Display Settings:

Format

Send to:

Choose Destination
See comment in PubMed Commons below
Plant J. 2009 Mar;57(5):895-904. doi: 10.1111/j.1365-313X.2008.03734.x. Epub 2008 Nov 4.

Involvement of OsSPX1 in phosphate homeostasis in rice.

Author information

  • 1State Key Laboratory of Plant Physiology and Biochemistry, College of Life Sciences, Zhejiang University, Hangzhou, China.

Abstract

Arabidopsis thaliana SPX (SYG/PHO81/XPR1) domain genes have recently been shown to be involved in the phosphate (Pi) signaling pathway. We show here that a rice (Oryza sativa) SPX gene, OsSPX1, is specifically induced by Pi starvation in roots. Suppression of OsSPX1 by RNA interference resulted in severe signs of toxicity caused by the over-accumulation of Pi, similar to that found in OsPHR2 (phosphate starvation response transcription factor 2) overexpressors and pho2 (phosphate-responsive mutant 2). Quantitative RT-PCR showed that expression of OsSPX1 was strongly induced in OsPHR2 overexpression and pho2 mutant plants, indicating that OsSPX1 occurs downstream of OsPHR2 and PHO2. The expression of 10 genes associated with the phosphate-starvation signal pathways was analyzed. Expression of OsPT2 (phosphate transporter 2) and OsPT8 was significantly induced in OsSPX1-RNAi (OsSPX1-Ri) plants, suggesting that over-accumulation of Pi in OsSPX1-Ri plants results from an increase in Pi transport. In contrast, overexpression of OsSPX1 suppressed the induction of expression by Pi starvation of all 10 phosphate starvation-induced genes tested: IPS1 (induced by phosphate starvation 1), IPS2, OsPAP10 (purple acid phosphatase 10), OsSQD2 (sulfoquinovosyldiacylglycerol 2), miR399d and miR399j (microRNA 399), OsPT2, OsPT3, OsPT6 and OsPT8. This suggests that OsSPX1 acts via a negative feedback loop to optimize growth under phosphate-limited conditions.

PMID:
19000161
[PubMed - indexed for MEDLINE]
PubMed Commons home

PubMed Commons

0 comments
How to join PubMed Commons

    Supplemental Content

    Icon for Blackwell Publishing
    Loading ...
    Write to the Help Desk