Abscisic acid accumulation and oxidative stress are two common responses of
plants to environmental stresses. However, little is known about their
relationships. The purpose of this article is to investigate the effects of
reactive oxygen species and nitric oxide on the plant hormone abscisic acid
synthesis in root tips of wheat (Triticum aestivum L.)
seedlings under drought stress. Detached root tips were subjected to drought
stress by naturally evaporating until 20% of their fresh weights were
lost. The activities of superoxide synthases and nitric oxide synthase (EC
1.14.13.39) increased after 20 min of treatment and abscisic acid began to
accumulate 60 min later. The induction of abscisic acid by drought was
strongly blocked by pretreating the root tips with reactive oxygen species
eliminators tiron or ascorbate acid, and with nitric oxide synthase inhibitor
Nω-nitro-L-arginine or nitric oxide eliminator
2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide. Consistent with these
results, reactive oxygen species generators diethyldithiocarbamic acid,
xanthine–xanthine oxidase and triazole or nitric oxide donor sodium
nitroprusside can also induce abscisic acid accumulation in root tips of wheat
seedlings. While potentiated by reactive oxygen species, the effect of sodium
nitroprusside on abscisic acid accumulation was blocked by
2-phenyl-4,4,5,5-tetramethyl-imidazoline-1-oxyl 3-oxide. Based on these
results, we suggest that reactive oxygen species and nitric oxide play
important roles in drought-induced abscisic acid synthesis in plant, they may
be the signals through which the plant can ‘sense’ the drought
condition.
Exogenous nitric oxide donor and arginine provide protection against short-term drought stress in wheat seedlings
