709 / 2019-05-05 17:35:55

FIP1 Can Interact with CPSF30-L and Plays an Important Role in Nitrate Signaling in Arabidopsis

FIP1, CPSF30-L, nitrate signaling, nitrate uptake and assimilation, CIPK8, CIPK23

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Unraveling the molecular mechanisms of nitrate regulation and deciphering the
underlying genetic network is vital for elucidating nitrate uptake and utilization in plants.
Such knowledge could lead to the improvement of nitrogen-use efficiency in agriculture.
Here, we report that the FIP1 gene plays an important role in nitrate signaling in Arabidopsis thaliana. We found that FIP1 interacts with the cleavage and CPSF30-L, which is also an essential player in nitrate signaling. The induction of nitrate-responsive genes following nitrate treatment was inhibited in the fip1 mutant. The nitrate content was also reduced in fip1 seedlings due to their decreased nitrate uptake activity. Furthermore, the nitrate content was higher in the roots but lower in the roots of fip1, which may result from the down-regulation of NRT1.8 and the up-regulation of the nitrate assimilation genes. In addition, qPCR analyses revealed that FIP1 negatively regulated the expression of CIPK8 and CIPK23, two protein kinases involved in nitrate signaling. In the fip1 mutant, the increased expression of CIPK23 may affect nitrate uptake, resulting in its lower nitrate content. Genetic and molecular evidence suggests that FIP1 and CPSF30-L function in the same nitrate-signaling pathway, with FIP1 mediating signaling through its interaction with CPSF30-L and its regulation of CIPK8 and CIPK23. Analysis of the 30-UTR of NRT1.1 showed that the pattern of polyadenylation sites was altered in the fip1 mutant.