Activity of δ-aminolevulinic acid dehydratase at Ramonda nathaliae and Ramonda serbica plants during dehydration and rehydration.

Abstract

Ramonda nathaliae and Ramonda serbica are resurrection plants belonging to homoiochlorophyllous desiccation-tolerant angiosperms. Chlorophyll biosynthesis is one of the most important metabolic pathways to tolerate desiccation in these plant species. To better understand the early pathway steps of chlorophyll biosynthesis, we have analyzed the enzyme δ-aminolevulinic acid dehydratase (ALA-D) and contents of δ-aminolevulinic acid (ALA) and total chlorophyll as a final product during dehydration and rehydration stages for these plant species. Our results showed that the activity of ALA-D in R. nathaliae and R. serbica plants rapidly decreased during dehydration and in the final stage of desiccation the activity of this enzyme was decreased by 79% and 86%, respectively. After rehydration of plants, the ALA-D activity was fully restored. In contrast, the ALA content of both plant species significantly increased during desiccation and decreased after 48 hr of rewatering. In each stage of dehydration or rehydration, a significant negative correlation was established between ALA-D activity and ALA content in both plant species. Total chlorophyll content was preserved more in R. nathaliae than in R. serbica during desiccation. Moreover, ALA-D activity was decreased to a minimal level but preserved its function during desiccation, and this suggests one possible mechanism of desiccation tolerance to retain the chlorophyll of these plant species.