Nitric oxide reduces the stress effects of aluminum on the process of germination and early root growth of rice

摘要

The present study examined the action of nitric oxide (NO) on the germination process of rice seeds and early root growth under aluminum (Al) stress. Seeds and seedlings of two rice genotypes, with different levels of sensitivity to aluminum stress, were examined after treatment with Al and NO or only with Al. Further, the histochemical localization of Al and NO was performed on the root tissues. In both genotypes, NO was able to neutralize the inhibitory Al effects on germination. In the roots of seedlings, a reduction of Al toxicity as mediated by NO was indicated by an increased root elongation and a reduction of Al accumulation on the root surface in the Al hematoxylin complexation, irrespective of the genotype. The histolocalization of NO in roots using diaminofluorescein diacetate (DAF-2DA) and confocal microscopy revealed endogenous Al-induced levels of NO. It is concluded that NO can alleviate Al stress in the seedlings of the studied rice genotypes by improving germination and early root growth and is likely to play a role in a specific stress-signaling pathway.