| Autor: |
He, Qiuju, Lu, Hong, Guo, Huaxing, Wang, Yan, Zhao, Peng, Li, Yong, Wang, Fei, Xu, Jiming, Mo, Xiaorong, Mao, Chuanzao |
| Předmět: |
|
| Zdroj: |
Plant Journal; Feb2021, Vol. 105 Issue 3, p649-667, 19p |
| Abstrakt: |
SUMMARY: Low soil phosphorus (P) availability is a major limitation for crop production. The molecular mechanisms underlying plant responses and adaptation to phosphate (Pi) deficiency are unclear. OsbHLH6 (hereafter bHLH6), an uncharacterized rice (Oryza sativa) Pi starvation response gene encoding a basic helix‐loop‐helix protein, was identified by yeast two‐hybrid screening using the phosphate response repressor OsSPX4 (hereafter SPX4) as bait. bHLH6 is expressed in shoots and roots, and its expression is significantly induced in shoots by Pi deficiency. bHLH6 overexpression lines showed Pi accumulation and enhanced Pi starvation responses, including upregulation of Pi starvation‐induced genes and longer root hairs. A bhlh6 mutant showed no significant phenotype variation at the seedling stage. A pull‐down assay indicated that bHLH6 had higher binding affinity with SPX4 compared to OsPHR2; therefore, bHLH6 competitively inhibited the interaction of SPX4 and OsPHR2. SPX4 overexpression rescued the Pi accumulation caused by bHLH6 overexpression under high‐ and low‐P conditions. Moreover, overexpression of bHLH6 in an spx4 background did not affect the Pi content of spx4 under high‐ and low‐P conditions. The bhlh6 spx4 double mutant showed lower shoot Pi concentrations and transcript levels of OsPT3 and OsPT10 compared with the spx4 mutant under high‐P conditions. RNA sequencing results indicated that bHLH6 overexpression and spx4 mutant lines share many differentially expressed Pi‐responsive genes. Therefore, bHLH6 is an important regulator for Pi signaling and homeostasis which antagonizes SPX4. This knowledge helps elucidate the molecular regulation of plant adaptation to Pi deficiency and will promote efforts toward the creation of low Pi‐tolerant crops. Significance Statement: This study identified a hitherto uncharacterized phosphate (Pi) starvation‐responsive bHLH family transcription factor, OsbHLH6, in rice (Oryza sativa). OsbHLH6 exclusively interacts with OsSPX4 but not with other SPX proteins and this interaction alters the subcellular localization of OsbHLH6. Our data indicate that OsbHLH6 is a positive regulator of Pi homeostasis and Pi signaling by antagonizing OsSPX4. This knowledge helps elucidate the molecular regulation of plant adaptation to Pi deficiency and will promote efforts toward the genetic improvement of low Pi‐tolerant crops. OsbHLH6 is the first transcription factor in Pi signaling that has been found to regulate SPX proteins. This helps to elucidate the Pi signaling pathway and lays the groundwork for further genetically improving low Pi tolerance in crops. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
|
Plný text