Polar-localized OsLTPG22 regulates rice leaf cuticle deposition and drought response

Abstract

The cuticle serves as a crucial protective barrier for plant survival, and recent studies have highlighted the essential roles of nonspecific lipid transfer proteins (nsLTPs) in cuticle formation. However, the specific function of nsLTPs in the rice leaf cuticle remains unclear. In this study, we functionally characterized OsLTPG22, a G-type nsLTP with a signal peptide (SP) domain and a glycosylphosphatidylinositol (GPI) anchor region. Mutation in OsLTPG22 led to a reduction in cuticular wax abundance, increased leaf epidermal permeability, and higher drought sensitivity in seedlings. OsLTPG22 was widely expressed in various tissues and exhibited distinct polar localization to the aerial surface of epidermal cells in expanding leaves. OsLTPG22 binds lipids and localizes to the plasma membrane. Protein truncation experiments demonstrated that OsLTPG22’s polar localization was regulated by the SP domain, while both the SP domain and GPI anchor region regulated OsLTPG22’s plasma membrane localization. This work provides genetic and cytological evidence for OsLTPG22’s role in leaf cuticle formation and drought response, enhancing our understanding of nsLTP function and offering insights for breeding drought-resistant crops.

Keywords

• Nonspecific lipid transfer proteins (nsLTPs)
• OsLTPG22
• Cuticular wax
• Leaf epidermal
• Permeability
• Polar localization