A Phosphate Transporter Promoter from Arabidopsis thaliana AtPHT1;4 Gene Drives Preferential Gene Expression in Transgenic Maize Roots Under Phosphorus Starvation

Phosphorus (P) stress responsive genes have been identified and characterized, including the high-affinity phosphate transporter AtPHT1;4 from Arabidopsis thaliana. This gene encodes a membrane protein that is primarily expressed in roots under phosphorus deficiency. A 2.3-kb promoter region from AtPHT1;4 has been fused with the β-glucuronidase (GUS) encoding gene and introduced into maize via biolistic bombardment to evaluate its spatiotemporal activity in a heterologous system. AtPHT1;4::GUS expression is detected preferentially in transgenic maize roots under P deficiency. Further analysis of transgenic plants has also revealed that GUS activity is higher in roots than in leaves by about sixfold. These results demonstrate the ability of AtPHT1;4 promoter to direct expression of the reporter gene in a monocot root system under P stress. This property of AtPHT1;4 promoter makes it useful to engineer maize plants to modify the soil’s rhizosphere and increase efficiency of P acquisition under P stress conditions.