abundance of stress regulator proteins were consistent with low levels of peroxidase activity, malondialdehyde content and phenylalanine ammonia lyase activity observed in NaLS-treated rice. These results suggest that NaLS plays a role in modulating cellular homeostasis to provide a conducive cellular environment for plant growth. Taken together, NaLS improved shoot growth of recalcitrant MR 219 rice by upregulation of photosynthetic activities and reduction of ROS accumulation leading to better plant growth. [ABSTRACT FROM AUTHOR]

Pluronic F-68 (PF-68) is a non-ionic surfactant used in plant tissue culture as a growth additive. Despite its usage as a plant growth enhancer, the mechanism underlying the growth-promoting effects of PF-68 remains largely unknown. Hence, this study was undertaken to elucidate the growth-promoting mechanism of PF-68 using recalcitrant MR 219 callus as a model. Supplementation of 0.04% PF-68 (optimum concentration) was shown to enhance callus proliferation. The treated callus recorded enhanced sugar content, protein content, and glutamate synthase activity as exemplified in the comparative proteome analysis, showing protein abundance involved in carbohydrate metabolism (alpha amylase), protein biosynthesis (ribosomal proteins), and nitrogen metabolism (glutamate synthase), which are crucial to plant growth and development. Moreover, an increase in nutrients uptake was also noted with potassium topping the list, suggesting a vital role of K in governing plant growth. In contrast, 0.10% PF-68 (high concentration) induced stress response in the callus, revealing an increment in phenylalanine ammonia lyase activity, malondialdehyde content, and peroxidase activity, which were consistent with high abundance of phenylalanine ammonia lyase, peroxidase, and peroxiredoxin proteins detected and concomitant with a reduced level of esterase activity. The data highlighted that incorporation of PF-68 at optimum concentration improved callus proliferation of recalcitrant MR 219 through enhanced carbohydrate metabolism, nitrogen metabolism, and nutrient uptake. However, growth-promoting effects of PF-68 are concentration dependent. [ABSTRACT FROM AUTHOR]

Plectranthus amboinicus (Lour.) Spreng is an aromatic medicinal herb known for its therapeutic and nutritional properties attributed by the presence of monoterpene and sesquiterpene compounds. Up until now, research on terpenoid biosynthesis has focused on a few mint species with economic importance such as thyme and oregano, yet the terpene synthases responsible for monoterpene production in P. amboinicus have not been described. Here we report the isolation, heterologous expression and functional characterization of a terpene synthase involved in P. amboinicus terpenoid biosynthesis. A putative monoterpene synthase gene (PamTps1) from P. amboinicus was isolated with an open reading frame of 1797 bp encoding a predicted protein of 598 amino acids with molecular weight of 69.6 kDa. PamTps1 shares 60–70% amino acid sequence similarity with other known terpene synthases of Lamiaceae. The in vitro enzymatic activity of PamTps1 demonstrated the conversion of geranyl pyrophosphate and farnesyl pyrophosphate exclusively into linalool and nerolidol, respectively, and thus PamTps1 was classified as a linalool/nerolidol synthase. In vivo activity of PamTps1 in a recombinant Escherichia coli strain revealed production of linalool and nerolidol which correlated with its in vitro activity. This outcome validated the multi-substrate usage of this enzyme in producing linalool and nerolidol both in in vivo and in vitro systems. The transcript level of PamTps1 was prominent in the leaf during daytime as compared to the stem. Gas chromatography-mass spectrometry (GC-MS) and quantitative real-time PCR analyses showed that maximal linalool level was released during the daytime and lower at night following a diurnal circadian pattern which correlated with the PamTps1 expression pattern. The PamTps1 cloned herein provides a molecular basis for the terpenoid biosynthesis in this local herb that could be exploited for valuable production using metabolic engineering in both microbial and plant systems. [ABSTRACT FROM AUTHOR]

Vanilla planifolia (V. planifolia) is a valuable orchidaceous plant, commonly grown for its pods that are used to produce the flavouring vanilla extract. Here, we evaluated the effect of calcium lignosulphonate (Ca-LIGN) and sodium lignosulphonate (Na-LIGN) on multiplication and regeneration of V. planifolia shoot tip culture. In 150 mg L−1 Ca-LIGN medium, the most number of shoots per explant (5.78 ± 0.63) was successfully obtained. Besides, Ca-LIGN also enhanced the shoot bud and primordial formation rate, as seen under scanning electron microscopy. In contrast, medium containing 150 mg L−1 Na-LIGN recorded the highest average of shoot length (4.72 ± 0.30 cm). Meanwhile, the best growth of root length (1.8 ± 0.32 cm) and root induction (96.67 ± 5.16%) were recorded on the explants treated with 150 mg L−1 Na-LIGN rooting medium. All rooted plantlets successfully acclimatized in the greenhouse (100.00% survival rate). Further biochemical analysis revealed that Ca-LIGN increased the total protein, chlorophyll, sugar, flavonoid and phenolic contents of V. planifolia. Notably, expression of both ribulose-1,5-bisphosphate carboxylase (Rubisco) and phosphoenolpyruvate carboxylase (PEPC) genes were also elevated under the treatment of Ca-LIGN, implying a positive role in the photosynthetic process. Taken together, LIGN being an environmental friendly product could be used to enhance the growth and micropropagation of V. planifolia. [ABSTRACT FROM AUTHOR]

This study was undertaken to evaluate growth-promoting effects of Pluronic F-68 (PF-68) on recalcitrant MR 219 rice callus. Our study shows that calli grown on Murashige and Skoog medium supplemented with 0.04% PF-68 significantly increased callus proliferation by 58.80% (fresh weight) and 23.98% (dry weight) while root formation from callus was enhanced by 28.57%. Enhanced callus proliferation was supported by biochemical analysis, whereby highest amount of soluble sugar (1.77 mg/mL) and protein (0.17 mg/mL) contents were recorded in calli grown on 0.04% PF-68. Furthermore, enhanced expression of sucrose synthase (2.65-folds) and NADH-dependent glutamate synthase (1.86-folds) genes in calli grown on 0.04% PF-68 also correlates with enhanced callus proliferation. In contrast, high concentration of PF-68 (0.10%) recorded highest amount of phenolic (0.74 mg/mL), flavonoid (0.08 mg/mL), and hydrogen peroxide content (0.06 mg/mL) as compared to other treatment groups indicates activation of plant defence mechanism towards stress. Similarly, high expression of 4-coumarate:CoA ligase 3 (1.28-folds), chalcone-flavonone isomerase (1.65-folds) and ascorbate peroxidase (1.61-folds) genes were observed in calli grown on 0.10% PF-68 further supports increasing stress caused by the high concentration of PF-68. Taken together, our study revealed that optimum concentration of PF-68 could improve recalcitrant rice callus proliferation via enhanced sugar metabolism and amino acid biosynthesis which are crucial towards plant growth and development. However, at high concentration, PF-68 induces stress in plant which enhance the production of secondary metabolite to maintain cellular homeostasis. [ABSTRACT FROM AUTHOR]

Carica papaya L. or commonly known as papaya, is a major tropical crop consumed worldwide either as a vegetable or fresh fruit or processed products. In Malaysia, papaya was initially planted as a smallholder crop throughout the country. Eventually after 15 years of breeding and selection, a new variety, named C. papaya L. var. Eksotika, was released by the Malaysian Agricultural Research and Development Institute (MARDI) in 1987. This event changed the outlook of papaya planting from a smallholder crop to a plantation crop. Despite the blooming papaya business, the industry faced various disease issues that jeopardize its future. The most devastating was the papaya dieback disease, which affected approximately 800 hectares of plantation, destroyed approximately 1 million trees nationwide with total losses estimated at US$ 58 million. Even though Eksotika is a favored commercial variety with good eating and aesthetic quality fruit, its potential for more lucrative distant markets is tarnished with its short-shelf life fruits. Several strategies had been reported to address the challenges faced by Eksotika specifically against the dieback disease and the fruit's short shelf-life. This review focuses on C. papaya L. var. Eksotika particularly on the strategies to address the challenges faced in order to sustain the economic value of this crop plant, which had contributed significantly to the Malaysian economy. [ABSTRACT FROM AUTHOR]

Despite wide applications in industries, phenol pollution leads to many health effects, and one of the technologies used to clean up phenol pollution is phytoremediation. The aim of this research was to assess the remediation ability of Ipomoea aquatica Forssk., which is easy to handle and and has a fast growth rate. Plantlet was grown in water spiked with 0.05, 0.10, 0.20, 0.30 and 0.40 g/L phenol, followed by daily observation of the plantlets morphology and tracking of phenol concentration in the water and plantlet extracts via 4-aminoantipyrine (4-AAP) assay. Plantlet's roots in 0.10 g/L phenol (57.42 ± 1.41 mm) were significantly longer (p < 0.05) than those of the control plantlets (43.57 ± 3.87 mm) in contrast to other phenol concentrations which had stunted roots growth. I. aquatica Forssk. was able to survive with 0.30 g/L phenol despite exhibiting yellowing of leaves and increased sensitivity to scarring on the stems. The plantlets were able to completely remove the phenol from the water spiked with phenol at 0.05 g/L after 12 days of growth. However, the highest average rate of phenol removal was 0.021 g/L/day from water spiked with 0.30 g/L phenol. Phenol analysis on the plantlets' extracts revealed that I. aquatica Forssk. had degraded the absorbed phenol. This observation is of significant interest as it highlights the potential of I. aquatica Forssk. for use as a phytoremediator to clean up phenol contaminated water. [ABSTRACT FROM AUTHOR]

Isoprenoids are a large, diverse group of secondary metabolites which has recently raised a renewed research interest due to genetic engineering advances, allowing specific isoprenoids to be produced and characterized in heterologous hosts. Many researches on metabolic engineering of heterologous hosts for increased isoprenoid production are focussed on Escherichia coli and yeasts. E. coli, as most prokaryotes, use the 2-C-methyl- d-erythritol-4-phosphate (MEP) pathway for isoprenoid production. Yeasts on the other hand, use the mevalonate pathway which is commonly found in eukaryotes. However, Lactococcus lactis is an attractive alternative host for heterologous isoprenoid production. Apart from being food-grade, this Gram-positive prokaryote uses the mevalonate pathway for isoprenoid production instead of the MEP pathway. Previous studies have shown that L. lactis is able to produce sesquiterpenes through heterologous expression of plant sesquiterpene synthases. In this work, we analysed the gene expression of the lactococcal mevalonate pathway through RT- qPCR to successfully engineer L. lactis as an efficient host for isoprenoid production. We then overexpressed the mvk gene singly or co-expressed with the mvaA gene as an attempt to increase β-sesquiphellandrene production in L. lactis. It was observed that co-expression of mvk with mvaA doubled the amount of β-sesquiphellandrene produced. [ABSTRACT FROM AUTHOR]

The emergence of antimicrobial resistance (AMR) has urged researchers to explore therapeutic alternatives, one of which includes the use of natural plant products such as essential oils (EO). In fact, EO obtained from clove, oregano, thymus, cinnamon bark, rosemary, eucalyptus, and lavender have been shown to present significant inhibitory effects on bacteria, fungi, and viruses; many studies have been done to measure EO efficacy against microorganisms. The strategy of combinatory effects via conventional and non-conventional methods revealed that the combined effects of EO–EO or EO–antibiotic exhibit enhanced efficacy. This paper aims to review the antimicrobial effects of EO, modes of EO action (membrane disruption, efflux inhibition, increase membrane permeability, and decrease in intracellular ATP), and their compounds' potential as effective agents against bacteria, fungi, and viruses. It is hoped that the integration of EO applications in this work can be used to consider EO for future clinical applications. [ABSTRACT FROM AUTHOR]

Seaweeds survive in marine waters with high sulfate concentration compared to those living at freshwater habitats. The cell wall polymer of Gracilaria spp. which supplies more than 50% of the world agar is heavily sulfated. Since sulfation reduces the agar quality, it is interesting to investigate the effects of sulfate deprivation on the sulfate contents of seaweed and agar, as well as the metabolic pathways of these seaweeds. In this study, two agarophytes G. changii and G. salicornia were treated under sulfate deprivation for 5 days. The sulfate contents in the seaweed/agar were generally lower in sulfate-deprivated samples compared to those in the controls, but the differences were only statistically significant for seaweed sample of G. changii and agar sample of G. salicornia. RNA sequencing (RNA-Seq) of sulfate-deprivated and untreated seaweed samples revealed 1,292 and 3,439 differentially expressed genes (DEGs; ≥1.5-fold) in sulfate-deprivated G. changii and G. salicornia, respectively, compared to their respective controls. Among the annotated DEGs were genes involved in putative agar biosynthesis, sulfur metabolism, metabolism of sulfur-containing amino acids, carbon metabolism and oxidative stress. These findings shed light on the sulfate deprivation responses in agarophytes and help to identify candidate genes involved in agar biosynthesis. [ABSTRACT FROM AUTHOR]