Long-term effects of seed priming with nanoencapsulated nitric oxide donors on the early development and drought tolerance of wheat plants

The objective of this work was to identify the effect of seed priming with nitric oxide (NO)-releasing nanoparticles on the germination process and initial growth of wheat plants (Triticum aestivum L.) under water deficit conditions in a laboratory and in a greenhouse environment, and compare the results with the non-nanoencapsulated NO donors. Initially, a dose-response curve was made for chitosan/tripolyphosphate nanoparticles containing S-nitroso-mercaptosuccinic acid (NP-MSNO) or S-nitrosoglutathione (NP-GSNO), which showed the optimal dose of 500 µM of both NO donors for the protection of wheat against water deficit. Subsequently, comparisons were made of the effects of priming with NP-GSNO and NP-MSNO in relation to priming with water, free MSNO and GSNO, and chitosan nanoparticles without NO donor, as well as the control without priming, under laboratory and greenhouse conditions, to evaluate morphological, physiological, and biochemical parameters. When the water deficit was applied in the laboratory, the NP-MSNO and NP-GSNO treatments led to greater increases in germination, chlorophyll content, and root morphological parameters compared to the other treatments. In the greenhouse, seed priming with NP-GSNO or NP-MSNO led to gains in root morphology, leaf water content, stomatal conductance, and S-nitrosothiol content in shoots and roots. In particular, nanoencapsulated GSNO promoted the best responses. In general, seed priming with nanoencapsulated NO donors provided benefits for germination and the vigor of wheat seedlings under water deficit, and these benefits remained in the greenhouse environment for a period of more than 30 days after treatment.