FaNRT2.7 transports nitrate and accelerates growth and development in plants

In fruit-bearing plants, nitrate absorbed by the roots is effectively transported to the leaves, flowers, and fruits, where it is then utilized for assimilation. This process enhances the yield and quality of fruits. In this study, the functional characteristics of FaNRT2.7, a member of the nitrate transporter 2 (NRT2) family in strawberries, were investigated. High expression of FaNRT2.7 was detected in strawberry leaves, achenes, flowers, and red-ripening fruit. Its expression reached a peak at 1 h under high-nitrate conditions and at 12 h under low-nitrate conditions. Analysis of the concentration-dependent nitrate uptake rates in Hansenula polymorpha showed that FaNRT2.7 mediates high-affinity nitrate transport. In three transgenic Arabidopsis lines with overexpression of FaNRT2.7, both under high or low nitrate conditions, FaNRT2.7 expression increased plant height, the number of branches, the number of pods, and the seed germination rate. It also enhanced the expression of genes related to nitrate transport and nitrogen metabolism within pods, as well as the nitrate and free amino acid concentrations in pods and seeds. Overexpression of FaNRT2.7 increased the nitrate content and accelerated ripening. Conversely, gene silencing decreased the nitrate content and postponed maturation in strawberry fruits injected with the corresponding expression vector.

Together, these data suggest that FaNRT2.7 can proficiently facilitate nitrate transport, which in turn affects flowering, regulates plant growth and development, accelerates seed yield, and improves the seed germination rate. These findings are highly significant as they clarify the previously unrecognized function of FaNRT2.7, providing valuable insights for enhancing nitrogen efficiency in strawberry production.