OsSPX1

Gene Details

MSU gene ID: LOC_Os06g40120
RAPdb gene ID: Os06g0603600
Gene Symbol: OsSPX1
Genome: MSU7 , IRGSP-1.0
Species: Oryza sativa

Functional Descriptions

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).
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.
Involvement of OsSPX1 in phosphate homeostasis in rice.
Recently, Arabidopsis AtSPX family genes have been found to possess diverse functions in plant tolerance to phosphorus starvation, and OsSPX1 is involved in phosphate homeostasis in rice and optimizes growth under phosphate-limited conditions through a negative feedback loop.
Among them, five genes, OsSPX1, 2, 3, 5 and 6 are responsive to Pi-starvation in shoots and/or in roots.
We show here that a rice (Oryza sativa) SPX gene, OsSPX1, is specifically induced by Pi starvation in roots.
In the present study, we generated rice antisense and sense transgenic lines of OsSPX1 and found that down-regulation of OsSPX1 caused high sensitivity to cold and oxidative stresses in rice seedlings.
Our study indicated that OsSPX1 may be involved in cross-talks between oxidative stress, cold stress and phosphate homeostasis in rice seedling leaves.
Down-regulation of OsSPX1 causes high sensitivity to cold and oxidative stresses in rice seedlings.
OsSPX1 acts as a repressor in the OsPHR2-mediated phosphate-signaling pathway.
Transgenic tobacco plants with constitutive expression of OsSPX1 were more tolerant to cold stress than were wild-type plants, and showed better seedling survival and reduced cellular electrolyte leakage.
Our data also show that OsSPX1 is a negative regulator of OsPHR2 and is involved in the feedback of Pi-signaling network in roots that is defined by OsPHR2 and OsPHO2.
OsSPX1 suppresses the function of OsPHR2 in the regulation of expression of OsPT2 and phosphate homeostasis in shoots of rice.
From real-time reverse transcriptase-polymerase chain reaction analysis, several Pi starvation-related genes, such as AtSPX1 (orthologue of OsSPX1), PHO2, PLDZ2 and ATSIZ1, showed differential expression between wild-type and transgenic plants during cold stress.
Our results indicate that OsSPX1 may play an important role in linking cold stress and Pi starvation signal transduction pathways.
Transcript analysis revealed that Pi-responsive genes–Phosphate starvation (OsIPS)1 and OsIPS2, SYG1/Pho81/XPR1(OsSPX1), Sulfoquinovosyldiacylglycerol 2 (OsSQD2), R2R3 MYB transcription factor (OsMYB2P-1) and Transport Inhibitor Response1 (OsTIR1)–were more abundant in the osarf12 and osarf12/25 mutants under +Pi/-Pi conditions.
To further establish a cause-and-effect relationship between intracellular Pi level and cold acclimatization in transgenic plants, we generated transgenic Arabidopsis plants with constitutive expression of OsSPX1.
Compared to wild-type and OsSPX1-sense transgenic lines, more hydrogen peroxide accumulated in seedling leaves of OsSPX1-antisense transgenic lines for controls, cold and methyl viologen (MV) treatments.
Previous reports have demonstrated that over-expression of OsPHR2 (the homolog of AtPHR1) and knockdown of OsSPX1 result in accumulation of excessive shoot Pi in rice.
OsSPX1 suppresses the regulation on expression of OsPT2 by OsPHR2 and the accumulation of excess shoot Pi, but it does not suppress induction of OsPT2 or the accumulation of excessive shoot Pi in the Ospho2 mutant.
Our previous work showed that constitutive overexpression of OsSPX1 in tobacco and Arabidopsis plants improved cold tolerance while also decreasing total leaf Pi.
Rice SPX domain gene, OsSPX1, plays an important role in the phosphate (Pi) signaling network.
Rice SPX1 and SPX2 inhibit phosphate starvation responses through interacting with PHR2 in a phosphate-dependent manner.
Through examination of anthers and pollens of the transgenic and wild-type plants by microscopy, we found that the antisense of OsSPX1 gene led to semi-male sterility, with lacking of mature pollen grains and phenotypes with a disordered surface of anthers and pollens.
Our study demonstrated that down-regulation of OsSPX1 disrupted rice normal anther and pollen development by affecting carbohydrate metabolism and sugar transport, leading to semi-male sterility, and ultimately resulted in low seed-setting rate and grain yield.
Down-regulation of OsSPX1 caused semi-male sterility, resulting in reduction of grain yield in rice.
Based on investigation of OsSPX1 antisense and sense transgenic rice lines in the paddy fields, we discovered that the down-regulation of OsSPX1 caused reduction of seed-setting rate and filled grain number.
The down-regulation of OsSPX1 significantly affected expression of genes involved in carbohydrate metabolism and sugar transport, anther development, cell cycle, etc.
In this study, we focused on the potential function of OsSPX1 during rice reproductive phase.

Functional Keywords

Literature and News

Gene Resources

Homologs

Sequences

cDNA Sequence

>LOC_Os06g40120.1
ATTCCCATCGTCTCCTTCCTCCTCTCCCCCGCATATCCTCCGCCTCCCTTTCCCCCCTCTCCTCCTCAACCCTATTTCACCACCACCTCCACCGCTGCCGCGGCGAGAATTCGATCGGTTCTTGGCAGCCGTAGTGCAGTTTTGTGCAGTTTTCTTCTCTCTTGTTGTTGAGGATGAAGTTTGGGAAGAGCCTGAGTAGCCAGATCGTGGAGACGCTCCCGGAGTGGCGGGACAAGTTCTTGTCGTACAAGGATCTCAAGAAGCGGCTCAAGCTGATTGGTGGGGGTGGGGGTGGGGAGGAGAGGCAGGCGAAGCGGGCACGCGTTGCAGCGGATGGCGGCGAGGAGGAGGCCGCCGCCGCGGCGATGACGCCCGAGGAGGCGGGCTTCATGCGGCTCCTGGAGGCCGAGCTCGACAAGTTCAACTCCTTCTTCGTCGAGAAGGAGGAGGAATACATCATCCGCCAGAAGGAGCTGCAGGACAGGGTGGCGAGGGCGGCGGGGAGGGAGTCGAAGGAGGAGCTGATGCGGGTGCGCAAGGAGATCGTCGACTTCCATGGCGAGATGGTGCTGCTCGAGAACTACAGCGCCCTCAACTACACCGGATTAGTTAAGATTCTCAAGAAGTATGACAAGAGGACTGGGGCTCTGATCCGTCTGCCTTTCATCCAGAAAGTGCTACAGCAGCCTTTCTTCACCACTGACCTCCTGTACAAGCTTGTGAAACAGTGTGAGGCCATGCTGGACCAGCTTCTACCATCAAACGAACTGTCTGTATCGAGTGAAGATGGGAGAGGCGATAGCACTAACGAGGACAAGCCTTCGAATCCCAGTTCATCCTTGGTTAATGGTGGCACTATTCCAGAGTTAGATGAGATCGAGTACATGGAAAGCATGTATATGAAGGGCACGGTCGCGGCGCTTAGGTCTCTGAAGGAGATCCGAAGCGGAAGCTCTACTGTTAGTGCATTCTCATTACCACCTCTCCAGGGCGACAGTTCGCCAGAGGAGCAGCAGGAACTGTGGAATAAGATTCCGGTGATTGAGCAGGCCGCCAAATGACACGACCGGCATTTCACTACATGGTTATGTACACTGCATGACCTTGATCTTGACATTTGCTGGAGATAGTACCGGGGATCTCATTCCCCTGTCATATATTCAGTAATTTGTATGATTCCAGGATTCCTAACAGTTGTAAAATGGTGGACATGTTCAGTATACATTGTAAAATCATAGAAACCCATCATAACCATCAGACAGAACTGAGATGTTTTGATTCACTATTGTGAGTTAAATCCTGTACTTTTTGCTGATCTACATCCTCTTTCATGAACTCTCGGTACAGAATTAGTTAATGTTGCAGTATAACAATTCTGATTTTGACAATCTCGATTCGGAGATGATTTTGTTAAA

CDS Sequence

>LOC_Os06g40120.1
ATGAAGTTTGGGAAGAGCCTGAGTAGCCAGATCGTGGAGACGCTCCCGGAGTGGCGGGACAAGTTCTTGTCGTACAAGGATCTCAAGAAGCGGCTCAAGCTGATTGGTGGGGGTGGGGGTGGGGAGGAGAGGCAGGCGAAGCGGGCACGCGTTGCAGCGGATGGCGGCGAGGAGGAGGCCGCCGCCGCGGCGATGACGCCCGAGGAGGCGGGCTTCATGCGGCTCCTGGAGGCCGAGCTCGACAAGTTCAACTCCTTCTTCGTCGAGAAGGAGGAGGAATACATCATCCGCCAGAAGGAGCTGCAGGACAGGGTGGCGAGGGCGGCGGGGAGGGAGTCGAAGGAGGAGCTGATGCGGGTGCGCAAGGAGATCGTCGACTTCCATGGCGAGATGGTGCTGCTCGAGAACTACAGCGCCCTCAACTACACCGGATTAGTTAAGATTCTCAAGAAGTATGACAAGAGGACTGGGGCTCTGATCCGTCTGCCTTTCATCCAGAAAGTGCTACAGCAGCCTTTCTTCACCACTGACCTCCTGTACAAGCTTGTGAAACAGTGTGAGGCCATGCTGGACCAGCTTCTACCATCAAACGAACTGTCTGTATCGAGTGAAGATGGGAGAGGCGATAGCACTAACGAGGACAAGCCTTCGAATCCCAGTTCATCCTTGGTTAATGGTGGCACTATTCCAGAGTTAGATGAGATCGAGTACATGGAAAGCATGTATATGAAGGGCACGGTCGCGGCGCTTAGGTCTCTGAAGGAGATCCGAAGCGGAAGCTCTACTGTTAGTGCATTCTCATTACCACCTCTCCAGGGCGACAGTTCGCCAGAGGAGCAGCAGGAACTGTGGAATAAGATTCCGGTGATTGAGCAGGCCGCCAAATGA

Protein Sequence

>LOC_Os06g40120.1
MKFGKSLSSQIVETLPEWRDKFLSYKDLKKRLKLIGGGGGGEERQAKRARVAADGGEEEAAAAAMTPEEAGFMRLLEAELDKFNSFFVEKEEEYIIRQKELQDRVARAAGRESKEELMRVRKEIVDFHGEMVLLENYSALNYTGLVKILKKYDKRTGALIRLPFIQKVLQQPFFTTDLLYKLVKQCEAMLDQLLPSNELSVSSEDGRGDSTNEDKPSNPSSSLVNGGTIPELDEIEYMESMYMKGTVAALRSLKEIRSGSSTVSAFSLPPLQGDSSPEEQQELWNKIPVIEQAAK*