Determination of adenine nucleotide levels and adenylate energy charge ratio in two Spartina species

Abstract

A method was developed for measuring adenine nucleotide levels in vascular plant tissue and the use of the adenylate energy charge (EC) ratio as a monitor of environmental stress in coastal plant communities. This method, which utilizes bioluminescence resulting from the reaction of ATP with the luciferin—luciferase substrate—enzyme complex, was found to be sensitive, reproducible and suitable for field sampling. Extraction of the adenylates from feeeze-dried tissue in boiling 1 m M ethylenediaminetetraacetic acid plus 5% polyvinylpolypyrrolidone solution yielded the highest ATP levels and recovery rates (98, 97 and 89% of added ATP, ADP and AMP, respectively) of the extraction solutions and extractant modifications tested. Sources of variation due to sampling, storage of tissue, extraction and analysis of the adenine nucleotides, and natural changes in the environment were examined in two ecologically important salt-marsh macrophytes, Spartina alterniflora Loisel. and Spartina patens (Aiton) Muhl. Also, the relatively greater stress associated with low-productivity inland Spartina marshes compared to high-productivity streamside sites was correctly delineated by the EC ratio methodology.