Effects of exogenously supplied sucrose on OsSUTs and OsSPSs transcript abundances and rice root ammonium assimilation

Abstract

Sucrose has been known as pivotal carbon source for plant nutrient metabolism including ammonium (NH4 +) assimilation. However, the correlation between rice root NH4 + assimilation and gene expression responsible for sucrose allocation has not been investigated. Here, we reported the transcriptional regulation of OsSUTs and OsSPSs by exogenously supplied sucrose and the response of NH4 + assimilation in rice roots. Spraying sucrose to mature leaves of rice (Oryza sativa L. cv. indica 9311) up-regulated transcript abundances of leaf OsSUT1, OsSUT2, OsSUT3, OsSUT4, OsSPS6, and OsSPS11, down-regulated mRNA expression of leaf OsSUT5, OsSPS1, OsSPS2, and OsSPS8, increased soluble sugar contents in leaves and roots, and promoted root NH4 + assimilation. The similar responses, except for leaf OsSPS1 mRNA expression, were observed when sucrose was fed to hydroponic media. Rice (indica 9311) treated by 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) exhibited altered transcript abundances of leaf OsSUTs and OsSPSs, lower contents of soluble sugars in leaves and roots, and reduced capacity of root NH4 + assimilation, which was partially reversed by sucrose supply. The results indicated that the exogenously supplied sucrose coordinately regulated leaf OsSUTs and OsSPSs mRNA expression and root NH4 + assimilation in rice seedlings.