NPR1like

NPR1like refers to a family of plant proteins related to NPR1 (Non-expressor of PR genes 1), a central regulator of systemic acquired resistance and salicylic acid–mediated defense signaling. Members of the NPR1-like family are found in many plant species and include NPR1 and multiple homologs that participate in transcriptional regulation of defense genes. Their common role is to link salicylic acid perception to the activation of defense responses, particularly pathogenesis-related genes.

Biochemically, NPR1-like proteins often harbor conserved interaction motifs that enable them to form oligomers in the cytoplasm and to interact with TGA transcription factors in the nucleus. The activity of NPR1-like proteins is tightly controlled by the cellular redox state and SA levels: pathogen cues raise SA, promote redox changes that favor monomerization and nuclear import, and enable interactions with TGAs to drive defense gene expression. In some species, NPR1-like paralogs function as SA receptors or modulators of NPR1 stability; for example, in Arabidopsis NPR3 and NPR4 act as SA receptors that recruit Cullin3-based E3 ligases to regulate NPR1 turnover, shaping the strength and duration of the response.

Role and diversity: Across flowering plants, NPR1-like genes comprise a small multigene family. NPR1 itself generally acts as a positive regulator of systemic acquired resistance, while other family members can have distinct or antagonistic roles depending on tissue, developmental stage, and environmental context. In crops, altering NPR1-like signaling has been explored to enhance resistance to pathogens, though practical applications must balance defense with growth and yield trade-offs.