Chemical Priming of Plants Against Multiple Abiotic Stresses: Mission Possible?

Seed priming to alleviate salinity stress in germinating seeds

Plants are exposed to any number of potentially adverse environmental conditions such as water deficit, high salinity, extreme temperature, submergence, etc. These abiotic stresses adversely affect the plant growth and productivity. Nowadays various strategies are employed to generate plants that can withstand these stresses. In recent years, seed priming has been developed as an indispensable method to produce tolerant plants against various stresses. Seed priming is the induction of a particular physiological state in plants by the treatment of natural and synthetic compounds to the seeds before germination. In plant defense, priming is defined as a physiological process by which a plant prepares to respond to imminent abiotic stress more quickly or aggressively. Moreover, plants raised from primed seeds showed sturdy and quick cellular defense response against abiotic stresses. Priming for enhanced resistance to abiotic stress obviously is operating via various pathways involved in different metabolic processes. The seedlings emerging from primed seeds showed early and uniform germination. Moreover, the overall growth of plants is enhanced due to the seed-priming treatments. The main objective of this review is to provide an overview of various crops in which seed priming is practiced and about various seed-priming methods and its effects.

Seed priming for abiotic stress tolerance: an overview

Application of nanomaterials for agriculture is relatively new as compared to their use in biomedical and industrial sectors. In order to promote sustainable nanoagriculture, biocompatible silver nanoparticles (AgNPs) have been synthesized through green route using kaffir lime leaf extract for use as nanopriming agent for enhancing seed germination of rice aged seeds. Results of various characterization techniques showed the successful formation of AgNPs which were capped with phytochemicals present in the plant extract. Rice aged seeds primed with phytosynthesized AgNPs at 5 and 10 ppm significantly improved germination performance and seedling vigor compared to unprimed control, AgNO3 priming, and conventional hydropriming. Nanopriming could enhance α-amylase activity, resulting in higher soluble sugar content for supporting seedlings growth. Furthermore, nanopriming stimulated the up-regulation of aquaporin genes in germinating seeds. Meanwhile, more ROS production was observed in germinating seeds of nanopriming treatment compared to unprimed control and other priming treatments, suggesting that both ROS and aquaporins play important roles in enhancing seed germination. Different mechanisms underlying nanopriming-induced seed germination were proposed, including creation of nanopores for enhanced water uptake, rebooting ROS/antioxidant systems in seeds, generation of hydroxyl radicals for cell wall loosening, and nanocatalyst for fastening starch hydrolysis.

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Nanopriming technology for enhancing germination and starch metabolism of aged rice seeds using phytosynthesized silver nanoparticles

Priming memory invokes seed stress-tolerance

Dynamics of the antioxidant system during seed osmopriming, post-priming germination, and seedling establishment in Spinach (Spinacia oleracea).

Dehydrin metabolism is altered during seed osmopriming and subsequent germination under chilling and desiccation in Spinacia oleracea L. cv. Bloomsdale: possible role in stress tolerance.

https://lib.dr.iastate.edu/cgi/viewcontent.cgi?article=4857&context=etd

Effect of short-term versus prolonged freezing on freeze–thaw injury and post-thaw recovery in spinach: Importance in laboratory freeze–thaw protocols

The ability of plants to recover from freeze-thaw injury is a critical component of freeze-thaw stress tolerance. To investigate the molecular basis of freeze-thaw recovery, here we compared the proteomes of onion scales from unfrozen control (UFC), freeze-thaw injured (INJ), and post-thaw recovered (REC) treatments. Injury-related proteins (IRPs) and recovery-related proteins (RRPs) were differentiated according to their accumulation patterns. Many IRPs decreased right after thaw without any significant re-accumulation during post-thaw recovery, while others were exclusively induced in INJ tissues. Most IRPs are antioxidants, stress proteins, molecular chaperones, those induced by physical injury or proteins involved in energy metabolism. Taken together, these observations suggest that while freeze-thaw compromises the constitutive stress protection and energy supply in onion scales, it might also recruit 'first-responders' (IRPs that were induced) to mitigate such injury. RRPs, on the other hand, are involved in the injury-repair program during post-thaw environment conducive for recovery. Some RRPs were restored in REC tissues after their first reduction right after thaw, while others exhibit higher abundance than their 'constitutive' levels. RRPs might facilitate new cellular homeostasis, potentially by re-establishing ion homeostasis and proteostasis, cell-wall remodelling, reactive oxygen species (ROS) scavenging, defence against possible post-thaw infection, and regulating the energy budget to sustain these processes.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/pce.12027

Keting Chen

Papers

Priming memory invokes seed stress-tolerance

Dynamics of the antioxidant system during seed osmopriming, post-priming germination, and seedling establishment in Spinach (Spinacia oleracea).

Dehydrin metabolism is altered during seed osmopriming and subsequent germination under chilling and desiccation in Spinacia oleracea L. cv. Bloomsdale: possible role in stress tolerance.

Effect of short-term versus prolonged freezing on freeze–thaw injury and post-thaw recovery in spinach: Importance in laboratory freeze–thaw protocols

Proteomic changes associated with freeze‐thaw injury and post‐thaw recovery in onion (Allium cepa L.) scales