Effect of enhanced UV-B radiation on adaxial leaf surface micromorphology and epicuticular wax biosynthesis of sugar maple

Sugar maple (Acer saccharum [Marsh.]) seedlings were exposed to UV-B-BE ranging from 0.61 kJ m(-2) d(-1) to 12.48 kJ m(-2) d(-1). Increasing UV-B intensity was associated with changes in micromorphological characteristics of the adaxial leaf surface. In vivo incorporation of [1-C-14] acetate into sugar maple adaxial leaf surface epicuticular wax indicated (p<0.05) a UV-B sensitivity threshold at or near 6.2 kJ m(-2) d(-1). Exposure to dosages greater than 6.2 kJ m(-2) d(-1) resulted in a significant (p<0.05) decrease in wax biosynthesis. The proportion of [1-C-14] acetate incorporated into each of the different epicuticular wax classes changed with increasing UV-B. Incorporation of [1-C-14] acetate into alkyl esters decreased while incorporation into alkanes increased with increasing UV-B dose. The effects of enhanced UV-B dose recorded in this experiment may have implications for cuticle function. Crown Copyright (C) 1998 Published by Elsevier Science Ltd.