Effects of nanoencapsulated nitric oxide donor on Cecropia pachystachya Trécul and Cariniana estrellensis (Raddi) Kuntze seedlings subjected to short and long-term water deficit

Key Message

Low-concentrations of nanoencapsulated NO donor protect tree seedlings from drought, enhancing photosynthesis, stomatal conductance, root hair growth, and stem water potential, but the effects are species-dependent.

Abstract

Nitric oxide (NO), a critical signaling molecule in plants, plays a protective role against water deficit (WD). However, its application is hindered by its relatively unstable chemical nature. To address this, researchers have explored the nanoencapsulation of NO donor molecules. The study aimed to evaluate the effects of treatments using chitosan nanoparticles (NPs) containing the NO donor S-nitrosoglutathione (GSNO) on neotropical tree seedlings (Cecropia pachystachya and Cariniana estrellensis) exposed to short and long-term WD in a greenhouse. Seedlings under long-term WD received nanoformulations in the substrate three times at ten-day intervals. Under short-term WD, seedlings were treated for three alternate days before initiating the WD. The treatment with NPs containing GSNO (50 µM) increased the stomatal conductance, photosynthetic rate, and plant water potential of C. pachystachya submitted to short and long-term WD, reaching levels similar to those of plants kept at field capacity. The same effects were not induced by free GSNO and NPs without NO. Under long-term WD, GSNO-loaded NPs also increased root and leaf biomass in comparison to other WD treatments and increased the amount and incidence of root hairs. In contrast, Cariniana estrellensis seedlings did not respond to the application of NPs containing GSNO at the tested concentrations (from 25 to 800 µM), in any WD condition. Results suggest that nanoencapsulated GSNO can protect C. pachystachya seedlings in both WD conditions, highlighting the potential for obtaining drought-tolerant tree seedlings in reforestation programs. However, this action is species-dependent, as no effect was induced in C. estrellensis.