Curcumin-based priming agent confers drought tolerance in wheat seedlings: A climate-smart approach

Drought has emerged as the deadliest abiotic stress that interferes with the physio-biochemical pathways in germinating seeds and growing plants severely damaging their germination, growth and final yield. It has become a major challenge for sustainable productivity of economically important and highly-demanded crops posing serious economic and food security issues. Considering ecotoxicity issues and the high impact of nanotechnology in agriculture, it is highly desirable to develop nanotech products with growth-promoting agents and stress emulating potential from natural antioxidants. Curcumin (Cur), a known polyphenol from Curcuma longa has a wide range of activities including exceptional antioxidant potential. The zinc oxide nanoparticles (ZnO NPs) have high growth-stimulating and antioxidant properties. This study reports the preparation of Cur-coated ZnO NPs as an ecofriendly nanopriming agent for the induction of drought tolerance in wheat seedlings. The control, nanoprimed (5, 10 and 15 ppm) and hydroprimed wheat seeds were germinated under normal and drought (osmotic potential of 15 % of PEG (-0.3 MPa)). Subsequently, the biochemical analyses and germination studies were performed using the established seedlings. The nanopriming induced significant increase in proteins, photosynthetic pigments and antioxidants (CAT, POD, APX and SOD) in seedlings under stress and normal conditions. They regulated the production of oxidants, controlled the osmoregulation and reduced malondialdehyde (MDA) ensuring the integrity of membranes as countermeasures of drought. The priming treatments positively influenced the germination parameters including germination index, germination energy and final germination by readjusting the biochemical pathways for mitigation of hazards of stress. The growth stimulatory effect of the prepared nanosystem caused a significant reduction in mean germination time. Thus, the priming-mediated memory imprints elicited resistance against drought at the germination and seedling development stage guaranteeing sustainable growth.