Effects of soil water availability on development of suberin lamellae in the endodermis and exodermis and on cortical cell wall thickening in red bayberry (Myrica rubra Sieb. et Zucc.) tree roots

The effects of soil water availability on suberin lamellae formation in the endodermis and exodermis and the occurrence of cell wall thickening in the cortex in red bayberry (Myrica rubra Sieb. et Zucc.) tree roots were examined during tissue aging. For several months, red bayberry trees were grown in small baskets under dry, normal, and waterlogged soil water conditions. Transverse sections of roots from 5 mm from the tip to the basal portion were stained with several staining solutions and the cell structure was observed. Root anatomical development was significantly changed by soil water conditions. The suberin lamellae in the endodermis formed later in plants grown under dry conditions than in those grown under waterlogged conditions. Cell wall thickening in the cortex near the endodermis was promoted by drought, but apparently not by waterlogged conditions.

► Crescent thickening could play an important role against drought conditions.
► Crescent thickening in the cortex of the roots developed dramatically in the dry-plot.
► Number of vessels per pole was used as a criterion of the root age.
► Suberin lamellae in the endodermis formed earlier in plants grown under waterlogged conditions.