https://cyberleninka.org/article/n/1302921.pdf

Plant biostimulants: Definition, concept, main categories and regulation

Chitosan is a biopolymer obtained from chitin, one of the most abundant and renewable materials on Earth Chitin is a primary component of cell walls in fungi, the exoskeletons of arthropods such as crustaceans, eg, crabs, lobsters and shrimps, and insects, the radulae of molluscs, cephalopod beaks, and the scales of fish and lissamphibians The discovery of chitin in 1811 is attributed to Henri Braconnot while the history of chitosan dates back to 1859 with the work of Charles Rouget The name of chitosan was, however, introduced in 1894 by Felix Hoppe-Seyler Chitosan has attracted major scientific and industrial interests from the late 1970s due to its particular macromolecular structure, biocompatibility, biodegradability and other intrinsic functional properties Chitosan and derivatives have practical applications in the food industry, agriculture, pharmacy, medicine, cosmetology, textile and paper industries, and in chemistry In recent years, chitosan has also received much attention in dentistry, ophthalmology, biomedicine and bioimaging, hygiene and personal care, veterinary medicine, packaging industry, agrochemistry, aquaculture, functional textiles and cosmetotextiles, catalysis, chromatography, beverage industry, photography, wastewater treatment and sludge dewatering, and biotechnology Nutraceuticals and cosmeceuticals are actually growing markets, and therapeutic and biomedical products should be the next markets in the development of chitosan Chitosan is also the object of numerous fundamental studies In this review, we highlight a selection of works on chitosan applications published over the past two decades

https://hal.archives-ouvertes.fr/hal-02402948/document

Applications of chitosan in food, pharmaceuticals, medicine, cosmetics, agriculture, textiles, pulp and paper, biotechnology, and environmental chemistry

Increasing temperature and consequent changes in climate adversely affect plant growth and development, resulting in catastrophic loss of wheat productivity. For each degree rise in temperature, wheat production is estimated to reduce by 6%. A detailed overview of morpho-physiological responses of wheat to heat stress may help formulating appropriate strategies for heat-stressed wheat yield improvement. Additionally, searching for possible management strategies may increase productivity and sustainability of growing wheat. The major findings from this review are as follows: (1) heat stress significantly reduces seed germination and seedling growth, cell turgidity, and plant water-use efficiency; (2) at a cellular level, heat stress disturbs cellular functions through generating excessive reactive oxygen species, leading to oxidative stress; (3) the major responses of wheat to heat stress include the enhancement of leaf senescence, reduction of photosynthesis, deactivation of photosynthetic enzymes, and generation of oxidative damages to the chloroplasts; (4) heat stress also reduces grain number and size by affecting grain setting, assimilate translocation and duration and growth rate of grains; (5) effective approaches for managing heat stress in wheat include screening available germplasm under field trials and/or employing marker-assisted selection, application of exogenous protectants to seeds or plants, mapping quantitative trait locus conferring heat resistance and breeding; (6) a well-integrated genetic and agronomic management option may enhance wheat tolerance to heat. However, the success of applying various techniques of heat stress management requires greater understanding of heat tolerance features, molecular cloning, and characterization of genes. The overall success of the complex plant heat stress management depends on the concerted efforts of crop modelers, molecular biologists, and plant physiologists.

/pdf/heat-stress-effects-and-management-in-wheat-a-review-ap23v8zq1r.pdf

Heat stress effects and management in wheat. A review

Electrophoretic deposition of chitosan-based composite coatings for biomedical applications: A review

Use of botanical insecticides for sustainable agriculture: Future perspectives

Chitosan is a natural biopolymer modified from chitins which act as a potential biostimulant and elicitor in agriculture. It is non-toxic, biodegradable and biocompatible which favors potentially broad application. It enhances the physiological response and mitigates the adverse effect of abiotic stresses through stress transduction pathway via secondary messenger(s). Chitosan treatment stimulates photosynthetic rate, stomatal closure through ABA synthesis; enhances antioxidant enzymes via nitric oxide and hydrogen peroxide signaling pathways, and induces production of organic acids, sugars, amino acids and other metabolites which are required for the osmotic adjustment, stress signaling, and energy metabolism under stresses. It is also known to form complexes with heavy metals and used as tool for phytoremediation and bioremediation of soil. Besides, this is used as antitranspirant compound through foliar application in many plants thus reducing water use and ensures protection from other negative effects. Based on such beneficial properties, chitosan is utilized in sustainable agricultural practices owing to changing climates. Our review gathers the recent information on chitosan centered upon the abiotic stress responses which could be useful in future crop improvement programs.

/pdf/application-of-chitosan-on-plant-responses-with-special-4tlam8ubkf.pdf

Application of chitosan on plant responses with special reference to abiotic stress

Biopolymer “Chitosan” has received much interest for potential wide application in agriculture due to its excellent biocompatibility, biodegradability and bioactivity. This naturally occurring molecule with interesting physiological potential has been getting more attention in recent years. Chitosan enhanced the efficacy of plants to reduce the deleterious effect of unfavorable conditions as well as on plant growth. Chitosan affects various physiological responses like plant immunity, defense mechanisms involving various enzymes such as, phenylalanine ammonium lyase, polyphenol oxidase, tyrosine ammonia lyase and antioxidant enzymes viz., activities superoxide dismutase, catalase and peroxide against adverse conditions. Recent studies have shown that chitosan induces mechanisms in plants against various biotic (fungi, bacteria, and insects) and abiotic (salinity, drought, heavy metal and cold) stresses and helps in formation of barriers that enhances plant's productivity. This paper takes a closer look at the physiological responses of chitosan molecule.

Chitosan as a promising natural compound to enhance potential physiological responses in plant: a review

The rising ambient temperature by plant cells is crucial for the timely activation of various molecular defences before the appearance of heat damage. The heat-threshold level varies considerably at different developmental stages. With a view to survive under heat stress, mechanisms of regulation at the molecular level enable plants to prosper. Traditional breeding contributed for improving heat tolerance meagrely. The genetic transformation approach needs to be accelerated that can mitigate harmful effects by developing improved thermotolerance of crop plants. In this background, a thorough understanding of physiological responses of plants to high temperature, mechanisms of heat tolerance and possible strategies is vital. Temperature changes are sensed through cellular responses due to signal transduction into the cell. A key ingredient for plants temperature sensing ability is a specialized histone protein, dubbed H2A.Z that wraps DNA into a more tightly packed structure. Further, metabolic reactions and internal conductance to CO 2 decrease Rubisco activation, inhibition of Rubisco activase and subsequently slowing down net photosynthesis (Pn). Importance of internal conductance to CO 2 , heat inducible transcription factor for heat shock response (HSR) involve different HSR genes. The mechanisms, which are regulated at the molecular level, facilitate plants to thrive under heat stress. Exogenous applications of protectants such as osmoprotectants, phytohormones, signaling molecules, trace elements etc. have shown beneficial effects on plants growing under high temperature, due to the growth promoting and antioxidant activities of these compounds. There is acute necessity of crop biotechnology research for evolving genetically modified (GM) crops for a high CO 2 world at this juncture. So, attaining thermotolerance is a lively process to escape damages caused by heat stress.

https://medcraveonline.com/APAR/APAR-01-00012.pdf

Heat stress responses and thermotolerance

Chitosan and its oligosaccharides have received much interest for potential application in agriculture biomedicine and biotechnology due to their biocompatibility biodegradability and bioactivity Synthetic bactericide treatment has been the main method for controlling diseases there is a growing international concern over the indiscriminate use of synthetic compounds on crops because of the possible harmful effects on human health and the emergence of pathogen resistance to bactericides Thus there is a worldwide trend to explore new alternatives in order to reduce the use of synthetic chemical agents This review focuses on the biological activities of chitosan and its oligosaccharides based on the latest research results Among the novel families of biological macromolecules whose relevance is increased in research are chitosan and chitooligosaccharides COS Both become a promising alternative treatment due to its antimicrobial activity They have a wide scope of application in the food pharmaceutical agricultural industries COS are known to have eliciting activities leading to a variety of defence responses in plants in response to microbial infections to reduce the negative impact of diseases on yield and quality of crops This review reiterates the properties and uses of chitosan and its oligosaccharides and focuses on their applications on plant bacterial infections

/pdf/a-future-perspective-in-crop-protection-chitosan-and-its-xw8iov2yto.pdf

A future perspective in crop protection chitosan and its oligosaccharides

Current soil management strategies are mainly dependent on inorganic chemical-based fertilizers, which caused a serious threat to human health and environment. Plant growth-promoting rhizobacteria (PGPR) are naturally occurring soil bacteria that aggressively colonize plant roots and benefit plants by providing growth promotion. Inoculation of crop plants with certain strains of PGPR at an early stage of development improves biomass production through direct effects on root and shoots growth. The major groups of PGPR can be found along with the phyla actinobacteria, bacteroidetes, firmicutes, and proteobacteria. Inoculation of agricultural crops with PGPR may result in multiple effects on early-season plant growth, as seen in the enhancement of seedling germination, plant health, vigor, height, shoot weight, nutrient content of shoot tissues, early bloom, chlorophyll content, and increased nodulation in legumes. PGPRs are reported to influence the growth, yield, and nutrient uptake by an array of mechanisms. They help in increasing nitrogen fixation in legumes, help in promoting free-living nitrogen-fixing bacteria, increase supply of other nutrients, such as phosphorus, iron and produce plant hormones that enhance other beneficial bacteria or fungi. Now a day’s an increasing number of PGPR being commercialized for various crops. Subsequently, there has been much research interest in PGPRs. Several reviews have discussed specific aspects of growth promotion by PGPRs. Therefore, PGPRs can help to generate wealth cooperatively in local communities, reducing the need for more expensive manufactured products, such as nitrogenous fertilizers and use of PGPR in world has the potential to provide valuable insight.

https://medcraveonline.com/APAR/APAR-04-00163.pdf

Deepmala Katiyar

Papers

Application of chitosan on plant responses with special reference to abiotic stress

Chitosan as a promising natural compound to enhance potential physiological responses in plant: a review

Heat stress responses and thermotolerance

A future perspective in crop protection chitosan and its oligosaccharides

Plant growth promoting Rhizobacteria-an efficient tool for agriculture promotion