ZmLBD1 confers multi-abiotic stress tolerance in Arabidopsis by enhancing root growth

Abstract

Lateral organ boundary domain (LBD) proteins are plant-specific transcription factors (TFs), featuring a highly conserved N-terminal lateral organ boundary (LOB) domain and a variable C-terminal region. Initially recognized as key regulators of organ development in plants, recent studies have rarely expanded their role to include stress response regulation. In this study, we isolated a maize protein ZmLBD1 and expressed it in Arabidopsis thaliana. While ZmLBD1 transcript levels remained consistent across wild-type (WT) and transgenic plants under low inorganic phosphate (Pi), NaCl, and drought stress, its protein accumulation increased in response to these stresses over time. ZmLBD1 transgenic Arabidopsis exhibited enhanced tolerance to low Pi, NaCl, and drought stress, with improved root development. Under low Pi conditions, transgenic plants showed higher leaf and root Pi content and increased transcript levels of PHO2. Additionally, transgenic plants displayed better drought tolerance traits, including reduced leaf wilting and curling, higher chlorophyll fluorescence (Fv/Fm), and lower ion leakage. RNA-seq and RT-qPCR revealed that PGIP1 was significantly upregulated under low Pi, NaCl, and drought stress transgenic plants, with ZmLBD1 binding to the ABRE motif in the promoter of PGIP1 to enhance its transcription. Protein interaction studies showed that ZmLBD1 interacts with ZmCDC48, which mediates ZmLBD1 degradation and affects its activity. Taken together, our findings indicate that ZmLBD1 is a versatile gene with potential for developing crops with improved tolerance to multiple abiotic stresses.