Saline-induced changes of epicuticular waxy layer on the Puccinellia tenuiflora and Oryza sativa leave surfaces
BACKGROUND: The epicuticular waxy layer of plant leaves enhances the extreme environmental stress tolerance. However, the relationship between waxy layer and saline tolerance was not established well. The epicuticular waxy layer of rice (Oryza sativa L.) was studied under the NaHCO3 stresses. In addition, strong saline tolerance Puccinellia tenuiflora was chosen for comparative studies. RESULTS: Scanning electron microscope (SEM) images showed that there were significant changes in waxy morphologies of the rice epicuticular surfaces, while no remarkable changes in those of P. tenuiflora epicuticular surfaces. The NaHCO3-induced morphological changes of the rice epicuticular surfaces appeared as enlarged silica cells, swollen corns-shapes and leaked salt columns under high stress. Energy dispersive X-ray (EDX) spectroscopic profiles supported that the changes were caused by significant increment and localization of [Na+] and [Cl-] in the shoot. Atomic absorption spectra showed that [Na+]shoot/[Na+]root for P. tenuiflora maintained stable as the saline stress increased, but that for rice increased significantly. CONCLUSION: In rice, NaHCO3 stress induced localization and accumulation of [Na+] and [Cl-] appeared as the enlarged silica cells (MSC), the swollen corns (S-C), and the leaked columns (C), while no significant changes in P. tenuiflora.