Purine metabolism in cells of a mangrove plant, Sonneratia alba, in tissue culture

A tissue culture system was established from pistils of flower buds of a mangrove plane, Sonneratia alba. The optimum growth rate of callus was observed in Murashige and Skoog's medium that contained 50 mM NaCl. In this tissue culture system, we examined the effects of short-term salt stress on the size of the pool of purine nucleotides, as well as the capacity for the salvage and the degradation of purines. At 100 mM NaCl, the size of the total adenylate pool was reduced, but the ''adenylate energy charge'' was, by contrast, increased. No marked change in the size of guanylate pool occurred in response to NaCl. The rate of conversion of [8-C-14] adenosine to adenylate was decreased by NaCl, but that to nucleic acids was not significantly affected. In contrast to the results obtained with maize root tips (Peterson et al., 1988), salt stress did not increase the catabolism of [8-C-14]hypoxanthine. Most of the radioactivity from [8-C-14]adenosine was accumulated in adenine while that in [8-C-14]hypoxanthine remained unaffected in Sonneratia alba. The low capacity of the purine-degradation system might ensure a supply of purine bases and nucleosides that can be utilized as substrates for the rapid and efficient biosynthesis of nucleotides by the salvage pathways.