Nitric oxide mediates aluminum-induced citrate secretion through regulating the metabolism and transport of citrate in soybean roots

Abstract

Aims

Citrate secretion is a kind of typical strategy for plant against aluminum (Al) toxicity. However, the signaling process in Al-activated citrate secretion needs to be clarified.

Methods

Physiological and biochemical methods as well as gene expression analysis were employed to examine the regulatory roles of nitric oxide (NO) in Al-activated citrate secretion in soybean roots.

Results

Application of NO donor alleviated root growth inhibition and decreased Al content in Al-treated root apices. Al-induced NO production and citrate secretion were further elevated by NO donor, but inhibited by NO scavenger. Inhibition of citrate synthase (CS) or plasma membrane (PM) H⁺-ATPase activity significantly decreased Al-induced secretion of citrate, but inhibition of aconitase (ACO) activity enhanced citrate secretion under Al stress. Furthermore, NO mediated Al-stimulated CS and PM H⁺-ATPase activities, but decreased ACO activity under Al stress. Further investigation showed that NO modulated Al-activated transcriptional expression of CS and PM H⁺-ATPase as well as GmMATE. Overexpression of GmMATE in soybean hairy roots caused an enhanced Al-induced citrate efflux and Al resistance.

Conclusions

Our findings suggest that NO-dependent up-regulation of citrate synthesis and activation of PM H⁺-ATPase-coupled MATE transporter co-transport system participates in Al-activated citrate exudation, thus conferring plant resistance to Al toxicity.

from Energy Ecology Environment Ambio via Terpsi Hori on Inoreader http://bit.ly/2IgY8lT