Abstract:The cellular structure, chemical characterization of foliar endodermis and element cellular distribution were investigated in Pinus bungeana leaves by the fluorescence microscope, Fourier transform infrared (FTIR) microspectroscopy and energy-dispersive X-ray analysis. The fluorescence microscopy showed that Casparian strips were absent from cotyledon endodermis, while the radial wall of endodermis in primary and two-year-old leaves were occupied with Casparian strips. The FTIR analysis indicated that there was no or very little suberin in endodermis radial wall of cotyledon compared with primary and two-year-old leaves. Furthermore, the content of suberin in endodermis of the primary leaves was lower than that of two-year-old leaves. The energy-dispersive X-ray analysis showed that the endodermis with Casparian strips in primary and two-year-old leaves functioned as apoplastic barriers against Na and Cl. However, no blockage of Na and Cl in cotyledon was observed when they passed endodermis. It was suggested that physiological function of endodermis with Casparian strips as apoplastic transportation depended on the content of suberin in endodermis cell wall.
