CHANGES IN TREHALOSE 6-PHOSPHATE SYNTHASE ACTIVITY IN Selaginella lepidophylla PLANTS IN RESPONSE TO HYDRATION AND DESICCATION

Abstract

This paper describes the Selaginella lepidophylla plant hydration and dehydration kinetics and its influence on trehalose-6-phosphate
synthase activity and trehalose levels. After dry plants were fully hydrated for 24 h, their relative water content increased from 3.2 % to
92.7 %, and their water potential increased from undetectable levels to -0.3 MPa. Dry plants had an activity of 0.023 U mg^-1 protein, which increased to 0.135 U mg^-1 protein (581 %) after 2 h of hydration and then it decreased to 0.081 U mg^-1 protein at 24 h. Trehalose concentration in dry plants was 11.9 mg g^-1 dw which increased to 53 mg g-1 dw during the first 8 h of rehydration. Fully hydrated plants
subjected to desiccation for 24 h lost water rapidly, changing their relative water content from 94.4 % to 4.8 %, and their water potential from -0.3 to –2.1 MPa during the first 12 h. Trehalose 6- phosphate synthase activity decreased during the first 2 h of desiccation and then it increased to 0.068 U mg^-1 protein at 8 h of treatment; after 24 h of desiccation the plant still conserved trehalose-6- phosphate synthase activity with a relative water content of 4.4 %. Trehalose concentration increased from 10.2 to 50.4 mg g^-1 dw after 8 h of desiccation, and after 24 h the concentration is still high (12 mg g^-1 dw).