Role of nitrate transporters in plant defense

Plants face constant environmental threats from various diseases, jeopardizing global food security. Over millions of years, plants have evolved sophisticated, multi-layered adaptive defense mechanisms to detect and combat several pathogens. Nitrogen (N) nutrition plays a crucial role in influencing plant defense, in the either forms of nitrogen, whether nitrate (NO₃⁻) or ammonium (NH₄⁺). Both these forms are tightly linked to nitrate transporters, a group of proteins vital for absorbing and transporting NO₃⁻ throughout the plant. While much research has been focused on their role in NO₃⁻ uptake, less is known about how these transporters reallocate NO₃⁻ in response to biotic (disease) and abiotic (environmental) stressors. Interestingly, plants often show improved stress tolerance when less NO₃⁻ is transported to their shoots. The varying amounts of NO₃⁻ translocated from roots to shoots under different environmental cues can, in turn, impact a plant's nitrogen use efficiency (NUE), either positively or negatively. This review explores the dual functionality of nitrate transporters in both nitrate metabolism and plant immunity.