Expression analysis suggests novel roles for members of the Pht1 family of phosphate transporters in Arabidopsis

Abstract

SummaryThe completion of the Arabidopsis thaliana genome has revealed that there are nine members of the Pht1 family of phosphate transporters in this species. As a step towards identifying the role of this gene family in phosphorus nutrition, we have isolated the promoter regions from each of these genes, and fused them to the reporter genes b-glucuronidase and/or green¯uorescent protein. These chimeric genes have been introduced into A. thaliana, and reporter gene expression has been assayed in plants grown in soil containing high and low concentrations of inorganic phosphate (Pi). Four of these promoters were found to direct reporter gene expression in the root epidermis, and were induced under conditions of phosphate deprivation in a manner similar to previously characterised Pht1 genes. Other members of this family, however, showed expression in a range of shoot tissues and in pollen grains, which was con®rmed by RT-PCR. We also provide evidence that the root epidermally expressed genes are expressed most strongly in trichoblasts, the primary sites for uptake of Pi. These results suggest that this gene family plays a wider role in phosphate uptake and remobilisation throughout the plant than was previously believed.

Structure and Expression Profile of the Phosphate Pht1 Transporter Gene Family in Mycorrhizal Populus trichocarpa

“…PtPT9 and PtPT11 are highly homologous to AtPT8 and AtPT9, two genes from the Pht1 subfamily II (Fig. 1), which were also shown to be strongly up-regulated during Pi starvation (Mudge et al, 2002). Therefore, these Pht1 transporters likely play a role in Pi scav- enging within the Pht1 family during conditions of low soil Pi availability.…”

“…During bud development, PtPT1 and PtPT2 were upregulated in a similar way as their homolog AtPT1 from Arabidopsis Pht1 subfamily III ( Figs. 1 and 2B; Mudge et al, 2002).…”

“…Members of this family are H + /Pi symporters (Bucher, 2007;Javot et al, 2007). Most of the genes of the Pht1 family that are expressed in roots are up-regulated in P-deprived plants (Mudge et al, 2002). The Pht2 family proteins share high similarity with mammalian Na + /Pi cotransporters but function as H + /Pi cotransporters in plastids of plants (Versaw and Harrison, 2002;Bucher, 2007).…”

The Phosphate Fast-Responsive Genes PECP1 and PPsPase1 Affect Phosphocholine and Phosphoethanolamine Content

“…Root architecture can be modified to facilitate Pi uptake by favoring the development of lateral roots (at the expense of primary root elongation in many plants including Arabidopsis), increasing the density and length of root hairs, and limiting the development of aerial parts (López-Bucio et al, 2002;Svistoonoff et al, 2007;Gruber et al, 2013). Pi uptake mechanisms are enhanced at the root/soil interface, particularly through the stimulation of Pi transport activity (Mudge et al, 2002;Shin et al, 2004;Nussaume et al, 2011; Ayadi et al, 2015). In parallel, mobilization of Pi sources from the soil is facilitated by the secretion of acid phosphatases and acidification of the soil surrounding roots (Raghothama, 1999;Plaxton and Tran, 2011;Wang et al, 2011;Zhang et al, 2014; Balzergue et al, 2017).…”

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

“…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). There is both intraspecific and interspecific genetic variation for P deficiency tolerance in crop species (Lynch andBrown, 2001, 2012;Mudge et al, 2002;Paszkowski et al, 2002;Rausch and Bucher, 2002;Huang et al, 2011;Zhang et al, 2011;Leiser et al, 2014a) that can be explored to develop P-efficient cultivars.…”