OsNAR2.1 Positively Regulates Drought Tolerance and Grain Yield Under Drought Stress Conditions in Rice

Abstract

Drought is an important environmental factor that severely restricts crop production. The high-affinity nitrate transporter partner protein OsNAR2.1 plays an essential role in nitrate absorption and translocation in rice. Our results suggest that OsNAR2.1 expression is markedly induced by water deficit. After drought stress conditions and irrigation, compared with wild-type (WT), the survival rate was significantly improved in OsNAR2.1 over-expression lines and decreased in OsNAR2.1 RNAi lines. The survival rate of Wuyunjing7 (WYJ), OsNRT2.1 over-expression lines and OsNRT2.3a over-expression lines was not significantly different. Compared with WT, overexpression of OsNAR2.1 could significantly increase nitrogen uptake in rice, and OsNAR2.1 RNAi could significantly reduce nitrogen uptake. Under drought conditions, the expression of OsNAC10, OsSNAC1, OsDREB2a , and OsAP37 was significantly reduced in OsNAR2.1 RNAi lines and increased substantially in OsNAR2.1 over-expression lines. Also, the chlorophyll content, relative water content, photosynthetic rate and water use efficiency were decreased considerably in OsNAR2.1 RNAi lines and increased significantly in OsNAR2.1 over-expression lines under drought conditions. Finally, compared to WT, grain yield increased by about 9.1 and 26.6%, in OsNAR2.1 over-expression lines under full and limited irrigation conditions, respectively. These results indicate that OsNAR2.1 regulates the response to drought stress in rice and increases drought tolerance.

Comparative Transcriptomics of Rice Genotypes with Contrasting Responses to Nitrogen Stress Reveals Genes Influencing Nitrogen Uptake through the Regulation of Root Architecture

“…The OsNRT2.1-overexpressing rice plant not only enhanced vegetative growth under low N conditions [42], but also enhanced the yield compared to the wild type under alternating wet and dry conditions [44] and drought stress [45] by increasing nitrogen uptake. This gene also promoted root elongation via auxin transport [43].…”

The intersection of nitrogen nutrition and water use in plants: new paths toward improved crop productivity

“…Overexpression of OsNAR2.1 had a positive impact on vegetative growth following treatment with PEG, and the transgenic lines had greater grain yield after drought treatment in a pot trial. Expression of genes associated with osmotic regulation in plants was altered by the overexpression of OsNAR2.1 , suggesting that there are molecular links between the two regulatory systems ( Chen et al , 2019 ). Increased NH 4 + supply improved the rate of water uptake and root hydraulic conductance, and increased transcript levels of several aquaporin genes in rice ( Ishikawa-Sakurai et al , 2014 ; Ren et al , 2015 ).…”

Orange Leafhopper Cicadulina bipunctata Feeding Induces Gall Formation Nitrogen Dependently and Regulates Gibberellin Signaling

“…We also demonstrated that the expressions of genes related to N-uptake and N-transport were increased by C. bipunctata feeding, even in N-deficiency conditions. It has been reported that the expressions of OsNRT2.1 and OsNRT2.3a respond not only to nitrate concentration but also to drought stress [ 25 ]. Yang et al reported that rice infected by the endophytic fungus Phomopsis liquidambari showed substantial changes in N uptake and N metabolism [ 26 ].…”