A specific NAP transcription factor LpNAC022 from perennial ryegrass positively regulates the basal salt tolerance

Soil salinization has become a global issue, affecting over 1 billion hectares of land worldwide. Perennial ryegrass (Lolium perenne L.) has excellent quality for forage and turf uses potentially in saline soils. In this study, a dominant salt-induced NAP (NAC-like, activated by apetala3/pistillata) family transcription factor LpNAC022 in Lolium perenne was identified. Morphological, physiological and transcriptomic analyses suggested that overexpression of LpNAC022 conferred salt tolerance during seed germination, root development and leaf growth of Arabidopsis thaliana. Moreover, LpNAC022 positively regulated genes involved in ion transportation, oxidative stress response, and root development under salt stress. Interestingly, LpNAC022 exhibited opposite transcriptional activities and biological functions in salt tolerance regulation compared to NAP orthologs in other plant species. The absence of amino acids at positions 337-349 in LpNAC022 reactivated its self-transcriptional activation activity. This study demonstrated a role of a novel specific NAP transcription factor in improving salt tolerance in plants.