NLA proteins: Master regulators that integrate nutrient homeostasis, stress adaptation, and plant development

As sessile organisms, plants rely on intricate molecular regulatory networks to navigate complex, fluctuating environments and diverse stress conditions. Nitrogen Limitation Adaptation (NLA), a RING-type ubiquitin ligase harboring an SPX domain, has emerged as a central hub integrating plant responses to nutrient availability, pathogen attack, and cold stress. This review provides a systematic overview of the structural features of NLA, with a particular focus on the regulatory role of inositol pyrophosphates (PP-InsPs) in plant phosphorus signaling. We highlight the core functions of NLA in maintaining nitrogen-phosphorus homeostasis and mediating the crosstalk between nutrient status and immune defense. A key mechanism we discuss is the role of maize ZmNLA in "cold-phosphorus" trade-off, whereby ZmNLA activates jasmonate signaling to enhance cold tolerance by mediating the ubiquitination and degradation of the signaling repressor ZmJAZ11, while simultaneously restricting phosphate uptake via targeting the phosphate transporter ZmPT4. Notably, the ZmNLAΔ12 variant, which has an impaired PP-InsPs binding site, functionally uncouples this trade-off through structure-guided protein design. Finally, we propose future research directions and discuss the potential for breeding new crop varieties with enhanced stress adaptation and improved nutrient use efficiency.