A phosphate starvation response regulator Ta-PHR1 is involved in phosphate signalling and increases grain yield in wheat

Abstract

Background and AimsPhosphorus deficiency is a major limiting factor for crop yield worldwide. Previous studies revealed that PHR1 and it homologues play a key role in regulating the phosphate starvation response in plants. However, the function of PHR homologues in common wheat (Triticum aestivum) is still not fully understood. The aim of the study was to characterize the function of PHR1 genes in regulating phosphate signalling and plant growth in wheat.MethodsWheat transgenic lines over-expressing a wheat PHR1 gene were generated and evaluated under phosphorus-deficient and -sufficient conditions in hydroponic culture, a soil pot trial and two field experiments.Key ResultsThree PHR1 homologous genes Ta-PHR1-A1, B1 and D1 were isolated from wheat, and the function of Ta-PHR1-A1 was analysed. The results showed that Ta-PHR1-A1 transcriptionally activated the expression of Ta-PHT1.2 in yeast cells. Over-expressing Ta-PHR1-A1 in wheat upregulated a subset of phosphate starvation response genes, stimulated lateral branching and improved phosphorus uptake when the plants were grown in soil and in nutrient solution. The data from two field trials demonstrated that over-expressing Ta-PHR1-A1 increased grain yield by increasing grain number per spike.ConclusionsTaPHR1 is involved in phosphate signalling in wheat, and was valuable in molecular breeding of crops, with improved phosphorus use efficiency and yield performance.

Physiological and molecular alterations in plants exposed to high [CO2] under phosphorus stress

“…Allele-specific markers for this gene have been reported recently (Pariasca-Tanaka et al, 2014).The systemic response to P starvation is carried through a complex signalling network which involves plant hormones (Nacry et al, 2005;Pérez-Torres et al, 2008;Li et al, 2012), sugars (Karthikeyan et al, 2007) and nitric oxide (Wang et al, 2010), and collectively result in the altered carbohydrate distribution between roots and shoots. Moreover, transcription factors such as PHR1 (OsPHR1, OsPHR2, PvPHR1, ZmPHR1, TaPHR1), PTF1 (OsPTF1, ZmPTF1), MYB2P-1 (OsMYB2P1), MYB62, WRKY (WRKY75, WRKY6), bHLH32 and ZAT6 are involved in the signalling network to regulate plant adaptation to P stress (Yi et al, 2005;Devaiah et al, 2007a, b;Chen et al, 2007;Valdes-Lopez et al, 2008;Zhou et al, 2008;Devaiah et al, 2009;Chen et al, 2009;Li et al, 2011;Dai et al, 2012;Wang et al, 2013). The posttranscriptional regulation as well as long-distance signal is carried out by microRNAs, for instance miR399 maintain P homeostasis by regulating P transporter PHO2 (Bari et al, 2006;Aung et al, 2006;Lin et al, 2008;Pant et al, 2008).…”

Duplicate and Conquer: Multiple Homologs ofPHOSPHORUS-STARVATION TOLERANCE1Enhance Phosphorus Acquisition and Sorghum Performance on Low-Phosphorus Soils

“…Due to low-P mobility on tropical soils, changes in root architecture and morphology enhance P uptake by facilitating soil exploration (Williamson et al, 2001;Ho et al, 2005;Walk et al, 2006;Svistoonoff et al, 2007;Lynch, 2011;Ingram et al, 2012;Niu et al, 2013). Root structural changes leading to higher P uptake include increased root hair growth (Yan et al, 2004;Haling et al, 2013;Lan et al, 2013) and length and enhancing lateral root over primary root growth (Williamson et al, 2001;Wang et al, 2013). In addition, increased root surface area is achieved by a combination of reduced root diameter and enhanced elongation of relatively thinner roots (Fitter et al, 2002).…”

Phosphorus Transport in Arabidopsis and Wheat: Emerging Strategies to Improve P Pool in Seeds

“…The P-allocation patterns in the multiple plant organs correlated with the transcript expression patterns, suggestive of molecular signatures for improved phosphorus use efficiency (PUE) during limited Pi supply. Few genes involved in Pi starvation signalling responses have been reported for hexaploid wheat [35], such as an ortholog of the Arabidopsis transcription factor PHR1 characterized for its function in regulating Pi-signalling and plant growth in wheat [49]. Under both Pi-sufficient and deficient conditions, over-expression of the TaPHR1-A1 homolog moderately up-regulated the expression levels of TaPHR1 throughout the plant, resulting in a moderate increase of leaf Pi concentration and thus avoiding resultant toxicity ( [49]).…”

“…Few genes involved in Pi starvation signalling responses have been reported for hexaploid wheat [35], such as an ortholog of the Arabidopsis transcription factor PHR1 characterized for its function in regulating Pi-signalling and plant growth in wheat [49]. Under both Pi-sufficient and deficient conditions, over-expression of the TaPHR1-A1 homolog moderately up-regulated the expression levels of TaPHR1 throughout the plant, resulting in a moderate increase of leaf Pi concentration and thus avoiding resultant toxicity ( [49]). Pi uptake was positively favoured by TaPHR1-A1 over-expression by increasing root tip number, lateral root length, and TaPHTs expression (TaPHT1.2 in roots and TaPHT1.6 in shoots).…”

“…Pi uptake was positively favoured by TaPHR1-A1 over-expression by increasing root tip number, lateral root length, and TaPHTs expression (TaPHT1.2 in roots and TaPHT1.6 in shoots). Utilizing bimolecular fluorescence complementation assays, it has been confirmed that wheat PHR1 forms a homodimer and confers transcriptional activation of a putative downstream target Pi-transporter TaPHT1.2 [49].…”