Influence of cytokinins on the expression of phosphate starvation responsive genes in Arabidopsis
Article first published online: 7 JUL 2008
The Plant Journal
Volume 24, Issue 5, pages 559–567, December 2000
How to Cite
Martín, A. C., Del Pozo, J. C., Iglesias, J., Rubio, V., Solano, R., De La Peña, A., Leyva, A. and Paz-Ares, J. (2000), Influence of cytokinins on the expression of phosphate starvation responsive genes in Arabidopsis. The Plant Journal, 24: 559–567. doi: 10.1046/j.1365-313x.2000.00893.x
- Issue published online: 7 JUL 2008
- Article first published online: 7 JUL 2008
- Received 16 May 2000; revised 11 August 2000; accepted 7 September 2000.
- phosphate starvation;
The increase in the ratio of root growth to shoot growth that occurs in response to phosphate (Pi) deprivation is paralleled by a decrease in cytokinin levels under the same conditions. However, the role of cytokinin in the rescue system for Pi starvation remains largely unknown. We have isolated a gene from Arabidopsis thaliana (AtIPS1) that is induced by Pi starvation, and studied the effect of cytokinin on its expression in response to Pi deprivation. AtIPS1 belongs to the TPSI1/Mt4 family, the members of which are specifically induced by Pi starvation, and the RNAs of which contain only short, non-conserved open reading frames. Pi deprivation induces AtIPS1 expression in all cells of wild-type plants, whereas in the pho1 mutant grown on Pi-rich soils, AtIPS1 expression in the root was delimited by the endodermis. This supports the view that pho1 is impaired in xylem loading of Pi, and that long-distance signals controlling the Pi starvation responses act via negative control. Exogenous cytokinins repress the expression of AtIPS1 and other Pi starvation-responsive genes in response to Pi deprivation. However, cytokinins did not repress the increase in root-hair number and length induced by Pi starvation, a response dependent on local Pi concentration rather than on whole-plant Pi status. Our results raise the possibility that cytokinins may be involved in the negative modulation of long-distance, systemically controlled Pi starvation responses, which are dependent on whole-plant Pi status.