Nitric oxide is involved in nano-titanium dioxide-induced activation of antioxidant defense system and accumulation of osmolytes under water deficit stress in Vicia faba L.
Nano-titanium dioxide (nTiO2) has been reported to improve tolerance of plants against different environmental
stresses by modulating various physiological and biochemical processes. Nitric oxide (NO) has been shown to act
as an important stress signaling molecule during plant responses to abiotic stresses. The present work was
planned to investigate the involvement of endogenous NO in nTiO2-induced activation of defense system of fava
bean (Vicia faba L.) plants under water-deficit stress (WDS) conditions. Water-suffered plants showed increased
concentration of hydrogen peroxide (H2O2) and superoxide (O2%−) content coupled with increased electrolyte
leakage and lipid peroxidation which adversely affected nitrate reductase (NR) activity, chlorophyll content and
growth of the plants. However, application of 15 mg L−1 nTiO2 to stressed plants significantly induced NR
activity and synthesis of NO which elevated enzymatic and non-enzymatic defense system of the stressed plants
and suppressed the generation of H2O2 and O2%− content, leakage of electrolytes, and lipid peroxidation.
Application of nTiO2, in association with NO, also enhanced the accumulation of osmolytes (proline and glycine
betaine) that assisted the stressed plants in osmotic adjustment as witnessed by improved hydration level of the
plants. Involvement of NO in nTiO2-induced activation of defense system was confirmed with NO scavenger
cPTIO [2-(4-carboxyphenyl)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide] which caused recurrence of WDS.
Abstract
Legumes are important source of protein for teeming human population. These are very sensitive to salt levels and soil drought status, experiencing water deficit due to osmotic stress possibly…