Efficient strategies for controlled release of nanoencapsulated phytohormones to improve plant stress tolerance

Abstract

Climate change due to different human activities is causing adverse environmental conditions and uncontrolled extreme weather events. These harsh conditions are directly affecting the crop areas, and consequently, their yield (both in quantity and quality) is often impaired. It is essential to seek new advanced technologies to allow plants to tolerate environmental stresses and maintain their normal growth and development. Treatments performed with exogenous phytohormones stand out because they mitigate the negative effects of stress and promote the growth rate of plants. However, the technical limitations in field application, the putative side effects, and the difficulty in determining the correct dose, limit their widespread use. Nanoencapsulated systems have attracted attention because they allow a controlled delivery of active compounds and for their protection with eco-friendly shell biomaterials. Encapsulation is in continuous evolution due to the development and improvement of new techniques economically affordable and environmentally friendly, as well as new biomaterials with high affinity to carry and coat bioactive compounds. Despite their potential as an efficient alternative to phytohormone treatments, encapsulation systems remain relatively unexplored to date. This review aims to emphasize the potential of phytohormone treatments as a means of enhancing plant stress tolerance, with a specific focus on the benefits that can be gained through the improved exogenous application of these treatments using encapsulation techniques. Moreover, the main encapsulation techniques, shell materials and recent work on plants treated with encapsulated phytohormones have been compiled.

Nanobiosensors and nanoformulations in agriculture: new advances and challenges for sustainable agriculture

“…Controlled release: nanocapsules and NPs can be designed and prepared to release the active substance suddenly in response to a specific stimulus (e.g. a pH change when reaching an insect's stomach or the action of an enzyme) or to release it continuously over time [ 33 , 34 ] ( Figure 3 ).…”

“…Wu et al [ 62 ] demonstrated that CeO NPs could increase Arabidopsis plants tolerance to salinity stress by directly acting on the cytosolic Na + /K + ratio (improving K + retention and reducing Na + efflux), resulting in improving plant leaf photosynthetic performance and biomass. Additionally, phytohormones play important roles in responses against abiotic stress [ 33 ]. Silica NPs loaded with abscisic acid resulted in prolonged release of the exogenous cargo in Arabidopsis thaliana plants, improving the drought resistance in seedlings [ 63 ].…”

Nanoenabled Enhancement of Plant Tolerance to Heat and Drought Stress on Molecular Response

“…Proline (5 mM) significantly reduced stress damage, increased leaf water content and chlorophyll, and significantly increased carbon sequestration and assimilation capacity in mung bean (SML 668) leaves under heat stress conditions . Of note, the exogenous applications of organic molecules are restricted because of technical issues with field application, potential adverse effects, and challenges in calculating the right dosage …”

“…57 Of note, the exogenous applications of organic molecules are restricted because of technical issues with field application, potential adverse effects, and challenges in calculating the right dosage. 58 Nanoenabled strategies are able to provide efficient, targeted migration and transport of active ingredients. 28 Nanomaterials have slow-release properties, and MoS 2 nanosheets in soybeans are able to achieve a slow-release effect by gradually decreasing the dissolution rate over 60 days.…”

Seed Priming with Nanoencapsulated Gibberellic Acid Triggers Beneficial Morphophysiological and Biochemical Responses of Tomato Plants under Different Water Conditions

“…Despite the advantages of using phytohormones to minimize the effects of stress, the application of these molecules has limitations, such as low physicochemical stability and high susceptibility to degradation processes, such as photolysis and hydrolysis, modifying their structure and decreasing the biological activity [20]. In addition, the difficulty of defining the correct dosage according to the purpose of application is one of the main limitations in the use of these products in the management of agricultural crops.…”