Spraying alginate oligosaccharide improves photosynthetic performance and sugar accumulation in citrus by regulating antioxidant system and related gene expression

Preserving refrigeration and shelf life quality of hardy kiwifruit (Actinidia arguta) with alginate oligosaccharides preharvest application

Alginate oligosaccharide (AOS) is a bioactive carbohydrate known for its preservation properties. However, the efficacy of preharvest AOS treatment in maintaining the postharvest quality of hardy kiwifruit (Actinidia arguta) has not been previously reported. This study explores the effects of preharvest AOS treatment (80 mg L-1) on A. arguta fruit, assessing visual quality, physiological attributes, aroma, and antioxidant capacity during refrigeration and shelf life. Results showed that AOS treatment maintained higher lightness, chroma, firmness, and antioxidant levels (total phenolics, flavonoids, ascorbic acid, and glutathione), along with antioxidant enzyme activities (peroxidase, catalase, and ascorbate peroxidase). Specifically, AOS-treated fruit had 9% higher chroma and double the firmness after 60 days of refrigeration. AOS treatment reduced ripening and senescence, with 25% lower soluble solids content, 22% lower respiration rate, 30% lower ethylene production, and 35% lower malondialdehyde content. Electronic nose analysis indicated that AOS treatment suppressed changes in fruit aroma and off-odor development, maintaining significantly higher quality during the shelf life period. These findings demonstrate the effectiveness of AOS as a sustainable method to extend shelf life and preserve the quality of A. arguta fruit, enhancing its market value and consumer appeal. PRACTICAL APPLICATION: The research on using alginate oligosaccharides (AOS) for preharvest treatment of hardy kiwifruit (Actinidia arguta) has practical applications in the food industry. By extending the shelf life and preserving the quality of the fruit during storage, this method can help reduce postharvest losses and improve the market value and consumer appeal of A. arguta fruit. This sustainable preservation technique offers an eco-friendly alternative to traditional methods, enhancing the freshness and nutritional quality of the fruit available to consumers.

Condensed tannins from Pinus radiata bark: Extraction and their nanoparticles preparation in water by green method

This work reports for the first time the production of condensed tannin nanoparticles stable in water via modification with glycine betaine. Pine bark, as a byproduct from the paper industry, was used as a source of condensed tannins of high molecular weight. Different glycine betaine concentrations were tested to produce condensed tannin nanoparticles, and the obtained nanoparticles were subjected to several characterization techniques (Dynamic Light Scattering, Field emission scanning electron microscopy, Zeta potential, Fourier transform infrared spectroscopy-Attenuated total reflectance, thermogravimetric analysis). The results showed that the highest stability possessed nanoparticles with 40 wt% glycine betaine. The average particle size distribution evaluated by scanning microscopy was 124 nm. Besides, the glycine betaine-modified condensed tannin nanoparticles demonstrated higher thermal stability with the starting degradation temperature at 238 °C. Finally, obtained nanoparticles showed an antioxidant capacity of 34,209 ± 2194 μmol ET/100 g and low cytotoxicity towards healthy human cells, representing the high potential to be used as a carrier of active compounds in agriculture, food, drug and medical sector.

Xylooligosaccharides Enhance Lettuce Root Morphogenesis and Growth Dynamics

Enhancing root development is pivotal for boosting crop yield and augmenting stress resilience. In this study, we explored the regulatory effects of xylooligosaccharides (XOSs) on lettuce root growth, comparing their impact with that of indole-3-butyric acid potassium salt (IBAP). Treatment with XOS led to a substantial increase in root dry weight (30.77%), total root length (29.40%), volume (21.58%), and surface area (25.44%) compared to the water-treated control. These enhancements were on par with those induced by IBAP. Comprehensive phytohormone profiling disclosed marked increases in indole-3-acetic acid (IAA), zeatin riboside (ZR), methyl jasmonate (JA-ME), and brassinosteroids (BRs) following XOS application. Through RNA sequencing, we identified 3807 differentially expressed genes (DEGs) in the roots of XOS-treated plants, which were significantly enriched in pathways associated with manganese ion homeostasis, microtubule motor activity, and carbohydrate metabolism. Intriguingly, approximately 62.7% of the DEGs responsive to XOS also responded to IBAP, underscoring common regulatory mechanisms. However, XOS uniquely influenced genes related to cutin, suberine, and wax biosynthesis, as well as plant hormone signal transduction, hinting at novel mechanisms of stress tolerance. Prominent up-regulation of genes encoding beta-glucosidase and beta-fructofuranosidase highlights enhanced carbohydrate metabolism as a key driver of XOS-induced root enhancement. Collectively, these results position XOS as a promising, sustainable option for agricultural biostimulation.

Role of gamma-irradiated sodium alginate on growth, physiological and active components of iceberg lettuce (Lactuca sativa) plant

BACKGROUND

One of the most widely recognized biostimulators of plant development; is oligoalginate, which regulates the biological processes of plants and was used in horticultural fields as a plant growth regulator. The plan of the current research was to study, however, the foliar application of un-irradiated and irradiated Na-alginate (UISA and ISA) to improve the growth, physiological activity, and other active components of the Egyptian iceberg lettuce plant. Degraded Na-alginate is equipped with exposure of sodium alginate in its solid state to gamma-rays at different dose levels (0.0, 25, 50, 75, and 100 kGy). The characterization of the oligo-alginates achieved by γ-radiation deprivation at different dose levels was performed by FTIR, XRD, TGA, SEM, and TEM. Different concentrations of irradiated sodium alginate at dose levels of 100 kGy (200, 400, 600, and 800 ppm, as well as deionized water used as a control) were sprayed with a hand sprayer every week after transplanting the iceberg lettuce seedlings in the field until the harvest stage. Morphological traits were evaluated, as well as pigments, ascorbic acid, phenols, flavonoids, soluble proteins, and antioxidant activity.

RESULTS

Irradiated Na-alginate resulted in the depolymerization of Na-alginate into small molecular-weight oligosaccharides, and the best dose to use was 100 kGy. Certain chemical modifications in the general structure were observed by FTIR analysis. Two absorbed bands at 3329 cm-1 and 1599 cm-1, were recognized that are assigned to O-H and C-O stretching, respectively, and peaks achieved at 1411 cm-1 represent the COO-stretching group connected to the sodium ion. The peak obtained at 1028 cm-1 was owing to the stretching vibration of C-O. The results of TGA provided that the minimum weight reminder was in the ISA at 100 kGy (28.12%) compared to the UISA (43.39%). The images of TEM pointed out that the Na-alginate was globular in shape, with the particle distribution between 12.8 and 21.7 nm in ISA at 100 kGy. Irradiated sodium alginate caused a noteworthy enhancement in the vegetative growth traits (leaf area, stem length, head weight, and leaf number). By spraying 400 ppm, ISA showed a maximum increase in total pigments (2.209 mg/g FW), ascorbic acid (3.13 mg/g fresh weight), phenols (1.399 mg/g FW), flavonoids (0.775 mg/g FW), and antioxidant activities (82.14. %). Also, there were correlation coefficients (R values) between leaf area, stem length, head weight, and leaf number values with total pigment content, antioxidant activity, total soluble proteins, and ascorbic acid.

CONCLUSIONS

The outcomes of the recent investigation demonstrated that the application of spraying irradiated Na-alginate (100 kGy) resulted in an improvement of the considered characters.

Advances in alginate lyases and the potential application of enzymatic prepared alginate oligosaccharides: A mini review

Alginate is mainly a linear polysaccharide composed of randomly arranged β-D-mannuronic acid and α-L-guluronic acid linked by α, β-(1,4)-glycosidic bonds. Alginate lyases degrade alginate mainly adopting a β-elimination mechanism, breaking the glycosidic bonds between the monomers and forming a double bond between the C4 and C5 sugar rings to produce alginate oligosaccharides consisting of 2-25 monomers, which have various physiological functions. Thus, it can be used for the continuous industrial production of alginate oligosaccharides with a specific degree of polymerization, in accordance with the requirements of green exploitation of marine resources. With the development of structural analysis, the quantity of characterized alginate lyase structures is progressively growing, leading to a concomitant improvement in understanding the catalytic mechanism. Additionally, the use of molecular modification methods including rational design, truncated expression of non-catalytic domains, and recombination of conserved domains can improve the catalytic properties of the original enzyme, enabling researchers to screen out the enzyme with the expected excellent performance with high success rate and less workload. This review presents the latest findings on the catalytic mechanism of alginate lyases and outlines the methods for molecular modifications. Moreover, it explores the connection between the degree of polymerization and the physiological functions of alginate oligosaccharides, providing a reference for enzymatic preparation development and utilization.

The roles of novel chitooligosaccharide-peanut oligopeptide carbon dots in improving the flavor quality of Chinese cabbage

Carbon dots (CDs), a novel type of nanomaterial, play crucial roles in the agriculture field. However, it remains unclear their impacts on the flavor quality of vegetables. The present study synthesized a novel chitooligosaccharide-peanut oligopeptide-carbon dots (COS-POP-CDs) material through the chitooligosaccharide (COS) and peanut oligopeptide (POP) high temperature Maillard reactions and studied its effect on the flavor quality of Chinese cabbage (Choy sum). Results indicated that COS-POP-CDs emit blue visible light that readily absorbed by chloroplasts, while also demonstrating some degree of antibacterial and antioxidant activities. After transplanting of Choy sum, foliar spraying 0.12 mg/mL COS-POP-CDs twice can increase the content of soluble proteins, Vitamin C, and enhance the strawberry and spicy flavors of Choy Sum. After harvest of Choy Sum, foliar spraying 0.12 mg/mL COS-POP-CDs once can slow down the spoilage. These results suggest that COS-POP-CDs have significant potential to improve crop quality.

Effects of Mars Global Simulant (MGS-1) on Growth and Physiology of Sweet Potato: A Space Model Plant

Growing food autonomously on Mars is challenging due to the Martian soil's low nutrient content and high salinity. Understanding how plants adapt and evaluating their nutritional attributes are pivotal for sustained Mars missions. This research delves into the regeneration, stress tolerance, and dietary metrics of sweet potato (Ipomoea batatas) across different Mars Global Simulant (MGS-1) concentrations (0, 25, 50, and 75%). In our greenhouse experiment, 75% MGS-1 concentration significantly inhibited sweet potato growth, storage root biomass, and chlorophyll content. This concentration also elevated the plant tissues' H2O2, proline, and ascorbic acid levels. Higher MGS-1 exposures (50 and 75%) notably boosted the vital amino acids and sugar groups in the plant's storage roots. However, increased MGS-1 concentrations notably diminished the total C:N ratio and elemental composition in both the vines and storage roots. In summary, sweet potato exhibited optimal growth, antioxidant properties, yield, and nutrient profiles at 25% MGS-1 exposure as compared to higher concentrations. This study underscores the need for future interventions, like nutrient enhancements and controlled metal accessibility, to render sweet potato a suitable plant for space-based studies.

Microwave Assisted Extraction of Raw Alginate as a Sustainable and Cost-Effective Method to Treat Beach-Accumulated Sargassum Algae

This paper highlights the potential of Sargassum algae, recovered from raw beach seaweed wastes, as a valid source of valuable sodium alginate. Alginate is a biodegradable, highly attractive polysaccharide widely used in food, pharmaceuticals, and biomedicine applications. The aim of this work is to employ a new eco-sustainable and cost-effective extractive method to obtain alginate as a raw material from pollutant organic Sargassum seaweeds. Algae were exposed to microwave pre-treatment under static and dynamic conditions, and three different extractive protocols were followed: (a) conventional, (b) hot water and (c) alkaline method. All samples were characterized by GPC, SEM, FTIR/ATR and TGA. It was found that alginate's best performances were obtained by the microwave dynamic pre-treatment method followed by alkaline extractive protocol. Nevertheless, the microwave pre-treatment of algae allowed the easiest breaking of their cell walls and the following fast releasing of sodium alginate. The authors demonstrated that microwave-enhanced extraction is an effective way to obtain sodium alginate from Sargassum-stranded seaweed waste materials in a cost-effective and eco-sustainable approach. They also assessed their applications as mulching films for agricultural applications.

Recent advances in the production, properties and applications of alginate oligosaccharides - a mini review

Alginate oligosaccharides (AOS) made from the degradation of alginate, to some extent, makes up for the poor solubility and bioavailability of alginate as a macromolecular substance and possess several beneficial biological activities that are absent in alginate. These properties include prebiotic, glycolipid regulatory, immunomodulatory, antimicrobial, antioxidant, anti-tumor, promoting plant growth and other activities. Consequently, AOS has significant potential for use in the agricultural, biomedical, and food industries, and has been the focus of research in the field of marine biological resources. This review comprehensively covers methods (physical, chemical, and enzymatic methods) for the production of AOS from alginate. More importantly, this paper reviews recent advances in the biological activity and potentially industrial and therapeutic applications of AOS, providing a reference for future research and applications of AOS.