Abstract
AS2/LOB transcription factors are crucial for plant organ development and stress responses, but their functions in fast-growing Phyllostachys edulis remain unclear. Here, we identified 36 Class I AS2/LOB genes (PeAS2) via genome-wide analysis. Phylogenetic, motif, and gene structure analyses revealed high family conservation, while collinearity analysis demonstrated segmental duplication as the primary driver of expansion. Promoter analysis detected enriched cis-elements responsive to abiotic stresses (drought, salinity) and phytohormones (ABA, JA, auxin). PeAS2–04 and PeAS2–39 were highly expressed in rapidly elongating shoots and stems, and markedly induced under salt and drought stress. Subcellular localization confirmed PeAS2–04 localizes to the nucleus, and PeAS2–39 to both the nucleus and nuclear membrane. Yeast two-hybrid assays demonstrated specific interactions among selected Class I members. Heterologous overexpression of PeAS2–04 and PeAS2–39 in Arabidopsis induced typical adaxial–abaxial polarity defects, including dwarfism and upward leaf curling, while markedly enhancing primary root elongation. Transgenic seeds showed significantly higher germination rates than wild-type under salt or drought stress. These findings indicate PeAS2–04 and PeAS2–39 are functional orthologs of Arabidopsis AS2, involved in leaf polarity, root development, and abiotic stress tolerance during seed germination and early seedling establishment, providing novel insights for bamboo molecular breeding.