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Nitrogen availability affects hydraulic conductivity of rice roots, possibly through changes in aquaporin gene expression

Ishikawa-Sakurai, Junko, Hayashi, Hidehiro, Murai-Hatano, Mari
Plant and soil 2014 v.379 no.1-2 pp. 289-300
Oryza sativa, aquaporins, dry matter partitioning, gene expression, gene expression regulation, hydraulic conductivity, nitrogen, rice, roots, water uptake
BACKGROUND AND AIMS: Nitrogen (N) availability affects water uptake from the roots, which decreases upon N deprivation and increases upon resupply. The aim of this study was to reveal possible mechanisms of regulation of water transport in roots through physiological and morphological adaptations to N availability. METHODS: The effects of continuous N deprivation and following resupply on root morphology, osmotic hydraulic conductivity, and expression of genes for aquaporins (water channels) were examined in rice (Oryza sativa L.) plants. The effect of local N availability was examined by using a split-root system. RESULTS: N deprivation decreased the expression of root-specific aquaporin genes, whereas N resupply increased their expression. Changes in aquaporin gene expression were correlated with changes in hydraulic conductivity. N deprivation increased dry matter allocation to the roots. In a split-root experiment, the expression of root-specific aquaporin genes was down-regulated in the N-deprived half, whereas it was up-regulated in the N-supplied half. CONCLUSION: Our results suggest that expression of genes for root-specific aquaporins underlies the changes in conductivity during continuous N deprivation and resupply. Rice plants seem to adapt to N availability through coordinated adjustment of root proliferation and abundance of aquaporins.