Abstract
The cuticle is a hydrophobic layer on the aerial surface of plants, and contains cuticular wax, which is a mixture of aliphatic very long-chain fatty acids and their derivatives. It plays a critical role in preventing non-stomatal water loss. However, molecular mechanisms underlying the cuticle development under various environmental conditions have remained largely unknown. The amount of total cuticular waxes on the leaves of drought-tolerant wild watermelon grown in high light condition was 2-fold larger than those grown in the low light condition. Moreover, drought treatment resulted in the 22-fold increase in the amount of total waxes compared to those in the low light condition. The real-time PCR analyses revealed that two key genes for the wax synthesis, i.e., β-ketoacyl-CoA synthase which catalyzes a committing step for the fatty acid elongation, and aldehyde decarbonylase for the conversion of long-chain aldehyde to alkane, were significantly up-regulated under drought. These observations suggested that the wax-related genes were coordinately up-regulated under drought, for the fortification of cuticle layer in this plant.
