Identification and Functional Characterization of MdNRT1.1 in Nitrogen Utilization and Abiotic Stress Tolerance in Malus domestica

Abstract

Nitrate is one of the main sources of nitrogen for plant growth. Nitrate transporters (NRTs) participate in nitrate uptake and transport, and they are involved in abiotic stress tolerance. Previous studies have shown that NRT1.1 has a dual role in nitrate uptake and utilization; however, little is known about the function of MdNRT1.1 in regulating apple growth and nitrate uptake. In this study, apple MdNRT1.1, a homolog of Arabidopsis NRT1.1, was cloned and functionally identified. Nitrate treatment induced an increased transcript level of MdNRT1.1, and overexpression of MdNRT1.1 promoted root development and nitrogen utilization. Ectopic expression of MdNRT1.1 in Arabidopsis repressed tolerance to drought, salt, and ABA stresses. Overall, this study identified a nitrate transporter, MdNRT1.1, in apples and revealed how MdNRT1.1 regulates nitrate utilization and abiotic stress tolerance.