Expression patterns of nitrate, phosphate, and sulfate transporters in Arabidopsis roots exposed to different nutritional regimes

Nitrate transporter AtNRT2.1 is the key component of the inducible high-affinity nitrate transport system in Arabidopsis thaliana. AtNRT2.1 is primarily expressed in roots and known to be mainly involved under fluctuating nitrogen supply conditions. It is still unknown whether AtNRT2.1 is involved in plant responses to other nutrient fluctuations. In this study, we found that the expression of AtNRT2.1 was also upregulated by phosphate and sulfate resupply, which may indicate a novel role in regulating phosphate and sulfate responses. Our study also demonstrated that expression of the major Pi transporter (Pht1) family member, AtPHT1;2, was suppressed by nitrate starvation and induced by nitrate resupply and sulfate starvation in comparison to the continuous nutrient treatment. Moreover, this study also showed that expression of sulfur transporter SULTR1;1 and AtNRT2.1 was suppressed by complete nutrient starvation and induced by complete nutrient resupply. These novel results provide strong evidence that there is crosstalk among the nitrate, sulfate, and phosphate transporters in regulating different nutrient fluctuations in Arabidopsis roots.