Approaches in biotechnological applications of natural polymers

Natural polymers, such as gums and mucilage, are biocompatible, cheap, easily available and non-toxic materials of native origin. These polymers are increasingly preferred over synthetic materials for industrial applications due to their intrinsic properties, as well as they are considered alternative sources of raw materials since they present characteristics of sustainability, biodegradability and biosafety. As definition, gums and mucilages are polysaccharides or complex carbohydrates consisting of one or more monosaccharides or their derivatives linked in bewildering variety of linkages and structures. Natural gums are considered polysaccharides naturally occurring in varieties of plant seeds and exudates, tree or shrub exudates, seaweed extracts, fungi, bacteria, and animal sources. Water-soluble gums, also known as hydrocolloids, are considered exudates and are pathological products; therefore, they do not form a part of cell wall. On the other hand, mucilages are part of cell and physiological products. It is important to highlight that gums represent the largest amounts of polymer materials derived from plants. Gums have enormously large and broad applications in both food and non-food industries, being commonly used as thickening, binding, emulsifying, suspending, stabilizing agents and matrices for drug release in pharmaceutical and cosmetic industries. In the food industry, their gelling properties and the ability to mold edible films and coatings are extensively studied. The use of gums depends on the intrinsic properties that they provide, often at costs below those of synthetic polymers. For upgrading the value of gums, they are being processed into various forms, including the most recent nanomaterials, for various biotechnological applications. Thus, the main natural polymers including galactomannans, cellulose, chitin, agar, carrageenan, alginate, cashew gum, pectin and starch, in addition to the current researches about them are reviewed in this article.. }To the Conselho Nacional de Desenvolvimento Cientfíico e Tecnológico (CNPq) for fellowships (LCBBC and MGCC) and the Coordenação de Aperfeiçoamento de Pessoal de Nvíel Superior (CAPES) (PBSA). This study was supported by the Portuguese Foundation for Science and Technology (FCT) under the scope of the strategic funding of UID/BIO/04469/2013 unit, the Project RECI/BBB-EBI/0179/2012 (FCOMP-01-0124-FEDER-027462) and COMPETE 2020 (POCI-01-0145-FEDER-006684) (JAT)

Redox-active ash gourd extract mitigates salt-stress toxicity through modulation of primary metabolites in rice

Salinity stress is considered as one of the major detrimental stresses for reducing plant growth and crop productivity. Hence, concerted efforts are going on to develop sustainable solutions for reducing salinity-induced negative effects on crop productivity. Given this, the present study evaluated the potential of ash gourd extract (AGE; 0.9 µg/mL) for ameliorating NaCl (100 mM) stress in rice, which is one of the major staple food crops worldwide. The differential phenotyping revealed growth reduction under NaCl treatment, as indicated by 0.27- and 0.36-fold decrease in survival and whole-seedling biomass, respectively, compared with those of control. In contrast, 24 h pre-treatment with AGE before NaCl exposure (AGE24h+NaCl) improved these growth attributes by 1.29- and 1.70-fold, respectively, compared with those of NaCl treatment. The differential phenotype of AGE was associated with its inherent ability to scavenge reactive oxygen species, which was equivalent to 0.08-fold of ascorbic acid. The higher accumulation of superoxide radicals and upregulated expression of stress marker genes including OsTSPO, OsCBS, OsHKT1;5, and OsNHX1 under AGE24h treatment also suggested AGE mediated priming effect. Under AGE24h+NaCl, the expression levels of these stress markers were either maintained or their extent of upregulation was further enhanced. In addition, the coordinated activation of antioxidant machinery and reduced Na-accumulation further supported stress amelioration under AGE24h+NaCl treatment. GC-MS-based metabolomics highlighted fatty acids, malic acid, myo-inositol, allose, trehalose, and L-oxoproline, as key metabolites, associated with AGE-mediated amelioration of NaCl stress. The foliar application of AGE increased seed yield and 1000 seed weight by 1.13- and 1.06-fold, respectively, compared with those of NaCl, validating its agronomic feasibility. Thus, the results highlighted the application of AGE, as a “green” bioregulator for ameliorating NaCl stress conditions in rice