Effectiveness of cuticular transpiration barriers in a desert plant at controlling water loss at high temperatures

The temperature-dependent increase of the leaf cuticular water permeability of the desert shrub Rhazya stricta (left) is much smaller than in all other species studied so far. It is proposed that large amounts of triterpenoids mechanically stabilize the cuticle (right) and, thus, prevent the thermal disruption of the cuticular transpiration barrier. Photo and drawing by M. Riederer.

Maintaining the integrity of the cuticular transpiration barrier even at elevated temperatures is of vital importance for hot-desert plants. In a new study published in AoB PLANTS, Schuster et al. investigated the effect of temperature on the leaf cuticular permeability of Rhazya stricta, an evergreen shrub from the Arabian Desert. Permeability increased 2.4-fold from 15° to 50° C, which is much less than in all other species studied so far. The authors propose that high amounts of pentacyclic triterpenoids (85.2% of total wax) act as fillers that mechanically stabilize the cuticle and thus prevent thermal disruption of the cuticular transpiration barrier.

Reference List

Ann-Christin Schuster, Markus Burghardt, Ahmed Alfarhan, Amauri Bueno, Rainer Hedrich, Jana Leide, Jacob Thomas, Markus Riederer, 2016, 'Effectiveness of cuticular transpiration barriers in a desert plant at controlling water loss at high temperatures', AoB Plants, vol. 8, p. plw027 http://dx.doi.org/10.1093/aobpla/plw027